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Sample records for film transistor technologies

  1. DEVICE TECHNOLOGY. Nanomaterials in transistors: From high-performance to thin-film applications.

    PubMed

    Franklin, Aaron D

    2015-08-14

    For more than 50 years, silicon transistors have been continuously shrunk to meet the projections of Moore's law but are now reaching fundamental limits on speed and power use. With these limits at hand, nanomaterials offer great promise for improving transistor performance and adding new applications through the coming decades. With different transistors needed in everything from high-performance servers to thin-film display backplanes, it is important to understand the targeted application needs when considering new material options. Here the distinction between high-performance and thin-film transistors is reviewed, along with the benefits and challenges to using nanomaterials in such transistors. In particular, progress on carbon nanotubes, as well as graphene and related materials (including transition metal dichalcogenides and X-enes), outlines the advances and further research needed to enable their use in transistors for high-performance computing, thin films, or completely new technologies such as flexible and transparent devices.

  2. Review on thin-film transistor technology, its applications, and possible new applications to biological cells

    NASA Astrophysics Data System (ADS)

    Tixier-Mita, Agnès; Ihida, Satoshi; Ségard, Bertrand-David; Cathcart, Grant A.; Takahashi, Takuya; Fujita, Hiroyuki; Toshiyoshi, Hiroshi

    2016-04-01

    This paper presents a review on state-of-the-art of thin-film transistor (TFT) technology and its wide range of applications, not only in liquid crystal displays (TFT-LCDs), but also in sensing devices. The history of the evolution of the technology is first given. Then the standard applications of TFT-LCDs, and X-ray detectors, followed by state-of-the-art applications in the field of chemical and biochemical sensing are presented. TFT technology allows the fabrication of dense arrays of independent and transparent microelectrodes on large glass substrates. The potential of these devices as electrical substrates for biological cell applications is then described. The possibility of using TFT array substrates as new tools for electrical experiments on biological cells has been investigated for the first time by our group. Dielectrophoresis experiments and impedance measurements on yeast cells are presented here. Their promising results open the door towards new applications of TFT technology.

  3. Study of Organic Thin Film Transistors on Ultraviolet-Curable Dielectrics with Periodic Patterns Fabricated by Nano Imprint Technology

    NASA Astrophysics Data System (ADS)

    Chen, Henry J. H.; Chen, Jun-Yu

    2013-06-01

    In this work, the organic thin film transistors (OTFTs) on UV-curable dielectrics with periodic patterns fabricated by nano imprint technology were investigated. The surface morphologies of pentacene and device performances with respect to line/space ratio of periodic patterns were studied. The anisotropic electrical characteristics of OTFTs were also investigated. This technique will be suitable for the future low-cost and flexible electronics applications.

  4. All solution processed organic thin film transistor-backplane with printing technology for electrophoretic display

    USGS Publications Warehouse

    Lee, Myung W.; Song, C.K.

    2012-01-01

    In this study, solution processes were developed for backplane using an organic thin film transistor (OTFT) as a driving device for an electrophoretic display (EPD) panel. The processes covered not only the key device of OTFTs but also interlayer and pixel electrodes. The various materials and printing processes were adopted to achieve the requirements of devices and functioning layers. The performance of OTFT of the backplane was sufficient to drive EPD sheet by producing a mobility of 0.12 cm2/v x sec and on/off current ratio of 10(5).

  5. Exploring Two-Dimensional Transport Phenomena in Metal Oxide Heterointerfaces for Next-Generation, High-Performance, Thin-Film Transistor Technologies.

    PubMed

    Labram, John G; Lin, Yen-Hung; Anthopoulos, Thomas D

    2015-11-01

    In the last decade, metal oxides have emerged as a fascinating class of electronic material, exhibiting a wide range of unique and technologically relevant characteristics. For example, thin-film transistors formed from amorphous or polycrystalline metal oxide semiconductors offer the promise of low-cost, large-area, and flexible electronics, exhibiting performances comparable to or in excess of incumbent silicon-based technologies. Atomically flat interfaces between otherwise insulating or semiconducting complex oxides, are also found to be highly conducting, displaying 2-dimensional (2D) charge transport properties, strong correlations, and even superconductivity. Field-effect devices employing such carefully engineered interfaces are hoped to one day compete with traditional group IV or III-V semiconductors for use in the next-generation of high-performance electronics. In this Concept article we provide an overview of the different metal oxide transistor technologies and potential future research directions. In particular, we look at the recent reports of multilayer oxide thin-film transistors and the possibility of 2D electron transport in these disordered/polycrystalline systems and discuss the potential of the technology for applications in large-area electronics. PMID:26349850

  6. Metal-induced unilaterally crystallized polycrystalline silicon thin-film transistor technology and application to flat-panel displays

    NASA Astrophysics Data System (ADS)

    Meng, Zhiguo

    High quality flat-panel displays (FPD) typically use active-matrix (AM) addressing, with the optical state of each pixel controlled by one or more active devices such as amorphous silicon (a-Si) thin film transistors (TFT). The successful examples are portable computer and liquid-crystal television (LC-TV). A high level of system on panel (SoP) electronic integration is required for versatile and compact systems. Meanwhile, many self-emitting display technologies are developing fast, active matrix for self-emitting display is typically current driven. The a-Si TFTs suffer from limited current driving capability, polycrystalline silicon (poly-Si) device technology is required. A new technology employing metal-induced unilaterally crystallization (MIUC) is presently reported. The device characteristics are obviously better than those in rapid-thermal annealed (RTA) and solid-phase crystallization (SPC) TFTs and the fabrication equipment is much cheaper than excimer laser crystallization (ELC) technology. The field effect mobility (muFE) of p- and n-channel MIUC TFTs is about 100cm2/Vs. Ion/I off is more than seven orders. Gate-induced leakage current in LT-MIUC poly-Si TFTs has been reduced by crystallization before heavy junction implantation to improve material quality and incorporating a gate-modulated lightly-doped drain (gamo-LDD) structure to reduce the electric field near the drain/channel junction region. At the same time, recrystallized (RC) MIUC TFT was researched with device characteristics improved. The 6.6cm 120 x 160 active matrix for OLED display is fabricated using LT-MIUC TFT technology on glass substrate. This display has the advantages of self-emitting, large intrinsic view angle and very fast response. At the same time, 6.6cm 120X160 AM-reflective twist nematic (RTN) display is fabricated using RC-MIUC TFT technology. This display is capable of producing 16 grade levels, 10:1 contrast and video image. The SOP display for AM-OLED were designed

  7. Thin Film Transistors On Plastic Substrates

    DOEpatents

    Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

    2004-01-20

    A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The silicon based thin film transistor produced by the process includes a low temperature substrate incapable of withstanding sustained processing temperatures greater than about 250.degree. C., an insulating layer on the substrate, a layer of silicon on the insulating layer having sections of doped silicon, undoped silicon, and poly-silicon, a gate dielectric layer on the layer of silicon, a layer of gate metal on the dielectric layer, a layer of oxide on sections of the layer of silicon and the layer of gate metal, and metal contacts on sections of the layer of silicon and layer of gate metal defining source, gate, and drain contacts, and interconnects.

  8. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Bilayer Photoresist Insulator for High Performance Organic Thin-Film Transistors on Plastic Films

    NASA Astrophysics Data System (ADS)

    Wang, He; Li, Chun-Hong; Pan, Feng; Wang, Hai-Bo; Yan, Dong-Hang

    2009-11-01

    A novel bilayer photoresist insulator is applied in flexible vanadyl-phthalocyanine (VOPc) organic thin-film transistors (OTFTs). The micron-size patterns of this photoresisit insulator can be directly defined only by photolithography without the etching process. Furthermore, these OTFTs exhibit high field-effect mobility (about 0.8 cm2/Vs) and current on/off ratio (about 106). In particular, they show rather low hysteresis (< 1 V). The results demonstrate that this bilayer photoresist insulator can be applied in large-area electronics and in the facilitation of patterning insulators.

  9. High Performance Airbrushed Organic Thin Film Transistors

    SciTech Connect

    Chan, C.; Richter, L; Dinardo, B; Jaye, C; Conrad, B; Ro, H; Germack, D; Fischer, D; DeLongchamp, D; Gunlach, D

    2010-01-01

    Spray-deposited poly-3-hexylthiophene (P3HT) transistors were characterized using electrical and structural methods. Thin-film transistors with octyltrichlorosilane treated gate dielectrics and spray-deposited P3HT active layers exhibited a saturation regime mobility as high as 0.1 cm{sup 2} V{sup -1} s{sup -1}, which is comparable to the best mobilities observed in high molecular mass P3HT transistors prepared using other methods. Optical and atomic force microscopy showed the presence of individual droplets with an average diameter of 20 {micro}m and appreciable large-scale film inhomogeneities. Despite these inhomogeneities, near-edge x-ray absorption fine structure spectroscopy of the device-relevant channel interface indicated excellent orientation of the P3HT.

  10. Stretchable transistors with buckled carbon nanotube films as conducting channels

    DOEpatents

    Arnold, Michael S; Xu, Feng

    2015-03-24

    Thin-film transistors comprising buckled films comprising carbon nanotubes as the conductive channel are provided. Also provided are methods of fabricating the transistors. The transistors, which are highly stretchable and bendable, exhibit stable performance even when operated under high tensile strains.

  11. Device and Circuit Modeling and Development of a Non-Volatile Random Access Memory Cell, Utilizing AN Amorphous Silicon Thin-Film Floating-Gate Transistor Based Technology.

    NASA Astrophysics Data System (ADS)

    Riggio, Salvatore Richard, Jr.

    1994-01-01

    High density storage mechanisms are generally created using either magnetic or optical implementation techniques. Both of these techniques require mechanical transport of the medium and, therefore, have low reliability factors. These devices also generate unwanted low level ambient noise, which is of particular concern when considering modern quiet office standards. Additionally, optical techniques tend to be read-only in nature. Both mechanisms exhibit random access times that are measured in milli-seconds, rather than in micro-seconds. Therefore, the creation of a non-volatile random access memory as a replacement for the above mentioned storage techniques would be of great advantage in terms of access time, reliability, and ambient noise level. Described within are the device and circuit modeling and fabrication techniques used to develop a non-volatile random access memory cell from an amorphous silicon thin -film transistor based technology. Amorphous silicon thin-film transistors are fabricated by depositing the metal, the insulator and the semiconductor materials with a sputtering mechanism in a vacuum at 220 degrees centigrade, rather than by diffusion at 2000 degrees centigrade, as is done with crystalline silicon. By depositing a metal in the insulator, which is located between the gate and the channel, and by using an insulator material with extremely high resistivity, one can store charge in the gate region for a long period of time without external power. For example, this period of time can be as little as one week or as long as over one year. With a periodic refresh, one can extend the memory time of this storage mechanism indefinitely. Thin-film transistors can be deposited on a variety of materials such as glass, quartz or plastic by means of a stationary or continuous motion fabrication system. This material can be either rigid or flexible, and can be comparatively large in size. This allows for much greater circuit density than a standard

  12. Solution-processed silicon films and transistors

    NASA Astrophysics Data System (ADS)

    Shimoda, Tatsuya; Matsuki, Yasuo; Furusawa, Masahiro; Aoki, Takashi; Yudasaka, Ichio; Tanaka, Hideki; Iwasawa, Haruo; Wang, Daohai; Miyasaka, Masami; Takeuchi, Yasumasa

    2006-04-01

    The use of solution processes-as opposed to conventional vacuum processes and vapour-phase deposition-for the fabrication of electronic devices has received considerable attention for a wide range of applications, with a view to reducing processing costs. In particular, the ability to print semiconductor devices using liquid-phase materials could prove essential for some envisaged applications, such as large-area flexible displays. Recent research in this area has largely been focused on organic semiconductors, some of which have mobilities comparable to that of amorphous silicon (a-Si); but issues of reliability remain. Solution processing of metal chalcogenide semiconductors to fabricate stable and high-performance transistors has also been reported. This class of materials is being explored as a possible substitute for silicon, given the complex and expensive manufacturing processes required to fabricate devices from the latter. However, if high-quality silicon films could be prepared by a solution process, this situation might change drastically. Here we demonstrate the solution processing of silicon thin-film transistors (TFTs) using a silane-based liquid precursor. Using this precursor, we have prepared polycrystalline silicon (poly-Si) films by both spin-coating and ink-jet printing, from which we fabricate TFTs with mobilities of 108cm2V-1s-1 and 6.5cm2V-1s-1, respectively. Although the processing conditions have yet to be optimized, these mobilities are already greater than those that have been achieved in solution-processed organic TFTs, and they exceed those of a-Si TFTs (<= 1cm2V-1s-1).

  13. Thin film transistor circuits for active matrix liquid crystal displays

    NASA Astrophysics Data System (ADS)

    Edwards, Martin John

    The demand for a high quality flat panel video display device for use in consumer and professional products has led to the rapid development of Active Matrix Liquid Crystal Displays (AMLCD). The majority of these displays use Thin Film Transistors (TFTs) as the active devices and improvements in the performance of these transistors is creating the opportunity to integrate increasingly sophisticated circuits onto the glass substrates of the displays. This thesis describes a number of aspects of the use of thin film transistor circuits for active matrix liquid crystal displays. The electrical characteristics of TFTs differ in a number of respects from those of conventional MOS devices. This is illustrated with measurements of transistors and simple circuits fabricated using two different low temperature poly-Si TFT technologies. At present the key application for TFT circuits is integration of the row and column drive circuits for active matrix liquid crystal displays. The issues which arise in the design of TFT drive circuits are discussed and the design and operation of a prototype display with integrated drive circuits is described. The availability of high mobility TFTs makes it possible to integrate signal processing functions within the pixels of a display. A novel technique employing digital to analogue conversion of the video data within the pixels of a display is presented. This technique allows the display to be addressed with digital column drive waveforms simplifying the column drive circuit. Operation of the pixel data converters has been demonstrated by the design and measurement of small arrays of test pixels.

  14. Method for double-sided processing of thin film transistors

    DOEpatents

    Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

    2008-04-08

    This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

  15. Liquid crystals for organic thin-film transistors

    PubMed Central

    Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-ichi

    2015-01-01

    Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V−1 s−1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics. PMID:25857435

  16. Liquid crystals for organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-Ichi

    2015-04-01

    Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V-1 s-1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics.

  17. A comparison of the kink effect in polysilicon thin film transistors and silicon on insulator transistors

    NASA Astrophysics Data System (ADS)

    Armstrong, G. A.; Brotherton, S. D.; Ayres, J. R.

    1996-09-01

    Polysilicon thin film transistors (TFTs) differ from conventional silicon on insulator (SOI) transistors in that the TFT exhibits a fundamental gate length dependence of the voltage at which a kink occurs in the output characteristics. This difference is shown to be caused by the peak lateral electric field being strongly dependent on the doping density in an SOI transistor, but relatively insensitive to trap distribution in a TFT. Source barrier lowering which occurs in SOI transistors is absent in a TFT, where the increase in current is the result of a field redistribution along the channel. For very short gate lengths, the TFT exhibits a small pseudo-bipolar gain. Estimates of this bipolar gain can be made by simulation of TFT characteristics with and without impact ionisation. The magnitude of the gain is shown to be approximately inversely proportional to gate length.

  18. Hysteresis free carbon nanotube thin film transistors comprising hydrophobic dielectrics

    NASA Astrophysics Data System (ADS)

    Lefebvre, J.; Ding, J.; Li, Z.; Cheng, F.; Du, N.; Malenfant, P. R. L.

    2015-12-01

    We present two examples of carbon nanotube network thin film transistors with strongly hydrophobic dielectrics comprising either Teflon-AF or a poly(vinylphenol)/poly(methyl silsesquioxane) (PVP/pMSSQ) blend. In the absence of encapsulation, bottom gated transistors in air ambient show no hysteresis between forward and reverse gate sweep direction. Device threshold gate voltage and On-current present excellent time dependent stability even under dielectric stress. Furthermore, threshold gate voltage for hole conduction is negative upon device encapsulation with PVP/pMSSQ enabling much improved current On/Off ratio at 0 V. This work addresses two major challenges impeding solution based fabrication of relevant thin film transistors with printable single-walled carbon nanotube channels.

  19. Examination of the ambient effects on the stability of amorphous indium-gallium-zinc oxide thin film transistors using a laser-glass-sealing technology

    SciTech Connect

    Yamada, Kazuo; Takeda, Satoshi; Nomura, Kenji; Abe, Katsumi; Hosono, Hideo

    2014-09-29

    The effect of an ambient atmosphere with a positive bias constant current stress (CCS) and a negative bias illumination stress (NBIS) on the stability of amorphous In-Ga-Zn-O thin film transistors (TFTs) is examined by utilizing a glass-hermetic-sealant with a moisture permeability of less than 10{sup −6} g/m{sup 2} · day. In the CCS test, the threshold voltage shift (ΔV{sub th}) was remarkably suppressed in the glass-sealed TFTs. The unsealed and resin-sealed TFTs exhibited large ΔV{sub th} values. During the NBIS tests, the glass-sealed TFTs had almost the same negative ΔV{sub th} as the unsealed and resin sealed TFTs. Among the different TFTs, no significant differences were observed in the threshold voltage, the subthreshold swing and the saturation mobility as a function of the photon energy. It is concluded that ambient molecules were the primary origin of the instability of the ΔV{sub th}, induced by a CCS, but they were not related to the NBIS instability. The major role of the effective passivation layers in the NBIS test was not to simply block out the ambient effects, but to reduce the extra density of states at/near the surface of the back channel.

  20. Performance of Indium Gallium Zinc Oxide Thin-Film Transistors in Saline Solution

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Lacour, S. P.

    2016-06-01

    Transistors are often envisioned as alternative transducing devices to microelectrodes to communicate with the nervous system. Independently of the selected technology, the transistors should have reliable performance when exposed to physiological conditions (37°C, 5% CO2). Here, we report on the reliable performance of parylene encapsulated indium gallium zinc oxide (IGZO) based thin-film transistors (TFTs) after prolonged exposure to phosphate buffer saline solution in an incubator. The encapsulated IGZO TFTs (W/L = 500 μm/20 μm) have an ON/OFF current ratio of 107 and field effect mobility of 8.05 ± 0.78 cm2/Vs. The transistors operate within 4 V; their threshold voltages and subthreshold slope are ~1.9 V and 200 mV/decade, respectively. After weeks immersed in saline solution and at 37°C, we did not observe any significant deterioration in the transistors' performance. The long-term stability of IGZO transistors at physiological conditions is a promising result in the direction of metal oxide bioelectronics.

  1. The Integration and Applications of Organic Thin Film Transistors and Ferroelectric Polymers

    NASA Astrophysics Data System (ADS)

    Hsu, Yu-Jen

    Organic thin film transistors and ferroelectric polymer (polyvinylidene difluoride) sheet material are integrated to form various sensors for stress/strain, acoustic wave, and Infrared (heat) sensing applications. Different from silicon-based transistors, organic thin film transistors can be fabricated and processed in room-temperature and integrated with a variety of substrates. On the other hand, polyvinylidene difluoride (PVDF) exhibits ferroelectric properties that are highly useful for sensor applications. The wide frequency bandwidth (0.001 Hz to 10 GHz), vast dynamic range (100n to 10M psi), and high elastic compliance (up to 3 percent) make PVDF a more suitable candidate over ceramic piezoelectric materials for thin and flexible sensor applications. However, the low Curie temperature may have impeded its integration with silicon technology. Organic thin film transistors, however, do not have the limitation of processing temperature, hence can serve as transimpedance amplifiers to convert the charge signal generated by PVDF into current signal that are more measurable and less affected by any downstream parasitics. Piezoelectric sensors are useful for a range of applications, but passive arrays suffer from crosstalk and signal attenuation which have complicated the development of array-based PVDF sensors. We have used organic field effect transistors, which are compatible with the low Curie temperature of a flexible piezoelectric polymer,PVDF, to monolithically fabricate transimpedance amplifiers directly on the sensor surface and convert the piezoelectric charge signal into a current signal which can be detected even in the presence of parasitic capacitances. The device couples the voltage generated by the PVDF film under strain into the gate of the organic thin film transistors (OFET) using an arrangement that allows the full piezoelectric voltage to couple to the channel, while also increasing the charge retention time. A bipolar detector is created by

  2. Printed organic thin-film transistor-based integrated circuits

    NASA Astrophysics Data System (ADS)

    Mandal, Saumen; Noh, Yong-Young

    2015-06-01

    Organic electronics is moving ahead on its journey towards reality. However, this technology will only be possible when it is able to meet specific criteria including flexibility, transparency, disposability and low cost. Printing is one of the conventional techniques to deposit thin films from solution-based ink. It is used worldwide for visual modes of information, and it is now poised to enter into the manufacturing processes of various consumer electronics. The continuous progress made in the field of functional organic semiconductors has achieved high solubility in common solvents as well as high charge carrier mobility, which offers ample opportunity for organic-based printed integrated circuits. In this paper, we present a comprehensive review of all-printed organic thin-film transistor-based integrated circuits, mainly ring oscillators. First, the necessity of all-printed organic integrated circuits is discussed; we consider how the gap between printed electronics and real applications can be bridged. Next, various materials for printed organic integrated circuits are discussed. The features of these circuits and their suitability for electronics using different printing and coating techniques follow. Interconnection technology is equally important to make this product industrially viable; much attention in this review is placed here. For high-frequency operation, channel length should be sufficiently small; this could be achievable with a combination of surface treatment-assisted printing or laser writing. Registration is also an important issue related to printing; the printed gate should be perfectly aligned with the source and drain to minimize parasitic capacitances. All-printed organic inverters and ring oscillators are discussed here, along with their importance. Finally, future applications of all-printed organic integrated circuits are highlighted.

  3. Heterojunction bipolar transistor technology for data acquisition and communication

    NASA Technical Reports Server (NTRS)

    Wang, C.; Chang, M.; Beccue, S.; Nubling, R.; Zampardi, P.; Sheng, N.; Pierson, R.

    1992-01-01

    Heterojunction Bipolar Transistor (HBT) technology has emerged as one of the most promising technologies for ultrahigh-speed integrated circuits. HBT circuits for digital and analog applications, data conversion, and power amplification have been realized, with speed performance well above 20 GHz. At Rockwell, a baseline AlGaAs/GaAs HBT technology has been established in a manufacturing facility. This paper describes the HBT technology, transistor characteristics, and HBT circuits for data acquisition and communication.

  4. Method for formation of thin film transistors on plastic substrates

    DOEpatents

    Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

    1998-10-06

    A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The process relies on techniques for depositing semiconductors, dielectrics, and metals at low temperatures; crystallizing and doping semiconductor layers in the TFT with a pulsed energy source; and creating top-gate self-aligned as well as back-gate TFT structures. The process enables the fabrication of amorphous and polycrystalline channel silicon TFTs at temperatures sufficiently low to prevent damage to plastic substrates. The process has use in large area low cost electronics, such as flat panel displays and portable electronics.

  5. Thin film transistors for flexible electronics: contacts, dielectrics and semiconductors.

    PubMed

    Quevedo-Lopez, M A; Wondmagegn, W T; Alshareef, H N; Ramirez-Bon, R; Gnade, B E

    2011-06-01

    The development of low temperature, thin film transistor processes that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, radiation detectors, etc. In this paper, we review the impact of gate dielectrics, contacts and semiconductor materials on thin film transistors for flexible electronics applications. We present our recent results to fully integrate hybrid complementary metal oxide semiconductors comprising inorganic and organic-based materials. In particular, we demonstrate novel gate dielectric stacks and semiconducting materials. The impact of source and drain contacts on device performance is also discussed.

  6. Method for formation of thin film transistors on plastic substrates

    DOEpatents

    Carey, P.G.; Smith, P.M.; Sigmon, T.W.; Aceves, R.C.

    1998-10-06

    A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The process relies on techniques for depositing semiconductors, dielectrics, and metals at low temperatures; crystallizing and doping semiconductor layers in the TFT with a pulsed energy source; and creating top-gate self-aligned as well as back-gate TFT structures. The process enables the fabrication of amorphous and polycrystalline channel silicon TFTs at temperatures sufficiently low to prevent damage to plastic substrates. The process has use in large area low cost electronics, such as flat panel displays and portable electronics. 5 figs.

  7. Chemical and biological sensing with organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Mabeck, Jeffrey Todd

    Organic thin-film transistors (OTFTs) offer a great deal of promise for applications in chemical and biological sensing where there is a demand for small, portable, and inexpensive sensors. OTFTs have many advantages over other types of sensors, including low-cost fabrication, straightforward miniaturization, simple instrumentation, and inherent signal amplification. This dissertation examines two distinct types of OTFTs: organic field-effect transistors (OFETs) based on pentacene, and organic electrochemical transistors (OECTs) based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The bulk of the previous work on sensing with OFETs has focused on gas sensing, and this dissertation contributes to this body of work by briefly treating the large, reversible response of pentacene OFETs to humidity. However, there are many applications where the analyte of interest must be detected in an aqueous environment rather than a gaseous environment, and very little work has been done in this area for OFETs. Therefore, the integration of pentacene OFETs with microfluidics is treated in detail. Using poly(dimethylsiloxane) (PDMS) microfluidic channels to confine aqueous solutions over the active region of pentacene transistors, it is demonstrated that the current-voltage characteristics remain stable under aqueous flow with a decrease in mobility of ˜30% compared to its value when dry. The operation of PEDOT:PSS transistors is also treated in detail. It is demonstrated that their transistor behavior cannot be attributed solely to a field effect and that ion motion is key to the switching mechanism. It is also demonstrated that simple glucose sensors based on PEDOT:PSS OECTs are sensitive to low glucose concentrations below 1 mM, therefore showing promise for potential application in the field of noninvasive glucose monitoring for diabetic patients using saliva rather than blood samples. Furthermore, a novel microfluidic gating technique has been

  8. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Growth Related Carrier Mobility Enhancement of Pentacene Thin-Film Transistors with High-k Oxide Gate Dielectric

    NASA Astrophysics Data System (ADS)

    Yu, Ai-Fang; Qi, Qiong; Jiang, Peng; Jiang, Chao

    2009-07-01

    Carrier mobility enhancement from 0.09 to 0.59 cm2/Vs is achieved for pentacene-based thin-film transistors (TFTs) by modifying the HfO2 gate dielectric with a polystyrene (PS) thin film. The improvement of the transistor's performance is found to be strongly related to the initial film morphologies of pentacene on the dielectrics. In contrast to the three-dimensional island-like growth mode on the HfO2 surface, the Stranski-Krastanov growth mode on the smooth and nonpolar PS/HfO2 surface is believed to be the origin of the excellent carrier mobility of the TFTs. A large well-connected first monolayer with fewer boundaries is formed via the Stranski-Krastanov growth mode, which facilitates a charge transport parallel to the substrate and promotes higher carrier mobility.

  9. Thin film transistors for displays on plastic substrates

    NASA Astrophysics Data System (ADS)

    Lee, M. J.; Judge, C. P.; Wright, S. W.

    2000-08-01

    We have successfully made thin film transistors on transparent, flexible polymer substrates. These transistors have electrical properties suitable for driving the pixels in active matrix liquid crystal displays and also for building integrated row driver circuits. The devices are fabricated on polyethylene naphthalate using a low temperature CdSe process at a maximum temperature of 150°C, by evaporation and radio frequency sputtering onto unheated substrates, with pattern definition using standard photolithography and etching. Electrical properties achieved include carrier field effect mobilities of >30 cm 2/V s, threshold voltages of ˜2 V, switching ratio >10 6, an off-state leakage current of <10 -12 A and an on-state drive current of >1 μA with a gate voltage swing of <10 V, and a sub-threshold slope of 0.25 V/decade for devices of unity aspect ratio. The electrical properties were found to scale with device channel length and width.

  10. Thin film transistors using PECVD-grown carbon nanotubes.

    PubMed

    Ono, Yuki; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2010-05-21

    Thin film transistors with a carbon nanotube (CNT) network as a channel have been fabricated using grid-inserted plasma-enhanced chemical vapor deposition (PECVD) which has the advantage of preferential growth of the CNTs with semiconducting behavior in the I-V characteristics of CNT field effect transistors (CNT-FETs). Taking advantage of the preferential growth and suppression of bundle formation, a large ON current of 170 microA mm(-1), which is among the largest in these kinds of devices with a large ON/OFF current ratio of about 10(5), has been realized in the relatively short channel length of 10 microm. The field effect mobility of the device was 5.8 cm(2) V(-1) s(-1). PMID:20418603

  11. Thin film transistors using PECVD-grown carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ono, Yuki; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2010-05-01

    Thin film transistors with a carbon nanotube (CNT) network as a channel have been fabricated using grid-inserted plasma-enhanced chemical vapor deposition (PECVD) which has the advantage of preferential growth of the CNTs with semiconducting behavior in the I-V characteristics of CNT field effect transistors (CNT-FETs). Taking advantage of the preferential growth and suppression of bundle formation, a large ON current of 170 µA mm - 1, which is among the largest in these kinds of devices with a large ON/OFF current ratio of about 105, has been realized in the relatively short channel length of 10 µm. The field effect mobility of the device was 5.8 cm2 V - 1 s - 1.

  12. Metal oxide semiconductor thin-film transistors for flexible electronics

    NASA Astrophysics Data System (ADS)

    Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

    2016-06-01

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  13. Black Phosphorus Flexible Thin Film Transistors at Gighertz Frequencies.

    PubMed

    Zhu, Weinan; Park, Saungeun; Yogeesh, Maruthi N; McNicholas, Kyle M; Bank, Seth R; Akinwande, Deji

    2016-04-13

    Black phosphorus (BP) has attracted rapidly growing attention for high speed and low power nanoelectronics owing to its compelling combination of tunable bandgap (0.3 to 2 eV) and high carrier mobility (up to ∼1000 cm(2)/V·s) at room temperature. In this work, we report the first radio frequency (RF) flexible top-gated (TG) BP thin-film transistors on highly bendable polyimide substrate for GHz nanoelectronic applications. Enhanced p-type charge transport with low-field mobility ∼233 cm(2)/V·s and current density of ∼100 μA/μm at VDS = -2 V were obtained from flexible BP transistor at a channel length L = 0.5 μm. Importantly, with optimized dielectric coating for air-stability during microfabrication, flexible BP RF transistors afforded intrinsic maximum oscillation frequency fMAX ∼ 14.5 GHz and unity current gain cutoff frequency fT ∼ 17.5 GHz at a channel length of 0.5 μm. Notably, the experimental fT achieved here is at least 45% higher than prior results on rigid substrate, which is attributed to the improved air-stability of fabricated BP devices. In addition, the high-frequency performance was investigated through mechanical bending test up to ∼1.5% tensile strain, which is ultimately limited by the inorganic dielectric film rather than the 2D material. Comparison of BP RF devices to other 2D semiconductors clearly indicates that BP offers the highest saturation velocity, an important metric for high-speed and RF flexible nanosystems. PMID:26977902

  14. Investigation of tungsten doped tin oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Yang, Jianwen; Meng, Ting; Yang, Zhao; Cui, Can; Zhang, Qun

    2015-11-01

    Tungsten doped tin oxide thin film transistors (TWO-TFTs) were fabricated by radio frequency magnetron sputtering. With TWO thin films as the channel layers, the TFTs show lower off-current and positive shift turn-on voltage than the intrinsic tin oxide TFTs, which can be explained by the reason that W doping is conducive to suppress the carrier concentration of the TWO channel layer. It is important to elect an appropriate channel thickness for improving the TFT performance. The optimum TFT performance in enhancement mode is achieved at W doping content of 2.7 at% and channel thickness of 12 nm, with the saturation mobility, turn-on voltage, subthreshold swing value and on-off current ratio of 5 cm2 V-1 s-1, 0.4 V, 0.4 V/decade and 2.4  ×  106, respectively.

  15. The Integration and Applications of Organic Thin Film Transistors and Ferroelectric Polymers

    NASA Astrophysics Data System (ADS)

    Hsu, Yu-Jen

    Organic thin film transistors and ferroelectric polymer (polyvinylidene difluoride) sheet material are integrated to form various sensors for stress/strain, acoustic wave, and Infrared (heat) sensing applications. Different from silicon-based transistors, organic thin film transistors can be fabricated and processed in room-temperature and integrated with a variety of substrates. On the other hand, polyvinylidene difluoride (PVDF) exhibits ferroelectric properties that are highly useful for sensor applications. The wide frequency bandwidth (0.001 Hz to 10 GHz), vast dynamic range (100n to 10M psi), and high elastic compliance (up to 3 percent) make PVDF a more suitable candidate over ceramic piezoelectric materials for thin and flexible sensor applications. However, the low Curie temperature may have impeded its integration with silicon technology. Organic thin film transistors, however, do not have the limitation of processing temperature, hence can serve as transimpedance amplifiers to convert the charge signal generated by PVDF into current signal that are more measurable and less affected by any downstream parasitics. Piezoelectric sensors are useful for a range of applications, but passive arrays suffer from crosstalk and signal attenuation which have complicated the development of array-based PVDF sensors. We have used organic field effect transistors, which are compatible with the low Curie temperature of a flexible piezoelectric polymer,PVDF, to monolithically fabricate transimpedance amplifiers directly on the sensor surface and convert the piezoelectric charge signal into a current signal which can be detected even in the presence of parasitic capacitances. The device couples the voltage generated by the PVDF film under strain into the gate of the organic thin film transistors (OFET) using an arrangement that allows the full piezoelectric voltage to couple to the channel, while also increasing the charge retention time. A bipolar detector is created by

  16. Controllable film densification and interface flatness for high-performance amorphous indium oxide based thin film transistors

    SciTech Connect

    Ou-Yang, Wei E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio; Gao, Xu; Lin, Meng-Fang; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2014-10-20

    To avoid the problem of air sensitive and wet-etched Zn and/or Ga contained amorphous oxide transistors, we propose an alternative amorphous semiconductor of indium silicon tungsten oxide as the channel material for thin film transistors. In this study, we employ the material to reveal the relation between the active thin film and the transistor performance with aid of x-ray reflectivity study. By adjusting the pre-annealing temperature, we find that the film densification and interface flatness between the film and gate insulator are crucial for achieving controllable high-performance transistors. The material and findings in the study are believed helpful for realizing controllable high-performance stable transistors.

  17. Fully-printed high-performance organic thin-film transistors and circuitry on one-micron-thick polymer films

    NASA Astrophysics Data System (ADS)

    Fukuda, Kenjiro; Takeda, Yasunori; Yoshimura, Yudai; Shiwaku, Rei; Tran, Lam Truc; Sekine, Tomohito; Mizukami, Makoto; Kumaki, Daisuke; Tokito, Shizuo

    2014-06-01

    Thin, ultra-flexible devices that can be manufactured in a process that covers a large area will be essential to realizing low-cost, wearable electronic applications including foldable displays and medical sensors. The printing technology will be instrumental in fabricating these novel electronic devices and circuits; however, attaining fully printed devices on ultra-flexible films in large areas has typically been a challenge. Here we report on fully printed organic thin-film transistor devices and circuits fabricated on 1-μm-thick parylene-C films with high field-effect mobility (1.0 cm2 V-1 s-1) and fast operating speeds (about 1 ms) at low operating voltages. The devices were extremely light (2 g m-2) and exhibited excellent mechanical stability. The devices remained operational even under 50% compressive strain without significant changes in their performance. These results represent significant progress in the fabrication of fully printed organic thin-film transistor devices and circuits for use in unobtrusive electronic applications such as wearable sensors.

  18. Flexible Electronics Powered by Mixed Metal Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Marrs, Michael

    A low temperature amorphous oxide thin film transistor (TFT) and amorphous silicon PIN diode backplane technology for large area flexible digital x-ray detectors has been developed to create 7.9-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide TFT and a-Si PIN photodiode process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication and assembly of the flexible detectors. Mixed oxide semiconductor TFTs on flexible plastic substrates suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer improves both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment to the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors. Low temperature (200°C) processed amorphous silicon photodiodes were developed successfully by balancing the tradeoffs

  19. Thin film transistors and solar cells. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    1995-01-01

    The bibliography contains citations of selected patents concerning the fabrication and application methods of thin film transistors and thin film solar cells. Methods of manufacturing thin film transistors for use in electronic display devices are presented. Techniques for continuously producing durable and reliable thin film solar cells are discussed. (Contains 250 citations and includes a subject term index and title list.)

  20. Solution-Processable Organic Semiconductors and Conductors: Viable Materials for Functional Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Loo, Yueh-Lin

    2006-03-01

    Large-area displays based on organic materials promise low-cost fabrication, lightweight construction, mechanical flexibility and durability. To truly realize the low-cost aspects of organic electronics, however, conventional high-vacuum deposition technologies will have to be replaced by solution processing methodologies. This need has in turn driven the development of solution-processable organic semiconductors and conductors. We have focused on fabricating thin-film transistors with triethynylsilyl antradithiophene (TES ADT), a solution-processable p-type organic semiconductor. Subjecting the as-cast thin films of TES ADT to short solvent vapor annealing dramatically increases the device characteristics: we observe three orders of magnitude increase in carrier mobility and current on/off ratio, and a decrease in current hysteresis and threshold voltage. The improvement in the electrical characteristics can be directly correlated with morphological transformations during solvent vapor annealing. Our efforts in solution-processable organic conductors focus on water-dispersible polyaniline (PANI). We have fabricated bottom-contact thin-film transistors with PANI electrodes, which function as effectively as gold electrodes, when on-characteristics are concerned. Examination of the linear source-drain voltage regime suggests that PANI devices exhibit markedly less contact resistance than gold devices.

  1. Highly stable thin film transistors using multilayer channel structure

    SciTech Connect

    Nayak, Pradipta K.; Wang, Zhenwei; Anjum, D. H.; Hedhili, M. N.; Alshareef, H. N.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO{sub 2}) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60 °C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO{sub 2} layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO{sub 2} layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  2. High-performance carbon nanotube thin-film transistors on flexible paper substrates

    NASA Astrophysics Data System (ADS)

    Liu, Na; Yun, Ki Nam; Yu, Hyun-Yong; Shim, Joon Hyung; Lee, Cheol Jin

    2015-03-01

    Single-walled carbon nanotubes (SWCNTs) are promising materials as active channels for flexible transistors owing to their excellent electrical and mechanical properties. However, flexible SWCNT transistors have never been realized on paper substrates, which are widely used, inexpensive, and recyclable. In this study, we fabricated SWCNT thin-film transistors on photo paper substrates. The devices exhibited a high on/off current ratio of more than 106 and a field-effect mobility of approximately 3 cm2/V.s. The proof-of-concept demonstration indicates that SWCNT transistors on flexible paper substrates could be applied as low-cost and recyclable flexible electronics.

  3. High-performance carbon nanotube thin-film transistors on flexible paper substrates

    SciTech Connect

    Liu, Na; Yun, Ki Nam; Yu, Hyun-Yong; Lee, Cheol Jin; Shim, Joon Hyung

    2015-03-09

    Single-walled carbon nanotubes (SWCNTs) are promising materials as active channels for flexible transistors owing to their excellent electrical and mechanical properties. However, flexible SWCNT transistors have never been realized on paper substrates, which are widely used, inexpensive, and recyclable. In this study, we fabricated SWCNT thin-film transistors on photo paper substrates. The devices exhibited a high on/off current ratio of more than 10{sup 6} and a field-effect mobility of approximately 3 cm{sup 2}/V·s. The proof-of-concept demonstration indicates that SWCNT transistors on flexible paper substrates could be applied as low-cost and recyclable flexible electronics.

  4. Water-soluble thin film transistors and circuits based on amorphous indium-gallium-zinc oxide.

    PubMed

    Jin, Sung Hun; Kang, Seung-Kyun; Cho, In-Tak; Han, Sang Youn; Chung, Ha Uk; Lee, Dong Joon; Shin, Jongmin; Baek, Geun Woo; Kim, Tae-il; Lee, Jong-Ho; Rogers, John A

    2015-04-22

    This paper presents device designs, circuit demonstrations, and dissolution kinetics for amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) comprised completely of water-soluble materials, including SiNx, SiOx, molybdenum, and poly(vinyl alcohol) (PVA). Collections of these types of physically transient a-IGZO TFTs and 5-stage ring oscillators (ROs), constructed with them, show field effect mobilities (∼10 cm2/Vs), on/off ratios (∼2×10(6)), subthreshold slopes (∼220 mV/dec), Ohmic contact properties, and oscillation frequency of 5.67 kHz at supply voltages of 19 V, all comparable to otherwise similar devices constructed in conventional ways with standard, nontransient materials. Studies of dissolution kinetics for a-IGZO films in deionized water, bovine serum, and phosphate buffer saline solution provide data of relevance for the potential use of these materials and this technology in temporary biomedical implants.

  5. Dual Gate Thin Film Transistors Based on Indium Oxide Active Layers

    SciTech Connect

    Kekuda, Dhananjaya; Rao, K. Mohan; Tolpadi, Amita; Chu, C. W.

    2011-07-15

    Polycrystalline Indium Oxide (In{sub 2}O{sub 3}) thin films were employed as an active channel layer for the fabrication of bottom and top gate thin film transistors. While conventional SiO{sub 2} served as a bottom gate dielectric, cross-linked poly-4-vinylphenol (PVP) was used a top gate dielectric. These nano-crystalline TFTs exhibited n-channel behavior with their transport behavior highly dependent on the thickness of the channel. The correlation between the thickness of the active layer and TFT parameters such as on/off ratio, field-effect mobility, threshold voltage were carried out. The optical spectra revealed a high transmittance in the entire visible region, thus making them promising candidates for the display technology.

  6. Metal-semiconductor hybrid thin films in field-effect transistors

    SciTech Connect

    Okamura, Koshi Dehm, Simone; Hahn, Horst

    2013-12-16

    Metal-semiconductor hybrid thin films consisting of an amorphous oxide semiconductor and a number of aluminum dots in different diameters and arrangements are formed by electron beam lithography and employed for thin-film transistors (TFTs). Experimental and computational demonstrations systematically reveal that the field-effect mobility of the TFTs enhances but levels off as the dot density increases, which originates from variations of the effective channel length that strongly depends on the electric field distribution in a transistor channel.

  7. High Electron Mobility Thin‐Film Transistors Based on Solution‐Processed Semiconducting Metal Oxide Heterojunctions and Quasi‐Superlattices

    PubMed Central

    Lin, Yen‐Hung; Faber, Hendrik; Labram, John G.; Stratakis, Emmanuel; Sygellou, Labrini; Kymakis, Emmanuel; Hastas, Nikolaos A.; Li, Ruipeng; Zhao, Kui; Amassian, Aram; Treat, Neil D.; McLachlan, Martyn

    2015-01-01

    High mobility thin‐film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin‐film transistors is reported that exploits the enhanced electron transport properties of low‐dimensional polycrystalline heterojunctions and quasi‐superlattices (QSLs) consisting of alternating layers of In2O3, Ga2O3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band‐like transport with electron mobilities approximately a tenfold greater (25–45 cm2 V−1 s−1) than single oxide devices (typically 2–5 cm2 V−1 s−1). Based on temperature‐dependent electron transport and capacitance‐voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas‐like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll‐to‐roll, etc.) and can be seen as an extremely promising technology for application in next‐generation large area optoelectronics such as ultrahigh definition optical displays and large‐area microelectronics where high performance is a key requirement.

  8. Nonvolatile Memory Effect in Organic Thin-Film Transistor Based on Aluminum Nanoparticle Floating Gate

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Ma, Dong-Ge

    2010-01-01

    A nonvolatile memory effect was observed in an organic thin-film transistor by introducing a Boating gate structure. The Boating gate was composed of an Al film in a thickness of nanometers, which was thermally deposited on a SiO2 insulator and exposed to air to spontaneously oxidize. It can be seen that the transistors exhibit significant hysteresis behaviors and storage circles in current-voltage characteristics in the dark and under illumination, indicating that the transistors may act as a nonvolatile memory element. The operational mechanism is discussed in the cases of dark and illumination via charge trapping by the Al floating gate.

  9. Metal contact effect on the performance and scaling behavior of carbon nanotube thin film transistors.

    PubMed

    Xia, Jiye; Dong, Guodong; Tian, Boyuan; Yan, Qiuping; Zhang, Han; Liang, Xuelei; Peng, Lianmao

    2016-05-21

    Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact resistivity was found to increase with channel length, which is a consequence of the percolating nature of the transport in CNT films, and this behavior does not exist in CNT-FETs and normal 2D Ohmic conductors. Electrical transport in CNT-TFTs has been predicted to scale with channel length by stick percolation theory. However, the scaling behavior is also impacted, or even covered up by the effect of Rc. Once the contact effect is excluded, the covered scaling behavior can be revealed correctly. A possible way of reducing Rc in CNT-TFTs was proposed. We believe the findings in this paper will strengthen our understanding of CNT-TFTs, and even accelerate the commercialization of CNT-TFT technology.

  10. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays

    PubMed Central

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V.; Powell, David A.; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-01-01

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications. PMID:27000419

  11. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays.

    PubMed

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V; Powell, David A; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-03-22

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications.

  12. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays

    NASA Astrophysics Data System (ADS)

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V.; Powell, David A.; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-03-01

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications.

  13. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays.

    PubMed

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V; Powell, David A; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-01-01

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications. PMID:27000419

  14. Electron and hole transport in ambipolar, thin film pentacene transistors

    SciTech Connect

    Saudari, Sangameshwar R.; Kagan, Cherie R.

    2015-01-21

    Solution-processed, ambipolar, thin-film pentacene field-effect transistors were employed to study both electron and hole transport simultaneously in a single, organic solid-state device. Electron and hole mobilities were extracted from the respective unipolar saturation regimes and show thermally activated behavior and gate voltage dependence. We fit the gate voltage dependent saturation mobility to a power law to extract the characteristic Meyer-Neldel (MN) energy, a measure of the width of the exponential distribution of localized states extending into the energy gap of the organic semiconductor. The MN energy is ∼78 and ∼28 meV for electrons and holes, respectively, which reflects a greater density of localized tail states for electrons than holes. This is consistent with the lower measured electron than hole mobility. For holes, the well-behaved linear regime allows for four-point probe measurement of the contact resistance independent mobility and separate characterization of the width of the localized density of states, yielding a consistent MN energy of 28 meV.

  15. High-Mobility Ambipolar Organic Thin-Film Transistor Processed From a Nonchlorinated Solvent.

    PubMed

    Sonar, Prashant; Chang, Jingjing; Kim, Jae H; Ong, Kok-Haw; Gann, Eliot; Manzhos, Sergei; Wu, Jishan; McNeill, Christopher R

    2016-09-21

    Polymer semiconductor PDPPF-DFT, which combines furan-substituted diketopyrrolopyrrole (DPP) and a 3,4-difluorothiophene base, has been designed and synthesized. PDPPF-DFT polymer semiconductor thin film processed from nonchlorinated hexane is used as an active layer in thin-film transistors. As a result, balanced hole and electron mobilities of 0.26 and 0.12 cm(2)/(V s) are achieved for PDPPF-DFT. This is the first report of using nonchlorinated hexane solvent for fabricating high-performance ambipolar thin-film transistor devices.

  16. High-Mobility Ambipolar Organic Thin-Film Transistor Processed From a Nonchlorinated Solvent.

    PubMed

    Sonar, Prashant; Chang, Jingjing; Kim, Jae H; Ong, Kok-Haw; Gann, Eliot; Manzhos, Sergei; Wu, Jishan; McNeill, Christopher R

    2016-09-21

    Polymer semiconductor PDPPF-DFT, which combines furan-substituted diketopyrrolopyrrole (DPP) and a 3,4-difluorothiophene base, has been designed and synthesized. PDPPF-DFT polymer semiconductor thin film processed from nonchlorinated hexane is used as an active layer in thin-film transistors. As a result, balanced hole and electron mobilities of 0.26 and 0.12 cm(2)/(V s) are achieved for PDPPF-DFT. This is the first report of using nonchlorinated hexane solvent for fabricating high-performance ambipolar thin-film transistor devices. PMID:27595165

  17. ADO-phosphonic acid self-assembled monolayer modified dielectrics for organic thin film transistors

    NASA Astrophysics Data System (ADS)

    Zhefeng, Li; Xianye, Luo

    2014-10-01

    This study explores a strategy of using the phosphonic acid derivative (11-((12-(anthracen-2-yl)dodecyl)oxy)-11-oxoundecyl) phosphonic acid (ADO-phosphonic acid) as self-assembled monolayers (SAMs) on a Si/SiO2 surface to induce the crystallization of rubrene in vacuum deposited thin film transistors, which showed a field-effect mobility as high as 0.18 cm2/(V·s). It is found that ADO-phosphonic acid SAMs play a unique role in modulating the morphology of rubrene to form a crystalline film in the thin-film transistors.

  18. Solution-Processed Indium Oxide Based Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Xu, Wangying

    Oxide thin-film transistors (TFTs) have attracted considerable attention over the past decade due to their high carrier mobility and excellent uniformity. However, most of these oxide TFTs are usually fabricated using costly vacuum-based techniques. Recently, the solution processes have been developed due to the possibility of low-cost and large-area fabrication. In this thesis, we have carried out a detailed and systematic study of solution-processed oxide thin films and TFTs. At first, we demonstrated a passivation method to overcome the water susceptibility of solution-processed InZnO TFTs by utilizing octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs). The unpassivated InZnO TFTs exhibited large hysteresis in their electrical characteristics due to the adsorbed water at the semiconductor surface. Formation of a SAM of ODPA on the top of InZnO removed water molecules weakly absorbed at the back channel and prevented water diffusion from the surroundings. Therefore the passivated devices exhibited significantly reduced hysteretic characteristics. Secondly, we developed a simple spin-coating approach for high- k dielectrics (Al2O3, ZrO2, Y 2O3 and TiO2). These materials were used as gate dielectrics for solution-processed In2O3 or InZnO TFTs. Among the high-k dielectrics, the Al2O3-based devices showed the best performance, which is attributed to the smooth dielectric/semiconductor interface and the low interface trap density besides its good insulating property. Thirdly, the formation and properties of Al2O3 thin films under various annealing temperatures were intensively studied, revealing that the sol-gel-derived Al2O3 thin film undergoes the decomposition of organic residuals and nitrate groups, as well as conversion of aluminum hydroxides to form aluminum oxide. Besides, the Al2O 3 film was used as gate dielectric for solution-processed oxide TFTs, resulting in high mobility and low operating voltage. Finally, we proposed a green route for

  19. Numerical simulation of offset-drain amorphous oxide-based thin-film transistors

    NASA Astrophysics Data System (ADS)

    Jeong, Jaewook

    2016-11-01

    In this study, we analyzed the electrical characteristics of amorphous indium–gallium–zinc-oxide (a-IGZO) thin-film transistors (TFTs) with an offset-drain structure by technology computer aided design (TCAD) simulation. When operating in a linear region, an enhancement-type TFT shows poor field-effect mobility because most conduction electrons are trapped in acceptor-like defects in an offset region when the offset length (L off) exceeds 0.5 µm, whereas a depletion-type TFT shows superior field-effect mobility owing to the high free electron density in the offset region compared with the trapped electron density. When operating in the saturation region, both types of TFTs show good field-effect mobility comparable to that of a reference TFT with a large gate overlap. The underlying physics of the depletion and enhancement types of offset-drain TFTs are systematically analyzed.

  20. Self-heating induced instability of oxide thin film transistors under dynamic stress

    NASA Astrophysics Data System (ADS)

    Kise, Kahori; Fujii, Mami N.; Urakawa, Satoshi; Yamazaki, Haruka; Kawashima, Emi; Tomai, Shigekazu; Yano, Koki; Wang, Dapeng; Furuta, Mamoru; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2016-01-01

    Degradation caused by Joule heating of transparent amorphous oxide semiconductor thin-film transistors (TFTs) is an important issue for display technology. Deep understanding of the mechanism of self-heating degradation generated by driving pulse voltage will pave the way for the development of highly reliable flexible displays. In this work, by using a pseudo interval measurement method, we examined the relationship of the highest and the lowest heating temperature in pulse 1 cycle and frequency. These self-heating converged to a constant temperature under pulse voltage applied at 1 kHz. Moreover, the long-term reliability under positive-bias stress voltage at 1 kHz of low converged temperature condition was improved relative to that of the stress voltage at 10 Hz of dynamic temperature change condition. We discussed the degradation mechanism of oxide TFTs generated by pulse voltage, and clarified that the degradation was accelerated by thermionic emission which occurred at low frequency.

  1. Performance enhancement of amorphous indium-zinc-oxide thin film transistors by microwave annealing

    NASA Astrophysics Data System (ADS)

    Xu, Rui; He, Jian; Li, Wei; Paine, David C.

    2015-12-01

    The effect of microwave annealing on the field effect mobility and threshold voltage of amorphous indium zinc oxide (a-IZO) thin film transistors (TFTs) is reported. A control device with traditional hotplate annealing at 200 °C for 1 h was applied for comparison. The results show that both microwave annealing and low-temperature hotplate annealing increase the field effect mobility from 12.3 cm2/V s in as-deposited state to ∼19 cm2/V s in annealed state. However, the negative shift in threshold voltage with microwave annealing (from 0.23 V to -2.86 V) is smaller than that with low-temperature hotplate annealing (to -9 V). A mechanism related with the electrical properties of a-IZO material is proposed. This rapid low-temperature annealing technology makes a-IZO TFTs promising for use in flexible, transparent electronics.

  2. Graphene as tunable contact for high performance thin film transistor

    NASA Astrophysics Data System (ADS)

    Liu, Yuan

    Graphene has been one of the most extensively studied materials due to its unique band structure, the linear dispersion at the K point. It gives rise to novel phenomena, such as the anomalous quantum Hall effect, and has opened up a new category of "Fermi-Dirac" physics. Graphene has also attracted enormous attention for future electronics because of its exceptional high carrier mobility, high carrier saturation velocity, and large critical current density. However, graphene has zero intrinsic band gap, thus can not be used as the active channel material for logic transistors with sufficient on/off current ratio. Previous approaches to address this challenge include the induction of a transport gap in graphene nanostructures or bilayer graphene. However, these approaches have proved successful in improving the on-- off ratio of the resulting devices, but often at a severe sacrifice of the deliverable current density. Alternatively, with a finite density of states, tunable work-function and optical transparency, graphene can function as a unique tunable contact material to create a new structure of electronic devices. In this thesis, I will present my effort toward on-off ratio of graphene based vertical thin film transistor. I will include the work form four of my first author publication. I will first present my research studies on the a dramatic enhancement of the overall quantum efficiency and spectral selectivity of graphene photodetector, by coupling with plasmonic nanostructures. It is observed that metallic plasmonic nanostructures can be integrated with graphene photodetectors to greatly enhance the photocurrent and external quantum efficiency by up to 1,500%. Plasmonic nanostructures of variable resonance frequencies selectively amplify the photoresponse of graphene to light of different wavelengths, enabling highly specific detection of multicolours. Then I will show a new design of highly flexible vertical TFTs (VTFTs) with superior electrical

  3. Graphene as tunable contact for high performance thin film transistor

    NASA Astrophysics Data System (ADS)

    Liu, Yuan

    Graphene has been one of the most extensively studied materials due to its unique band structure, the linear dispersion at the K point. It gives rise to novel phenomena, such as the anomalous quantum Hall effect, and has opened up a new category of "Fermi-Dirac" physics. Graphene has also attracted enormous attention for future electronics because of its exceptional high carrier mobility, high carrier saturation velocity, and large critical current density. However, graphene has zero intrinsic band gap, thus can not be used as the active channel material for logic transistors with sufficient on/off current ratio. Previous approaches to address this challenge include the induction of a transport gap in graphene nanostructures or bilayer graphene. However, these approaches have proved successful in improving the on-- off ratio of the resulting devices, but often at a severe sacrifice of the deliverable current density. Alternatively, with a finite density of states, tunable work-function and optical transparency, graphene can function as a unique tunable contact material to create a new structure of electronic devices. In this thesis, I will present my effort toward on-off ratio of graphene based vertical thin film transistor. I will include the work form four of my first author publication. I will first present my research studies on the a dramatic enhancement of the overall quantum efficiency and spectral selectivity of graphene photodetector, by coupling with plasmonic nanostructures. It is observed that metallic plasmonic nanostructures can be integrated with graphene photodetectors to greatly enhance the photocurrent and external quantum efficiency by up to 1,500%. Plasmonic nanostructures of variable resonance frequencies selectively amplify the photoresponse of graphene to light of different wavelengths, enabling highly specific detection of multicolours. Then I will show a new design of highly flexible vertical TFTs (VTFTs) with superior electrical

  4. Self-formed copper oxide contact interlayer for high-performance oxide thin film transistors

    SciTech Connect

    Gao, Xu E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya; Mitoma, Nobuhiko; Lin, Meng-Fang; Kizu, Takio; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2014-07-14

    Oxide thin film transistor employing copper source/drain electrodes shows a small turn on voltage and reduced hysteresis. Cross-sectional high-resolution transmission electron microscopy image confirmed the formation of ∼4 nm CuO{sub x} related interlayer. The lower bond-dissociation energy of Cu-O compared to Si-O and In-O suggests that the interlayer was formed by adsorbing oxygen molecules from surrounding environment instead of getting oxygen atoms from the semiconductor film. The formation of CuO{sub x} interlayer acting as an acceptor could suppress the carrier concentration in the transistor channel, which would be utilized to control the turn on voltage shifts in oxide thin film transistors.

  5. Characterization of novel BaZnSnO thin films by solution process and applications in thin film transistors

    SciTech Connect

    Li, Jun; Huang, Chuan-Xin; Zhang, Jian-Hua; Zhu, Wen-Qing; Jiang, Xue-Yin; Zhang, Zhi-Lin

    2015-08-15

    Graphical abstract: This work reports the Ba content on thin film transistor based on a novel BaZnSnO semiconductor using solution process. - Highlights: • No reports about BaZnSnO thin film using solution process. • BaZnSnO thin film transistor (TFT) was firstly fabricated. • BaZnSnO-TFT shows a acceptable performace. • Influence of Ba content on BaZnSnO-TFT. - Abstract: A novel BaZnSnO semiconductor is fabricated using solution process and the influence of Ba addition on the structure, the chemical state of oxygen and electrical performance of BaZnSnO thin films are investigated. A high performance BaZnSnO-based thin film transistor with 15 mol% Ba is obtained, showing a saturation mobility of 1.94 cm{sup 2}/V s, a threshold voltage of 3.6 V, an on/off current ratio of 6.2 × 10{sup 6}, a subthreshold swing of 0.94 V/decade, and a good bias stability. Transistors with solution processed BaZnSnO films are promising candidates for the development of future large-area, low-cost and high-performance electronic devices.

  6. Metal contact effect on the performance and scaling behavior of carbon nanotube thin film transistors

    NASA Astrophysics Data System (ADS)

    Xia, Jiye; Dong, Guodong; Tian, Boyuan; Yan, Qiuping; Zhang, Han; Liang, Xuelei; Peng, Lianmao

    2016-05-01

    Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact resistivity was found to increase with channel length, which is a consequence of the percolating nature of the transport in CNT films, and this behavior does not exist in CNT-FETs and normal 2D Ohmic conductors. Electrical transport in CNT-TFTs has been predicted to scale with channel length by stick percolation theory. However, the scaling behavior is also impacted, or even covered up by the effect of Rc. Once the contact effect is excluded, the covered scaling behavior can be revealed correctly. A possible way of reducing Rc in CNT-TFTs was proposed. We believe the findings in this paper will strengthen our understanding of CNT-TFTs, and even accelerate the commercialization of CNT-TFT technology.Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact

  7. High mobility organic thin-film transistors based on p-p heterojunction buffer layer

    NASA Astrophysics Data System (ADS)

    Qian, Xianrui; Wang, Tong; Yan, Donghang

    2013-10-01

    The p-p heterojunction of 5, 6, 11, 12-tetraphenylnaphthacene/vanadyl phthalocyanine, which has been used as the buffer layer, is demonstrated. The highest field-effect mobility is 5.1 cm2/Vs, which is one of the highest reported for polycrystalline rubrene thin film transistors. Current versus voltage characteristics of heterojunction diodes are utilized to investigate the charge injection mechanism, revealing the factors that bring about the improvement of carrier injection and the reduction of contact resistance. These results suggest that our approach is very promising to fabricate high performance organic thin-film transistors for practical applications in organic electronics.

  8. Influence of underneath pentacene thickness on performance of p-n heterojunction organic thin film transistors

    NASA Astrophysics Data System (ADS)

    Zhou, Jianlin; Jiang, Yuyu; Wang, Zhen; Hu, Shengdong; Gan, Ping; Shen, Xiaoqing

    2016-02-01

    Organic thin film transistors (OTFTs) with heterojunction semiconducting layers composed of p-type pentacene and n-type fluorinated copper phthalocyanine (F16CuPc) have been fabricated. The influence of pentacene film thickness on performance of transistors is carefully investigated. It has been found that, with the increase of pentacene film thickness, the electron mobility increases at first and then decreases intensely. But the shift of VT is opposite comparing with electron mobility. The performance improvement can be attributed to the increase of free electron carriers by band bending at the pentacene/F16CuPc interface, and better F16CuPc film quality grown upon pentacene. Comparing with island growth-mode, layer-by-layer growth-mode of pentacene facilitates the growth of the upper F16CuPc film.

  9. Controlling the dimensionality of charge transport in organic thin-film transistors

    PubMed Central

    Laiho, Ari; Herlogsson, Lars; Forchheimer, Robert; Crispin, Xavier; Berggren, Magnus

    2011-01-01

    Electrolyte-gated organic thin-film transistors (OTFTs) can offer a feasible platform for future flexible, large-area and low-cost electronic applications. These transistors can be divided into two groups on the basis of their operation mechanism: (i) field-effect transistors that switch fast but carry much less current than (ii) the electrochemical transistors which, on the contrary, switch slowly. An attractive approach would be to combine the benefits of the field-effect and the electrochemical transistors into one transistor that would both switch fast and carry high current densities. Here we report the development of a polyelectrolyte-gated OTFT based on conjugated polyelectrolytes, and we demonstrate that the OTFTs can be controllably operated either in the field-effect or the electrochemical regime. Moreover, we show that the extent of electrochemical doping can be restricted to a few monolayers of the conjugated polyelectrolyte film, which allows both high current densities and fast switching speeds at the same time. We propose an operation mechanism based on self-doping of the conjugated polyelectrolyte backbone by its ionic side groups. PMID:21876143

  10. BIMOS transistor solutions for ESD protection in FD-SOI UTBB CMOS technology

    NASA Astrophysics Data System (ADS)

    Galy, Philippe; Athanasiou, S.; Cristoloveanu, S.

    2016-01-01

    We evaluate the Electro-Static Discharge (ESD) protection capability of BIpolar MOS (BIMOS) transistors integrated in ultrathin silicon film for 28 nm Fully Depleted SOI (FD-SOI) Ultra Thin Body and BOX (UTBB) high-k metal gate technology. Using as a reference our measurements in hybrid bulk-SOI structures, we extend the BIMOS design towards the ultrathin silicon film. Detailed study and pragmatic evaluations are done based on 3D TCAD simulation with standard physical models using Average Current Slope (ACS) method and quasi-static DC stress (Average Voltage Slope AVS method). These preliminary 3D TACD results are very encouraging in terms of ESD protection efficiency in advanced FD-SOI CMOS.

  11. Metal-oxide thin-film transistor-based pH sensor with a silver nanowire top gate electrode

    NASA Astrophysics Data System (ADS)

    Yoo, Tae-Hee; Sang, Byoung-In; Wang, Byung-Yong; Lim, Dae-Soon; Kang, Hyun Wook; Choi, Won Kook; Lee, Young Tack; Oh, Young-Jei; Hwang, Do Kyung

    2016-04-01

    Amorphous InGaZnO (IGZO) metal-oxide-semiconductor thin-film transistors (TFTs) are one of the most promising technologies to replace amorphous and polycrystalline Si TFTs. Recently, TFT-based sensing platforms have been gaining significant interests. Here, we report on IGZO transistor-based pH sensors in aqueous medium. In order to achieve stable operation in aqueous environment and enhance sensitivity, we used Al2O3 grown by using atomic layer deposition (ALD) and a porous Ag nanowire (NW) mesh as the top gate dielectric and electrode layers, respectively. Such devices with a Ag NW mesh at the top gate electrode rapidly respond to the pH of solutions by shifting the turn-on voltage. Furthermore, the output voltage signals induced by the voltage shifts can be directly extracted by implantation of a resistive load inverter.

  12. Variable temperature film and contact resistance measurements on operating n-channel organic thin film transistors

    NASA Astrophysics Data System (ADS)

    Chesterfield, Reid J.; McKeen, John C.; Newman, Christopher R.; Frisbie, C. Daniel; Ewbank, Paul C.; Mann, Kent R.; Miller, Larry L.

    2004-06-01

    We report structural and electrical properties in thin films of an n-channel organic semiconductor, N,N'-dipentyl-3,4,9,10-perylene tetracarboxylic dimide (PTCDI-C5). The structure of polycrystalline thin films of PTCDI-C5 was studied using x-ray diffraction and atomic force microscopy. Films order with single crystal-like packing, and the direction of π-π overlap is in the substrate plane. Organic thin film transistors (OTFTs) based on PTCDI-C5 were fabricated on hydrophobic and hydrophilic substrates. OTFTs showed effective mobility as high as 0.1 cm2/V s. Contact resistance of operating OTFTs was studied using resistance versus length plots and a four-probe method for three different contact metals (Au, Ag, Ca). Typical OTFTs had a specific contact resistance of 8×104 Ω cm at high gate voltage. There was no dependence of contact resistance with contact metal. Variable temperature measurements revealed that film resistance in the OTFT was activated in the temperature range 100-300 K, with typical activation energies of 60-80 meV. Contact resistance showed similar activated behavior, implying that the Schottky barrier at the contact is not the limiting resistance for the contact. Film resistance data showed a Meyer-Neldel relationship with characteristic energy EMN=20-25 meV, for various samples. The common TFT instability of threshold voltage shift (TVS) was observed in PTCDI-C5 OTFTs. A model is proposed to explain positive TVS in gate bias stress and oxygen exposure experiments. The model is based on the formation of a metastable complex between PTCDI-C5 and oxygen, which creates a deep acceptor-like trap state.

  13. Polycrystalline thin film photovoltaic technology

    SciTech Connect

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

    1991-03-01

    Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

  14. All diamond self-aligned thin film transistor

    DOEpatents

    Gerbi, Jennifer

    2008-07-01

    A substantially all diamond transistor with an electrically insulating substrate, an electrically conductive diamond layer on the substrate, and a source and a drain contact on the electrically conductive diamond layer. An electrically insulating diamond layer is in contact with the electrically conductive diamond layer, and a gate contact is on the electrically insulating diamond layer. The diamond layers may be homoepitaxial, polycrystalline, nanocrystalline or ultrananocrystalline in various combinations.A method of making a substantially all diamond self-aligned gate transistor is disclosed in which seeding and patterning can be avoided or minimized, if desired.

  15. Use of cermet thin film resistors with nitride passivated metal insulator field effect transistor

    NASA Technical Reports Server (NTRS)

    Brown, G. A.; Harrap, V.

    1971-01-01

    Film deposition of cermet resistors on same chip with metal nitride oxide silicon field effect transistors permits protection of contamination sensitive active devices from contaminants produced in cermet deposition and definition processes. Additional advantages include lower cost, greater reliability, and space savings.

  16. A furan-containing conjugated polymer for high mobility ambipolar organic thin film transistors.

    PubMed

    Sonar, Prashant; Foong, Thelese Ru Bao; Singh, Samarendra P; Li, Yuning; Dodabalapur, Ananth

    2012-08-28

    Furan substituted diketopyrrolopyrrole (DBF) combined with benzothiadiazole based polymer semiconductor PDPP-FBF has been synthesized and evaluated as an ambipolar semiconductor in organic thin-film transistors. Hole and electron mobilities as high as 0.20 cm(2) V(-1) s(-1) and 0.56 cm(2) V(-1) s(-1), respectively, are achieved for PDPP-FBF.

  17. Solvent-induced changes in PEDOT:PSS films for organic electrochemical transistors

    SciTech Connect

    Zhang, Shiming; Kumar, Prajwal; Nouas, Amel Sarah; Fontaine, Laurie; Tang, Hao; Cicoira, Fabio

    2015-01-01

    Organic electrochemical transistors based on the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) are of interest for several bioelectronic applications. In this letter, we investigate the changes induced by immersion of PEDOT:PSS films, processed by spin coating from different mixtures, in water and other solvents of different polarities. We found that the film thickness decreases upon immersion in polar solvents, while the electrical conductivity remains unchanged. The decrease in film thickness is minimized via the addition of a cross-linking agent to the mixture used for the spin coating of the films.

  18. Charge carrier transport in polycrystalline organic thin film based field effect transistors

    NASA Astrophysics Data System (ADS)

    Rani, Varsha; Sharma, Akanksha; Ghosh, Subhasis

    2016-05-01

    The charge carrier transport mechanism in polycrystalline thin film based organic field effect transistors (OFETs) has been explained using two competing models, multiple trapping and releases (MTR) model and percolation model. It has been shown that MTR model is most suitable for explaining charge carrier transport in grainy polycrystalline organic thin films. The energetic distribution of traps determined independently using Mayer-Neldel rule (MNR) is in excellent agreement with the values obtained by MTR model for copper phthalocyanine and pentacene based OFETs.

  19. Flexible pH sensors based on polysilicon thin film transistors and ZnO nanowalls

    NASA Astrophysics Data System (ADS)

    Maiolo, L.; Mirabella, S.; Maita, F.; Alberti, A.; Minotti, A.; Strano, V.; Pecora, A.; Shacham-Diamand, Y.; Fortunato, G.

    2014-09-01

    A fully flexible pH sensor using nanoporous ZnO on extended gate thin film transistor (EGTFT) fabricated on polymeric substrate is demonstrated. The sensor adopts the Low Temperature Polycrystalline Silicon (LTPS) TFT technology for the active device, since it allows excellent electrical characteristics and good stability and opens the way towards the possibility of exploiting CMOS architectures in the future. The nanoporous ZnO sensitive film, consisting of very thin (20 nm) crystalline ZnO walls with a large surface-to-volume ratio, was chemically deposited at 90 °C, allowing simple process integration with conventional TFT micro-fabrication processes compatible with wide range of polymeric substrates. The pH sensor showed a near-ideal Nernstian response (˜59 mV/pH), indicating an ideality factor α ˜ 1 according to the conventional site binding model. The present results can pave the way to advanced flexible sensing systems, where sensors and local signal conditioning circuits will be integrated on the same flexible substrate.

  20. Water-soluble thin film transistors and circuits based on amorphous indium-gallium-zinc oxide.

    PubMed

    Jin, Sung Hun; Kang, Seung-Kyun; Cho, In-Tak; Han, Sang Youn; Chung, Ha Uk; Lee, Dong Joon; Shin, Jongmin; Baek, Geun Woo; Kim, Tae-il; Lee, Jong-Ho; Rogers, John A

    2015-04-22

    This paper presents device designs, circuit demonstrations, and dissolution kinetics for amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) comprised completely of water-soluble materials, including SiNx, SiOx, molybdenum, and poly(vinyl alcohol) (PVA). Collections of these types of physically transient a-IGZO TFTs and 5-stage ring oscillators (ROs), constructed with them, show field effect mobilities (∼10 cm2/Vs), on/off ratios (∼2×10(6)), subthreshold slopes (∼220 mV/dec), Ohmic contact properties, and oscillation frequency of 5.67 kHz at supply voltages of 19 V, all comparable to otherwise similar devices constructed in conventional ways with standard, nontransient materials. Studies of dissolution kinetics for a-IGZO films in deionized water, bovine serum, and phosphate buffer saline solution provide data of relevance for the potential use of these materials and this technology in temporary biomedical implants. PMID:25805699

  1. Influence of annealing atmospheres and synthetic air treatment on solution processed zinc oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Busch, C.; Schierning, G.; Theissmann, R.; Schmechel, R.

    2012-08-01

    Thin film transistors (TFTs) based on active layers of zinc oxide prepared from a solution process were fabricated under different annealing conditions. The influence of the annealing gas as well as the influence of a subsequent exposure to synthetic air to the device properties is considered. Annealing under N2 or H2 atmosphere leads to a strong negative threshold voltage shift. With respect to known defect states in ZnO, two different donor states are suggested to be responsible for the negative threshold voltage. A subsequent synthetic air treatment causes in general a positive threshold voltage shift. However, transistors annealed under H2 degrade very fast under synthetic air in contrast to transistors annealed under N2. In order to obtain more information about the density of states (DOS) distribution, a transistor model for thin film transistors in the hopping transport regime (Vissenberg model) was utilized. For positive threshold voltages, the DOS distribution is independent from the gas treatment and the threshold voltage within the experimental accuracy. This indicates a shift of the Fermi-level within an exponentially decaying DOS. The change in the charge carrier density is either due to shallow donors or due to a charge transfer with acceptors at the surface. In contrast, for negative threshold voltages, the DOS distribution parameter rises, indicating a flatter DOS distribution. We suggest that the difference is due to the change from accumulation mode to the depletion mode of the device.

  2. Radiation sensitivity of graphene field effect transistors and other thin film architectures

    NASA Astrophysics Data System (ADS)

    Cazalas, Edward

    An important contemporary motivation for advancing radiation detection science and technology is the need for interdiction of nuclear and radiological materials, which may be used to fabricate weapons of mass destruction. The detection of such materials by nuclear techniques relies on achieving high sensitivity and selectivity to X-rays, gamma-rays, and neutrons. To be attractive in field deployable instruments, it is desirable for detectors to be lightweight, inexpensive, operate at low voltage, and consume low power. To address the relatively low particle flux in most passive measurements for nuclear security applications, detectors scalable to large areas that can meet the high absolute detection efficiency requirements are needed. Graphene-based and thin-film-based radiation detectors represent attractive technologies that could meet the need for inexpensive, low-power, size-scalable detection architectures, which are sensitive to X-rays, gamma-rays, and neutrons. The utilization of graphene to detect ionizing radiation relies on the modulation of graphene charge carrier density by changes in local electric field, i.e. the field effect in graphene. Built on the principle of a conventional field effect transistor, the graphene-based field effect transistor (GFET) utilizes graphene as a channel and a semiconducting substrate as an absorber medium with which the ionizing radiation interacts. A radiation interaction event that deposits energy within the substrate creates electron-hole pairs, which modify the electric field and modulate graphene charge carrier density. A detection event in a GFET is therefore measured as a change in graphene resistance or current. Thin (micron-scale) films can also be utilized for radiation detection of thermal neutrons provided nuclides with high neutron absorption cross section are present with appreciable density. Detection in thin-film detectors could be realized through the collection of charge carriers generated within the

  3. Detection of saliva-range glucose concentrations using organic thin-film transistors

    SciTech Connect

    Elkington, D.; Belcher, W. J.; Dastoor, P. C.; Zhou, X. J.

    2014-07-28

    We describe the development of a glucose sensor through direct incorporation of an enzyme (glucose oxidase) into the gate of an organic thin film transistor (OTFT). We show that glucose diffusion is the key determinant of the device response time and present a mechanism of glucose sensing in these devices that involves protonic doping of the transistor channel via enzymatic oxidation of glucose. The integrated OTFT sensor is sensitive across 4 decades of glucose concentration; a range that encompasses both the blood and salivary glucose concentration levels. As such, this work acts as a proof-of-concept for low-cost printed biosensors for salivary glucose.

  4. Zinc oxide integrated area efficient high output low power wavy channel thin film transistor

    SciTech Connect

    Hanna, A. N.; Ghoneim, M. T.; Bahabry, R. R.; Hussain, A. M.; Hussain, M. M.

    2013-11-25

    We report an atomic layer deposition based zinc oxide channel material integrated thin film transistor using wavy channel architecture allowing expansion of the transistor width in the vertical direction using the fin type features. The experimental devices show area efficiency, higher normalized output current, and relatively lower power consumption compared to the planar architecture. This performance gain is attributed to the increased device width and an enhanced applied electric field due to the architecture when compared to a back gated planar device with the same process conditions.

  5. Detection of saliva-range glucose concentrations using organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Elkington, D.; Belcher, W. J.; Dastoor, P. C.; Zhou, X. J.

    2014-07-01

    We describe the development of a glucose sensor through direct incorporation of an enzyme (glucose oxidase) into the gate of an organic thin film transistor (OTFT). We show that glucose diffusion is the key determinant of the device response time and present a mechanism of glucose sensing in these devices that involves protonic doping of the transistor channel via enzymatic oxidation of glucose. The integrated OTFT sensor is sensitive across 4 decades of glucose concentration; a range that encompasses both the blood and salivary glucose concentration levels. As such, this work acts as a proof-of-concept for low-cost printed biosensors for salivary glucose.

  6. Organic/inorganic hybrid synaptic transistors gated by proton conducting methylcellulose films

    NASA Astrophysics Data System (ADS)

    Wan, Chang Jin; Zhu, Li Qiang; Wan, Xiang; Shi, Yi; Wan, Qing

    2016-01-01

    The idea of building a brain-inspired cognitive system has been around for several decades. Recently, electric-double-layer transistors gated by ion conducting electrolytes were reported as the promising candidates for synaptic electronics and neuromorphic system. In this letter, indium-zinc-oxide transistors gated by proton conducting methylcellulose electrolyte films were experimentally demonstrated with synaptic plasticity including paired-pulse facilitation and spatiotemporal-correlated dynamic logic. More importantly, a model based on proton-related electric-double-layer modulation and stretched-exponential decay function was proposed, and the theoretical results are in good agreement with the experimentally measured synaptic behaviors.

  7. Liquid-crystalline processing of highly oriented carbon nanotube arrays for thin-film transistors.

    PubMed

    Ko, Hyunhyub; Tsukruk, Vladimir V

    2006-07-01

    We introduce a simple solution-based method for the fabrication of highly oriented carbon nanotube (CNT) arrays to be used for thin-film transistors. We exploit the liquid-crystalline behavior of a CNT solution near the receding contact line during tilted-drop casting and produced long-range nematic-like ordering of carbon nanotube stripes caused by confined micropatterned geometry. We further demonstrate that the performance of thin-film transistors based on these densely packed and uniformly oriented CNT arrays is largely improved compared to random CNTs. This approach has great potential in low-cost, large-scale processing of high-performance electronic devices based on high-density oriented CNT films with record electrical characteristics such as high conductance, low resistivity, and high career mobility.

  8. σ-π molecular dielectric multilayers for low-voltage organic thin-film transistors

    PubMed Central

    Yoon, Myung-Han; Facchetti, Antonio; Marks, Tobin J.

    2005-01-01

    Very thin (2.3-5.5 nm) self-assembled organic dielectric multilayers have been integrated into organic thin-film transistor structures to achieve sub-1-V operating characteristics. These new dielectrics are fabricated by means of layer-by-layer solution phase deposition of molecular silicon precursors, resulting in smooth, nanostructurally well defined, strongly adherent, thermally stable, virtually pinhole-free, organosiloxane thin films having exceptionally large electrical capacitances (up to ≈2,500 nF·cm-2), excellent insulating properties (leakage current densities as low as 10-9 A·cm-2), and single-layer dielectric constant (k)of ≈16. These 3D self-assembled multilayers enable organic thin-film transistor function at very low source-drain, gate, and threshold voltages (<1 V) and are compatible with a broad variety of vapor- or solution-deposited p- and n-channel organic semiconductors. PMID:15781860

  9. Molybdenum as a contact material in zinc tin oxide thin film transistors

    SciTech Connect

    Hu, W.; Peterson, R. L.

    2014-05-12

    Amorphous oxide semiconductors are of increasing interest for a variety of thin film electronics applications. Here, the contact properties of different source/drain electrode materials to solution-processed amorphous zinc tin oxide (ZTO) thin-film transistors are studied using the transmission line method. The width-normalized contact resistance between ZTO and sputtered molybdenum is measured to be 8.7 Ω-cm, which is 10, 20, and 600 times smaller than that of gold/titanium, indium tin oxide, and evaporated molybdenum electrodes, respectively. The superior contact formed using sputtered molybdenum is due to a favorable work function lineup, an insulator-free interface, bombardment of ZTO during molybdenum sputtering, and trap-assisted tunneling. The transfer length of the sputtered molybdenum/ZTO contact is 0.34 μm, opening the door to future radio-frequency sub-micron molybdenum/ZTO thin film transistors.

  10. Organic Gate Silicon Field Effect Transistors with Poly Methylmethacrylate Films for Science Education

    NASA Astrophysics Data System (ADS)

    Hirose, Fumihiko; Miyagi, Tatsuro; Narita, Yuzuru

    We have developed an easy fabrication method of Si field effect transistors (FETs) with poly (methyl methacrylate) (PMMA) gate films for science education. In this process, we can easily fabricate the silicon FETs only by means of metal deposition and thermal diffusion without any lithography processes. The organic isolation films of PMMA can be deposited by casting or painting at room temperature in air. The metal-organic-semiconductor FETs with PMMA exhibited almost the same drain current — gate voltage characteristics as those of conventional Si metal-oxide-semiconductor FETs, which are suitable for the education material of semiconductor engineering. The organic gate Si FETs can be used not only for education but also as thin film transistors for active matrix displays.

  11. Thin-film transistors based on p-type Cu{sub 2}O thin films produced at room temperature

    SciTech Connect

    Fortunato, Elvira; Figueiredo, Vitor; Barquinha, Pedro; Elamurugu, Elangovan; Goncalves, Goncalo; Martins, Rodrigo; Park, Sang-Hee Ko; Hwang, Chi-Sun

    2010-05-10

    Copper oxide (Cu{sub 2}O) thin films were used to produce bottom gate p-type transparent thin-film transistors (TFTs). Cu{sub 2}O was deposited by reactive rf magnetron sputtering at room temperature and the films exhibit a polycrystalline structure with a strongest orientation along (111) plane. The TFTs exhibit improved electrical performance such as a field-effect mobility of 3.9 cm{sup 2}/V s and an on/off ratio of 2x10{sup 2}.

  12. Organic nanodielectrics for low voltage carbon nanotube thin film transistors and complementary logic gates.

    PubMed

    Hur, Seung-Hyun; Yoon, Myung-Han; Gaur, Anshu; Shim, Moonsub; Facchetti, Antonio; Marks, Tobin J; Rogers, John A

    2005-10-12

    We report the implementation of three dimensionally cross-linked, organic nanodielectric multilayers as ultrathin gate dielectrics for a type of thin film transistor device that uses networks of single-walled carbon nanotubes as effective semiconductor thin films. Unipolar n- and p-channel devices are demonstrated by use of polymer coatings to control the behavior of the networks. Monolithically integrating these devices yields complementary logic gates. The organic multilayers provide exceptionally good gate dielectrics for these systems and allow for low voltage, low hysteresis operation. The excellent performance characteristics suggest that organic dielectrics of this general type could provide a promising path to SWNT-based thin film electronics.

  13. A water-gated organic thin film transistor as a sensor for water-borne amines.

    PubMed

    Algarni, Saud A; Althagafi, Talal M; Naim, Abdullah Al; Grell, Martin

    2016-06-01

    The p-type semiconducting polymer Poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT) displays innate sensitivity to water-borne amines. We demonstrate this with the help of water-gated PBTTT thin film transistors (TFTs). When octylamine is added to the gating water, TFTs respond with a significantly reduced saturated drain current. Underlying TFT drift is minimised by initial conditioning, and remaining drift can be accounted for by normalising current response to the current level under purge immediately before exposure. Normalised current response vs. amine concentration is reproducible between different transistors, and can be modelled by a Langmuir surface adsorption isotherm, which suggests physisorption of analyte at the PBTTT surface, rather than bulk penetration. Same PBTTT transistors do not respond to 1- octanol, confirming the specific affinity between amines and thiophene- based organic semiconductors.

  14. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors.

    PubMed

    Lee, Sungsik; Nathan, Arokia

    2016-01-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage.

  15. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors

    PubMed Central

    Lee, Sungsik; Nathan, Arokia

    2016-01-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage. PMID:26932790

  16. Variability of electrical contact properties in multilayer MoS2 thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Seong Yeoul; Park, Seonyoung; Choi, Woong

    2014-09-01

    We report the variability of electrical properties of Ti contacts in back-gated multilayer MoS2 thin-film transistors based on mechanically exfoliated flakes. By measuring current-voltage characteristics from room temperature to 240 °C, we demonstrate the formation of both ohmic and Schottky contacts at the Ti-MoS2 junctions of MoS2 transistors fabricated using identical electrode materials under the same conditions. While MoS2 transistors with ohmic contacts exhibit a typical signature of band transport, those with Schottky contacts indicate thermally activated transport behavior for the given temperature range. These results provide the experimental evidence of the variability of Ti metal contacts on MoS2, highlighting the importance of understanding the variability of electronic properties of naturally occurring MoS2 for further investigation.

  17. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors.

    PubMed

    Lee, Sungsik; Nathan, Arokia

    2016-01-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage. PMID:26932790

  18. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Lee, Sungsik; Nathan, Arokia

    2016-03-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage.

  19. Protolytic carbon film technology

    SciTech Connect

    Renschler, C.L.; White, C.A.

    1996-04-01

    This paper presents a technique for the deposition of polyacrylonitrile (PAN) on virtually any surface allowing carbon film formation with only the caveat that the substrate must withstand carbonization temperatures of at least 600 degrees centigrade. The influence of processing conditions upon the structure and properties of the carbonized film is discussed. Electrical conductivity, microstructure, and morphology control are also described.

  20. Film Fabrication Technologies at NREL

    NASA Technical Reports Server (NTRS)

    Mcconnell, Robert D.

    1993-01-01

    The National Renewable Energy Laboratory (NREL) has extensive capabilities for fabricating a variety of high-technology films. Much of the in-house work in NREL's large photovoltaics (PV) program involves the fabrication of multiple thin-film semiconducting layers constituting a thin-film PV device. NREL's smaller program in superconductivity focuses on the fabrication of superconducting films on long, flexible tape substrates. This paper focuses on four of NREL's in-house research groups and their film fabrication techniques, developed for a variety of elements, alloys, and compounds to be deposited on a variety of substrates. As is the case for many national laboratories, NREL's technology transfer efforts are focusing on Cooperative Research and Development Agreements (CRADA's) between NREL researchers and private industry researchers.

  1. Oxide semiconductor thin-film transistors: a review of recent advances.

    PubMed

    Fortunato, E; Barquinha, P; Martins, R

    2012-06-12

    Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which

  2. Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Yang, Jyun-Bao; Chang, Ting-Chang; Huang, Jheng-Jie; Chen, Yu-Chun; Chen, Yu-Ting; Tseng, Hsueh-Chih; Chu, Ann-Kuo; Sze, Simon M.

    2014-04-01

    In this study, indium-gallium-zinc-oxide thin film transistors can be operated either as transistors or resistance random access memory devices. Before the forming process, current-voltage curve transfer characteristics are observed, and resistance switching characteristics are measured after a forming process. These resistance switching characteristics exhibit two behaviors, and are dominated by different mechanisms. The mode 1 resistance switching behavior is due to oxygen vacancies, while mode 2 is dominated by the formation of an oxygen-rich layer. Furthermore, an easy approach is proposed to reduce power consumption when using these resistance random access memory devices with the amorphous indium-gallium-zinc-oxide thin film transistor.

  3. Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors

    SciTech Connect

    Yang, Jyun-Bao; Chen, Yu-Ting; Chu, Ann-Kuo; Chang, Ting-Chang; Huang, Jheng-Jie; Chen, Yu-Chun; Tseng, Hsueh-Chih; Sze, Simon M.

    2014-04-14

    In this study, indium-gallium-zinc-oxide thin film transistors can be operated either as transistors or resistance random access memory devices. Before the forming process, current-voltage curve transfer characteristics are observed, and resistance switching characteristics are measured after a forming process. These resistance switching characteristics exhibit two behaviors, and are dominated by different mechanisms. The mode 1 resistance switching behavior is due to oxygen vacancies, while mode 2 is dominated by the formation of an oxygen-rich layer. Furthermore, an easy approach is proposed to reduce power consumption when using these resistance random access memory devices with the amorphous indium-gallium-zinc-oxide thin film transistor.

  4. Lateral protonic/electronic hybrid oxide thin-film transistor gated by SiO{sub 2} nanogranular films

    SciTech Connect

    Zhu, Li Qiang Chao, Jin Yu; Xiao, Hui

    2014-12-15

    Ionic/electronic interaction offers an additional dimension in the recent advancements of condensed materials. Here, lateral gate control of conductivities of indium-zinc-oxide (IZO) films is reported. An electric-double-layer (EDL) transistor configuration was utilized with a phosphorous-doped SiO{sub 2} nanogranular film to provide a strong lateral electric field. Due to the strong lateral protonic/electronic interfacial coupling effect, the IZO EDL transistor could operate at a low-voltage of 1 V. A resistor-loaded inverter is built, showing a high voltage gain of ∼8 at a low supply voltage of 1 V. The lateral ionic/electronic coupling effects are interesting for bioelectronics and portable electronics.

  5. Lateral protonic/electronic hybrid oxide thin-film transistor gated by SiO2 nanogranular films

    NASA Astrophysics Data System (ADS)

    Zhu, Li Qiang; Chao, Jin Yu; Xiao, Hui

    2014-12-01

    Ionic/electronic interaction offers an additional dimension in the recent advancements of condensed materials. Here, lateral gate control of conductivities of indium-zinc-oxide (IZO) films is reported. An electric-double-layer (EDL) transistor configuration was utilized with a phosphorous-doped SiO2 nanogranular film to provide a strong lateral electric field. Due to the strong lateral protonic/electronic interfacial coupling effect, the IZO EDL transistor could operate at a low-voltage of 1 V. A resistor-loaded inverter is built, showing a high voltage gain of ˜8 at a low supply voltage of 1 V. The lateral ionic/electronic coupling effects are interesting for bioelectronics and portable electronics.

  6. All-inkjet-printed thin-film transistors: manufacturing process reliability by root cause analysis

    PubMed Central

    Sowade, Enrico; Ramon, Eloi; Mitra, Kalyan Yoti; Martínez-Domingo, Carme; Pedró, Marta; Pallarès, Jofre; Loffredo, Fausta; Villani, Fulvia; Gomes, Henrique L.; Terés, Lluís; Baumann, Reinhard R.

    2016-01-01

    We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement. PMID:27649784

  7. Pulse Thermal Processing for Low Thermal Budget Integration of IGZO Thin Film Transistors

    DOE PAGES

    Noh, Joo Hyon; Joshi, Pooran C.; Kuruganti, Teja; Rack, Philip D.

    2014-11-26

    Pulse thermal processing (PTP) has been explored for low thermal budget integration of indium gallium zinc oxide (IGZO) thin film transistors (TFTs). The IGZO TFTs are exposed to a broadband (0.2-1.4 m) arc lamp radiation spectrum with 100 pulses of 1 msec pulse width. The impact of radiant exposure power on the TFT performance was analyzed in terms of the switching characteristics and bias stress reliability characteristics, respectively. The PTP treated IGZO TFTs with power density of 3.95 kW/cm2 and 0.1 sec total irradiation time showed comparable switching properties, at significantly lower thermal budget, to furnace annealed IGZO TFT. Themore » typical field effect mobility FE, threshold voltage VT, and sub-threshold gate swing S.S were calculated to be 7.8 cm2/ V s, 8.1 V, and 0.22 V/ decade, respectively. The observed performance shows promise for low thermal budget TFT integration on flexible substrates exploiting the large-area, scalable PTP technology.« less

  8. All-inkjet-printed thin-film transistors: manufacturing process reliability by root cause analysis.

    PubMed

    Sowade, Enrico; Ramon, Eloi; Mitra, Kalyan Yoti; Martínez-Domingo, Carme; Pedró, Marta; Pallarès, Jofre; Loffredo, Fausta; Villani, Fulvia; Gomes, Henrique L; Terés, Lluís; Baumann, Reinhard R

    2016-01-01

    We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement. PMID:27649784

  9. All-inkjet-printed thin-film transistors: manufacturing process reliability by root cause analysis.

    PubMed

    Sowade, Enrico; Ramon, Eloi; Mitra, Kalyan Yoti; Martínez-Domingo, Carme; Pedró, Marta; Pallarès, Jofre; Loffredo, Fausta; Villani, Fulvia; Gomes, Henrique L; Terés, Lluís; Baumann, Reinhard R

    2016-09-21

    We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement.

  10. Wafer scale fabrication of carbon nanotube thin film transistors with high yield

    NASA Astrophysics Data System (ADS)

    Tian, Boyuan; Liang, Xuelei; Yan, Qiuping; Zhang, Han; Xia, Jiye; Dong, Guodong; Peng, Lianmao; Xie, Sishen

    2016-07-01

    Carbon nanotube thin film transistors (CNT-TFTs) are promising candidates for future high performance and low cost macro-electronics. However, most of the reported CNT-TFTs are fabricated in small quantities on a relatively small size substrate. The yield of large scale fabrication and the performance uniformity of devices on large size substrates should be improved before the CNT-TFTs reach real products. In this paper, 25 200 devices, with various geometries (channel width and channel length), were fabricated on 4-in. size ridged and flexible substrates. Almost 100% device yield were obtained on a rigid substrate with high out-put current (>8 μA/μm), high on/off current ratio (>105), and high mobility (>30 cm2/V.s). More importantly, uniform performance in 4-in. area was achieved, and the fabrication process can be scaled up. The results give us more confidence for the real application of the CNT-TFT technology in the near future.

  11. Pulse Thermal Processing for Low Thermal Budget Integration of IGZO Thin Film Transistors

    SciTech Connect

    Noh, Joo Hyon; Joshi, Pooran C.; Kuruganti, Teja; Rack, Philip D.

    2014-11-26

    Pulse thermal processing (PTP) has been explored for low thermal budget integration of indium gallium zinc oxide (IGZO) thin film transistors (TFTs). The IGZO TFTs are exposed to a broadband (0.2-1.4 m) arc lamp radiation spectrum with 100 pulses of 1 msec pulse width. The impact of radiant exposure power on the TFT performance was analyzed in terms of the switching characteristics and bias stress reliability characteristics, respectively. The PTP treated IGZO TFTs with power density of 3.95 kW/cm2 and 0.1 sec total irradiation time showed comparable switching properties, at significantly lower thermal budget, to furnace annealed IGZO TFT. The typical field effect mobility FE, threshold voltage VT, and sub-threshold gate swing S.S were calculated to be 7.8 cm2/ V s, 8.1 V, and 0.22 V/ decade, respectively. The observed performance shows promise for low thermal budget TFT integration on flexible substrates exploiting the large-area, scalable PTP technology.

  12. All-inkjet-printed thin-film transistors: manufacturing process reliability by root cause analysis

    NASA Astrophysics Data System (ADS)

    Sowade, Enrico; Ramon, Eloi; Mitra, Kalyan Yoti; Martínez-Domingo, Carme; Pedró, Marta; Pallarès, Jofre; Loffredo, Fausta; Villani, Fulvia; Gomes, Henrique L.; Terés, Lluís; Baumann, Reinhard R.

    2016-09-01

    We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement.

  13. Microcrystallinity of Undoped Amorphous Silicon Films and Its Effects on the Transfer Characteristics of Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Liang, Chia-Wen; Chiang, Wen-Chuan; Feng, Ming-Shiann

    1995-11-01

    The microcrystallinity of hydrogenated amorphous silicon films deposited by the conventional radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) method and its dependence on chamber pressure are discussed. In a wide range of pressure at which the microcrystalline film can be formed, a critical pressure (500 mT) is found. Films deposited at this critical pressure possess the highest crystalline volume fraction and the smallest grain size. An ion-bombardment-assisted model is proposed to explain the experimental results. Concerning the applications of microcrystalline films to thin-film transistors (TFTs), the subthreshold swing and the field effect mobility are studied, both of which are found to be smaller than those of the hydrogenated amorphous silicon (a-Si:H) TFTs.

  14. Thin film transistors gas sensors based on reduced graphene oxide poly(3-hexylthiophene) bilayer film for nitrogen dioxide detection

    NASA Astrophysics Data System (ADS)

    Xie, Tao; Xie, Guangzhong; Zhou, Yong; Huang, Junlong; Wu, Mei; Jiang, Yadong; Tai, Huiling

    2014-10-01

    Reduced graphene oxide (RGO)/poly(3-hexylthiophene) (P3HT) bilayer films were firstly utilized as active layers in OTFT gas sensors for nitrogen dioxide (NO2) detection. The OTFT with RGO/P3HT bilayer film exhibited the typical transistor characteristics and better gas sensing properties at room temperature. The electrical parameters of OTFTs based on pure P3HT film and RGO/P3HT bilayer film were calculated. The threshold voltage of OTFT was positively shifted due to the high concentration carriers in RGO. The sensing properties of the sensor with RGO/P3HT bilayer film were also investigated. Moreover, the sensing mechanism was analyzed as well.

  15. Short channel effects in regioregular poly(thiophene) thin film transistors

    NASA Astrophysics Data System (ADS)

    Chabinyc, Michael L.; Lu, Jeng-Ping; Street, Robert A.; Wu, Yiliang; Liu, Ping; Ong, Beng S.

    2004-08-01

    The effects of the physical channel length on the current-voltage characteristics of thin film transistors (TFTs) made with poly[5,5'-bis(3-dodecyl-2-thienyl)-2,2'-bithiophene] were examined. Coplanar transistors with fully patterned electrodes on insulating substrates and with a common gate structure on thermal oxide were fabricated. The output characteristics of TFTs with channel lengths shorter than 10μm showed the presence of a parasitic contact resistance and the lack of current saturation. The origin of these nonidealities was examined by the application of models that included self-heating effects and breakdown of the channel region at high applied biases. The analysis suggests that carriers can break away from the channel at high bias voltages and flow through a bulk region of the semiconducting film leading to higher currents than otherwise expected.

  16. Solution-processed hybrid organic-inorganic complementary thin-film transistor inverter

    NASA Astrophysics Data System (ADS)

    Cheong, Heajeong; Kuribara, Kazunori; Ogura, Shintaro; Fukuda, Nobuko; Yoshida, Manabu; Ushijima, Hirobumi; Uemura, Sei

    2016-04-01

    We investigated hybrid organic-inorganic complementary inverters with a solution-processed indium-gallium-zinc-oxide (IGZO) n-channel thin-film transistor (TFT) and p-channel TFTs using the high-uniformity polymer poly[2,5-bis(alkyl)pyrrolo[3,4-c]pyrrolo-1,4(2H,5H)-dione-alt-5,5-di(thiophene-2-yl)-2,2-(E)-2-(2-(thiophen-2-yl)vinyl)thiophene] (PDVT-10). The IGZO TFT was fabricated at 150 °C for 1 min. It showed a high field-effect mobility of 0.9 cm2·V-1·s-1 and a high on/off current ratio of 107. A hybrid complementary inverter was fabricated by combining IGZO with a PDVT-10 thin-film transistor and its operation was confirmed.

  17. Investigation of Ultraviolet Light Curable Polysilsesquioxane Gate Dielectric Layers for Pentacene Thin Film Transistors.

    PubMed

    Shibao, Hideto; Nakahara, Yoshio; Uno, Kazuyuki; Tanaka, Ichiro

    2016-04-01

    Polysilsesquioxane (PSQ) comprising 3-methacryloxypropyl groups was investigated as an ultraviolet (UV)-light curable gate dielectric-material for pentacene thin film transistors (TFTs). The surface of UV-light cured PSQ films was smoother than that of thermally cured ones, and the pentacene layers deposited on the UV-Iight cured PSQ films consisted of larger grains. However, carrier mobility of the TFTs using the UV-light cured PSQ films was lower than that of the TFTs using the thermally cured ones. It was shown that the cross-linker molecules, which were only added to the UV-light cured PSQ films, worked as a major mobility-limiting factor for the TFTs.

  18. Investigation of Ultraviolet Light Curable Polysilsesquioxane Gate Dielectric Layers for Pentacene Thin Film Transistors.

    PubMed

    Shibao, Hideto; Nakahara, Yoshio; Uno, Kazuyuki; Tanaka, Ichiro

    2016-04-01

    Polysilsesquioxane (PSQ) comprising 3-methacryloxypropyl groups was investigated as an ultraviolet (UV)-light curable gate dielectric-material for pentacene thin film transistors (TFTs). The surface of UV-light cured PSQ films was smoother than that of thermally cured ones, and the pentacene layers deposited on the UV-Iight cured PSQ films consisted of larger grains. However, carrier mobility of the TFTs using the UV-light cured PSQ films was lower than that of the TFTs using the thermally cured ones. It was shown that the cross-linker molecules, which were only added to the UV-light cured PSQ films, worked as a major mobility-limiting factor for the TFTs. PMID:27451626

  19. Organic transistors manufactured using inkjet technology with subfemtoliter accuracy

    PubMed Central

    Sekitani, Tsuyoshi; Noguchi, Yoshiaki; Zschieschang, Ute; Klauk, Hagen; Someya, Takao

    2008-01-01

    A major obstacle to the development of organic transistors for large-area sensor, display, and circuit applications is the fundamental compromise between manufacturing efficiency, transistor performance, and power consumption. In the past, improving the manufacturing efficiency through the use of printing techniques has inevitably resulted in significantly lower performance and increased power consumption, while attempts to improve performance or reduce power have led to higher process temperatures and increased manufacturing cost. Here, we lift this fundamental limitation by demonstrating subfemtoliter inkjet printing to define metal contacts with single-micrometer resolution on the surface of high-mobility organic semiconductors to create high-performance p-channel and n-channel transistors and low-power complementary circuits. The transistors employ an ultrathin low-temperature gate dielectric based on a self-assembled monolayer that allows transistors and circuits on rigid and flexible substrates to operate with very low voltages. PMID:18362348

  20. Codoping of zinc and tungsten for practical high-performance amorphous indium-based oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Kizu, Takio; Mitoma, Nobuhiko; Miyanaga, Miki; Awata, Hideaki; Nabatame, Toshihide; Tsukagoshi, Kazuhito

    2015-09-01

    Using practical high-density sputtering targets, we investigated the effect of Zn and W codoping on the thermal stability of the amorphous film and the electrical characteristics in thin film transistors. zinc oxide is a potentially conductive component while W oxide is an oxygen vacancy suppressor in oxide films. The oxygen vacancy from In-O and Zn-O was suppressed by the W additive because of the high oxygen bond dissociation energy. With controlled codoping of W and Zn, we demonstrated a high mobility with a maximum mobility of 40 cm2/V s with good stability under a negative bias stress in InWZnO thin film transistors.

  1. Black Phosphorus RF Transistor

    NASA Astrophysics Data System (ADS)

    Wang, Han; Wang, Xiaomu; Xia, Fengnian; Wang, Luhao; Jiang, Hao; Xia, Qiangfei; Chin, Mattew L.; Dubey, Madan; Han, Shu-Jen

    2015-03-01

    Few-layer and thin film form of layered black phosphorus (BP) has recently emerged as a promising material for applications in high performance thin film electronics and infrared optoelectronics. Layered BP offers a ~ 0.3eV bandgap and high mobility, leading to transistor devices with decent on/off ratio and high on-state current density. Here, we demonstrate the GHz frequency operation of black phosphorus field-effect transistor for the first time. BP transistors demonstrated here show excellent current saturation with an on-off ratio exceeding 2 × 103. The S-parameter characterization is performed for the first time on black phosphorus transistors, giving a 12 GHz short-circuit current-gain cut-off frequency and 20 GHz maximum oscillation frequency in 300 nm channel length devices. A current density in excess of 270 mA/mm and DC transconductance above 180 mS/mm are achieved for hole conductions. The results reveal the promising potential of black phosphorus transistors for enabling the next generation thin film transistor technology that can operate in the multi-GHz frequency range and beyond.

  2. Thin film transistors on plastic substrates with reflective coatings for radiation protection

    SciTech Connect

    Wolfe, Jesse D.; Theiss, Steven D.; Carey, Paul G.; Smith, Patrick M.; Wickboldt, Paul

    2003-11-04

    Fabrication of silicon thin film transistors (TFT) on low-temperature plastic substrates using a reflective coating so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The TFT can be used in large area low cost electronics, such as flat panel displays and portable electronics such as video cameras, personal digital assistants, and cell phones.

  3. Thin film transistors on plastic substrates with reflective coatings for radiation protection

    SciTech Connect

    Wolfe, Jesse D.; Theiss, Steven D.; Carey, Paul G.; Smith, Patrick M.; Wickbold, Paul

    2006-09-26

    Fabrication of silicon thin film transistors (TFT) on low-temperature plastic substrates using a reflective coating so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The TFT can be used in large area low cost electronics, such as flat panel displays and portable electronics such as video cameras, personal digital assistants, and cell phones.

  4. Nonlinear Transport in Organic Thin Film Transistors with Soluble Small Molecule Semiconductor.

    PubMed

    Kim, Hyeok; Song, Dong-Seok; Kwon, Jin-Hyuk; Jung, Ji-Hoon; Kim, Do-Kyung; Kim, SeonMin; Kang, In Man; Park, Jonghoo; Tae, Heung-Sik; Battaglini, Nicolas; Lang, Philippe; Horowitz, Gilles; Bae, Jin-Hyuk

    2016-03-01

    Nonlinear transport is intensively explained through Poole-Frenkel (PF) transport mechanism in organic thin film transistors with solution-processed small molecules, which is, 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene. We outline a detailed electrical study that identifies the source to drain field dependent mobility. Devices with diverse channel lengths enable the extensive exhibition of field dependent mobility due to thermal activation of carriers among traps. PMID:27455707

  5. Nonlinear Transport in Organic Thin Film Transistors with Soluble Small Molecule Semiconductor.

    PubMed

    Kim, Hyeok; Song, Dong-Seok; Kwon, Jin-Hyuk; Jung, Ji-Hoon; Kim, Do-Kyung; Kim, SeonMin; Kang, In Man; Park, Jonghoo; Tae, Heung-Sik; Battaglini, Nicolas; Lang, Philippe; Horowitz, Gilles; Bae, Jin-Hyuk

    2016-03-01

    Nonlinear transport is intensively explained through Poole-Frenkel (PF) transport mechanism in organic thin film transistors with solution-processed small molecules, which is, 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene. We outline a detailed electrical study that identifies the source to drain field dependent mobility. Devices with diverse channel lengths enable the extensive exhibition of field dependent mobility due to thermal activation of carriers among traps.

  6. Carbon nanotube network thin-film transistors on flexible/stretchable substrates

    DOEpatents

    Takei, Kuniharu; Takahashi, Toshitake; Javey, Ali

    2016-03-29

    This disclosure provides systems, methods, and apparatus for flexible thin-film transistors. In one aspect, a device includes a polymer substrate, a gate electrode disposed on the polymer substrate, a dielectric layer disposed on the gate electrode and on exposed portions of the polymer substrate, a carbon nanotube network disposed on the dielectric layer, and a source electrode and a drain electrode disposed on the carbon nanotube network.

  7. Method of fabrication of display pixels driven by silicon thin film transistors

    DOEpatents

    Carey, Paul G.; Smith, Patrick M.

    1999-01-01

    Display pixels driven by silicon thin film transistors are fabricated on plastic substrates for use in active matrix displays, such as flat panel displays. The process for forming the pixels involves a prior method for forming individual silicon thin film transistors on low-temperature plastic substrates. Low-temperature substrates are generally considered as being incapable of withstanding sustained processing temperatures greater than about 200.degree. C. The pixel formation process results in a complete pixel and active matrix pixel array. A pixel (or picture element) in an active matrix display consists of a silicon thin film transistor (TFT) and a large electrode, which may control a liquid crystal light valve, an emissive material (such as a light emitting diode or LED), or some other light emitting or attenuating material. The pixels can be connected in arrays wherein rows of pixels contain common gate electrodes and columns of pixels contain common drain electrodes. The source electrode of each pixel TFT is connected to its pixel electrode, and is electrically isolated from every other circuit element in the pixel array.

  8. Direct wafer bonding technology for large-scale InGaAs-on-insulator transistors

    SciTech Connect

    Kim, SangHyeon E-mail: sh-kim@kist.re.kr; Ikku, Yuki; Takenaka, Mitsuru; Takagi, Shinichi; Yokoyama, Masafumi; Nakane, Ryosho; Li, Jian; Kao, Yung-Chung

    2014-07-28

    Heterogeneous integration of III-V devices on Si wafers have been explored for realizing high device performance as well as merging electrical and photonic applications on the Si platform. Existing methodologies have unavoidable drawbacks such as inferior device quality or high cost in comparison with the current Si-based technology. In this paper, we present InGaAs-on-insulator (-OI) fabrication from an InGaAs layer grown on a Si donor wafer with a III-V buffer layer instead of growth on a InP donor wafer. This technology allows us to yield large wafer size scalability of III-V-OI layers up to the Si wafer size of 300 mm with a high film quality and low cost. The high film quality has been confirmed by Raman and photoluminescence spectra. In addition, the fabricated InGaAs-OI transistors exhibit the high electron mobility of 1700 cm{sup 2}/V s and uniform distribution of the leakage current, indicating high layer quality with low defect density.

  9. Simple push coating of polymer thin-film transistors

    PubMed Central

    Ikawa, Mitsuhiro; Yamada, Toshikazu; Matsui, Hiroyuki; Minemawari, Hiromi; Tsutsumi, Jun'ya; Horii, Yoshinori; Chikamatsu, Masayuki; Azumi, Reiko; Kumai, Reiji; Hasegawa, Tatsuo

    2012-01-01

    Solution processibility is a unique advantage of organic semiconductors, permitting the low-cost production of flexible electronics under ambient conditions. However, the solution affinity to substrate surfaces remains a serious dilemma; liquid manipulation is more difficult on highly hydrophobic surfaces, but the use of such surfaces is indispensable for improving device characteristics. Here we demonstrate a simple technique, which we call ‘push coating’, to produce uniform large-area semiconducting polymer films over a hydrophobic surface with eliminating material loss. We utilize a poly(dimethylsiloxane)-based trilayer stamp whose conformal contact with the substrate enables capillarity-induced wetting of the surface. Films are formed through solvent sorption and retention in the stamp, allowing the stamp to be peeled perfectly from the film. The planar film formation on hydrophobic surfaces also enables subsequent fine film patterning. The technique improves the crystallinity and field-effect mobility of stamped semiconductor films, constituting a major step towards flexible electronics production. PMID:23132026

  10. A new drain current model for amorphous IGZO thin film transistors

    NASA Astrophysics Data System (ADS)

    Qiang, Lei; Yao, Ruo-He

    2015-04-01

    Based on the conduction mechanisms of amorphous InGaZnO (a-IGZO) thin film transistors, generalized equations are derived which permit the determination of drain current characteristics. A geometry-independent definition for field effect mobility considering the ratio of free-to-trapped carriers is introduced, which conveys the properties of the active semiconducting layer. It is suggested that a drain current model that includes different charge transports gives a consistent and accurate description of the electrical behavior. The good agreement between measured and calculated results confirms the efficiency of this model for the design of integrated large-area thin-film circuits.

  11. A magnetosensitive thin-film silicon Hall-type field-effect transistor with operating temperature range expanded up to 350°C

    NASA Astrophysics Data System (ADS)

    Leonov, A. V.; Malykh, A. A.; Mordkovich, V. N.; Pavlyuk, M. I.

    2016-01-01

    We describe a magnetosensitive device consisting of a combination of a thin-film Si transistor with built-in conducting channel (fabricated by the silicon-on-insulator technology) and a Hall-type sensor (HS). The transistor has a double-gate field control system of the metal-insulator-semiconductor-insulator-metal type and operates in the regime of carrier accumulation in the channel at partial depletion of adjacent regions of the Si film. It is established that the device can operate at temperatures up to about 350°C, which is 160-180°C higher than the maximum operating temperature of HSs based on bulk Si crystals and comparable with HSs based on wide-bandgap semiconductors.

  12. In situ preparation, electrical and surface analytical characterization of pentacene thin film transistors

    PubMed Central

    Lassnig, R.; Striedinger, B.; Hollerer, M.; Fian, A.; Stadlober, B.; Winkler, A.

    2015-01-01

    The fabrication of organic thin film transistors with highly reproducible characteristics presents a very challenging task. We have prepared and analyzed model pentacene thin film transistors under ultra-high vacuum conditions, employing surface analytical tools and methods. Intentionally contaminating the gold contacts and SiO2 channel area with carbon through repeated adsorption, dissociation, and desorption of pentacene proved to be very advantageous in the creation of devices with stable and reproducible parameters. We mainly focused on the device properties, such as mobility and threshold voltage, as a function of film morphology and preparation temperature. At 300 K, pentacene displays Stranski-Krastanov growth, whereas at 200 K fine-grained, layer-like film growth takes place, which predominantly influences the threshold voltage. Temperature dependent mobility measurements demonstrate good agreement with the established multiple trapping and release model, which in turn indicates a predominant concentration of shallow traps in the crystal grains and at the oxide-semiconductor interface. Mobility and threshold voltage measurements as a function of coverage reveal that up to four full monolayers contribute to the overall charge transport. A significant influence on the effective mobility also stems from the access resistance at the gold contact-semiconductor interface, which is again strongly influenced by the temperature dependent, characteristic film growth mode. PMID:25814770

  13. Novel Low Temperature Processing for Enhanced Properties of Ion Implanted Thin Films and Amorphous Mixed Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Vemuri, Rajitha

    This research emphasizes the use of low energy and low temperature post processing to improve the performance and lifetime of thin films and thin film transistors, by applying the fundamentals of interaction of materials with conductive heating and electromagnetic radiation. Single frequency microwave anneal is used to rapidly recrystallize the damage induced during ion implantation in Si substrates. Volumetric heating of the sample in the presence of the microwave field facilitates quick absorption of radiation to promote recrystallization at the amorphous-crystalline interface, apart from electrical activation of the dopants due to relocation to the substitutional sites. Structural and electrical characterization confirm recrystallization of heavily implanted Si within 40 seconds anneal time with minimum dopant diffusion compared to rapid thermal annealed samples. The use of microwave anneal to improve performance of multilayer thin film devices, e.g. thin film transistors (TFTs) requires extensive study of interaction of individual layers with electromagnetic radiation. This issue has been addressed by developing detail understanding of thin films and interfaces in TFTs by studying reliability and failure mechanisms upon extensive stress test. Electrical and ambient stresses such as illumination, thermal, and mechanical stresses are inflicted on the mixed oxide based thin film transistors, which are explored due to high mobilities of the mixed oxide (indium zinc oxide, indium gallium zinc oxide) channel layer material. Semiconductor parameter analyzer is employed to extract transfer characteristics, useful to derive mobility, subthreshold, and threshold voltage parameters of the transistors. Low temperature post processing anneals compatible with polymer substrates are performed in several ambients (oxygen, forming gas and vacuum) at 150 °C as a preliminary step. The analysis of the results pre and post low temperature anneals using device physics fundamentals

  14. Metal Oxide Thin Film Transistors on Paper Substrate: Fabrication, Characterization, and Printing Process

    NASA Astrophysics Data System (ADS)

    Choi, Nack-Bong

    Flexible electronics is an emerging next-generation technology that offers many advantages such as light weight, durability, comfort, and flexibility. These unique features enable many new applications such as flexible display, flexible sensors, conformable electronics, and so forth. For decades, a variety of flexible substrates have been demonstrated for the application of flexible electronics. Most of them are plastic films and metal foils so far. For the fundamental device of flexible circuits, thin film transistors (TFTs) using poly silicon, amorphous silicon, metal oxide and organic semiconductor have been successfully demonstrated. Depending on application, low-cost and disposable flexible electronics will be required for convenience. Therefore it is important to study inexpensive substrates and to explore simple processes such as printing technology. In this thesis, paper is introduced as a new possible substrate for flexible electronics due to its low-cost and renewable property, and amorphous indium gallium zinc oxide (a-IGZO) TFTs are realized as the promising device on the paper substrate. The fabrication process and characterization of a-IGZO TFT on the paper substrate are discussed. a-IGZO TFTs using a polymer gate dielectric on the paper substrate demonstrate excellent performances with field effect mobility of ˜20 cm2 V-1 s-1, on/off current ratio of ˜106, and low leakage current, which show the enormous potential for flexible electronics application. In order to complement the n-channel a-IGZO TFTs and then enable complementary metal-oxide semiconductor (CMOS) circuit architectures, cuprous oxide is studied as a candidate material of p-channel oxide TFTs. In this thesis, a printing process is investigated as an alternative method for the fabrication of low-cost and disposable electronics. Among several printing methods, a modified offset roll printing that prints high resolution patterns is presented. A new method to fabricate a high resolution

  15. Stable and High-Performance Flexible ZnO Thin-Film Transistors by Atomic Layer Deposition.

    PubMed

    Lin, Yuan-Yu; Hsu, Che-Chen; Tseng, Ming-Hung; Shyue, Jing-Jong; Tsai, Feng-Yu

    2015-10-14

    Passivation is a challenging issue for the oxide thin-film transistor (TFT) technologies because it requires prolonged high-temperature annealing treatments to remedy defects produced in the process, which greatly limits its manufacturability as well as its compatibility with temperature-sensitive materials such as flexible plastic substrates. This study investigates the defect-formation mechanisms incurred by atomic layer deposition (ALD) passivation processes on ZnO TFTs, based on which we demonstrate for the first time degradation-free passivation of ZnO TFTs by a TiO2/Al2O3 nanolaminated (TAO) film deposited by a low-temperature (110 °C) ALD process. By combining the TAO passivation film with ALD dielectric and channel layers into an integrated low-temperature ALD process, we successfully fabricate flexible ZnO TFTs on plastics. Thanks to the exceptional gas-barrier property of the TAO film (water vapor transmission rate (WVTR)<10(-6) g m(-2) day(-1)) as well as the defect-free nature of the ALD dielectric and ZnO channel layers, the TFTs exhibit excellent device performance with high stability and flexibility: field-effect mobility>20 cm2 V(-1) s(-1), subthreshold swing<0.4 V decade(-1) after extended bias-stressing (>10,000 s), air-storage (>1200 h), and bending (1.3 cm radius for 1000 times). PMID:26436832

  16. Stable and High-Performance Flexible ZnO Thin-Film Transistors by Atomic Layer Deposition.

    PubMed

    Lin, Yuan-Yu; Hsu, Che-Chen; Tseng, Ming-Hung; Shyue, Jing-Jong; Tsai, Feng-Yu

    2015-10-14

    Passivation is a challenging issue for the oxide thin-film transistor (TFT) technologies because it requires prolonged high-temperature annealing treatments to remedy defects produced in the process, which greatly limits its manufacturability as well as its compatibility with temperature-sensitive materials such as flexible plastic substrates. This study investigates the defect-formation mechanisms incurred by atomic layer deposition (ALD) passivation processes on ZnO TFTs, based on which we demonstrate for the first time degradation-free passivation of ZnO TFTs by a TiO2/Al2O3 nanolaminated (TAO) film deposited by a low-temperature (110 °C) ALD process. By combining the TAO passivation film with ALD dielectric and channel layers into an integrated low-temperature ALD process, we successfully fabricate flexible ZnO TFTs on plastics. Thanks to the exceptional gas-barrier property of the TAO film (water vapor transmission rate (WVTR)<10(-6) g m(-2) day(-1)) as well as the defect-free nature of the ALD dielectric and ZnO channel layers, the TFTs exhibit excellent device performance with high stability and flexibility: field-effect mobility>20 cm2 V(-1) s(-1), subthreshold swing<0.4 V decade(-1) after extended bias-stressing (>10,000 s), air-storage (>1200 h), and bending (1.3 cm radius for 1000 times).

  17. Air-Flow Navigated Crystal Growth for TIPS Pentacene-Based Organic Thin-Film Transistors

    SciTech Connect

    He, Zhengran; Chen, Jihua; Sun, Zhenzhong; Szulczewski, Greg; Li, Dawen

    2012-01-01

    6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene) is a promising active channel material of organic thin-film transistors (OTFTs) due to its solubility, stability, and high mobility. However, the growth of TIPS pentacene crystals is intrinsically anisotropic and thus leads to significant variation in the performance of OTFTs. In this paper, air flow is utilized to effectively reduce the TIPS pentacene crystal anisotropy and enhance performance consistency in OTFTs, and the resulted films are examined with optical microscopy, grazing-incidence X-ray diffraction, and thin-film transistor measurements. Under air-flow navigation (AFN), TIPS pentacene drop-cast from toluene solution has been observed to form thin films with improved crystal orientation and increased areal coverage on substrates, which subsequently lead to a four-fold increase of average hole mobility and one order of magnitude enhancement in performance consistency defined by the ratio of average mobility to the standard deviation of the field-effect mobilities.

  18. Organic ferroelectric gate field-effect transistor memory using high-mobility rubrene thin film

    NASA Astrophysics Data System (ADS)

    Kanashima, Takeshi; Katsura, Yuu; Okuyama, Masanori

    2014-01-01

    An organic ferroelectric gate field-effect transistor (FET) memory has been fabricated using an organic semiconductor of rubrene thin film with a high mobility and a gate insulating layer of poly(vinylidene fluoride-tetrafluoroethylene) [P(VDF-TeFE)] thin film. A rubrene thin-film sheet was grown by physical vapor transport (PVT), and placed onto a spin-coated P(VDF-TeFE) thin-film layer, and Au source and drain electrodes were formed on this rubrene thin film. A hysteresis loop of the drain current-gate voltage (ID-VG) characteristic has been clearly observed in the ferroelectric gate FET, and is caused by the ferroelectricity. The maximum drain current is 1.5 × 10-6 A, which is about two orders of magnitude larger than that of the P(VDF-TeFE) gate FET using a pentacene thin film. Moreover, the mobility of this organic ferroelectric gate FET using rubrene thin film is 0.71 cm2 V-1 s-1, which is 35 times larger than that of the FET with pentacene thin film.

  19. Printable ion-gel gate dielectrics for low-voltage polymer thin-film transistors on plastic

    NASA Astrophysics Data System (ADS)

    Cho, Jeong Ho; Lee, Jiyoul; Xia, Yu; Kim, Bongsoo; He, Yiyong; Renn, Michael J.; Lodge, Timothy P.; Daniel Frisbie, C.

    2008-11-01

    An important strategy for realizing flexible electronics is to use solution-processable materials that can be directly printed and integrated into high-performance electronic components on plastic. Although examples of functional inks based on metallic, semiconducting and insulating materials have been developed, enhanced printability and performance is still a challenge. Printable high-capacitance dielectrics that serve as gate insulators in organic thin-film transistors are a particular priority. Solid polymer electrolytes (a salt dissolved in a polymer matrix) have been investigated for this purpose, but they suffer from slow polarization response, limiting transistor speed to less than 100Hz. Here, we demonstrate that an emerging class of polymer electrolytes known as ion gels can serve as printable, high-capacitance gate insulators in organic thin-film transistors. The specific capacitance exceeds that of conventional ceramic or polymeric gate dielectrics, enabling transistor operation at low voltages with kilohertz switching frequencies.

  20. Differentiation of Effects due to Grain and Grain Boundary Traps in Laser Annealed Poly-Si Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Armstrong, G.; Uppal, S.; Brotherton, S.; Ayres, J.

    1998-04-01

    A new physical model based on two dimensional simulations for high quality laser re-crystallised poly-Si thin film transistors is presented. It has been shown that to adequately explain the improved subthreshold slope and the lack of saturation of the output characteristics in these transistors, it is essential to distribute the density of defect states between traps in the grains alongside traps localised at grain boundaries. A double exponential density of states has been extracted for thin film transistors (TFTs) annealed at different excimer laser energies, using the field effect conductance method. By splitting the density of states between grain traps and grain boundary traps good fits to the output characteristics have been achieved. Lack of saturation is shown to be due to decrease in potential barrier at grain boundaries with increase in drain bias. At high gate voltages, however, evidence of a self-heating effect similar to that observed in silicon-on-insulator (SOI) transistors is apparent.

  1. Transparent ambipolar organic thin film transistors based on multilayer transparent source-drain electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Nan; Hu, Yongsheng; Lin, Jie; Li, Yantao; Liu, Xingyuan

    2016-08-01

    A fabrication method for transparent ambipolar organic thin film transistors with transparent Sb2O3/Ag/Sb2O3 (SAS) source and drain electrodes has been developed. A pentacene/N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic di-imide (PTCDI-C13) bilayer heterojunction is used as the active semiconductor. The electrodes are deposited by room temperature electron beam evaporation. The devices are fabricated without damaging the active layers. The SAS electrodes have high transmittance (82.5%) and low sheet resistance (8 Ω/sq). High performance devices with hole and electron mobilities of 0.3 cm2/V s and 0.027 cm2/V s, respectively, and average visible range transmittance of 72% were obtained. These transistors have potential for transparent logic integrated circuit applications.

  2. Conduction mechanism in amorphous InGaZnO thin film transistors

    NASA Astrophysics Data System (ADS)

    Bhoolokam, Ajay; Nag, Manoj; Steudel, Soeren; Genoe, Jan; Gelinck, Gerwin; Kadashchuk, Andrey; Groeseneken, Guido; Heremans, Paul

    2016-01-01

    We validate a model which is a combination of multiple trapping and release and percolation model for describing the conduction mechanism in amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFT). We show that using just multiple trapping and release or percolation model is insufficient to explain TFT behavior as a function of temperature. We also show the intrinsic mobility is dependent on temperature due to scattering by ionic impurities or lattice. In solving the Poisson equation to find the surface potential and back potential as a function of gate voltage, we explicitly allow for the back surface to be floating, as is the case for a-IGZO transistors. The parameters for gap states, percolation barriers and intrinsic mobility at room temperature that we extract with this comprehensive model are in good agreement with those extracted in literature with partially-complete models.

  3. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    SciTech Connect

    Aïssa, B.; Nedil, M.; Kroeger, J.; Haddad, T.; Rosei, F.

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  4. Directional solidification of C8-BTBT films induced by temperature gradients and its application for transistors

    NASA Astrophysics Data System (ADS)

    Fujieda, Ichiro; Iizuka, Naoki; Onishi, Yosuke

    2015-03-01

    Because charge transport in a single crystal is anisotropic in nature, directional growth of single crystals would enhance device performance and reduce its variation among devices. For an organic thin film, a method based on a temperature gradient would offer advantages in throughput and cleanliness. In experiments, a temperature gradient was established in a spin-coated film of 2,7-dioctyl [1]benzothieno[3,2-b]benzothiophene (C8-BTBT) by two methods. First, a sample was placed on a metal plate bridging two heat stages. When one of the heat stages was cooled, the material started to solidify from the colder region. The melt-solid interface proceeded along the temperature gradient. Cracks were formed perpendicular to the solidification direction. Second, a line-shaped region on the film was continuously exposed to the light from a halogen lamp. After the heat stage was cooled, cracks similar to the first experiment were observed, indicating that the melt-solid interface moved laterally. We fabricated top-contact, bottom-gate transistors with these films. Despite the cracks, field-effect mobility of the transistors fabricated with these films was close to 6 cm2 /Vs and 4 cm2 /Vs in the first and second experiment, respectively. Elimination of cracks would improve charge transport and reduce performance variation among devices. It should be noted that the intense light from the halogen lamp did not damage the C8-BTBT films. The vast knowledge on laser annealing is now available for directional growth of this type of materials. The associated cost would be much smaller because an organic thin film melts at a low temperature.

  5. Noise Characterization of Polycrystalline Silicon Thin Film Transistors for X-ray Imagers Based on Active Pixel Architectures.

    PubMed

    Antonuk, L E; Koniczek, M; McDonald, J; El-Mohri, Y; Zhao, Q; Behravan, M

    2008-01-01

    An examination of the noise of polycrystalline silicon thin film transistors, in the context of flat panel x-ray imager development, is reported. The study was conducted in the spirit of exploring how the 1/f, shot and thermal noise components of poly-Si TFTs, determined from current noise power spectral density measurements, as well as through calculation, can be used to assist in the development of imagers incorporating pixel amplification circuits based on such transistors. PMID:20862269

  6. High-density carrier-accumulated and electrically stable oxide thin-film transistors from ion-gel gate dielectric

    NASA Astrophysics Data System (ADS)

    Fujii, Mami N.; Ishikawa, Yasuaki; Miwa, Kazumoto; Okada, Hiromi; Uraoka, Yukiharu; Ono, Shimpei

    2015-12-01

    The use of indium-gallium-zinc oxide (IGZO) has paved the way for high-resolution uniform displays or integrated circuits with transparent and flexible devices. However, achieving highly reliable devices that use IGZO for low-temperature processes remains a technological challenge. We propose the use of IGZO thin-film transistors (TFTs) with an ionic-liquid gate dielectric in order to achieve high-density carrier-accumulated IGZO TFTs with high reliability, and we discuss a distinctive mechanism for the degradation of this organic-inorganic hybrid device under long-term electrical stress. Our results demonstrated that an ionic liquid or gel gate dielectric provides highly reliable and low-voltage operation with IGZO TFTs. Furthermore, high-density carrier accumulation helps improve the TFT characteristics and reliability, and it is highly relevant to the electronic phase control of oxide materials and the degradation mechanism for organic-inorganic hybrid devices.

  7. High-density carrier-accumulated and electrically stable oxide thin-film transistors from ion-gel gate dielectric.

    PubMed

    Fujii, Mami N; Ishikawa, Yasuaki; Miwa, Kazumoto; Okada, Hiromi; Uraoka, Yukiharu; Ono, Shimpei

    2015-01-01

    The use of indium-gallium-zinc oxide (IGZO) has paved the way for high-resolution uniform displays or integrated circuits with transparent and flexible devices. However, achieving highly reliable devices that use IGZO for low-temperature processes remains a technological challenge. We propose the use of IGZO thin-film transistors (TFTs) with an ionic-liquid gate dielectric in order to achieve high-density carrier-accumulated IGZO TFTs with high reliability, and we discuss a distinctive mechanism for the degradation of this organic-inorganic hybrid device under long-term electrical stress. Our results demonstrated that an ionic liquid or gel gate dielectric provides highly reliable and low-voltage operation with IGZO TFTs. Furthermore, high-density carrier accumulation helps improve the TFT characteristics and reliability, and it is highly relevant to the electronic phase control of oxide materials and the degradation mechanism for organic-inorganic hybrid devices. PMID:26677773

  8. High-density carrier-accumulated and electrically stable oxide thin-film transistors from ion-gel gate dielectric

    PubMed Central

    Fujii, Mami N.; Ishikawa, Yasuaki; Miwa, Kazumoto; Okada, Hiromi; Uraoka, Yukiharu; Ono, Shimpei

    2015-01-01

    The use of indium–gallium–zinc oxide (IGZO) has paved the way for high-resolution uniform displays or integrated circuits with transparent and flexible devices. However, achieving highly reliable devices that use IGZO for low-temperature processes remains a technological challenge. We propose the use of IGZO thin-film transistors (TFTs) with an ionic-liquid gate dielectric in order to achieve high-density carrier-accumulated IGZO TFTs with high reliability, and we discuss a distinctive mechanism for the degradation of this organic–inorganic hybrid device under long-term electrical stress. Our results demonstrated that an ionic liquid or gel gate dielectric provides highly reliable and low-voltage operation with IGZO TFTs. Furthermore, high-density carrier accumulation helps improve the TFT characteristics and reliability, and it is highly relevant to the electronic phase control of oxide materials and the degradation mechanism for organic–inorganic hybrid devices. PMID:26677773

  9. MgZnO High Voltage Thin Film Transistors on Glass for Inverters in Building Integrated Photovoltaics

    NASA Astrophysics Data System (ADS)

    Hong, Wen-Chiang; Ku, Chieh-Jen; Li, Rui; Abbaslou, Siamak; Reyes, Pavel; Wang, Szu-Ying; Li, Guangyuan; Lu, Ming; Sheng, Kuang; Lu, Yicheng

    2016-10-01

    Building integrated photovoltaics (BIPV) have attracted considerable interests because of its aesthetically attractive appearance and overall low cost. In BIPV, system integration on a glass substrate like windows is essential to cover a large area of a building with low cost. However, the conventional high voltage devices in inverters have to be built on the specially selected single crystal substrates, limiting its application for large area electronic systems, such as the BIPV. We demonstrate a Magnesium Zinc Oxide (MZO) based high voltage thin film transistor (HVTFT) built on a transparent glass substrate. The devices are designed with unique ring-type structures and use modulated Mg doping in the channel - gate dielectric interface, resulting in a blocking voltage of over 600 V. In addition to BIPV, the MZO HVTFT based inverter technology also creates new opportunities for emerging self-powered smart glass.

  10. MgZnO High Voltage Thin Film Transistors on Glass for Inverters in Building Integrated Photovoltaics

    PubMed Central

    Hong, Wen-Chiang; Ku, Chieh-Jen; Li, Rui; Abbaslou, Siamak; Reyes, Pavel; Wang, Szu-Ying; Li, Guangyuan; Lu, Ming; Sheng, Kuang; Lu, Yicheng

    2016-01-01

    Building integrated photovoltaics (BIPV) have attracted considerable interests because of its aesthetically attractive appearance and overall low cost. In BIPV, system integration on a glass substrate like windows is essential to cover a large area of a building with low cost. However, the conventional high voltage devices in inverters have to be built on the specially selected single crystal substrates, limiting its application for large area electronic systems, such as the BIPV. We demonstrate a Magnesium Zinc Oxide (MZO) based high voltage thin film transistor (HVTFT) built on a transparent glass substrate. The devices are designed with unique ring-type structures and use modulated Mg doping in the channel - gate dielectric interface, resulting in a blocking voltage of over 600 V. In addition to BIPV, the MZO HVTFT based inverter technology also creates new opportunities for emerging self-powered smart glass. PMID:27721484

  11. Tungsten oxide proton conducting films for low-voltage transparent oxide-based thin-film transistors

    SciTech Connect

    Zhang, Hongliang; Wan, Qing; Wan, Changjin; Wu, Guodong; Zhu, Liqiang

    2013-02-04

    Tungsten oxide (WO{sub x}) electrolyte films deposited by reactive magnetron sputtering showed a high room temperature proton conductivity of 1.38 Multiplication-Sign 10{sup -4} S/cm with a relative humidity of 60%. Low-voltage transparent W-doped indium-zinc-oxide thin-film transistors gated by WO{sub x}-based electrolytes were self-assembled on glass substrates by one mask diffraction method. Enhancement mode operation with a large current on/off ratio of 4.7 Multiplication-Sign 10{sup 6}, a low subthreshold swing of 108 mV/decade, and a high field-effect mobility 42.6 cm{sup 2}/V s was realized. Our results demonstrated that WO{sub x}-based proton conducting films were promising gate dielectric candidates for portable low-voltage oxide-based devices.

  12. Tungsten oxide proton conducting films for low-voltage transparent oxide-based thin-film transistors

    NASA Astrophysics Data System (ADS)

    Zhang, Hongliang; Wan, Qing; Wan, Changjin; Wu, Guodong; Zhu, Liqiang

    2013-02-01

    Tungsten oxide (WOx) electrolyte films deposited by reactive magnetron sputtering showed a high room temperature proton conductivity of 1.38 × 10-4 S/cm with a relative humidity of 60%. Low-voltage transparent W-doped indium-zinc-oxide thin-film transistors gated by WOx-based electrolytes were self-assembled on glass substrates by one mask diffraction method. Enhancement mode operation with a large current on/off ratio of 4.7 × 106, a low subthreshold swing of 108 mV/decade, and a high field-effect mobility 42.6 cm2/V s was realized. Our results demonstrated that WOx-based proton conducting films were promising gate dielectric candidates for portable low-voltage oxide-based devices.

  13. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    SciTech Connect

    Lee, Ching-Ting Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-28

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance g{sub m} change, threshold voltage V{sub T} change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  14. Crystallization behavior of amorphous indium-gallium-zinc-oxide films and its effects on thin-film transistor performance

    NASA Astrophysics Data System (ADS)

    Suko, Ayaka; Jia, JunJun; Nakamura, Shin-ichi; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki; Shigesato, Yuzo

    2016-03-01

    Amorphous indium-gallium-zinc oxide (a-IGZO) films were deposited by DC magnetron sputtering and post-annealed in air at 300-1000 °C for 1 h to investigate the crystallization behavior in detail. X-ray diffraction, electron beam diffraction, and high-resolution electron microscopy revealed that the IGZO films showed an amorphous structure after post-annealing at 300 °C. At 600 °C, the films started to crystallize from the surface with c-axis preferred orientation. At 700-1000 °C, the films totally crystallized into polycrystalline structures, wherein the grains showed c-axis preferred orientation close to the surface and random orientation inside the films. The current-gate voltage (Id-Vg) characteristics of the IGZO thin-film transistor (TFT) showed that the threshold voltage (Vth) and subthreshold swing decreased markedly after the post-annealing at 300 °C. The TFT using the totally crystallized films also showed the decrease in Vth, whereas the field-effect mobility decreased considerably.

  15. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-01

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance gm change, threshold voltage VT change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  16. High-Performance Thin Film Transistor from Solution-Processed P3HT Polymer Semiconductor Nanoparticles

    NASA Astrophysics Data System (ADS)

    Darwis, Darmawati; Elkington, Daniel; Ulum, Syahrul; Stapleton, Andrew; Bryant, Glenn; Zhou, Xiaojing; Belcher, Warwick; Dastoor, Paul

    2011-12-01

    Nanoparticulate suspensions of semiconducting polymer poly-3-hexylthiophene (P3HT) have been prepared in water through a mini-emulsion process using sodium dodecyl sulphate (SDS) as the surfactant. Using these suspensions, we have fabricated organic thin film transistors (OTFTs) in a top gate configuration. These devices operate at a low voltage and show output characteristics similar to those achieved when the P3HT film is spun from chloroform. To characterize the properties of the film made from the nanoparticle suspension, differential thermal analysis (TGA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), fluorescence spectra analysis, ultraviolet/visible (UV/VIS) spectrophotometry and X-ray photoelectron spectroscopy (XPS) have been used.

  17. Electric bistability in pentacene film-based transistor embedding gold nanoparticles.

    PubMed

    Tseng, Chiao-Wei; Tao, Yu-Tai

    2009-09-01

    Pentacene films were deposited on a silica surface decorated with gold nanoparticles (Au-NPs). The crystallinity and packing orientation of the film are critically dependent on the surface properties of the nanoparticles, which can be tuned by a self-assembled monolayer (SAM) of organic thiolate on the nanoparticles. High-performance field-effect transistors based on the Au-NPs-embedded pentacene films can be prepared if the nanoparticles are made "hydrophobic" as well as "oleophobic" by appropriate SAMs. Electrical bistability was observed in these devices, with a memory window that depends on the size and surface modification of the Au-NPs. The structural characterization and electronic characteristics of the devices will be detailed. PMID:19655797

  18. Fabrication of InGaN thin-film transistors using pulsed sputtering deposition

    PubMed Central

    Itoh, Takeki; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-01-01

    We report the first demonstration of operational InGaN-based thin-film transistors (TFTs) on glass substrates. The key to our success was coating the glass substrate with a thin amorphous layer of HfO2, which enabled a highly c-axis-oriented growth of InGaN films using pulsed sputtering deposition. The electrical characteristics of the thin films were controlled easily by varying their In content. The optimized InGaN-TFTs exhibited a high on/off ratio of ~108, a field-effect mobility of ~22 cm2 V−1 s−1, and a maximum current density of ~30 mA/mm. These results lay the foundation for developing high-performance electronic devices on glass substrates using group III nitride semiconductors. PMID:27383148

  19. Fabrication of InGaN thin-film transistors using pulsed sputtering deposition.

    PubMed

    Itoh, Takeki; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-07-07

    We report the first demonstration of operational InGaN-based thin-film transistors (TFTs) on glass substrates. The key to our success was coating the glass substrate with a thin amorphous layer of HfO2, which enabled a highly c-axis-oriented growth of InGaN films using pulsed sputtering deposition. The electrical characteristics of the thin films were controlled easily by varying their In content. The optimized InGaN-TFTs exhibited a high on/off ratio of ~10(8), a field-effect mobility of ~22 cm(2) V(-1) s(-1), and a maximum current density of ~30 mA/mm. These results lay the foundation for developing high-performance electronic devices on glass substrates using group III nitride semiconductors.

  20. Germanium and Silicon Nanocrystal Thin-Film Field-Effect Transistors from Solution

    SciTech Connect

    Holman, Zachary C.; Liu, Chin-Yi; Kortshagen, Uwe R.

    2010-07-09

    Germanium and silicon have lagged behind more popular II-VI and IV-VI semiconductor materials in the emerging field of semiconductor nanocrystal thin film devices. We report germanium and silicon nanocrystal field-effect transistors fabricated by synthesizing nanocrystals in a plasma, transferring them into solution, and casting thin films. Germanium devices show n-type, ambipolar, or p-type behavior depending on annealing temperature with electron and hole mobilities as large as 0.02 and 0.006 cm2 V-1 s-1, respectively. Silicon devices exhibit n-type behavior without any postdeposition treatment, but are plagued by poor film morphology.

  1. High-mobility ambipolar ZnO-graphene hybrid thin film transistors

    PubMed Central

    Song, Wooseok; Kwon, Soon Yeol; Myung, Sung; Jung, Min Wook; Kim, Seong Jun; Min, Bok Ki; Kang, Min-A; Kim, Sung Ho; Lim, Jongsun; An, Ki-Seok

    2014-01-01

    In order to combine advantages of ZnO thin film transistors (TFTs) with a high on-off ratio and graphene TFTs with extremely high carrier mobility, we present a facile methodology for fabricating ZnO thin film/graphene hybrid two-dimensional TFTs. Hybrid TFTs exhibited ambipolar behavior, an outstanding electron mobility of 329.7 ± 16.9 cm2/V·s, and a high on-off ratio of 105. The ambipolar behavior of the ZnO/graphene hybrid TFT with high electron mobility could be due to the superimposed density of states involving the donor states in the bandgap of ZnO thin films and the linear dispersion of monolayer graphene. We further established an applicable circuit model for understanding the improvement in carrier mobility of ZnO/graphene hybrid TFTs. PMID:24513629

  2. Suppression of excess oxygen for environmentally stable amorphous In-Si-O thin-film transistors

    SciTech Connect

    Aikawa, Shinya E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2015-05-11

    We discuss the environmental instability of amorphous indium oxide (InO{sub x})-based thin-film transistors (TFTs) in terms of the excess oxygen in the semiconductor films. A comparison between amorphous InO{sub x} doped with low and high concentrations of oxygen binder (SiO{sub 2}) showed that out-diffusion of oxygen molecules causes drastic changes in the film conductivity and TFT turn-on voltages. Incorporation of sufficient SiO{sub 2} could suppress fluctuations in excess oxygen because of the high oxygen bond-dissociation energy and low Gibbs free energy. Consequently, the TFT operation became rather stable. The results would be useful for the design of reliable oxide TFTs with stable electrical properties.

  3. Electric bistability in pentacene film-based transistor embedding gold nanoparticles.

    PubMed

    Tseng, Chiao-Wei; Tao, Yu-Tai

    2009-09-01

    Pentacene films were deposited on a silica surface decorated with gold nanoparticles (Au-NPs). The crystallinity and packing orientation of the film are critically dependent on the surface properties of the nanoparticles, which can be tuned by a self-assembled monolayer (SAM) of organic thiolate on the nanoparticles. High-performance field-effect transistors based on the Au-NPs-embedded pentacene films can be prepared if the nanoparticles are made "hydrophobic" as well as "oleophobic" by appropriate SAMs. Electrical bistability was observed in these devices, with a memory window that depends on the size and surface modification of the Au-NPs. The structural characterization and electronic characteristics of the devices will be detailed.

  4. Fabrication of InGaN thin-film transistors using pulsed sputtering deposition

    NASA Astrophysics Data System (ADS)

    Itoh, Takeki; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-07-01

    We report the first demonstration of operational InGaN-based thin-film transistors (TFTs) on glass substrates. The key to our success was coating the glass substrate with a thin amorphous layer of HfO2, which enabled a highly c-axis-oriented growth of InGaN films using pulsed sputtering deposition. The electrical characteristics of the thin films were controlled easily by varying their In content. The optimized InGaN-TFTs exhibited a high on/off ratio of ~108, a field-effect mobility of ~22 cm2 V-1 s-1, and a maximum current density of ~30 mA/mm. These results lay the foundation for developing high-performance electronic devices on glass substrates using group III nitride semiconductors.

  5. Source-gated transistors for order-of-magnitude performance improvements in thin-film digital circuits

    PubMed Central

    Sporea, R. A.; Trainor, M. J.; Young, N. D.; Shannon, J. M.; Silva, S. R. P.

    2014-01-01

    Ultra-large-scale integrated (ULSI) circuits have benefited from successive refinements in device architecture for enormous improvements in speed, power efficiency and areal density. In large-area electronics (LAE), however, the basic building-block, the thin-film field-effect transistor (TFT) has largely remained static. Now, a device concept with fundamentally different operation, the source-gated transistor (SGT) opens the possibility of unprecedented functionality in future low-cost LAE. With its simple structure and operational characteristics of low saturation voltage, stability under electrical stress and large intrinsic gain, the SGT is ideally suited for LAE analog applications. Here, we show using measurements on polysilicon devices that these characteristics lead to substantial improvements in gain, noise margin, power-delay product and overall circuit robustness in digital SGT-based designs. These findings have far-reaching consequences, as LAE will form the technological basis for a variety of future developments in the biomedical, civil engineering, remote sensing, artificial skin areas, as well as wearable and ubiquitous computing, or lightweight applications for space exploration. PMID:24599023

  6. High performance solution-processed indium oxide thin-film transistors.

    PubMed

    Kim, Hyun Sung; Byrne, Paul D; Facchetti, Antonio; Marks, Tobin J

    2008-09-24

    In2O3 thin-film transistors (TFTs) were fabricated on various dielectrics [SiO2, self-assembled nanodielectrics (SANDs)] by spin-coating In2O3 film precursor solutions consisting of ethanolamine (EAA) and InCl3 in methoxyethanol. Optimized film microstructures are characterized by the high-mobility In2O3 00 L orientation and are obtained only within a well-defined range of base: In3+ molar ratios. Electron mobilities as high as approximately 44 cm2 V(-1) s(-1) are measured for n+-Si/SAND/In2O3/Au devices using an EAA/In3+ molar ratio = 10. This result combined with Ion/Ioff ratios of approximately 10(6) and <5 V operating voltages is encouraging for high-speed applications.In2O3 thin-film transistors (TFTs) were fabricated on various dielectrics [SiO2, self-assembled nanodielectrics (SANDs)] by spin-coating In2O3 film precursor solutions consisting of ethanolamine (EAA) and InCl3 in methoxyethanol. Optimized film microstructures are characterized by the high-mobility In2O3 00 L orientation and are obtained only within a well-defined range of base: In3+ molar ratios. Electron mobilities as high as ~44 cm2 V(-1) s(-1) are measured for n+-Si/SAND/In2O3/Au devices using an EAA/In3+ molar ratio = 10. This result combined with Ion/Ioff ratios of approximately 10(6) and <5 V operating voltages is encouraging for high-speed applications.

  7. Synthesis and characterization of pentathiophene based copolymer for organic thin film transistor.

    PubMed

    Park, Jonggwang; Ju, Jin-Uk; Kim, Ran; Hwang, Jaeyoung; Park, Jong-Man; Kim, Yun-Hi

    2014-08-01

    The new dialkylated pentathiophene based copolymer was synthesized by Suzuki coupling reaction. The PD5TADF is synthesized and used as an active material for organic thin film transistor (OTFTs). The copolymer has good solubility in common organic solvent such as toluene, tetrahydrofuran (THF), chloroform, chlorobenzene and dichlorobenzene. The number average molecular weight (Mn) was measured to be 148,000. The TGA curve shows that the polymers exhibit good thermal stability with a weight loss of less than 5% upon heating to 419 °C with glass temperature at 184.9 °C. The ultraviolet (UV) maximum of the polymer was found at 494 nm in solution and 498 nm in the film. A thin-film transistor with PD5TADF was found to exhibit typical p-channel FET characteristics with a hole mobility of 2.6 x 10(-4) cm2/Vs and an on/off ratio of 3.04 x 10(4) with a threshold voltage of -4.5 V. PMID:25936053

  8. Concept of a thin film memory transistor based on ZnO nanoparticles insulated by a ligand shell.

    PubMed

    Hirschmann, Johannes; Faber, Hendrik; Halik, Marcus

    2012-01-21

    In this work, we report on the synthesis and the electrical properties of ZnO nanoparticles, which differ in their organic shell. The introduction of a 2-ethylhexanoate shell instead of a common acetate shell has an impact on the accessible size of the ZnO nanoparticles and changes the electrical properties of thin films in transistors. While acetate covered ZnO particles behave as a semiconductor with an electron mobility of 0.38 cm(2) V(-1) s(-1), the 2-ethylhexanoate ligand shell inhibits a charge transport resulting in insulating films (with an average ε(r) = 9.4). These films can be reconverted to semiconductive layers by removing the ligand shell with oxygen plasma treatment or they can be used as a solution processed dielectric layer in organic transistors. Its use as dielectric allows low voltage device operation and shows potential application as a charge storage layer as needed in non-volatile memory transistors.

  9. Heterojunction effect on contact resistance minimization in staggered pentacene thin-film transistors

    NASA Astrophysics Data System (ADS)

    Zhong, Ya-Nan; Gao, Xu; Wang, Chen-Huan; Xu, Jian-Long; Wang, Sui-Dong

    2016-11-01

    The MoO3/pentacene heterojunction is demonstrated to be effective for reducing the contact resistance in staggered organic thin-film transistors. The heterojunction-induced doping is nondestructive and may form a top conducting channel close to the pentacene surface. Contact interface doping and channel doping both significantly reduced the contact resistance. The effect of channel doping was prominent at low gate bias values, which is ascribed to the negligible access resistance owing to the presence of the top channel. Interface doping and channel doping were combined to obtain a complete heterojunction, which exhibited minimized contact resistance for a wide range of gate bias values.

  10. Ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory

    SciTech Connect

    Han, Jinhua; Wang, Wei Ying, Jun; Xie, Wenfa

    2014-01-06

    An ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory was demonstrated, with discrete distributed gold nanoparticles, tetratetracontane (TTC), pentacene as the floating-gate layer, tunneling layer, and active layer, respectively. The electron traps at the TTC/pentacene interface were significantly suppressed, which resulted in an ambipolar operation in present memory. As both electrons and holes were supplied in the channel and trapped in the floating-gate by programming/erasing operations, respectively, i.e., one type of charge carriers was used to overwrite the other, trapped, one, a large memory window, extending on both sides of the initial threshold voltage, was realized.

  11. Thin-film transistor fabricated in single-crystalline transparent oxide semiconductor.

    PubMed

    Nomura, Kenji; Ohta, Hiromichi; Ueda, Kazushige; Kamiya, Toshio; Hirano, Masahiro; Hosono, Hideo

    2003-05-23

    We report the fabrication of transparent field-effect transistors using a single-crystalline thin-film transparent oxide semiconductor, InGaO3(ZnO)5, as an electron channel and amorphous hafnium oxide as a gate insulator. The device exhibits an on-to-off current ratio of approximately 106 and a field-effect mobility of approximately 80 square centimeters per volt per second at room temperature, with operation insensitive to visible light irradiation. The result provides a step toward the realization of transparent electronics for next-generation optoelectronics. PMID:12764192

  12. Technology of YIG film growth

    SciTech Connect

    Shone, M.

    1985-01-01

    This paper presents information regarding the technology of yttrium iron garnet (YIG) film growth for magnetostatic wave (MSW) applications. The method used for film growth is liquid phase epitaxy from a molten solution of PbO/B/sub 2/O/sub 3/ into which Y/sub 2/O/sub 3/ and Fe/sub 2/O/sub 3/ have been added. An introduction to the crystalline and magnetic features found in YIG is first given. A second section deals with growth techniques and apparatus. In a third section, the melt composition, conditions of growth and homogeneity of as grown material are explored. Growth temperatures varying from 848 to 998 C have been shown to successfully produce YIG films. Possible sources of MSW loss are explored in the fourth section. It is seen that material contamination and physical irregularities may have a negative effect on Delta-H. The final section summarizes the state in which YIG film production now stands. The finding is that although usable films are producible routinely, intrinsic performance is not yet achievable on a regular basis. 53 references.

  13. Electrical in-situ characterisation of interface stabilised organic thin-film transistors

    PubMed Central

    Striedinger, Bernd; Fian, Alexander; Petritz, Andreas; Lassnig, Roman; Winkler, Adolf; Stadlober, Barbara

    2015-01-01

    We report on the electrical in-situ characterisation of organic thin film transistors under high vacuum conditions. Model devices in a bottom-gate/bottom-contact (coplanar) configuration are electrically characterised in-situ, monolayer by monolayer (ML), while the organic semiconductor (OSC) is evaporated by organic molecular beam epitaxy (OMBE). Thermal SiO2 with an optional polymer interface stabilisation layer serves as the gate dielectric and pentacene is chosen as the organic semiconductor. The evolution of transistor parameters is studied on a bi-layer dielectric of a 150 nm of SiO2 and 20 nm of poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) and compared to the behaviour on a pure SiO2 dielectric. The thin layer of PNDPE, which is an intrinsically photo-patternable organic dielectric, shows an excellent stabilisation performance, significantly reducing the calculated interface trap density at the OSC/dielectric interface up to two orders of magnitude, and thus remarkably improving the transistor performance. PMID:26457122

  14. Fully transparent thin film transistors based on zinc oxide channel layer and molybdenum doped indium oxide electrodes

    NASA Astrophysics Data System (ADS)

    MÄ dzik, Mateusz; Elamurugu, Elangovan; Viegas, Jaime

    2016-03-01

    In this work we report the fabrication of thin film transistors (TFT) with zinc oxide channel and molybdenum doped indium oxide (IMO) electrodes, achieved by room temperature sputtering. A set of devices was fabricated, with varying channel width and length from 5μm to 300μm. Output and transfer characteristics were then extracted to study the performance of thin film transistors, namely threshold voltage and saturation current, enabling to determine optimal fabrication process parameters. Optical transmission in the UV-VIS-IR are also reported.

  15. Simulation of ultra thin film SOI transistors using a non-local ballistic model for impact ionisation

    NASA Astrophysics Data System (ADS)

    Armstrong, G. A.; French, W. D.

    1992-12-01

    To model bipolar snapback in thin film SOI transistors accurately, it is necessary to employ a non-local model of impact ionisation. Such a model, based on the "Lucky electron" theory, has been incorporated in a two-dimensional device simulator. Accurate prediction of bipolar holding voltage has been obtained for SOI transistors with sub-micron gate lengths. The model has been applied to analyse separately the effects of both lightly doped source and lightly doped drain in maximising the holding voltage. The advantage of using ultra thin highly doped SOI films in conjunction with a lightly doped drain is discussed.

  16. Investigation of oxygen and argon plasma treatment on Mg-doped InZnO thin film transistors

    NASA Astrophysics Data System (ADS)

    Hu, Chun-Feng; Feng, Ji-Yu; Zhou, Jin; Qu, Xin-Ping

    2016-11-01

    Mg-doped InZnO (MIZO) films were prepared by sol-gel method, and bottom-gate structured thin film transistors (TFTs) were prepared by using the MIZO films. Oxygen and argon (Ar) plasma treatments were carried out on the film and TFTs. The X-ray photoelectron spectroscopy (XPS) results show that both Ar and oxygen etching can increase the oxygen deficiencies, which effectively increase the content of carrier concentration in MIZO films. After both kinds of plasma treatment, the field effect mobility of the MIZO TFTs is greatly improved and the on/off current ratio increases two orders of magnitude.

  17. Fabrication of flexible MoS2 thin-film transistor arrays for practical gas-sensing applications.

    PubMed

    He, Qiyuan; Zeng, Zhiyuan; Yin, Zongyou; Li, Hai; Wu, Shixin; Huang, Xiao; Zhang, Hua

    2012-10-01

    By combining two kinds of solution-processable two-dimensional materials, a flexible transistor array is fabricated in which MoS(2) thin film is used as the active channel and reduced graphene oxide (rGO) film is used as the drain and source electrodes. The simple device configuration and the 1.5 mm-long MoS(2) channel ensure highly reproducible device fabrication and operation. This flexible transistor array can be used as a highly sensitive gas sensor with excellent reproducibility. Compared to using rGO thin film as the active channel, this new gas sensor exhibits much higher sensitivity. Moreover, functionalization of the MoS(2) thin film with Pt nanoparticles further increases the sensitivity by up to ∼3 times. The successful incorporation of a MoS(2) thin-film into the electronic sensor promises its potential application in various electronic devices. PMID:22778003

  18. Intrinsically stretchable and transparent thin-film transistors based on printable silver nanowires, carbon nanotubes and an elastomeric dielectric

    PubMed Central

    Liang, Jiajie; Li, Lu; Chen, Dustin; Hajagos, Tibor; Ren, Zhi; Chou, Shu-Yu; Hu, Wei; Pei, Qibing

    2015-01-01

    Thin-film field-effect transistor is a fundamental component behind various mordern electronics. The development of stretchable electronics poses fundamental challenges in developing new electronic materials for stretchable thin-film transistors that are mechanically compliant and solution processable. Here we report the fabrication of transparent thin-film transistors that behave like an elastomer film. The entire fabrication is carried out by solution-based techniques, and the resulting devices exhibit a mobility of ∼30 cm2 V−1 s−1, on/off ratio of 103–104, switching current >100 μA, transconductance >50 μS and relative low operating voltages. The devices can be stretched by up to 50% strain and subjected to 500 cycles of repeated stretching to 20% strain without significant loss in electrical property. The thin-film transistors are also used to drive organic light-emitting diodes. The approach and results represent an important progress toward the development of stretchable active-matrix displays. PMID:26173436

  19. Intrinsically stretchable and transparent thin-film transistors based on printable silver nanowires, carbon nanotubes and an elastomeric dielectric

    NASA Astrophysics Data System (ADS)

    Liang, Jiajie; Li, Lu; Chen, Dustin; Hajagos, Tibor; Ren, Zhi; Chou, Shu-Yu; Hu, Wei; Pei, Qibing

    2015-07-01

    Thin-film field-effect transistor is a fundamental component behind various mordern electronics. The development of stretchable electronics poses fundamental challenges in developing new electronic materials for stretchable thin-film transistors that are mechanically compliant and solution processable. Here we report the fabrication of transparent thin-film transistors that behave like an elastomer film. The entire fabrication is carried out by solution-based techniques, and the resulting devices exhibit a mobility of ~30 cm2 V-1 s-1, on/off ratio of 103-104, switching current >100 μA, transconductance >50 μS and relative low operating voltages. The devices can be stretched by up to 50% strain and subjected to 500 cycles of repeated stretching to 20% strain without significant loss in electrical property. The thin-film transistors are also used to drive organic light-emitting diodes. The approach and results represent an important progress toward the development of stretchable active-matrix displays.

  20. Interface Engineering of Organic Thin Film Transistors with Self-assembled Organophosphonic Acids

    NASA Astrophysics Data System (ADS)

    Liu, Danqing

    Organic thin film transistors (OTFTs) are interface devices with their performance highly dependent on the interface between organic semiconductors and gate dielectrics no matter whether the organic semiconductors are processed by vacuum deposition or solution-based methods. Detailed in this thesis are studies of interface engineering for OTFTs with self-assembled organophosphonic acids, which play important roles in tuning the properties of the dielectric surface for high-performance OTFTs. The poor crystallinity of rubrene in conventional vacuum deposited films is a well-known obstacle limiting practical applications of rubrene in thin film transistors. As described in Chapter 2, a template layer of diazapentacene (DAP) is introduced to induce crystallization of rubrene in thin film transistors. This study demonstrates that DAP is a suitable template molecule with negligible contribution to the conduction channel leading to polycrystalline thin films of rubrene with field effect mobility as high as 0.68 cm2 V --1 s--1. This induced-crystallization strategy highly depends on a unique octadecylphosphonic acid (ODPA) bilayer-step surface, which plays important roles in controlling the growth of both DAP and rubrene. In solution-processed OTFTs, one key factor that affects the nucleation and growth of semiconductor molecules during solution-based processing is the wetting behavior of the semiconductor solution on the dielectric surface. Reported in Chapter 3 is a new strategy for preparing solution-processed OTFTs based on enhancing the surface energy of self-assembled monolayers (SAMs) by inserting polar oxygen atoms into the long alkyl chain of phosphonic acids. SAMs of these phosphonic acids on a high-k metal oxide layer of AlOy /TiOx lead to solution-processed n-channel OTFTs with high field effect mobility of up to 2.5 cm2 V--1 s--1 and low operational voltage. Chapter 4 puts forth a new design of SAMs for interface engineering of high-performance OTFTs. This

  1. Microstructural control of charge transport in organic blend thin-film transistors

    DOE PAGES

    Hunter, Simon; Chen, Jihua; Anthopoulos, Thomas D.

    2014-07-17

    In this paper, the charge-transport processes in organic p-channel transistors based on the small-molecule 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES ADT), the polymer poly(triarylamine)(PTAA) and blends thereof are investigated. In the case of blend films, lateral conductive atomic force microscopy in combination with energy filtered transmission electron microscopy are used to study the evolution of charge transport as a function of blends composition, allowing direct correlation of the film's elemental composition and morphology with hole transport. Low-temperature transport measurements reveal that optimized blend devices exhibit lower temperature dependence of hole mobility than pristine PTAA devices while also providing a narrower bandgap trap distribution thanmore » pristine diF-TES ADT devices. These combined effects increase the mean hole mobility in optimized blends to 2.4 cm2/Vs; double the value measured for best diF-TES ADT-only devices. The bandgap trap distribution in transistors based on different diF-TES ADT:PTAA blend ratios are compared and the act of blending these semiconductors is seen to reduce the trap distribution width yet increase the average trap energy compared to pristine diF-TES ADT-based devices. In conclusion, our measurements suggest that an average trap energy of <75 meV and a trap distribution of <100 meV is needed to achieve optimum hole mobility in transistors based on diF-TES ADT:PTAA blends.« less

  2. Microstructural control of charge transport in organic blend thin-film transistors

    SciTech Connect

    Hunter, Simon; Chen, Jihua; Anthopoulos, Thomas D.

    2014-07-17

    In this paper, the charge-transport processes in organic p-channel transistors based on the small-molecule 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES ADT), the polymer poly(triarylamine)(PTAA) and blends thereof are investigated. In the case of blend films, lateral conductive atomic force microscopy in combination with energy filtered transmission electron microscopy are used to study the evolution of charge transport as a function of blends composition, allowing direct correlation of the film's elemental composition and morphology with hole transport. Low-temperature transport measurements reveal that optimized blend devices exhibit lower temperature dependence of hole mobility than pristine PTAA devices while also providing a narrower bandgap trap distribution than pristine diF-TES ADT devices. These combined effects increase the mean hole mobility in optimized blends to 2.4 cm2/Vs; double the value measured for best diF-TES ADT-only devices. The bandgap trap distribution in transistors based on different diF-TES ADT:PTAA blend ratios are compared and the act of blending these semiconductors is seen to reduce the trap distribution width yet increase the average trap energy compared to pristine diF-TES ADT-based devices. In conclusion, our measurements suggest that an average trap energy of <75 meV and a trap distribution of <100 meV is needed to achieve optimum hole mobility in transistors based on diF-TES ADT:PTAA blends.

  3. Significant electrical control of amorphous oxide thin film transistors by an ultrathin Ti surface polarity modifier

    SciTech Connect

    Cho, Byungsu; Choi, Yonghyuk; Shin, Seokyoon; Jeon, Heeyoung; Seo, Hyungtak; Jeon, Hyeongtag

    2014-01-27

    We demonstrate an enhanced electrical stability through a Ti oxide (TiO{sub x}) layer on the amorphous InGaZnO (a-IGZO) back-channel; this layer acts as a surface polarity modifier. Ultrathin Ti deposited on the a-IGZO existed as a TiO{sub x} thin film, resulting in oxygen cross-binding with a-IGZO surface. The electrical properties of a-IGZO thin film transistors (TFTs) with TiO{sub x} depend on the surface polarity change and electronic band structure evolution. This result indicates that TiO{sub x} on the back-channel serves as not only a passivation layer protecting the channel from ambient molecules or process variables but also a control layer of TFT device parameters.

  4. Unstrained Epitaxial Zn-Substituted Fe3O4 Films for Ferromagnetic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Ichimura, Takashi; Fujiwara, Kohei; Kushizaki, Takayoshi; Kanki, Teruo; Tanaka, Hidekazu

    2013-06-01

    A field-effect transistor has been fabricated utilizing an epitaxial film of unstrained zinc-substituted magnetite (Fe3O4) as the active channel. A thin film of Fe2.5Zn0.5O4 was grown on a lattice-matched MgO(001) substrate by pulsed-laser deposition and covered by a parylene gate insulator to dope charge carriers by a field effect. The device showed a field-effect mobility of 1.2 ×10-2 cm2 V-1 s-1 at 300 K, which is higher by a factor of 15 than those of the devices with strained Fe2.5Zn0.5O4 channels on perovskite-type substrates. The enhanced response to the gate electric field is useful in exploring gate-tunable magnetism in magnetite.

  5. The stability of tin silicon oxide thin-film transistors with different annealing temperatures

    NASA Astrophysics Data System (ADS)

    Yang, Jianwen; Fu, Ruofan; Han, Yanbing; Meng, Ting; Zhang, Qun

    2016-07-01

    The influence of annealing temperature on the electrical properties of tin silicon oxide (TSO) thin-film transistors (TFTs) and the corresponding bias stress stability have been investigated. With increasing annealing temperature, the TSO films present a structure which is closer to crystallization, and it is conducive to the improvement of the mobility of TSO TFTs. Meanwhile, the positive bias stress (PBS) stability of TSO TFTs is ameliorated due to the decreasing traps at the interface of dielectric layer and channel layer. The threshold voltage shifts in opposite direction after being stressed under negative bias stress (NBS), which is due to the competition between electrons captured by defects related to oxygen vacancies in the channel layer and water molecule adsorption on the back channel.

  6. Nondestructive Method for Mapping Metal Contact Diffusion in In2O3 Thin-Film Transistors.

    PubMed

    Kryvchenkova, Olga; Abdullah, Isam; Macdonald, John Emyr; Elliott, Martin; Anthopoulos, Thomas D; Lin, Yen-Hung; Igić, Petar; Kalna, Karol; Cobley, Richard J

    2016-09-28

    The channel width-to-length ratio is an important transistor parameter for integrated circuit design. Contact diffusion into the channel during fabrication or operation alters the channel width and this important parameter. A novel methodology combining atomic force microscopy and scanning Kelvin probe microscopy (SKPM) with self-consistent modeling is developed for the nondestructive detection of contact diffusion on active devices. Scans of the surface potential are modeled using physically based Technology Computer Aided Design (TCAD) simulations when the transistor terminals are grounded and under biased conditions. The simulations also incorporate the tip geometry to investigate its effect on the measurements due to electrostatic tip-sample interactions. The method is particularly useful for semiconductor- and metal-semiconductor interfaces where the potential contrast resulting from dopant diffusion is below that usually detectable with scanning probe microscopy. PMID:27581104

  7. α,ω-dihexyl-sexithiophene thin films for solution-gated organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Schamoni, Hannah; Noever, Simon; Nickel, Bert; Stutzmann, Martin; Garrido, Jose A.

    2016-02-01

    While organic semiconductors are being widely investigated for chemical and biochemical sensing applications, major drawbacks such as the poor device stability and low charge carrier mobility in aqueous electrolytes have not yet been solved to complete satisfaction. In this work, solution-gated organic field-effect transistors (SGOFETs) based on the molecule α,ω-dihexyl-sexithiophene (DH6T) are presented as promising platforms for in-electrolyte sensing. Thin films of DH6T were investigated with regard to the influence of the substrate temperature during deposition on the grain size and structural order. The performance of SGOFETs can be improved by choosing suitable growth parameters that lead to a two-dimensional film morphology and a high degree of structural order. Furthermore, the capability of the SGOFETs to detect changes in the pH or ionic strength of the gate electrolyte is demonstrated and simulated. Finally, excellent transistor stability is confirmed by continuously operating the device over a period of several days, which is a consequence of the low threshold voltage of DH6T-based SGOFETs. Altogether, our results demonstrate the feasibility of high performance and highly stable organic semiconductor devices for chemical or biochemical applications.

  8. Organic Semiconductors and Nanodielectrics for Flexible, Low Voltage Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Marks, Tobin

    2006-03-01

    Molecular materials scientists are skilled at designing and constructing individual molecules with the goal of imbuing them with predetermined chemical and physical properties. However, the subsequent task of rationally assembling them into organized, functional supramolecular architectures with precise, nanometer-level control of bulk opt-electronic properties presents another level of challenge. In this lecture, synthetic and computational approaches to addressing such problems are described in which the ultimate goal is the fabrication of flexible electronic circuits employing unconventional materials classes and unconventional fabrication techniques. The issues here concern not only the rational design, realization, and understanding of high-mobility p- and n-type organic semiconductors, but also robust enabling nanoscopic gate dielectrics having ultra-high capacitance, low leakage, and high breakdown fields. In the former area, routes to and properties of, new high-mobility heterocyclic materials are described. These materials are then used to fabricate high-performance organic thin film transistors and CMOS circuits. In the latter topic, the design, synthesis, and characterization of new high-k nanoscopic gate dielectrics are described. It is then shown how these dielectrics can be employed to significantly enhance the performance of thin-film transistors and other devices fabricated from a wide variety of both organic as well as inorganic semiconductors.

  9. Photo-Patterned Ion Gel Electrolyte-Gated Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Choi, Jae-Hong; Gu, Yuanyan; Hong, Kihyun; Frisbie, C. Daniel; Lodge, Timothy P.

    2014-03-01

    We have developed a novel fabrication route to pattern electrolyte thin films in electrolyte-gated transistors (EGTs) using a chemically crosslinkable ABA-triblock copolymer ion gel. In the self-assembly of poly[(styrene-r-vinylbenzylazide)-b-ethylene oxide-b-(styrene-r-vinylbenzylazide)] (SOS-N3) triblock copolymer and the ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]), the azide groups of poly(styrene-r-vinylbenzylazide) (PS-N3) end-blocks in the cores can be chemically cross-linked via UV irradiation (λ = 254 nm). Impedance spectroscopy and small-angle X-ray scattering confirmed that ion transport and microstructure of the ion gel are not affected by UV cross-linking. Using this chemical cross-linking strategy, we demonstrate a photo-patterning of ion gels through a patterned mask and the fabricated electrolyte-gated thin film transistors with photo-patterned ion gels as high-capacitance gate insulators exhibited high device performance (low operation voltages and high on/off current ratios).

  10. High-mobility thin film transistors with neodymium-substituted indium oxide active layer

    SciTech Connect

    Lin, Zhenguo; Lan, Linfeng Xiao, Peng; Sun, Sheng; Li, Yuzhi; Song, Wei; Gao, Peixiong; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2015-09-14

    Thin-film transistors (TFTs) with neodymium-substituted indium oxide (InNdO) channel layer were demonstrated. The structural properties of the InNdO films as a function of annealing temperature have been analyzed using X-ray diffraction and transmission electron microscopy. The InNdO thin films showed polycrystalline nature when annealed at 450 °C with a lattice parameter (cubic cell) of 10.255 Å, which is larger than the cubic In{sub 2}O{sub 3} film (10.117 Å). The high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy showed that no Nd{sub 2}O{sub 3} clusters were found in the InNdO film, implying that Nd was incorporated into the In{sub 2}O{sub 3} lattice. The InNdO TFTs annealed at 450 °C exhibited more excellent electrical properties with a high mobility of 20.4 cm{sup 2} V{sup −1} s{sup −1} and better electric bias stability compared to those annealed at 300 °C, which was attributed to the reduction of the scattering centers and/or charge traps due to the decrease of the |Nd3d{sub 5/2}{sup 5}4f{sup 4}O2p{sup −1}〉 electron configuration.

  11. Air-stable solution-processed n-channel organic thin film transistors with polymerenhanced morphology

    DOE PAGES

    He, Zhengran; Shaik, Shoieb; Bi, Sheng; Chen, Jihua; Li, Dawen

    2015-05-04

    N,N0-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) is an n-type semiconductor exhibiting high electron mobility and excellent air stability. However, the reported electron mobility based on spin-coated PDIF-CN2 film is much lower than the value of PDIF-CN2 single crystals made from vapor phase deposition, indicating significant room for mobility enhancement. In this study, various insulating polymers, including poly(vinyl alcohol), poly(methyl methacrylate) (PMMA), and poly(alpha-methylstyrene) (PaMS), are pre-coated on silicon substrate aiming to enhance the morphology of the PDIF-CN2 thin film, thereby improving the charge transport and air stability. Atomic force microscopy images reveal that with the pre-deposition of PaMS or PMMA polymers, the morphologymore » of the PDIF-CN2 polycrystalline films is optimized in semiconducting crystal connectivity, domain size, and surface roughness, which leads to significant improvement of organic thin-film transistor (OTFT) performance. Particularly, an electron mobility of up to 0.55 cm2/V s has been achieved from OTFTs based on the PDIF-CN2 film with the pre-deposition of PaMS polymer.« less

  12. Air-stable solution-processed n-channel organic thin film transistors with polymerenhanced morphology

    SciTech Connect

    He, Zhengran; Shaik, Shoieb; Bi, Sheng; Chen, Jihua; Li, Dawen

    2015-05-04

    N,N0-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) is an n-type semiconductor exhibiting high electron mobility and excellent air stability. However, the reported electron mobility based on spin-coated PDIF-CN2 film is much lower than the value of PDIF-CN2 single crystals made from vapor phase deposition, indicating significant room for mobility enhancement. In this study, various insulating polymers, including poly(vinyl alcohol), poly(methyl methacrylate) (PMMA), and poly(alpha-methylstyrene) (PaMS), are pre-coated on silicon substrate aiming to enhance the morphology of the PDIF-CN2 thin film, thereby improving the charge transport and air stability. Atomic force microscopy images reveal that with the pre-deposition of PaMS or PMMA polymers, the morphology of the PDIF-CN2 polycrystalline films is optimized in semiconducting crystal connectivity, domain size, and surface roughness, which leads to significant improvement of organic thin-film transistor (OTFT) performance. Particularly, an electron mobility of up to 0.55 cm2/V s has been achieved from OTFTs based on the PDIF-CN2 film with the pre-deposition of PaMS polymer.

  13. 3.4-Inch Quarter High Definition Flexible Active Matrix Organic Light Emitting Display with Oxide Thin Film Transistor

    NASA Astrophysics Data System (ADS)

    Hatano, Kaoru; Chida, Akihiro; Okano, Tatsuya; Sugisawa, Nozomu; Inoue, Tatsunori; Seo, Satoshi; Suzuki, Kunihiko; Oikawa, Yoshiaki; Miyake, Hiroyuki; Koyama, Jun; Yamazaki, Shunpei; Eguchi, Shingo; Katayama, Masahiro; Sakakura, Masayuki

    2011-03-01

    In this paper, we report a 3.4-in. flexible active matrix organic light emitting display (AMOLED) display with remarkably high definition (quarter high definition: QHD) in which oxide thin film transistors (TFTs) are used. We have developed a transfer technology in which a TFT array formed on a glass substrate is separated from the substrate by physical force and then attached to a flexible plastic substrate. Unlike a normal process in which a TFT array is directly fabricated on a thin plastic substrate, our transfer technology permits a high integration of high performance TFTs, such as low-temperature polycrystalline silicon TFTs (LTPS TFTs) and oxide TFTs, on a plastic substrate, because a flat, rigid, and thermally-stable glass substrate can be used in the TFT fabrication process in our transfer technology. As a result, this technology realized an oxide TFT array for an AMOLED on a plastic substrate. Furthermore, in order to achieve a high-definition AMOLED, color filters were incorporated in the TFT array and a white organic light-emitting diode (OLED) was combined. One of the features of this device is that the whole body of the device can be bent freely because a source driver and a gate driver can be integrated on the substrate due to the high mobility of an oxide TFT. This feature means “true” flexibility.

  14. Fabrication of water-stable organic transistors using crystalline rubrene thin-film and polymer-treated dielectric (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kim, Jaejoon; Lee, Hyoek Moo; Cho, Sung Oh

    2015-10-01

    For the real application of organic electronics, stable operation of electronic devices in humid or aqueous condition is essential and desirable. However, most of organic semiconductors were very weak to the oxygen or water and especially, cannot be operated well in aqueous condition without an encapsulation. Here, we present water-stable organic thin-film transistors with highly crystallized rubrene and polymer-treated dielectrics. These high water-stability could be achieved by two factors. First, rubrene, a well-known p-type semiconducting material, showed high air and water stability after the crystallization of `abrupt heating'. By the fabrication and aqueous operation of rubrene thin film transistor, we could show the water stability of crystallized thin-film rubrene. Such high environmental stability is attributed to the fact that rubrene has comparatively low HOMO level of -5.4 eV and large bandgap energy of 3.2 eV and that the rubrene thin-film is composed of well-interconnected orthorhombic rubrene crystals. Second, the polymer-treatment of dielectrics can enhance long-term water stability of fabricated rubrene thin-film transistor. By the complete immersion test of transistors, we could characterize the increase of water-stability after the treatment of dielectrics with cross-linked polymer. For this purpose, polystyrene is cross-linked by electron irradiation and the water penetration into semiconductor/dielectric interface was decreased due to the decreased surface energy of polymer dielectric compared to the SiO₂. The fabricated rubrene thin-film transistors showed a field-effect mobility of ~0.5 cm2V-1s-1 and long-term stability under ambient and aqueous conditions. Also, we investigated their potential applications in chemical or bio sensors.

  15. Codoping of zinc and tungsten for practical high-performance amorphous indium-based oxide thin film transistors

    SciTech Connect

    Kizu, Takio E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Miyanaga, Miki; Awata, Hideaki; Nabatame, Toshihide

    2015-09-28

    Using practical high-density sputtering targets, we investigated the effect of Zn and W codoping on the thermal stability of the amorphous film and the electrical characteristics in thin film transistors. zinc oxide is a potentially conductive component while W oxide is an oxygen vacancy suppressor in oxide films. The oxygen vacancy from In-O and Zn-O was suppressed by the W additive because of the high oxygen bond dissociation energy. With controlled codoping of W and Zn, we demonstrated a high mobility with a maximum mobility of 40 cm{sup 2}/V s with good stability under a negative bias stress in InWZnO thin film transistors.

  16. Grain Boundary Induced Bias Instability in Soluble Acene-Based Thin-Film Transistors

    PubMed Central

    Nguyen, Ky V.; Payne, Marcia M.; Anthony, John E.; Lee, Jung Hun; Song, Eunjoo; Kang, Boseok; Cho, Kilwon; Lee, Wi Hyoung

    2016-01-01

    Since the grain boundaries (GBs) within the semiconductor layer of organic field-effect transistors (OFETs) have a strong influence on device performance, a substantial number of studies have been devoted to controlling the crystallization characteristics of organic semiconductors. We studied the intrinsic effects of GBs within 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) thin films on the electrical properties of OFETs. The GB density was easily changed by controlling nulceation event in TES-ADT thin films. When the mixing time was increased, the number of aggregates in as-spun TES-ADT thin films were increased and subsequent exposure of the films to 1,2-dichloroethane vapor led to a significant increase in the number of nuleation sites, thereby increasing the GB density of TES-ADT spherulites. The density of GBs strongly influences the angular spread and crystallographic orientation of TES-ADT spherulites. Accordingly, the FETs with higher GB densities showed much poorer electrical characteristics than devices with lower GB density. Especially, GBs provide charge trapping sites which are responsible for bias-stress driven electrical instability. Dielectric surface treatment with a polystyrene brush layer clarified the GB-induced charge trapping by reducing charge trapping at the semiconductor-dielectric interface. Our study provides an understanding on GB induced bias instability for the development of high performance OFETs. PMID:27615358

  17. High mobility amorphous zinc oxynitride semiconductor material for thin film transistors

    SciTech Connect

    Ye Yan; Lim, Rodney; White, John M.

    2009-10-01

    Zinc oxynitride semiconductor material is produced through a reactive sputtering process in which competition between reactions responsible for the growth of hexagonal zinc oxide (ZnO) and for the growth of cubic zinc nitride (Zn{sub 3}N{sub 2}) is promoted. In contrast to processes in which the reaction for either the oxide or the nitride is dominant, the multireaction process yields a substantially amorphous or a highly disordered nanocrystalline film with higher Hall mobility, 47 cm{sup 2} V{sup -1} s{sup -1} for the as-deposited film produced at 50 deg. C and 110 cm{sup 2} V{sup -1} s{sup -1} after annealing at 400 deg. C. In addition, it has been observed that the Hall mobility of the material increases as the carrier concentration decreases in a carrier concentration range where a multicomponent metal oxide semiconductor, indium-gallium-zinc oxide, follows the opposite trend. This indicates that the carrier transports in the single-metal compound and the multimetal compound are probably dominated by different mechanisms. Film stability and thin film transistor performance of the material have also been tested, and results are presented herein.

  18. Nitrogen-doped amorphous oxide semiconductor thin film transistors with double-stacked channel layers

    NASA Astrophysics Data System (ADS)

    Xie, Haiting; Wu, Qi; Xu, Ling; Zhang, Lei; Liu, Guochao; Dong, Chengyuan

    2016-11-01

    The amorphous oxide semiconductor (AOS) thin film transistors (TFTs) with the double-stacked channel layers (DSCL) combing the amorphous InZnO (a-IZO) films and the nitrogen-doped amorphous InGaZnO (a-IGZO:N) films were proposed and fabricated, which showed the excellent performance with the field-effect mobility of 49.6 cm2 V-1 s-1 and the subthreshold swing of 0.5 V/dec. More interestingly, very stable properties were observed in the bias stress and light illumination tests for these a-IZO/a-IGZO:N TFTs, as seemed to be the evident improvements over the prior arts. The improved performance and stability might be mainly due to the hetero-junctions in the channel layers and less interface/bulk trap density from the in situ nitrogen doping process in the a-IGZO layers. In addition, the passivation effect of the a-IGZO:N films also made some contributions to the stable properties exhibited in these novel DSCL TFTs.

  19. Grain Boundary Induced Bias Instability in Soluble Acene-Based Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Nguyen, Ky V.; Payne, Marcia M.; Anthony, John E.; Lee, Jung Hun; Song, Eunjoo; Kang, Boseok; Cho, Kilwon; Lee, Wi Hyoung

    2016-09-01

    Since the grain boundaries (GBs) within the semiconductor layer of organic field-effect transistors (OFETs) have a strong influence on device performance, a substantial number of studies have been devoted to controlling the crystallization characteristics of organic semiconductors. We studied the intrinsic effects of GBs within 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) thin films on the electrical properties of OFETs. The GB density was easily changed by controlling nulceation event in TES-ADT thin films. When the mixing time was increased, the number of aggregates in as-spun TES-ADT thin films were increased and subsequent exposure of the films to 1,2-dichloroethane vapor led to a significant increase in the number of nuleation sites, thereby increasing the GB density of TES-ADT spherulites. The density of GBs strongly influences the angular spread and crystallographic orientation of TES-ADT spherulites. Accordingly, the FETs with higher GB densities showed much poorer electrical characteristics than devices with lower GB density. Especially, GBs provide charge trapping sites which are responsible for bias-stress driven electrical instability. Dielectric surface treatment with a polystyrene brush layer clarified the GB-induced charge trapping by reducing charge trapping at the semiconductor-dielectric interface. Our study provides an understanding on GB induced bias instability for the development of high performance OFETs.

  20. Grain Boundary Induced Bias Instability in Soluble Acene-Based Thin-Film Transistors.

    PubMed

    Nguyen, Ky V; Payne, Marcia M; Anthony, John E; Lee, Jung Hun; Song, Eunjoo; Kang, Boseok; Cho, Kilwon; Lee, Wi Hyoung

    2016-01-01

    Since the grain boundaries (GBs) within the semiconductor layer of organic field-effect transistors (OFETs) have a strong influence on device performance, a substantial number of studies have been devoted to controlling the crystallization characteristics of organic semiconductors. We studied the intrinsic effects of GBs within 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) thin films on the electrical properties of OFETs. The GB density was easily changed by controlling nulceation event in TES-ADT thin films. When the mixing time was increased, the number of aggregates in as-spun TES-ADT thin films were increased and subsequent exposure of the films to 1,2-dichloroethane vapor led to a significant increase in the number of nuleation sites, thereby increasing the GB density of TES-ADT spherulites. The density of GBs strongly influences the angular spread and crystallographic orientation of TES-ADT spherulites. Accordingly, the FETs with higher GB densities showed much poorer electrical characteristics than devices with lower GB density. Especially, GBs provide charge trapping sites which are responsible for bias-stress driven electrical instability. Dielectric surface treatment with a polystyrene brush layer clarified the GB-induced charge trapping by reducing charge trapping at the semiconductor-dielectric interface. Our study provides an understanding on GB induced bias instability for the development of high performance OFETs. PMID:27615358

  1. Thin film nanotube transistors based on self-assembled, aligned, semiconducting carbon nanotube arrays.

    PubMed

    Engel, Michael; Small, Joshua P; Steiner, Mathias; Freitag, Marcus; Green, Alexander A; Hersam, Mark C; Avouris, Phaedon

    2008-12-23

    Thin film transistors (TFTs) are now poised to revolutionize the display, sensor, and flexible electronics markets. However, there is a limited choice of channel materials compatible with low-temperature processing. This has inhibited the fabrication of high electrical performance TFTs. Single-walled carbon nanotubes (CNTs) have very high mobilities and can be solution-processed, making thin film CNT-based TFTs a natural direction for exploration. The two main challenges facing CNT-TFTs are the difficulty of placing and aligning CNTs over large areas and low on/off current ratios due to admixture of metallic nanotubes. Here, we report the self-assembly and self-alignment of CNTs from solution into micron-wide strips that form regular arrays of dense and highly aligned CNT films covering the entire chip, which is ideally suitable for device fabrication. The films are formed from pre-separated, 99% purely semiconducting CNTs and, as a result, the CNT-TFTs exhibit simultaneously high drive currents and large on/off current ratios. Moreover, they deliver strong photocurrents and are also both photo- and electroluminescent.

  2. Bismuth ferrite based thin films, nanofibers, and field effect transistor devices

    NASA Astrophysics Data System (ADS)

    Rivera-Beltran, Rut

    In this research an attempt has been made to explore bismuth ferrite thin films with low leakage current and nanofibers with high photoconductivity. Thin films were deposited with pulsed laser deposition (PLD) method. An attempt has been made to develop thin films under different deposition parameters with following target compositions: i) 0.6BiFeO3-0.4(Bi0.5 K0.5)TiO3 (BFO-BKT) and ii) bi-layered 0.88Bi 0.5Na0.5TiO3-0.08Bi0.5K0.5TiO 3-0.04BaTiO3/BiFeO3 (BNT-BKT-BT/BFO). BFO-BKT thin film shows suppressed leakage current by about four orders of magnitude which in turn improve the ferroelectric and dielectric properties of the films. The optimum remnant polarization is 19 muC.cm-2 at the oxygen partial pressure of 300 mtorr. The BNT-BKT-BT/BFO bi-layered thin films exhibited ferroelectric behavior as: Pr = 22.0 muC.cm-2, Ec = 100 kV.cm-1 and epsilonr = 140. The leakage current of bi-layered thin films have been reduced two orders of magnitude compare to un-doped bismuth ferrite. Bismuth ferrite nanofibers were developed by electrospinning technique and its electronic properties such as photoconductivity and field effect transistor performance were investigated extensively. Nanofibers were deposited by electrospinning of sol-gel solution on SiO2/Si substrate at driving voltage of 10 kV followed by heat treatment at 550 °C for 2 hours. The composition analysis through energy dispersive detector and electron energy loss spectroscopy revealed the heterogeneous nature of the composition with Bi rich and Fe deficient regions. X-ray photoelectron spectroscopy results confirmed the combination of Fe3+ and Fe2+ valence state in the fibers. The photoresponse result is almost hundred times higher for a fiber of 40 nm diameter compared to a fiber with 100 nm diameter. This effect is described by a size dependent surface recombination mechanism. A single and multiple BFO nanofibers field effect transistors devices were fabricated and characterized. Bismuth ferrite FET behaves

  3. Sensing extremely limited H₂ contents by Pd nanogap connected to an amorphous InGaZnO thin-film transistor.

    PubMed

    Lee, Young Tack; Jung, Hwaebong; Nam, Seung Hee; Jeon, Pyo Jin; Kim, Jin Sung; Jang, Byungjin; Lee, Wooyoung; Im, Seongil

    2013-10-01

    A palladium (Pd) nanogap-based thin-film has been connected to an electrically stable amorphous InGaZnO thin-film transistor, to form a hydrogen sensor demonstrating a dramatic sensing capability. As a result of the Pd connection to the transistor source, our sensor circuit greatly enhances the hydrogen-induced signal and sensing speed in the sense of output voltage, clearly resolving a minimum hydrogen content of 0.05%. When the nanogap-based Pd thin-film was connected to the transistor gate, an extremely limited hydrogen content of even less than 0.05% was visibly detected through gate voltage shifts. Our results exhibit the most promising and practical ways to sense extremely limited hydrogen contents, originating from two methods: transistor-to-Pd nanogap resistor and transistor-to-Pd nanogap capacitor coupling.

  4. Method for producing silicon thin-film transistors with enhanced forward current drive

    DOEpatents

    Weiner, Kurt H.

    1998-01-01

    A method for fabricating amorphous silicon thin film transistors (TFTs) with a polycrystalline silicon surface channel region for enhanced forward current drive. The method is particularly adapted for producing top-gate silicon TFTs which have the advantages of both amorphous and polycrystalline silicon TFTs, but without problem of leakage current of polycrystalline silicon TFTs. This is accomplished by selectively crystallizing a selected region of the amorphous silicon, using a pulsed excimer laser, to create a thin polycrystalline silicon layer at the silicon/gate-insulator surface. The thus created polysilicon layer has an increased mobility compared to the amorphous silicon during forward device operation so that increased drive currents are achieved. In reverse operation the polysilicon layer is relatively thin compared to the amorphous silicon, so that the transistor exhibits the low leakage currents inherent to amorphous silicon. A device made by this method can be used, for example, as a pixel switch in an active-matrix liquid crystal display to improve display refresh rates.

  5. Flexible All-organic, All-solution Processed Thin Film Transistor Array with Ultrashort Channel.

    PubMed

    Xu, Wei; Hu, Zhanhao; Liu, Huimin; Lan, Linfeng; Peng, Junbiao; Wang, Jian; Cao, Yong

    2016-01-01

    Shrinking the device dimension has long been the pursuit of the semiconductor industry to increase the device density and operation speed. In the application of thin film transistors (TFTs), all-organic TFT arrays made by all-solution process are desired for low cost and flexible electronics. One of the greatest challenges is how to achieve ultrashort channel through a cost-effective method. In our study, ultrashort-channel devices are demonstrated by direct inkjet printing conducting polymer as source/drain and gate electrodes without any complicated substrate's pre-patterning process. By modifying the substrate's wettability, the conducting polymer's contact line is pinned during drying process which makes the channel length well-controlled. An organic TFT array of 200 devices with 2 μm channel length is fabricated on flexible substrate through all-solution process. The simple and scalable process to fabricate high resolution organic transistor array offers a low cost approach in the development of flexible and wearable electronics.

  6. Compositional tuning of atomic layer deposited MgZnO for thin film transistors

    SciTech Connect

    Wrench, J. S.; Brunell, I. F.; Chalker, P. R.; Jin, J. D.; Shaw, A.; Mitrovic, I. Z.; Hall, S.

    2014-11-17

    Thin film transistors (TFTs) have been fabricated using magnesium zinc oxide (MgZnO) layers deposited by atomic layer deposition at 200 °C. The composition of the MgZnO is systematically modified by varying the ratio of MgO and ZnO deposition cycles. A blue-shift of the near band-edge photoluminescence after post-deposition annealing at 300 °C indicates significant activation of the Mg dopant. A 7:1 ratio of ZnO:MgO deposition cycles was used to fabricate a device with a TFT channel width of 2000 μm and a channel length of 60 μm. This transistor yielded an effective saturation mobility of 4 cm{sup 2}/V s and a threshold voltage of 7.1 V, respectively. The on/off ratio was 1.6×10{sup 6} and the maximum interface state density at the ZnO/SiO{sub 2} interface is ∼6.5×10{sup 12} cm{sup −2}.

  7. Flexible All-organic, All-solution Processed Thin Film Transistor Array with Ultrashort Channel

    PubMed Central

    Xu, Wei; Hu, Zhanhao; Liu, Huimin; Lan, Linfeng; Peng, Junbiao; Wang, Jian; Cao, Yong

    2016-01-01

    Shrinking the device dimension has long been the pursuit of the semiconductor industry to increase the device density and operation speed. In the application of thin film transistors (TFTs), all-organic TFT arrays made by all-solution process are desired for low cost and flexible electronics. One of the greatest challenges is how to achieve ultrashort channel through a cost-effective method. In our study, ultrashort-channel devices are demonstrated by direct inkjet printing conducting polymer as source/drain and gate electrodes without any complicated substrate’s pre-patterning process. By modifying the substrate’s wettability, the conducting polymer’s contact line is pinned during drying process which makes the channel length well-controlled. An organic TFT array of 200 devices with 2 μm channel length is fabricated on flexible substrate through all-solution process. The simple and scalable process to fabricate high resolution organic transistor array offers a low cost approach in the development of flexible and wearable electronics. PMID:27378163

  8. Method for producing silicon thin-film transistors with enhanced forward current drive

    DOEpatents

    Weiner, K.H.

    1998-06-30

    A method is disclosed for fabricating amorphous silicon thin film transistors (TFTs) with a polycrystalline silicon surface channel region for enhanced forward current drive. The method is particularly adapted for producing top-gate silicon TFTs which have the advantages of both amorphous and polycrystalline silicon TFTs, but without problem of leakage current of polycrystalline silicon TFTs. This is accomplished by selectively crystallizing a selected region of the amorphous silicon, using a pulsed excimer laser, to create a thin polycrystalline silicon layer at the silicon/gate-insulator surface. The thus created polysilicon layer has an increased mobility compared to the amorphous silicon during forward device operation so that increased drive currents are achieved. In reverse operation the polysilicon layer is relatively thin compared to the amorphous silicon, so that the transistor exhibits the low leakage currents inherent to amorphous silicon. A device made by this method can be used, for example, as a pixel switch in an active-matrix liquid crystal display to improve display refresh rates. 1 fig.

  9. Flexible All-organic, All-solution Processed Thin Film Transistor Array with Ultrashort Channel.

    PubMed

    Xu, Wei; Hu, Zhanhao; Liu, Huimin; Lan, Linfeng; Peng, Junbiao; Wang, Jian; Cao, Yong

    2016-01-01

    Shrinking the device dimension has long been the pursuit of the semiconductor industry to increase the device density and operation speed. In the application of thin film transistors (TFTs), all-organic TFT arrays made by all-solution process are desired for low cost and flexible electronics. One of the greatest challenges is how to achieve ultrashort channel through a cost-effective method. In our study, ultrashort-channel devices are demonstrated by direct inkjet printing conducting polymer as source/drain and gate electrodes without any complicated substrate's pre-patterning process. By modifying the substrate's wettability, the conducting polymer's contact line is pinned during drying process which makes the channel length well-controlled. An organic TFT array of 200 devices with 2 μm channel length is fabricated on flexible substrate through all-solution process. The simple and scalable process to fabricate high resolution organic transistor array offers a low cost approach in the development of flexible and wearable electronics. PMID:27378163

  10. Flexible All-organic, All-solution Processed Thin Film Transistor Array with Ultrashort Channel

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Hu, Zhanhao; Liu, Huimin; Lan, Linfeng; Peng, Junbiao; Wang, Jian; Cao, Yong

    2016-07-01

    Shrinking the device dimension has long been the pursuit of the semiconductor industry to increase the device density and operation speed. In the application of thin film transistors (TFTs), all-organic TFT arrays made by all-solution process are desired for low cost and flexible electronics. One of the greatest challenges is how to achieve ultrashort channel through a cost-effective method. In our study, ultrashort-channel devices are demonstrated by direct inkjet printing conducting polymer as source/drain and gate electrodes without any complicated substrate’s pre-patterning process. By modifying the substrate’s wettability, the conducting polymer’s contact line is pinned during drying process which makes the channel length well-controlled. An organic TFT array of 200 devices with 2 μm channel length is fabricated on flexible substrate through all-solution process. The simple and scalable process to fabricate high resolution organic transistor array offers a low cost approach in the development of flexible and wearable electronics.

  11. Impact of glycerol on zinc-oxide-based thin film transistors with indium molybdenum oxide transparent electrodes

    NASA Astrophysics Data System (ADS)

    MÄ dzik, Mateusz; Elamurugu, Elangovan; Flores, Raquel; Viegas, Jaime

    2016-02-01

    We report the fabrication of thin film transistors with ZnO channel and indium molybdenum oxide electrodes by sputtering. The fabricated transistors were then exposed to glycerol. We observe a temporary change in device performance after immersion of the FET in glycerol. Control structures without channel material are also used for demonstrating that the effect of saturation current increase is not due to glycerol alone as sugar alcohol is a low conductive medium. Various electrical and optical parameters are extracted. The presented results are useful for further integration of photonics and electronics in sensing applications

  12. Solution-processed InGaZnO-based thin film transistors for printed electronics applications

    NASA Astrophysics Data System (ADS)

    Lim, Jun Hyung; Shim, Jong Hyun; Choi, Jun Hyuk; Joo, Jinho; Park, Kyung; Jeon, Haseok; Moon, Mi Ran; Jung, Donggeun; Kim, Hyoungsub; Lee, Hoo-Jeong

    2009-07-01

    This letter reports the utility of using the sol-gel process for exploring the library of multicomponent ZnO-based oxides as an active layer of thin film transistors. We chose InGaZnO as a starting material and modulated the Ga content to examine the potential of this material. Increasing the Ga ratio from 0.1 to 1 brought about a dynamic shift in the electrical behavior from conductor to semiconductor. This exploratory work critically helped us fabricate a device with robust device performance (a mobility of 1˜2 cm2 V-1 s-1 for the 400 °C-sintered samples and 0.2 cm2 V-1 s-1 for the 300 °C-sintered samples).

  13. Analytical approximation of the InGaZnO thin-film transistors surface potential

    NASA Astrophysics Data System (ADS)

    Colalongo, Luigi

    2016-10-01

    Surface-potential-based mathematical models are among the most accurate and physically based compact models of thin-film transistors, and in turn of indium gallium zinc oxide TFTs, available today. However, the need of iterative computations of the surface potential limits their computational efficiency and diffusion in CAD applications. The existing closed-form approximations of the surface potential are based on regional approximations and empirical smoothing functions that could result not accurate enough in particular to model transconductances and transcapacitances. In this work we present an extremely accurate (in the range of nV) and computationally efficient non-iterative approximation of the surface potential that can serve as a basis for advanced surface-potential-based indium gallium zinc oxide TFTs models.

  14. The ergonomics approach for thin film transistor-liquid crystal display manufacturing process.

    PubMed

    Lu, Chih-Wei; Yao, Chia-Chun; Kuo, Chein-Wen

    2012-01-01

    The thin film transistor-liquid crystal display (TFT-LCD) has been used all over the world. Although the manufacture process of TFT-LCD was highly automated, employees are hired to do manual job in module assembly process. The operators may have high risk of musculoskeletal disorders because of the long work hours and the repetitive activities in an unfitted work station. The tools of this study were questionnaire, checklist and to evaluate the work place design. The result shows that the participants reported high musculoskeletal disorder symptoms in shoulder (59.8%), neck (49.5%), wrist (39.5%), and upper back (30.6%). And, to reduce the ergonomic risk factors, revising the height of the work benches, chairs and redesigning the truck to decrease the chance of unsuitable positions were recommended and to reduce other ergonomics hazards and seta good human machine interface and appropriate job design.

  15. Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals

    NASA Astrophysics Data System (ADS)

    Wei Shih, Chen; Chin, Albert; Fu Lu, Chun; Fang Su, Wei

    2016-01-01

    High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals.

  16. Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals.

    PubMed

    Shih, Chen Wei; Chin, Albert; Lu, Chun Fu; Su, Wei Fang

    2016-01-08

    High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm(2)/Vs field-effect mobility, high ION/IOFF of 2.3 × 10(7), small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals.

  17. Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals

    PubMed Central

    Wei Shih, Chen; Chin, Albert; Fu Lu, Chun; Fang Su, Wei

    2016-01-01

    High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals. PMID:26744240

  18. Restorative effect of oxygen annealing on device performance in HfIZO thin-film transistors

    SciTech Connect

    Ha, Tae-Jun

    2015-03-15

    Metal-oxide based thin-film transistors (oxide-TFTs) are very promising for use in next generation electronics such as transparent displays requiring high switching and driving performance. In this study, we demonstrate an optimized process to secure excellent device performance with a favorable shift of the threshold voltage toward 0V in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs by using post-treatment with oxygen annealing. This enhancement results from the improved interfacial characteristics between gate dielectric and semiconductor layers due to the reduction in the density of interfacial states related to oxygen vacancies afforded by oxygen annealing. The device statistics confirm the improvement in the device-to-device and run-to-run uniformity. We also report on the photo-induced stability in such oxide-TFTs against long-term UV irradiation, which is significant for transparent displays.

  19. Low Temperature Polycrystalline Silicon Thin Film Transistor Pixel Circuits for Active Matrix Organic Light Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Lin, Yu-Sheng; Liu, Yan-Wei

    A new pixel design and driving method for active matrix organic light emitting diode (AMOLED) displays that use low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) with a voltage programming method are proposed and verified using the SPICE simulator. We had employed an appropriate TFT model in SPICE simulation to demonstrate the performance of the pixel circuit. The OLED anode voltage variation error rates are below 0.35% under driving TFT threshold voltage deviation (Δ Vth =± 0.33V). The OLED current non-uniformity caused by the OLED threshold voltage degradation (Δ VTO =+0.33V) is significantly reduced (below 6%). The simulation results show that the pixel design can improve the display image non-uniformity by compensating for the threshold voltage deviation in the driving TFT and the OLED threshold voltage degradation at the same time.

  20. Interface location-controlled indium gallium zinc oxide thin-film transistors using a solution process

    NASA Astrophysics Data System (ADS)

    Na, Jae Won; Kim, Yeong-gyu; Jung, Tae Soo; Tak, Young Jun; Park, Sung Pyo; Park, Jeong Woo; Kim, Si Joon; Kim, Hyun Jae

    2016-03-01

    The role of an interface as an electron-trapping layer in double-stacked indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) was investigated and interface location-controlled (ILC) IGZO TFTs were introduced. In the ILC TFTs, the thickness of the top and bottom IGZO layers is controlled to change the location of the interface layer. The system exhibited improved electrical characteristics as the location of the interface layer moved further from the gate insulator: field-effect mobility increased from 0.36 to 2.17 cm2 V-1 s-1, and the on-current increased from 2.43  ×  10-5 to 1.33  ×  10-4 A. The enhanced electrical characteristics are attributed to the absence of an electron-trapping interface layer in the effective channel layer where electrons are accumulated under positive gate bias voltage.

  1. Contact resistance improvement using interfacial silver nanoparticles in amorphous indium-zinc-oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Xu, Rui; He, Jian; Song, Yang; Li, Wei; Zaslavsky, A.; Paine, D. C.

    2014-09-01

    We describe an approach to reduce the contact resistance at compositional conducting/semiconducting indium-zinc-oxide (IZO) homojunctions used for contacts in thin film transistors (TFTs). By introducing silver nanoparticles (Ag NPs) at the homojunction interface between the conducting IZO electrodes and the amorphous IZO channel, we reduce the specific contact resistance, obtained by transmission line model measurements, down to ˜10-2 Ω cm2, ˜3 orders of magnitude lower than either NP-free homojunction contacts or solid Ag metal contacts. The resulting back-gated TFTs with Ag NP contacts exhibit good field effect mobility of ˜27 cm2/V s and an on/off ratio >107. We attribute the improved contact resistance to electric field concentration by the Ag NPs.

  2. Influence of curvature on the device physics of thin film transistors on flexible substrates

    SciTech Connect

    Amalraj, Rex; Sambandan, Sanjiv

    2014-10-28

    Thin film transistors (TFTs) on elastomers promise flexible electronics with stretching and bending. Recently, there have been several experimental studies reporting the behavior of TFTs under bending and buckling. In the presence of stress, the insulator capacitance is influenced due to two reasons. The first is the variation in insulator thickness depending on the Poisson ratio and strain. The second is the geometric influence of the curvature of the insulator-semiconductor interface during bending or buckling. This paper models the role of curvature on TFT performance and brings to light an elegant result wherein the TFT characteristics is dependent on the area under the capacitance-distance curve. The paper compares models with simulations and explains several experimental findings reported in literature.

  3. Improved Stability Of Amorphous Zinc Tin Oxide Thin Film Transistors Using Molecular Passivation

    SciTech Connect

    Rajachidambaram, Meena Suhanya; Pandey, Archana; Vilayur Ganapathy, Subramanian; Nachimuthu, Ponnusamy; Thevuthasan, Suntharampillai; Herman, Gregory S.

    2013-10-21

    The role of back channel surface chemistry on amorphous zinc tin oxide (ZTO) bottom gate thin film transistors (TFT) have been characterized by positive bias-stress measurements and x-ray photoelectron spectroscopy. Positive bias-stress turn-on voltage shifts for ZTO-TFTs were significantly reduced by passivation of back channel surfaces with self-assembled monolayers of n-hexylphosphonic acid (n-HPA) when compared to ZTO-TFTs with no passivation. These results indicate that adsorption of molecular species on exposed back channel of ZTO-TFTs strongly influence observed turn-on voltage shifts, as opposed to charge injection into the dielectric or trapping due to oxygen vacancies.

  4. Numerical Analysis on the Mechanical Properties of Organic Thin Film Transistor

    NASA Astrophysics Data System (ADS)

    Lee, S. C.; Lee, D. K.; Seol, Y. G.; Ahn, J. H.; Lee, N. E.; Kim, Y. J.

    The organic thin film transistor (OTFT) on flexible substrate electroplated electrodes has many advantages as in the fabrication of low cost sensors, e-paper, smart cards, and flexible displays. In this study, we simulated the mechanical and electrical characteristics of the OTFT with various voltage conditions by using COMSOL. The model consisting of a channel, source and drain was employed to investigate the temperature distribution and thermal stress concentration. The channel length is 40 µm and the voltage ranged between -20V and -40V. The OTFT was fabricated using pentacene as a semiconducting layer and electroplated Ni as a gate electrode. Mechanical properties of the fabricated OTFT were characterized by thermal stress which was predicted with the result of stress distribution.

  5. Double-metal-gate nanocrystalline Si thin film transistors with flexible threshold voltage controllability

    SciTech Connect

    Chiou, Uio-Pu; Pan, Fu-Ming; Shieh, Jia-Min E-mail: jmshieh@faculty.nctu.edu.tw; Yang, Chih-Chao; Huang, Wen-Hsien; Kao, Yo-Tsung

    2013-11-11

    We fabricated nano-crystalline Si (nc-Si:H) thin-film transistors (TFTs) with a double-metal-gate structure, which showed a high electron-mobility (μ{sub FE}) and adjustable threshold voltages (V{sub th}). The nc-Si:H channel and source/drain (S/D) of the multilayered TFT were deposited at 375 °C by inductively coupled plasma chemical vapor deposition. The low grain-boundary defect density of the channel layer is responsible for the high μ{sub FE} of 370 cm{sup 2}/V-s, a steep subthreshold slope of 90 mV/decade, and a low V{sub th} of −0.64 V. When biased with the double-gate driving mode, the device shows a tunable V{sub th} value extending from −1 V up to 2.7 V.

  6. Contact resistance improvement using interfacial silver nanoparticles in amorphous indium-zinc-oxide thin film transistors

    SciTech Connect

    Xu, Rui; He, Jian; Song, Yang; Li, Wei; Zaslavsky, A.; Paine, D. C.

    2014-09-01

    We describe an approach to reduce the contact resistance at compositional conducting/semiconducting indium-zinc-oxide (IZO) homojunctions used for contacts in thin film transistors (TFTs). By introducing silver nanoparticles (Ag NPs) at the homojunction interface between the conducting IZO electrodes and the amorphous IZO channel, we reduce the specific contact resistance, obtained by transmission line model measurements, down to ∼10{sup −2 }Ω cm{sup 2}, ∼3 orders of magnitude lower than either NP-free homojunction contacts or solid Ag metal contacts. The resulting back-gated TFTs with Ag NP contacts exhibit good field effect mobility of ∼27 cm{sup 2}/V s and an on/off ratio >10{sup 7}. We attribute the improved contact resistance to electric field concentration by the Ag NPs.

  7. A simple and continuous polycrystalline silicon thin-film transistor model for SPICE implementation

    NASA Astrophysics Data System (ADS)

    Pappas, I.; Hatzopoulos, A. T.; Tassis, D. H.; Arpatzanis, N.; Siskos, S.; Dimitriadis, C. A.; Kamarinos, G.

    2006-09-01

    A simple current-voltage model for polycrystalline silicon thin-film transistors (polysilicon TFTs) is proposed, including the sixth-order polynomial function coefficients fitted to the effective mobility versus gate voltage data, the channel length modulation, and impact ionization effects. The model possesses continuity of current in the transfer characteristics from weak to strong inversion and in the output characteristics throughout the linear and saturation regions of operation. The model parameters are used as input parameters in AIM-SPICE circuit simulator for device modeling. The model has been applied in a number of long and short channel TFTs, and the statistical distributions of the model parameters have been derived which are useful for checking the functionality of TFTs circuits with AIM-SPICE.

  8. High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer

    SciTech Connect

    Chiang, H.Q.; Wager, J.F.; Hoffman, R.L.; Jeong, J.; Keszler, D.A.

    2005-01-03

    Transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated. Field-effect mobilities of 5-15 and 20-50 cm{sup 2} V{sup -1} s{sup -1} are obtained for devices post-deposition annealed at 300 and 600 deg. C, respectively. TTFTs processed at 300 and 600 deg. C yield devices with turn-on voltage of 0-15 and -5-5 V, respectively. Under both processing conditions, a drain current on-to-off ratio greater than 10{sup 7} is obtained. Zinc tin oxide is one example of a new class of high performance TTFT channel materials involving amorphous oxides composed of heavy-metal cations with (n-1)d{sup 10} ns{sup 0} (n{>=}4) electronic configurations.

  9. All-printed and transparent single walled carbon nanotube thin film transistor devices

    NASA Astrophysics Data System (ADS)

    Sajed, Farzam; Rutherglen, Christopher

    2013-09-01

    We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V-1s-1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.

  10. A high-k ferroelectric relaxor terpolymer as a gate dielectric for orgnaic thin film transistors

    SciTech Connect

    Wu, Shan; Shao, Ming; Burlingame, Quinn; Chen, Xiangzhong; Lin, Minren; Xiao, Kai; Zhang, Qiming

    2013-01-01

    Poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) is a ferroelectric terpolymer relaxor with a static dielectric constant of 50, which was developed using defect modification to eliminate remnant polarization in the normal ferroelectric PVDF. In this work, this solution processable terpolymer was used as the gate insulator in bottom gated organic thin-film transistors with a pentacene semiconductor layer. Due to the high dielectric constant of P(VDF-TrFE- CFE), a large capacitive coupling between the gate and channel can be achieved which causes a high charge concentration at the interface of the semiconductor and dielectric layers. In this device, an on/ off ratio of 104 and a low minimum operation gate voltage (5-10 V) were attained

  11. Numerical simulation of transient emission from deep level traps in polysilicon thin film transistors

    NASA Astrophysics Data System (ADS)

    Armstrong, G. A.; Ayres, J. R.; Brotherton, S. D.

    1997-06-01

    Numerical simulation was used to model transient carrier emission from deep level traps in polycrystalline silicon (poly-Si) thin film transistors and to validate the analytical approximations used to interpret DLTS measurements. Transient emission from a single trap was compared with that from a continuous density of states. Numerical simulation was used to quantify the degree of error in the analytical analysis and show that it yields substantially correct values for a typical double exponential poly-Si trap state density as a function of energy, to within ± 10%. The major source of discrepancy was associated with the omission of the effects of displacement current from the analytical analysis. The DLTS spectra associated with a constant density of states was shown to give a decreasing signal with decreasing temperature, while that of an exponential density of states was found to be essentially flat.

  12. Low-voltage polymer/small-molecule blend organic thin-film transistors and circuits fabricated via spray deposition

    SciTech Connect

    Hunter, By Simon; Anthopoulos, Thomas D.; Ward, Jeremy W.; Jurchescu, Oana D.; Payne, Marcia M.; Anthony, John E.

    2015-06-01

    Organic thin-film electronics have long been considered an enticing candidate in achieving high-throughput manufacturing of low-power ubiquitous electronics. However, to achieve this goal, more work is required to reduce operating voltages and develop suitable mass-manufacture techniques. Here, we demonstrate low-voltage spray-cast organic thin-film transistors based on a semiconductor blend of 2,8-difluoro- 5,11-bis (triethylsilylethynyl) anthradithiophene and poly(triarylamine). Both semiconductor and dielectric films are deposited via successive spray deposition in ambient conditions (air with 40%–60% relative humidity) without any special precautions. Despite the simplicity of the deposition method, p-channel transistors with hole mobilities of >1 cm{sup 2}/Vs are realized at −4 V operation, and unipolar inverters operating at −6 V are demonstrated.

  13. Improvement in the Positive Bias Temperature Stability of SnOx-Based Thin Film Transistors by Hf and Zn Doping.

    PubMed

    Han, Dongsuk; Park, Jaehyung; Kang, Minsoo; Jeon, Hyeongtag; Park, Jongwan

    2015-10-01

    We investigated the performance of tin oxide thin film transistors (TFTs) using DC magnetron sputtering. A remarkable improvement in the transfer characteristics was obtained for the Hf-doped tin oxide (HTO) TFT. We also developed amorphous hafnium-zinc-tin oxide (HZTO) thin film transistors and investigated the effects of hafnium doping on the electrical characteristics of the HTO TFTs. Doping with hafnium resulted in a reduced defect density in the tin oxide channel layer related to oxygen vacancies, which may result from increased field effect mobility. Zinc atoms have relatively higher oxidation potential compared to tin atoms, so more oxygen molecules can be absorbed and more electrons are trapped in the HZTO films. The HZTO TFTs exhibited good electrical characteristics with a field effect mobility of 10.98 cm2/Vs, and a high ION/IOFF ratio over 10(8). PMID:26726382

  14. Improvement in the Positive Bias Temperature Stability of SnOx-Based Thin Film Transistors by Hf and Zn Doping.

    PubMed

    Han, Dongsuk; Park, Jaehyung; Kang, Minsoo; Jeon, Hyeongtag; Park, Jongwan

    2015-10-01

    We investigated the performance of tin oxide thin film transistors (TFTs) using DC magnetron sputtering. A remarkable improvement in the transfer characteristics was obtained for the Hf-doped tin oxide (HTO) TFT. We also developed amorphous hafnium-zinc-tin oxide (HZTO) thin film transistors and investigated the effects of hafnium doping on the electrical characteristics of the HTO TFTs. Doping with hafnium resulted in a reduced defect density in the tin oxide channel layer related to oxygen vacancies, which may result from increased field effect mobility. Zinc atoms have relatively higher oxidation potential compared to tin atoms, so more oxygen molecules can be absorbed and more electrons are trapped in the HZTO films. The HZTO TFTs exhibited good electrical characteristics with a field effect mobility of 10.98 cm2/Vs, and a high ION/IOFF ratio over 10(8).

  15. Design, fabrication and characterization of a high-sensitivity pressure sensor based on nano-polysilicon thin film transistors

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaofeng; Yu, Yang; Li, Dandan; Wen, Dianzhong

    2015-12-01

    Based on the nano-polysilicon thin film transistors (TFTs), a high-sensitivity pressure sensor was designed and fabricated in this paper. The pressure sensing element is composed of a Wheatstone bridge with four nano-polysilicon TFTs designed on different positions of the square silicon diaphragm. Via taking the four channel resistors of the TFTs as piezoresistors, the measurement to the external pressure can be realized according to the piezoresistive effects of channel layer. Through adopting complementary metal oxide semiconductor (CMOS) technology and micro-electromechanical system (MEMS) technology, the chips of sensor were fabricated on <100 > orientation silicon wafer with a high resistivity. At room temperature, when applying a voltage 5.0 V to the Wheatstone bridge, the full scale (100 kPa) output voltage and the sensitivity of the sensor with 35 μm-thick silicon diaphragm are 267 mV and 2.58 mV/kPa, respectively. The experimental results show that the pressure sensors can achieve a much higher sensitivity.

  16. Fabrication of high performance thin-film transistors via pressure-induced nucleation

    PubMed Central

    Kang, Myung-Koo; Kim, Si Joon; Kim, Hyun Jae

    2014-01-01

    We report a method to improve the performance of polycrystalline Si (poly-Si) thin-film transistors (TFTs) via pressure-induced nucleation (PIN). During the PIN process, spatial variation in the local solidification temperature occurs because of a non-uniform pressure distribution during laser irradiation of the amorphous Si layer, which is capped with an SiO2 layer. This leads to a four-fold increase in the grain size of the poly-Si thin-films formed using the PIN process, compared with those formed using conventional excimer laser annealing. We find that thin films with optimal electrical properties can be achieved with a reduction in the number of laser irradiations from 20 to 6, as well as the preservation of the interface between the poly-Si and the SiO2 gate insulator. This interface preservation becomes possible to remove the cleaning process prior to gate insulator deposition, and we report devices with a field-effect mobility greater than 160 cm2/Vs. PMID:25358809

  17. Novel top-contact monolayer pentacene-based thin-film transistor for ammonia gas detection.

    PubMed

    Mirza, Misbah; Wang, Jiawei; Li, Dexing; Arabi, S Atika; Jiang, Chao

    2014-04-23

    We report on the fabrication of an organic field-effect transistor (OFET) of a monolayer pentacene thin film with top-contact electrodes for the aim of ammonia (NH3) gas detection by monitoring changes in its drain current. A top-contact configuration, in which source and drain electrodes on a flexible stamp [poly(dimethylsiloxane)] were directly contacted with the monolayer pentacene film, was applied to maintain pentacene arrangement ordering and enhance the monolayer OFET detection performance. After exposure to NH3 gas, the carrier mobility at the monolayer OFET channel decreased down to one-third of its original value, leading to a several orders of magnitude decrease in the drain current, which tremendously enhanced the gas detection sensitivity. This sensitivity enhancement to a limit of the 10 ppm level was attributed to an increase of charge trapping in the carrier channel, and the amount of trapped states was experimentally evaluated by the threshold voltage shift induced by the absorbed NH3 molecular analyte. In contrast, a conventional device with a 50-nm-thick pentacene layer displayed much higher mobility but lower response to NH3 gas, arising from the impediment of analyte penetrating into the conductive channel, owing to the thick pentacene film.

  18. Absorption and optical conduction in InSe/ZnSe/InSe thin film transistors

    NASA Astrophysics Data System (ADS)

    Al Garni, S. E.; Qasrawi, A. F.

    2016-01-01

    In this work, (n)InSe/(p)ZnSe and (n)InSe/(p)ZnSe/(n)InSe heterojunction thin film transistor (TFT) devices are produced by the thermal evaporation technique. They are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy and optical spectroscopy techniques. While the InSe films are found to be amorphous, the ZnSe and InSe/ZnSe films exhibited polycrystalline nature of crystallization. The optical analysis has shown that these devices exhibit a conduction band offsets of 0.47 and valence band offsets of 0.67 and 0.74eV, respectively. In addition, while the dielectric spectra of the InSe and ZnSe displayed resonance peaks at 416 and 528THz, the dielectric spectra of InSe/ZnSe and InSe/ZnSe/InSe layers indicated two additional peaks at 305 and 350THz, respectively. On the other hand, the optical conductivity analysis and modeling in the light of free carrier absorption theory reflected low values of drift mobilities associated with incident alternating electric fields at terahertz frequencies. The drift mobility of the charge carrier particles at femtoseconds scattering times increased as a result of the ZnSe sandwiching between two InSe layers. The valence band offsets, the dielectric resonance at 305 and 350THz and the optical conductivity values nominate TFT devices for use in optoelectronics.

  19. Low temperature atomic layer deposited ZnO photo thin film transistors

    SciTech Connect

    Oruc, Feyza B.; Aygun, Levent E.; Donmez, Inci; Biyikli, Necmi; Okyay, Ali K.; Yu, Hyun Yong

    2015-01-01

    ZnO thin film transistors (TFTs) are fabricated on Si substrates using atomic layer deposition technique. The growth temperature of ZnO channel layers are selected as 80, 100, 120, 130, and 250 °C. Material characteristics of ZnO films are examined using x-ray photoelectron spectroscopy and x-ray diffraction methods. Stoichiometry analyses showed that the amount of both oxygen vacancies and interstitial zinc decrease with decreasing growth temperature. Electrical characteristics improve with decreasing growth temperature. Best results are obtained with ZnO channels deposited at 80 °C; I{sub on}/I{sub off} ratio is extracted as 7.8 × 10{sup 9} and subthreshold slope is extracted as 0.116 V/dec. Flexible ZnO TFT devices are also fabricated using films grown at 80 °C. I{sub D}–V{sub GS} characterization results showed that devices fabricated on different substrates (Si and polyethylene terephthalate) show similar electrical characteristics. Sub-bandgap photo sensing properties of ZnO based TFTs are investigated; it is shown that visible light absorption of ZnO based TFTs can be actively controlled by external gate bias.

  20. Enhanced photocurrent of Ge-doped InGaO thin film transistors with quantum dots

    SciTech Connect

    Lee, Sang Moo; Park, Si Jin; Kang, Seong Jun; Lee, Kwang Ho; Park, Jin-Seong; Park, Soohyung; Yi, Yeonjin

    2015-01-19

    The photocurrent of germanium-doped indium-gallium oxide (GIGO) thin film transistors (TFTs) can be observed when the device is exposed to a ultra-violet light because GIGO is a wide band gap semiconducting material. Therefore, we decorated cadmium selenide (CdSe) quantum-dots (QDs) on the surface of GIGO to increase the photocurrent for low-energy light, i.e., visible light. A 10 nm GIGO film was deposited on the SiO{sub 2}/Si substrate by a radio frequency sputter system. Also, we prepared CdSe QDs with sizes of ∼6.3 nm, which can absorb red visible light. QDs were spin-coated onto the GIGO film, and post-annealing was done to provide cross-linking between QDs. The prepared devices showed a 231% increase in photocurrent when exposed to 650 nm light due to the QDs on the GIGO surface. Measurements to construct an energy level diagram were made using ultraviolet photoelectron spectroscopy to determine the origin of the photocurrent, and we found that the small band gap of CdSe QDs enables the increase in photocurrent in the GIGO TFTs. This result is relevant for developing highly transparent photosensors based on oxide semiconductors and QDs.

  1. Fully Solution-Processed Flexible Organic Thin Film Transistor Arrays with High Mobility and Exceptional Uniformity

    PubMed Central

    Fukuda, Kenjiro; Takeda, Yasunori; Mizukami, Makoto; Kumaki, Daisuke; Tokito, Shizuo

    2014-01-01

    Printing fully solution-processed organic electronic devices may potentially revolutionize production of flexible electronics for various applications. However, difficulties in forming thin, flat, uniform films through printing techniques have been responsible for poor device performance and low yields. Here, we report on fully solution-processed organic thin-film transistor (TFT) arrays with greatly improved performance and yields, achieved by layering solution-processable materials such as silver nanoparticle inks, organic semiconductors, and insulating polymers on thin plastic films. A treatment layer improves carrier injection between the source/drain electrodes and the semiconducting layer and dramatically reduces contact resistance. Furthermore, an organic semiconductor with large-crystal grains results in TFT devices with shorter channel lengths and higher field-effect mobilities. We obtained mobilities of over 1.2 cm2 V−1 s−1 in TFT devices with channel lengths shorter than 20 μm. By combining these fabrication techniques, we built highly uniform organic TFT arrays with average mobility levels as high as 0.80 cm2 V−1 s−1 and ideal threshold voltages of 0 V. These results represent major progress in the fabrication of fully solution-processed organic TFT device arrays. PMID:24492785

  2. Fabrication of Amorphous Indium Gallium Zinc Oxide Thin Film Transistor by using Focused Ion Beam

    NASA Astrophysics Data System (ADS)

    Zhu, Wencong

    Compared with other transparent semiconductors, amorphous indium gallium zinc oxide (a-IGZO) has both good uniformity and high electron mobility, which make it as a good candidate for displays or large-scale transparent circuit. The goal of this research is to fabricate alpha-IGZO thin film transistor (TFT) with channel milled by focused ion beam (FIB). TFTs with different channel geometries can be achieved by applying different milling strategies, which facilitate modifying complex circuit. Technology Computer-Aided Design (TCAD) was also introduced to understand the effect of trapped charges on the device performance. The investigation of the trapped charge at IGZO/SiO2 interface was performed on the IGZO TFT on p-Silicon substrate with thermally grown SiO2 as dielectric. The subgap density-of-state model was used for the simulation, which includes conduction band-tail trap states and donor-like state in the subgap. The result shows that the de-trapping and donor-state ionization determine the interface trapped charge density at various gate biases. Simulation of IGZO TFT with FIB defined channel on the same substrate was also applied. The drain and source were connected intentionally during metal deposition and separated by FIB milling. Based on the simulation, the Ga ions in SiO2 introduced by the ion beam was drifted by gate bias and affects the saturation drain current. Both side channel and direct channel transparent IGZO TFTs were fabricated on the glass substrate with coated ITO. Higher ion energy (30 keV) was used to etch through the substrate between drain and source and form side channels at the corner of milled trench. Lower ion energy (16 keV) was applied to stop the milling inside IGZO thin film and direct channel between drain and source was created. Annealing after FIB milling removed the residual Ga ions and the devices show switch feature. Direct channel shows higher saturation drain current (~10-6 A) compared with side channel (~10-7 A) because

  3. Low-temperature, high-performance solution-processed thin-film transistors with peroxo-zirconium oxide dielectric.

    PubMed

    Park, Jee Ho; Yoo, Young Bum; Lee, Keun Ho; Jang, Woo Soon; Oh, Jin Young; Chae, Soo Sang; Baik, Hong Koo

    2013-01-23

    We demonstrated solution-processed thin film transistors on a peroxo-zirconium oxide (ZrO(2)) dielectric with a maximum temperature of 350 °C. The formation of ZrO(2) films was investigated by TG-DTA, FT-IR, and XPS analyses at various temperatures. We synthesized a zirconium oxide solution by adding hydrogen peroxide (H(2)O(2)). The H(2)O(2) forms peroxo groups in the ZrO(2) film producing a dense-amorphous phase and a smooth surface film. Because of these characteristics, the ZrO(2) film successfully blocked leakage current even in annealing at 300 °C. Finally, to demonstrate that the ZrO(2) film is dielectric, we fabricated thin-film transistors (TFTs) with a solution-processed channel layer of indium zinc oxide (IZO) on ZrO(2) films at 350 °C. These TFTs had a mobility of 7.21 cm(2)/(V s), a threshold voltage (V(th)) of 3.22 V, and a V(th) shift of 1.6 V under positive gate bias stress.

  4. Vacuum filtration based formation of liquid crystal films of semiconducting carbon nanotubes and high performance transistor devices.

    PubMed

    King, Benjamin; Panchapakesan, Balaji

    2014-05-01

    In this paper, we report ultra-thin liquid crystal films of semiconducting carbon nanotubes using a simple vacuum filtration process. Vacuum filtration of nanotubes in aqueous surfactant solution formed nematic domains on the filter membrane surface and exhibited local ordering. A 2D fast Fourier transform was used to calculate the order parameters from scanning electron microscopy images. The order parameter was observed to be sensitive to the filtration time demonstrating different regions of transformation namely nucleation of nematic domains, nanotube accumulation and large domain growth.Transmittance versus sheet resistance measurements of such films resulted in optical to dc conductivity of σ(opt)/σ(dc) = 9.01 indicative of purely semiconducting nanotube liquid crystal network.Thin films of nanotube liquid crystals with order parameters ranging from S = 0.1-0.5 were patterned into conducting channels of transistor devices which showed high I(on)/I(off) ratios from 10-19,800 and electron mobility values μ(e) = 0.3-78.8 cm(2) (V-s)(-1), hole mobility values μ(h) = 0.4-287 cm(2) (V-s)(-1). High I on/I off ratios were observed at low order parameters and film mass. A Schottky barrier transistor model is consistent with the observed transistor characteristics. Electron and hole mobilities were seen to increase with order parameters and carbon nanotube mass fractions. A fundamental tradeoff between decreasing on/off ratio and increasing mobility with increasing nanotube film mass and order parameter is therefore concluded. Increase in order parameters of nanotubes liquid crystals improved the electronic transport properties as witnessed by the increase in σ(dc)/σ(opt) values on macroscopic films and high mobilities in microscopic transistors. Liquid crystal networks of semiconducting nanotubes as demonstrated here are simple to fabricate, transparent, scalable and could find wide ranging device applications.

  5. Vacuum filtration based formation of liquid crystal films of semiconducting carbon nanotubes and high performance transistor devices

    NASA Astrophysics Data System (ADS)

    King, Benjamin; Panchapakesan, Balaji

    2014-05-01

    In this paper, we report ultra-thin liquid crystal films of semiconducting carbon nanotubes using a simple vacuum filtration process. Vacuum filtration of nanotubes in aqueous surfactant solution formed nematic domains on the filter membrane surface and exhibited local ordering. A 2D fast Fourier transform was used to calculate the order parameters from scanning electron microscopy images. The order parameter was observed to be sensitive to the filtration time demonstrating different regions of transformation namely nucleation of nematic domains, nanotube accumulation and large domain growth.Transmittance versus sheet resistance measurements of such films resulted in optical to dc conductivity of σ opt/σ dc = 9.01 indicative of purely semiconducting nanotube liquid crystal network.Thin films of nanotube liquid crystals with order parameters ranging from S = 0.1-0.5 were patterned into conducting channels of transistor devices which showed high I on/I off ratios from 10-19 800 and electron mobility values μ e = 0.3-78.8 cm2 (V-s)-1, hole mobility values μ h = 0.4-287 cm2 (V-s)-1. High I on/I off ratios were observed at low order parameters and film mass. A Schottky barrier transistor model is consistent with the observed transistor characteristics. Electron and hole mobilities were seen to increase with order parameters and carbon nanotube mass fractions. A fundamental tradeoff between decreasing on/off ratio and increasing mobility with increasing nanotube film mass and order parameter is therefore concluded. Increase in order parameters of nanotubes liquid crystals improved the electronic transport properties as witnessed by the increase in σ dc/σ opt values on macroscopic films and high mobilities in microscopic transistors. Liquid crystal networks of semiconducting nanotubes as demonstrated here are simple to fabricate, transparent, scalable and could find wide ranging device applications.

  6. Effects of Ta Addition Through Co-Sputtering on the Electrical Characteristics of Indium Tin Oxide Thin Film Transistors.

    PubMed

    Park, Si-Nae; Son, Dae-Ho; Sung, Shi-Joon; Kang, Jin-Kyu; Kim, Dae-Hwan

    2015-01-01

    We have investigated the effects of adding (Ta) ions to InSnO thin films by co-sputtering on the performance of InSnO thin film transistors (TFTs). TaInSnO TFTs exhibited significantly lower off currents and higher on/off current ratios. Ta ions, owing to their strong affinity to oxygen suppress the formation of free electron carriers in thin films; and hence, play an important role in enhancing the electrical characteristics of the TFTs. The optimized TaInSnO TFTs showed high on/off ratios and low subthreshold swings. PMID:26328366

  7. Proton induced multilevel storage capability in self-assembled indium-zinc-oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Guo, Li Qiang; Jin Wan, Chang; Qiang Zhu, Li; Wan, Qing

    2013-09-01

    Multilevel memory capability of self-assembled indium-zinc-oxide (IZO) electric-double-layer (EDL) thin-film transistors gated by nanogranular SiO2 proton conducting electrolytes is investigated. More than four distinct memory states are obtained by programming gate voltage. The observed multilevel storage behavior is mainly due to the controlled interfacial electrochemical doping of IZO channel by penetrated protons under programmed gate voltages. In addition, such IZO-based EDL transistor multilevel memory exhibits good characteristics of programming/erasing endurance and data retention. Such oxide-based EDL transistors with proton-induced multilevel memory behavior are interesting for low-cost memory and neuromorphic system applications after further properties and size optimization.

  8. Temperature and layer thickness dependent in situ investigations on epindolidione organic thin-film transistors

    PubMed Central

    Lassnig, R.; Striedinger, B.; Jones, A.O.F.; Scherwitzl, B.; Fian, A.; Głowacl, E.D.; Stadlober, B.; Winkler, A.

    2016-01-01

    We report on in situ performance evaluations as a function of layer thickness and substrate temperature for bottom-gate, bottom-gold contact epindolidione organic thin-film transistors on various gate dielectrics. Experiments were carried out under ultra-high vacuum conditions, enabling quasi-simultaneous electrical and surface analysis. Auger electron spectroscopy and thermal desorption spectroscopy (TDS) were applied to characterize the quality of the substrate surface and the thermal stability of the organic films. Ex situ atomic force microscopy (AFM) was used to gain additional information on the layer formation and surface morphology of the hydrogen-bonded organic pigment. The examined gate dielectrics included SiO2, in its untreated and sputtered forms, as well as the spin-coated organic capping layers poly(vinyl-cinnamate) (PVCi) and poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE, from the class of polynorbornenes). TDS and AFM revealed Volmer-Weber island growth dominated film formation with no evidence of a subjacent wetting layer. This growth mode is responsible for the comparably high coverage required for transistor behavior at 90–95% of a monolayer composed of standing molecules. Surface sputtering and an increased sample temperature during epindolidione deposition augmented the surface diffusion of adsorbing molecules and therefore led to a lower number of better-ordered islands. Consequently, while the onset of charge transport was delayed, higher saturation mobility was obtained. The highest, bottom-contact configuration, mobilities of approximately 2.5 × 10−3cm2/Vs were found for high coverages (50 nm) on sputtered samples. The coverage dependence of the mobility showed very different characteristics for the different gate dielectrics, while the change of the threshold voltage with coverage was approximately the same for all systems. An apparent decrease of the mobility with increasing coverage on the

  9. Influence of the contact metal on the performance of n-type carbonyl-functionalized quaterthiophene organic thin-film transistors

    SciTech Connect

    Schols, S.; Willigenburg, L. van; Mueller, R.; Bode, D.; Debucquoy, M.; Jonge, S. de; Genoe, J.; Heremans, P.

    2008-12-29

    Organic thin-film transistors using 5, 5-diperfluorohexylcarbonyl-2,2:5,2:5,2-quaterthiophene (DFHCO-4T) as the electron conducting organic semiconductor are fabricated and the performance of these transistors with different top-contact metals is investigated. Transistors with Au source-drain top contacts attain an apparent saturation mobility of 4.6 cm{sup 2}/V s, whereas this parameter is 100 times lower for similar transistors with Al/LiF top contacts. We explain this lower performance by the formation of a thin interfacial layer with poor charge injection properties resulting from a redox reaction between Al and DFHCO-4T.

  10. Superconducting transistor

    DOEpatents

    Gray, Kenneth E.

    1979-01-01

    A superconducting transistor is formed by disposing three thin films of superconducting material in a planar parallel arrangement and insulating the films from each other by layers of insulating oxides to form two tunnel junctions. One junction is biased above twice the superconducting energy gap and the other is biased at less than twice the superconducting energy gap. Injection of quasiparticles into the center film by one junction provides a current gain in the second junction.

  11. Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering

    NASA Astrophysics Data System (ADS)

    Niang, K. M.; Cho, J.; Heffernan, S.; Milne, W. I.; Flewitt, A. J.

    2016-08-01

    The influence of the stoichiometry of amorphous zinc tin oxide (a-ZTO) thin films used as the semiconducting channel in thin film transistors (TFTs) is investigated. A-ZTO has been deposited using remote-plasma reactive sputtering from zinc:tin metal alloy targets with 10%, 33%, and 50% Sn at. %. Optimisations of thin films are performed by varying the oxygen flow, which is used as the reactive gas. The structural, optical, and electrical properties are investigated for the optimised films, which, after a post-deposition annealing at 500 °C in air, are also incorporated as the channel layer in TFTs. The optical band gap of a-ZTO films slightly increases from 3.5 to 3.8 eV with increasing tin content, with an average transmission ˜90% in the visible range. The surface roughness and crystallographic properties of the films are very similar before and after annealing. An a-ZTO TFT produced from the 10% Sn target shows a threshold voltage of 8 V, a switching ratio of 108, a sub-threshold slope of 0.55 V dec-1, and a field effect mobility of 15 cm2 V-1 s-1, which is a sharp increase from 0.8 cm2 V-1 s-1 obtained in a reference ZnO TFT. For TFTs produced from the 33% Sn target, the mobility is further increased to 21 cm2 V-1 s-1, but the sub-threshold slope is slightly deteriorated to 0.65 V dec-1. For TFTs produced from the 50% Sn target, the devices can no longer be switched off (i.e., there is no channel depletion). The effect of tin content on the TFT electrical performance is explained in the light of preferential sputtering encountered in reactive sputtering, which resulted in films sputtered from 10% and 33% Sn to be stoichiometrically close to the common Zn2SnO4 and ZnSnO3 phases.

  12. Low-temperature spray-deposited indium oxide for flexible thin-film transistors and integrated circuits

    SciTech Connect

    Petti, Luisa; Faber, Hendrik; Anthopoulos, Thomas D.; Münzenrieder, Niko; Cantarella, Giuseppe; Tröster, Gerhard; Patsalas, Panos A.

    2015-03-02

    Indium oxide (In{sub 2}O{sub 3}) films were deposited by ultrasonic spray pyrolysis in ambient air and incorporated into bottom-gate coplanar and staggered thin-film transistors. As-fabricated devices exhibited electron-transporting characteristics with mobility values of 1 cm{sup 2}V{sup −1}s{sup −1} and 16 cm{sup 2}V{sup −1}s{sup −1} for coplanar and staggered architectures, respectively. Integration of In{sub 2}O{sub 3} transistors enabled realization of unipolar inverters with high gain (5.3 V/V) and low-voltage operation. The low temperature deposition (≤250 °C) of In{sub 2}O{sub 3} also allowed transistor fabrication on free-standing 50 μm-thick polyimide foils. The resulting flexible In{sub 2}O{sub 3} transistors exhibit good characteristics and remain fully functional even when bent to tensile radii of 4 mm.

  13. Fabrication and characterization of oxide-based thin film transistors, and process development for oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Lim, Wantae

    2009-12-01

    This dissertation is focused on the development of thin film transistors (TFTs) using oxide materials composed of post-transitional cations with (n-1)d 10ns0 (n≥4). The goal is to achieve high performance oxide-based TFTs fabricated at low processing temperature on either glass or flexible substrates for next generation display applications. In addition, etching mechanism and Ohmic contact formation for oxide heterostructure (ZnO/CuCrO 2) system is demonstrated. The deposition and characterization of oxide semiconductors (In 2O3-ZnO, and InGaZnO4) using a RF-magnetron sputtering system are studied. The main influence on the resistivity of the films is found to be the oxygen partial pressure in the sputtering ambient. The films remained amorphous and transparent (> 70%) at all process conditions. These films showed good transmittance at suitable conductivity for transistor fabrication. The electrical characteristics of both top- and bottom-gate type Indium Zinc Oxide (InZnO) and Indium Gallium Zinc Oxide (InGaZnO4)-based TFTs are reported. The InZnO films were favorable for depletion-mode TFTs due to their tendency to form oxygen vacancies, while enhancement-mode devices were realized with InGaZnO4 films. The InGaZnO4-based TFTs fabricated on either glass or plastic substrates at low temperature (<100°C) exhibit good electrical properties: the saturation mobility of 5--12 cm2.V-1.s-1 and threshold voltage of 0.5--2.5V. The devices are also examined as a function of aging time in order to verify long-term stability in air. The effect of gate dielectric materials on electrical properties of InGaZnO 4-based TFTs was investigated. The use of SiNx film as a gate dielectric reduces the trap density and the roughness at the channel/gate dielectric interface compared to SiO2 gate dielectric, resulting in an improvement of device parameters by reducing scattering of trapped charges at the interface. The quality of interface is shown to have large effect on TFT performance

  14. Persistent photocurrent (PPC) in solution-processed organic thin film transistors: Mechanisms of gate voltage control

    NASA Astrophysics Data System (ADS)

    Singh, Subhash; Mohapatra, Y. N.

    2016-07-01

    There is a growing need to understand mechanisms of photoresponse in devices based on organic semiconductor thin films and interfaces. The phenomenon of persistent photocurrent (PPC) has been systematically investigated in solution processed TIPS-Pentacene based organic thin film transistors (OTFTs) as an important example of an organic semiconductor material system. With increasing light intensity from dark to 385 mW/cm2, there is a significant shift in threshold voltage (VTh) while the filed-effect mobility remains unchanged. The OTFT shows large photoresponse under white light illumination due to exponential tail states with characteristic energy parameter of 86 meV. The photo-induced current is observed to persist even for several hours after turning the light off. To investigate the origin of PPC, its quenching mechanism is investigated by a variety of methods involving a combination of gate bias, illumination and temperature. We show that a coherent model of trap-charge induced carrier concentration is able to account for the quenching behavior. Analysis of isothermal transients using time-analyzed transient spectroscopy shows that the emission rates are activated and are also field enhanced due to Poole-Frankel effect. The results shed light on the nature, origin, and energetic distribution of the traps controlling PPC in solution processed organic semiconductors and their interfaces.

  15. Laser direct patterning of indium tin oxide for defining a channel of thin film transistor.

    PubMed

    Wang, Jian-Xun; Kwon, Sang Jik; Han, Jae-Hee; Cho, Eou Sik

    2013-11-01

    In this work, using a Q-switched diode-pumped neodymium-doped yttrium vanadate (Nd:YVO4, lambda = 1064 nm) laser, a direct patterning of indium tin oxide (ITO) channel was realized on glass substrates and the results were compared and analyzed in terms of the effect of repetition rate, scanning speed on etching characteristics. The results showed that the laser conditions of 40 kHz repetition rate with a scanning speed of 500 mm/s were appropriate for the channeling of ITO electrodes. The length of laser-patterned channel was maintained at about 55 microm. However, residual spikes (about 50 nm in height) of ITO were found to be formed at the edges of the laser ablated area and a few ITO residues remained on the glass substrate after laser scanning. By dipping the laser-ablated ITO film in ITO diluted etchant (ITO etchant/DI water: 1/10) at 50 degrees C for 3 min, the spikes and residual ITO were effectively removed. At last, using the laser direct patterning, a bottom-source-drain indium gallium zinc oxide thin film transistor (IGZO-TFT) was fabricated. It is successfully demonstrated that the laser direct patterning can be utilized instead of photolithography to simplify the fabrication process of TFT channel, resulting in the increase of productivity and reduction of cost. PMID:24245327

  16. Solution processed lanthanum aluminate gate dielectrics for use in metal oxide-based thin film transistors

    NASA Astrophysics Data System (ADS)

    Esro, M.; Mazzocco, R.; Vourlias, G.; Kolosov, O.; Krier, A.; Milne, W. I.; Adamopoulos, G.

    2015-05-01

    We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (LaxAl1-xOy) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the LaxAl1-xOy films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlOy dielectrics exhibit a wide band gap (˜6.18 eV), high dielectric constant (k ˜ 16), low roughness (˜1.9 nm), and very low leakage currents (<3 nA/cm2). TFTs employing solution processed LaAlOy gate dielectrics and ZnO semiconducting channels exhibit excellent electron transport characteristics with hysteresis-free operation, low operation voltages (˜10 V), high on/off current modulation ratio of >106, subthreshold swing of ˜650 mV dec-1, and electron mobility of ˜12 cm2 V-1 s-1.

  17. High Performance, Low Temperature Solution-Processed Barium and Strontium Doped Oxide Thin Film Transistors.

    PubMed

    Banger, Kulbinder K; Peterson, Rebecca L; Mori, Kiyotaka; Yamashita, Yoshihisa; Leedham, Timothy; Sirringhaus, Henning

    2014-01-28

    Amorphous mixed metal oxides are emerging as high performance semiconductors for thin film transistor (TFT) applications, with indium gallium zinc oxide, InGaZnO (IGZO), being one of the most widely studied and best performing systems. Here, we investigate alkaline earth (barium or strontium) doped InBa(Sr)ZnO as alternative, semiconducting channel layers and compare their performance of the electrical stress stability with IGZO. In films fabricated by solution-processing from metal alkoxide precursors and annealed to 450 °C we achieve high field-effect electron mobility up to 26 cm(2) V(-1) s(-1). We show that it is possible to solution-process these materials at low process temperature (225-200 °C yielding mobilities up to 4.4 cm(2) V(-1) s(-1)) and demonstrate a facile "ink-on-demand" process for these materials which utilizes the alcoholysis reaction of alkyl metal precursors to negate the need for complex synthesis and purification protocols. Electrical bias stress measurements which can serve as a figure of merit for performance stability for a TFT device reveal Sr- and Ba-doped semiconductors to exhibit enhanced electrical stability and reduced threshold voltage shift compared to IGZO irrespective of the process temperature and preparation method. This enhancement in stability can be attributed to the higher Gibbs energy of oxidation of barium and strontium compared to gallium. PMID:24511184

  18. Solution processed lanthanum aluminate gate dielectrics for use in metal oxide-based thin film transistors

    SciTech Connect

    Esro, M.; Adamopoulos, G.; Mazzocco, R.; Kolosov, O.; Krier, A.; Vourlias, G.; Milne, W. I.

    2015-05-18

    We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (La{sub x}Al{sub 1−x}O{sub y}) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the La{sub x}Al{sub 1−x}O{sub y} films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlO{sub y} dielectrics exhibit a wide band gap (∼6.18 eV), high dielectric constant (k ∼ 16), low roughness (∼1.9 nm), and very low leakage currents (<3 nA/cm{sup 2}). TFTs employing solution processed LaAlO{sub y} gate dielectrics and ZnO semiconducting channels exhibit excellent electron transport characteristics with hysteresis-free operation, low operation voltages (∼10 V), high on/off current modulation ratio of >10{sup 6}, subthreshold swing of ∼650 mV dec{sup −1}, and electron mobility of ∼12 cm{sup 2} V{sup −1} s{sup −1}.

  19. INFLUENCE OF FILM STRUCTURE AND LIGHT ON CHARGE TRAPPING AND DISSIPATION DYNAMICS IN SPUN-CAST ORGANIC THIN-FILM TRANSISTORS MEASURED BY SCANNING KELVIN PROBE MICROSCOPY

    SciTech Connect

    Teague, L.; Moth, M.; Anthony, J.

    2012-05-03

    Herein, time-dependent scanning Kelvin probe microscopy of solution processed organic thin film transistors (OTFTs) reveals a correlation between film microstructure and OTFT device performance with the location of trapped charge within the device channel. The accumulation of the observed trapped charge is concurrent with the decrease in I{sub SD} during operation (V{sub G}=-40 V, V{sub SD}= -10 V). We discuss the charge trapping and dissipation dynamics as they relate to the film structure and show that application of light quickly dissipates the observed trapped charge.

  20. Graphene and thin-film semiconductor heterojunction transistors integrated on wafer scale for low-power electronics.

    PubMed

    Heo, Jinseong; Byun, Kyung-Eun; Lee, Jaeho; Chung, Hyun-Jong; Jeon, Sanghun; Park, Seongjun; Hwang, Sungwoo

    2013-01-01

    Graphene heterostructures in which graphene is combined with semiconductors or other layered 2D materials are of considerable interest, as a new class of electronic devices has been realized. Here we propose a technology platform based on graphene-thin-film-semiconductor-metal (GSM) junctions, which can be applied to large-scale and power-efficient electronics compatible with a variety of substrates. We demonstrate wafer-scale integration of vertical field-effect transistors (VFETs) based on graphene-In-Ga-Zn-O (IGZO)-metal asymmetric junctions on a transparent 150 × 150 mm(2) glass. In this system, a triangular energy barrier between the graphene and metal is designed by selecting a metal with a proper work function. We obtain a maximum current on/off ratio (Ion/Ioff) up to 10(6) with an average of 3010 over 2000 devices under ambient conditions. For low-power logic applications, an inverter that combines complementary n-type (IGZO) and p-type (Ge) devices is demonstrated to operate at a bias of only 0.5 V.

  1. A multifunctional polymer-graphene thin-film transistor with tunable transport regimes.

    PubMed

    Mosciatti, Thomas; Haar, Sébastien; Liscio, Fabiola; Ciesielski, Artur; Orgiu, Emanuele; Samorì, Paolo

    2015-03-24

    Here we describe a strategy to fabricate multifunctional graphene-polymer hybrid thin-film transistors (PG-TFT) whose transport properties are tunable by varying the deposition conditions of liquid-phase exfoliated graphene (LPE-G) dispersions onto a dielectric surface and via thermal annealing post-treatments. In particular, the ionization energy (IE) of the LPE-G drop-cast on SiO2 can be finely adjusted prior to polymer deposition via thermal annealing in air environment, exhibiting values gradually changing from 4.8 eV up to 5.7 eV. Such a tunable graphene's IE determines dramatically different electronic interactions between the LPE-G and the semiconducting polymer (p- or n-type) sitting on its top, leading to devices where the output current of the PG-TFT can be operated from being completely turned off up to modulable. In fact upon increasing the surface coverage of graphene nanoflakes on the SiO2 the charge transport properties within the top polymer layer are modified from being semiconducting up to truly conductive (graphite-like). Significantly, when the IE of LPE-G is outside the polymer band gap, the PG-TFT can operate as a multifunctional three terminal switch (transistor) and/or memory device featuring high number of erase-write cycles. Our PG-TFT, based on a fine energy level engineering, represents a memory device operating without the need of a dielectric layer separating a floating gate from the active channel.

  2. Fabrication and Electrical Characterization of InZnO:N Thin Film Transistors Prepared by Radio Frequency Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Peng, Yunfei; Wang, Hailong; Zhang, Wenqi; Li, Bin; Zhou, Dongzhan; Zhang, Xiqing; Wang, Yongsheng

    2016-07-01

    The fabrication and electrical characterization of InZnO:N thin film transistors (TFTs) were investigated in this work. The InZnO:N film was deposited on SiO2/ p-type Si substrates by radio frequency magnetron sputtering as the active layer of the TFTs at room temperature. In order to optimize the performance of the InZnO:N TFTs, the effect of the oxygen contents in the preparation of the active layer is investigated. We found that an appropriate O2/Ar gas flow ratio is very beneficial for the InZnO:N TFTs, and when the O2/Ar gas flow ratio is at 1/30, the transistor exhibited a high field-effect mobility of 39.3 cm2/Vs, a threshold voltage of 2.4 V and a I ON/OFF ratio of 1.1 × 107.

  3. SEMICONDUCTOR DEVICES Low voltage copper phthalocyanine organic thin film transistors with a polymer layer as the gate insulator

    NASA Astrophysics Data System (ADS)

    Xueqiang, Liu; Weihong, Bi; Tong, Zhang

    2010-12-01

    Low voltage organic thin film transistors (OTFTs) were created using polymethyl-methacrylate-co g-lyciclyl-methacrylate (PMMA-GMA) as the gate dielectric. The OTFTs performed acceptably at supply voltages of about 10 V. From a densely packed copolymer brush, a leakage current as low as 2 × 10-8 A/cm2 was obtained. From the measured capacitance—insulator frequency characteristics, a dielectric constant in the range 3.9-5.0 was obtained. By controlling the thickness of the gate dielectric, the threshold voltage was reduced from -3.5 to -2.0 V. The copper phthalocyanine (CuPc) based organic thin film transistor could be operated at low voltage and 1.2 × 10-3 cm2/(V·s) mobility.

  4. Novel low voltage and solution processable organic thin film transistors based on water dispersed polymer semiconductor nanoparticulates.

    PubMed

    Darwis, Darmawati; Elkington, Daniel; Ulum, Syahrul; Bryant, Glenn; Belcher, Warwick; Dastoor, Paul; Zhou, Xiaojing

    2013-07-01

    Two novel organic thin film transistor structures that combine a hygroscopic insulator with the use of water-dispersed polymer nanoparticles as the active layer are presented. In the first device structure, the semiconducting layer was fabricated from a nanoparticulate suspension of poly-(3-hexylthiophene) prepared through a mini-emulsion process using sodium dodecyl sulfate as the surfactant whereas a surfactant-free precipitation method has been used for the second device structure. In both cases, fully solution processable transistors have been fabricated in a top gate configuration with hygroscopic poly(4-vinylphenol) as the dielectric layer. Both device structures operate at low voltages (0 to -4V) but exhibit contrasting output characteristics. A systematic study is presented on the effect of surfactant on the synthesis of semiconducting nanoparticles, the formation of thin nanoparticulate films and, consequently, on device performance.

  5. Electrical dependence on the chemical composition of the gate dielectric in indium gallium zinc oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Tari, Alireza; Lee, Czang-Ho; Wong, William S.

    2015-07-01

    Bottom-gate thin-film transistors were fabricated by depositing a 50 nm InGaZnO (IGZO) channel layer at 150 °C on three separate gate dielectric films: (1) thermal SiO2, (2) plasma-enhanced chemical-vapor deposition (PECVD) SiNx, and (3) a PECVD SiOx/SiNx dual-dielectric. X-ray photoelectron and photoluminescence spectroscopy showed the Vo concentration was dependent on the hydrogen concentration of the underlying dielectric film. IGZO films on SiNx (high Vo) and SiO2 (low Vo) had the highest and lowest conductivity, respectively. A PECVD SiOx/SiNx dual-dielectric layer was effective in suppressing hydrogen diffusion from the nitride layer into the IGZO and resulted in higher resistivity films.

  6. Green processing of metal oxide core-shell nanoparticles as low-temperature dielectrics in organic thin-film transistors.

    PubMed

    Portilla, Luis; Etschel, Sebastian H; Tykwinski, Rik R; Halik, Marcus

    2015-10-21

    TiO2 , Fe3 O4, AlOx , ITO (indium tin oxide), and CeO2 nanoparticles are tailored to exhibit excellent dispersability in deionized water and alcohols. The latter provides an ecofriendly solution for processing metal oxide nanoparticles at a neutral pH. Water-processed dielectrics from the metal oxide nanoparticles are incorporated into organic thin-film transistors fabricated on rigid and flexible substrates. PMID:26308740

  7. Green processing of metal oxide core-shell nanoparticles as low-temperature dielectrics in organic thin-film transistors.

    PubMed

    Portilla, Luis; Etschel, Sebastian H; Tykwinski, Rik R; Halik, Marcus

    2015-10-21

    TiO2 , Fe3 O4, AlOx , ITO (indium tin oxide), and CeO2 nanoparticles are tailored to exhibit excellent dispersability in deionized water and alcohols. The latter provides an ecofriendly solution for processing metal oxide nanoparticles at a neutral pH. Water-processed dielectrics from the metal oxide nanoparticles are incorporated into organic thin-film transistors fabricated on rigid and flexible substrates.

  8. Integrating Epitaxial-Like Pb(Zr,Ti)O3 Thin-Film into Silicon for Next-Generation Ferroelectric Field-Effect Transistor.

    PubMed

    Park, Jae Hyo; Kim, Hyung Yoon; Jang, Gil Su; Seok, Ki Hwan; Chae, Hee Jae; Lee, Sol Kyu; Kiaee, Zohreh; Joo, Seung Ki

    2016-03-23

    The development of ferroelectric random-access memory (FeRAM) technology with control of grain boundaries would result in a breakthrough for new nonvolatile memory devices. The excellent piezoelectric and electrical properties of bulk ferroelectrics are degraded when the ferroelectric is processed into thin films because the grain boundaries then form randomly. Controlling the nature of nucleation and growth are the keys to achieving a good crystalline thin-film. However, the sought after high-quality ferroelectric thin-film has so far been thought to be impossible to make, and research has been restricted to atomic-layer deposition which is extremely expensive and has poor reproducibility. Here we demonstrate a novel epitaxial-like growth technique to achieve extremely uniform and large rectangular-shaped grains in thin-film ferroelectrics by dividing the nucleation and growth phases. With this technique, it is possible to achieve 100-μm large uniform grains, even made available on Si, which is large enough to fabricate a field-effect transistor in each grain. The electrical and reliability test results, including endurance and retention test results, were superior to other FeRAMs reported so far and thus the results presented here constitute the first step toward the development of FeRAM using epitaxial-like ferroelectric thin-films.

  9. Integrating Epitaxial-Like Pb(Zr,Ti)O3 Thin-Film into Silicon for Next-Generation Ferroelectric Field-Effect Transistor

    PubMed Central

    Park, Jae Hyo; Kim, Hyung Yoon; Jang, Gil Su; Seok, Ki Hwan; Chae, Hee Jae; Lee, Sol Kyu; Kiaee, Zohreh; Joo, Seung Ki

    2016-01-01

    The development of ferroelectric random-access memory (FeRAM) technology with control of grain boundaries would result in a breakthrough for new nonvolatile memory devices. The excellent piezoelectric and electrical properties of bulk ferroelectrics are degraded when the ferroelectric is processed into thin films because the grain boundaries then form randomly. Controlling the nature of nucleation and growth are the keys to achieving a good crystalline thin-film. However, the sought after high-quality ferroelectric thin-film has so far been thought to be impossible to make, and research has been restricted to atomic-layer deposition which is extremely expensive and has poor reproducibility. Here we demonstrate a novel epitaxial-like growth technique to achieve extremely uniform and large rectangular-shaped grains in thin-film ferroelectrics by dividing the nucleation and growth phases. With this technique, it is possible to achieve 100-μm large uniform grains, even made available on Si, which is large enough to fabricate a field-effect transistor in each grain. The electrical and reliability test results, including endurance and retention test results, were superior to other FeRAMs reported so far and thus the results presented here constitute the first step toward the development of FeRAM using epitaxial-like ferroelectric thin-films. PMID:27005886

  10. Nano-crystallization in ZnO-doped In2O3 thin films via excimer laser annealing for thin-film transistors

    NASA Astrophysics Data System (ADS)

    Fujii, Mami N.; Ishikawa, Yasuaki; Ishihara, Ryoichi; van der Cingel, Johan; Mofrad, Mohammad R. T.; Bermundo, Juan Paolo Soria; Kawashima, Emi; Tomai, Shigekazu; Yano, Koki; Uraoka, Yukiharu

    2016-06-01

    In a previous work, we reported the high field effect mobility of ZnO-doped In2O3 (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

  11. Electrical properties of solution-deposited ZnO thin-film transistors by low-temperature annealing.

    PubMed

    Lim, Chul; Oh, Ji Young; Koo, Jae Bon; Park, Chan Woo; Jung, Soon-Won; Na, Bock Soon; Chu, Hye Yong

    2014-11-01

    Flexible oxide thin-film transistors (Oxide-TFTs) have emerged as next generation transistors because of their applicability in electronic device. In particular, the major driving force behind solution-processed zinc oxide film research is its prospective use in printing for electronics. A low-temperature process to improve the performance of solution-processed n-channel ZnO thin-film transistors (TFTs) fabricated via spin-coating and inkjet-printing is introduced here. ZnO nanoparticles were synthesized using a facile sonochemical method that was slightly modified based on a previously reported method. The influence of the annealing atmosphere on both nanoparticle-based TFT devices fabricated via spin-coating and those created via inkjet printing was investigated. For the inkjet-printed TFTs, the characteristics were improved significantly at an annealing temperature of 150 degrees C. The field effect mobility, V(th), and the on/off current ratios were 3.03 cm2/Vs, -3.3 V, and 10(4), respectively. These results indicate that annealing at 150 degrees C 1 h is sufficient to obtain a mobility (μ(sat)) as high as 3.03 cm2/Vs. Also, the active layer of the solution-based ZnO nanoparticles allowed the production of high-performance TFTs for low-cost, large-area electronics and flexible devices. PMID:25958581

  12. Dual-gate photo thin-film transistor: a “smart” pixel for high- resolution and low-dose X-ray imaging

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Ou, Hai; Chen, Jun

    2015-06-01

    Since its emergence a decade ago, amorphous silicon flat panel X-ray detector has established itself as a ubiquitous platform for an array of digital radiography modalities. The fundamental building block of a flat panel detector is called a pixel. In all current pixel architectures, sensing, storage, and readout are unanimously kept separate, inevitably compromising resolution by increasing pixel size. To address this issue, we hereby propose a “smart” pixel architecture where the aforementioned three components are combined in a single dual-gate photo thin-film transistor (TFT). In other words, the dual-gate photo TFT itself functions as a sensor, a storage capacitor, and a switch concurrently. Additionally, by harnessing the amplification effect of such a thin-film transistor, we for the first time created a single-transistor active pixel sensor. The proof-of-concept device had a W/L ratio of 250μm/20μm and was fabricated using a simple five-mask photolithography process, where a 130nm transparent ITO was used as the top photo gate, and a 200nm amorphous silicon as the absorbing channel layer. The preliminary results demonstrated that the photocurrent had been increased by four orders of magnitude due to light-induced threshold voltage shift in the sub-threshold region. The device sensitivity could be simply tuned by photo gate bias to specifically target low-level light detection. The dependence of threshold voltage on light illumination indicated that a dynamic range of at least 80dB could be achieved. The "smart" pixel technology holds tremendous promise for developing high-resolution and low-dose X-ray imaging and may potentially lower the cancer risk imposed by radiation, especially among paediatric patients.

  13. One-step formation of a single atomic-layer transistor by the selective fluorination of a graphene film.

    PubMed

    Ho, Kuan-I; Liao, Jia-Hong; Huang, Chi-Hsien; Hsu, Chang-Lung; Zhang, Wenjing; Lu, Ang-Yu; Li, Lain-Jong; Lai, Chao-Sung; Su, Ching-Yuan

    2014-03-12

    In this study, the scalable and one-step fabrication of single atomic-layer transistors is demonstrated by the selective fluorination of graphene using a low-damage CF4 plasma treatment, where the generated F-radicals preferentially fluorinated the graphene at low temperature (<200 °C) while defect formation was suppressed by screening out the effect of ion damage. The chemical structure of the C-F bonds is well correlated with their optical and electrical properties in fluorinated graphene, as determined by X-ray photoelectron spectroscopy, Raman spectroscopy, and optical and electrical characterizations. The electrical conductivity of the resultant fluorinated graphene (F-graphene) was demonstrated to be in the range between 1.6 kΩ/sq and 1 MΩ/sq by adjusting the stoichiometric ratio of C/F in the range between 27.4 and 5.6, respectively. Moreover, a unique heterojunction structure of semi-metal/semiconductor/insulator can be directly formed in a single layer of graphene using a one-step fluorination process by introducing a Au thin-film as a buffer layer. With this heterojunction structure, it would be possible to fabricate transistors in a single graphene film via a one-step fluorination process, in which pristine graphene, partial F-graphene, and highly F-graphene serve as the source/drain contacts, the channel, and the channel isolation in a transistor, respectively. The demonstrated graphene transistor exhibits an on-off ratio above 10, which is 3-fold higher than that of devices made from pristine graphene. This efficient transistor fabrication method produces electrical heterojunctions of graphene over a large area and with selective patterning, providing the potential for the integration of electronics down to the single atomic-layer scale.

  14. InN thin-film transistors fabricated on polymer sheets using pulsed sputtering deposition at room temperature

    NASA Astrophysics Data System (ADS)

    Lye, Khe Shin; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-07-01

    Indium nitride (InN) is potentially suitable for the fabrication of high performance thin-film transistors (TFTs) because of its high electron mobility and peak electron velocity. However, InN is usually grown using a high temperature growth process, which is incompatible with large-area and lightweight TFT substrates. In this study, we report on the room temperature growth of InN films on flexible polyimide sheets using pulsed sputtering deposition. In addition, we report on the fabrication of InN-based TFTs on flexible polyimide sheets and the operation of these devices.

  15. Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer.

    PubMed

    Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

    2016-02-28

    Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (±2 V) and subthreshold swing (SS) (122-161 mV dec(-1)), high effective mobility (up to 17.6-37.7 cm(2) V(-1) s(-1)) and high on/off ratio (10(4)-10(7)). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption.

  16. Impact of active layer thickness in thin-film transistors based on Zinc Oxide by ultrasonic spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Dominguez, Miguel A.; Flores, Francisco; Luna, Adan; Martinez, Javier; Luna-Lopez, Jose A.; Alcantara, Salvador; Rosales, Pedro; Reyes, Claudia; Orduña, Abdu

    2015-07-01

    In this work, the preparation of Zinc Oxide (ZnO) films by ultrasonic spray pyrolysis at low-temperature and its application in thin-film transistors (TFTs) are presented, as well, the impact of the active layer thickness and gate dielectric thickness in the electrical performance of the ZnO TFTs. A thinner active layer resulted in better transfer characteristics such as higher on/off-current ratio, while a thicker active layer resulted in better output characteristics. The ZnO films were deposited from 0.2 M precursor solution of Zinc acetate in methanol, using air as carrier gas on a hotplate at 200 °C. The ZnO films obtained at 200 °C were characterized by optical transmittance, Photoluminescence spectroscopy and X-ray diffraction.

  17. Nitrogen-doped graphene films from simple photochemical doping for n-type field-effect transistors

    SciTech Connect

    Li, Xinyu; Tang, Tao; Li, Ming E-mail: lixinyu5260@163.com; He, Xiancong E-mail: lixinyu5260@163.com

    2015-01-05

    Highly nitrogen-doped GO (NGO) and n-type graphene field effect transistor (FET) have been achieved by simple irradiation of graphene oxide (GO) thin films in NH{sub 3} atmosphere. The electrical properties of the NGO film were performed on electric field effect measurements, and it displays an n-type FET behavior with a charge neutral point (Dirac point) located at around −8 V. It is suggested that the amino-like nitrogen (N-A) mainly contributes to the n-type behavior. Furthermore, compared to the GO film irradiated in Ar atmosphere, the NGO film is much more capable to improve the electrical conductivity. It may attribute to nitrogen doping and oxygen reduction, both of which can effectively enhance the electrical conductivity.

  18. Physical/chemical properties of tin oxide thin film transistors prepared using plasma-enhanced atomic layer deposition

    SciTech Connect

    Lee, Byung Kook; Jung, Eunae; Kim, Seok Hwan; Moon, Dae Chul; Lee, Sun Sook; Park, Bo Keun; Hwang, Jin Ha; Chung, Taek-Mo; Kim, Chang Gyoun; An, Ki-Seok

    2012-10-15

    Thin film transistors (TFTs) with tin oxide films as the channel layer were fabricated by means of plasma enhanced atomic layer deposition (PE-ALD). The as-deposited tin oxide films show n-type conductivity and a nano-crystalline structure of SnO{sub 2}. Notwithstanding the relatively low deposition temperatures of 70, 100, and 130 °C, the bottom gate tin oxide TFTs show an on/off drain current ratio of 10{sup 6} while the device mobility values were increased from 2.31 cm{sup 2}/V s to 6.24 cm{sup 2}/V s upon increasing the deposition temperature of the tin oxide films.

  19. Effects of thermomechanical properties of polarizer components on light leakage in thin-film transistor liquid-crystal displays

    NASA Astrophysics Data System (ADS)

    Lin, Taiy-In; Chen, Alexander; Chen, Shou-I.; Leu, Jihperng

    2015-07-01

    In this paper, we present static thermal analysis of stress and strain on a thin-film transistor liquid-crystal display (TFT-LCD) panel and their correlation with light leakage phenomena under high-temperature durability test. Three-dimensional (3D) finite element analysis (FEA) is coupled with experimental parameters of key components of the TFT-LCD panel for the analysis. A strong correlation exists between light leakage and retardation difference induced by stress on triacetyl cellulose (TAC) films. Moreover, shrinkage in stretched poly(vinyl alcohol) (PVA) film and modulus of the adhesive layer are key factors affecting stress distribution and displacement of polarizer stack. An increase in Young’s modulus (E) of the adhesive layer effectively reduces polarizer shrinkage and light leakage at the center of the panel. A TAC film with lower Young’s modulus and/or coefficient of thermal expansion (CTE) is also an effective solution.

  20. Sputtering technology in solid film lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Current and potential sputtering technology is reviewed as it applies primarily to the deposition of MoS2, though such lubricants as WS2 and PTFE are also considered. It is shown by electron microscopy and surface sensitive analytical techniques that the lubricating properties of sputtered MoS2 films are directly influenced by the sputtering parameters selected (i.e., power density, pressure, sputter etching, dc-biasing, etc.), substrate temperature, chemistry, topography, and environmental conditions during the friction test. Electron micrographs and diffractograms of sputtered MoS2 films clearly show the resultant changes in film morphology which affect film adherence and frictional properties.

  1. How to Read a Film: The Art, Technology, Language, History and Theory of Film and Media.

    ERIC Educational Resources Information Center

    Monaco, James

    This book discusses film as a narrative technique directly comparable to expression in prose narrative, in painting, and in music; it presents an overview of film as technology, the language of film and television, the history of film in America, Europe, and Asia, and the growth of film criticism. Chapters include "Film As an Art,""Technology:…

  2. Highly Crystalline CVD-grown Multilayer MoSe2 Thin Film Transistor for Fast Photodetector

    PubMed Central

    Jung, Chulseung; Kim, Seung Min; Moon, Hyunseong; Han, Gyuchull; Kwon, Junyeon; Hong, Young Ki; Omkaram, Inturu; Yoon, Youngki; Kim, Sunkook; Park, Jozeph

    2015-01-01

    Hexagonal molybdenum diselenide (MoSe2) multilayers were grown by chemical vapor deposition (CVD). A relatively high pressure (>760 Torr) was used during the CVD growth to achieve multilayers by creating multiple nuclei based on the two-dimensional crystal growth model. Our CVD-grown multilayer MoSe2 thin-film transistors (TFTs) show p-type-dominant ambipolar behaviors, which are attributed to the formation of Se vacancies generated at the decomposition temperature (650 °C) after the CVD growth for 10 min. Our MoSe2 TFT with a reasonably high field-effect mobility (10 cm2/V · s) exhibits a high photoresponsivity (93.7 A/W) and a fast photoresponse time (τrise ~ 0.4 s) under the illumination of light, which demonstrates the practical feasibility of multilayer MoSe2 TFTs for photodetector applications. PMID:26477744

  3. Ar plasma treated ZnON transistor for future thin film electronics

    SciTech Connect

    Lee, Eunha E-mail: jeonsh@korea.ac.kr; Benayad, Anass; Kim, HeeGoo; Park, Gyeong-Su; Kim, Taeho; Jeon, Sanghun E-mail: jeonsh@korea.ac.kr

    2015-09-21

    To achieve high-mobility and high-reliability oxide thin film transistors (TFTs), ZnON has been investigated following an anion control strategy based on the substitution of oxygen with nitrogen in ZnO. However, as nitrogen possesses, compared to oxygen, a low reactivity with Zn, the chemical composition of ZnON changes easily, causing in turn a degradation of both the performance and the stability. Here, we have solved the issues of long-time stability and composition non-uniformity while maintaining a high channel mobility by adopting the argon plasma process, which can delay the reaction of oxygen with Zn–O–N; as a result, owing to the formation of very fine nano-crystalline structure in stable glassy phase without changes in the chemical composition, the material properties and stability under e-radiation have significantly improved. In particular, the channel mobility of the ZnON TFTs extracted from the pulsed I−V method was measured to be 138 cm{sup 2}/V s.

  4. Electric Field-aided Selective Activation for Indium-Gallium-Zinc-Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Lee, Heesoo; Chang, Ki Soo; Tak, Young Jun; Jung, Tae Soo; Park, Jeong Woo; Kim, Won-Gi; Chung, Jusung; Jeong, Chan Bae; Kim, Hyun Jae

    2016-10-01

    A new technique is proposed for the activation of low temperature amorphous InGaZnO thin film transistor (a-IGZO TFT) backplanes through application of a bias voltage and annealing at 130 °C simultaneously. In this ‘electrical activation’, the effects of annealing under bias are selectively focused in the channel region. Therefore, electrical activation can be an effective method for lower backplane processing temperatures from 280 °C to 130 °C. Devices fabricated with this method exhibit equivalent electrical properties to those of conventionally-fabricated samples. These results are analyzed electrically and thermodynamically using infrared microthermography. Various bias voltages are applied to the gate, source, and drain electrodes while samples are annealed at 130 °C for 1 hour. Without conventional high temperature annealing or electrical activation, current-voltage curves do not show transfer characteristics. However, electrically activated a-IGZO TFTs show superior electrical characteristics, comparable to the reference TFTs annealed at 280 °C for 1 hour. This effect is a result of the lower activation energy, and efficient transfer of electrical and thermal energy to a-IGZO TFTs. With this approach, superior low-temperature a-IGZO TFTs are fabricated successfully.

  5. Compact modeling of charge carrier mobility in organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Marinov, O.; Deen, M. J.; Datars, R.

    2009-09-01

    Finding the common points in theoretical models for mobility in thin-film transistors (TFTs), we demonstrate that there exists a generic analytical model for the mobility in organic TFTs (OTFTs), and the generic model is then converted into a TFT Compact Mobility Model, which is physically derivable from one perspective, and properly arranged to be suitable for compact modeling of OTFTs from another perspective, by separation and proper interfacing of temperature and bias dependence of the mobility, both significant for OTFTs, with the compact models for electrical current in OTFT. The proposed TFT Compact Mobility Model is verified theoretically and against experimental data, and the model is applicable even for high temperatures T >To, above the characteristic temperature To of the distribution of states in the organic material, a condition at which other models diverge in principle. The improvement is achieved by the identification of a temperature "shaping" function, which contains a diverging function when derived theoretically elsewhere at idealized assumptions, and we suggest an approach to remedy the problem, since divergence in characteristic equations of compact models is not allowed. However, an open question remains for the bias enhancement in mobility at high temperatures, for which case no physical model is available at present. Another essential practical feature of the TFT Compact Mobility Model is that the model is both upgradable and reducible, allowing for easier implementation, modifications and independence of characterization techniques, enabling a systematic fitting of experimental data with large scattering in the values, which is the case for OTFT nowadays.

  6. Universal diffusion-limited injection and the hook effect in organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Liu, Chuan; Huseynova, Gunel; Xu, Yong; Long, Dang Xuan; Park, Won-Tae; Liu, Xuying; Minari, Takeo; Noh, Yong-Young

    2016-07-01

    The general form of interfacial contact resistance was derived for organic thin-film transistors (OTFTs) covering various injection mechanisms. Devices with a broad range of materials for contacts, semiconductors, and dielectrics were investigated and the charge injections in staggered OTFTs was found to universally follow the proposed form in the diffusion-limited case, which is signified by the mobility-dependent injection at the metal-semiconductor interfaces. Hence, real ohmic contact can hardly ever be achieved in OTFTs with low carrier concentrations and mobility, and the injection mechanisms include thermionic emission, diffusion, and surface recombination. The non-ohmic injection in OTFTs is manifested by the generally observed hook shape of the output conductance as a function of the drain field. The combined theoretical and experimental results show that interfacial contact resistance generally decreases with carrier mobility, and the injection current is probably determined by the surface recombination rate, which can be promoted by bulk-doping, contact modifications with charge injection layers and dopant layers, and dielectric engineering with high-k dielectric materials.

  7. The Helium Field Effect Transistor (I): Storing Surface State Electrons on Helium Films

    NASA Astrophysics Data System (ADS)

    Ashari, M.; Rees, D. G.; Kono, K.; Scheer, E.; Leiderer, P.

    2012-04-01

    We present investigations of surface state electrons on liquid helium films in confined geometry, using a suitable substrate structure microfabricated on a silicon wafer, similar to a Field Effect Transistor (FET). The sample has a source and drain region, separated by a gate structure, which consists of two gold electrodes with a narrow gap (channel) through which the transport of the surface state electrons takes place. The sample is illuminated to provide a sufficient number of free carriers in the silicon substrate, such that a well-defined potential distribution is achieved. The eventual goal of these experiments is to study the electron transport through a narrow channel in the various states of the phase diagram of the 2D electron system. In the present work we focus on storing the electrons in the source area of the FET, and investigate the spatial distribution of these electrons. It is shown that under the influence of a potential gradient in the silicon substrate the electrons accumulate in front of the potential barrier of the gate. The electron distribution, governed by Coulomb repulsion and by the substrate potential, is determined experimentally. The result is found to be in good agreement with a parallel-plate capacitor model of the system, developed with the aid of a finite element calculation of the surface potential profile of the device.

  8. Organic thin-film transistor arrays for active-matrix organic light emitting diode

    NASA Astrophysics Data System (ADS)

    Lee, Sangyun; Moon, Hyunsik; Kim, Do H.; Koo, Bon-Won; Jeong, Eun-Jeong; Lee, Bang-Lin; Kim, Joo-Young; Lee, Eunkyung; Hahn, Kook-Min; Han, Jeong-Seok; Park, Jung-Il; Seon, Jong-Baek; Kim, Jung-Woo; Chun, Young-Tea; Kim, Sangyeol; Kang, Sung K.

    2007-09-01

    We developed an active matrix organic light-emitting diodes (AMOLEDs) on a glass using two organic thin-film transistors (OTFTs) and a capacitor in a pixel. OTFTs switching-arrays with 64 scan lines and 64 (RGB) data lines were designed and fabricated to drive OLED arrays. In this study, OTFT devices have bottom contact structures with an ink-jet printed polymer semiconductor and an organic insulator as a gate dielectric. The width and length of the switching OTFT is 500μm and 10μm, respectively and the driving OTFT has 900μm channel width with the same channel length. The characteristics of the OTFTs were examined using test cells around display area. On/off ratio, mobility, on-current of switching OTFT and on-current of driving OTFT were 10 6, 0.1 cm2/V-sec, order of 8μA and over 70 μA respectively. These properties were enough to drive the AMOLEDs over 60 Hz frame rate. AMOLEDs composed of the OTFT switching arrays and OLEDs made by deposition of small molecule materials were fabricated and driven to make moving images, successfully.

  9. Solution-processed zinc oxide nanoparticles/single-walled carbon nanotubes hybrid thin-film transistors

    NASA Astrophysics Data System (ADS)

    Liu, Fangmei; Sun, Jia; Qian, Chuan; Hu, Xiaotao; Wu, Han; Huang, Yulan; Yang, Junliang

    2016-09-01

    Solution-processed thin-film transistors (TFTs) are the essential building blocks for manufacturing the low-cost and large-area consumptive electronics. Herein, solution-processed TFTs based on the composites of zinc oxide (ZnO) nanoparticles and single-walled carbon nanotubes (SWCNTs) were fabricated by the methods of spin-coating and doctor-blading. Through controlling the weight of SWCNTs, the ZnO/SWCNTs TFTs fabricated by spin-coating demonstrated a field-effect mobility of 4.7 cm2/Vs and a low threshold voltage of 0.8 V, while the TFTs devices fabricated by doctor-blading technique showed reasonable electrical performance with a mobility of 0.22 cm2/Vs. Furthermore, the ion-gel was used as an efficient electrochemical gate dielectric because of its large electric double-layer capacitance. The operating voltage of all the TFTs devices is as low as 4.0 V. The research suggests that ZnO/SWCNTs TFTs have the potential applications in low-cost, large-area and flexible consumptive electronics, such as chemical-biological sensors and smart label.

  10. Effective contact resistance of zinc-tin oxide-based thin film transistors.

    PubMed

    Kang, Youjin; Han, Dongsuk; Park, Jaehyung; Shin, Sora; Choi, Duckkyun; Park, Jongwan

    2014-11-01

    We investigated different source/drain (S/D) electrode materials in thin-film transistors (TFTs) based on amorphous zinc-tin oxide (ZTO) semiconductors. The transfer length, channel conductance, and effective contact resistance between the S/D electrodes and the a-ZTO channel layer were examined. Total ON resistance (R(T)), transfer length (L(T)) and effective contact resistance (R(c-eff)) were extracted by the well-known transmission-line method (TLM) using a series of TFTs with different channel lengths. When the width of ZTO channel layer was fixed as 50 μm, the lengths were varying from 10 to 50 μm. The channel layer and S/D electrode were defined by lift-off process and for the S/D electrodes, indium-tin oxide (ITO), Cu, and Mo were used. The resistivity and work function values of electrode materials were considered when selected as candidates for S/D electrodes of ZTO-TFTs. The results showed that the ZTO-TFTs with Mo S/D electrodes had the lowest effective contact resistance indicating that ZTO-TFTs with Mo electrodes have better electrical performance compared to others. PMID:25958489

  11. Quasi-unipolar pentacene films embedded with fullerene for non-volatile organic transistor memories

    SciTech Connect

    Lee, Juhee; Lee, Sungpyo; Lee, Moo Hyung; Kang, Moon Sung

    2015-02-09

    Quasi-unipolar non-volatile organic transistor memory (NOTM) can combine the best characteristics of conventional unipolar and ambipolar NOTMs and, as a result, exhibit improved device performance. Unipolar NOTMs typically exhibit a large signal ratio between the programmed and erased current signals but also require a large voltage to program and erase the memory cells. Meanwhile, an ambipolar NOTM can be programmed and erased at lower voltages, but the resulting signal ratio is small. By embedding a discontinuous n-type fullerene layer within a p-type pentacene film, quasi-unipolar NOTMs are fabricated, of which the signal storage utilizes both electrons and holes while the electrical signal relies on only hole conduction. These devices exhibit superior memory performance relative to both pristine unipolar pentacene devices and ambipolar fullerene/pentacene bilayer devices. The quasi-unipolar NOTM exhibited a larger signal ratio between the programmed and erased states while also reducing the voltage required to program and erase a memory cell. This simple approach should be readily applicable for various combinations of advanced organic semiconductors that have been recently developed and thereby should make a significant impact on organic memory research.

  12. Wireless thin film transistor based on micro magnetic induction coupling antenna

    NASA Astrophysics Data System (ADS)

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-12-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

  13. Evaluation of nanocomposite gate insulators for flexible organic thin-film transistors.

    PubMed

    Kim, Jin Soo; Cho, Sung Won; Kim, Ii; Hwang, Byeong Ung; Seol, Young Gug; Kim, Tae Woong; Lee, Nae-Eung

    2014-11-01

    To develop physically flexible electronics, high performance and mechanical stability of component materials and devices are required. For a flexible display, a backplane with flexible thin-film transistors (TFTs) must be developed. Gate insulating materials with excellent electrical and mechanical properties are highly important to the development of flexible TFTs. We investigated nanocomposite gate dielectrics composed of polyimide (PI) because of their superior thermal stability, as well as different inorganic HfO2, TiO2, and Al2O3 nanoparticles with high dielectric constants. Nanocomposite gate dielectrics of HfO2 nanoparticles and PI lowered leakage current density and increased the relative dielectric constant compared to PI solely because of a high degree of dispersion. Pentacene TFTs with HfO2 nanocomposite gate insulators also showed higher field-effect mobility (μ), smaller subthreshold swing, and an enhanced on/off current ratio (I(on/off)) compared to those of the PI gate dielectric. In addition, mechanical cyclic bending tests involving bending cycles of 2 x 10(5) time sat a bending radius of 5 mm showed improvement in electrical stability of nanocomposite gate insulators with a change in leakage current density of nanocomposite gate insulators below 30%.

  14. Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection

    NASA Astrophysics Data System (ADS)

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Gao, Xike; di, Chong-An; Zhu, Daoben

    2015-03-01

    The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa-1, a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications.

  15. Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection.

    PubMed

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Gao, Xike; Di, Chong-An; Zhu, Daoben

    2015-03-03

    The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa(-1), a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications.

  16. Evaluation of interface trap densities and quantum capacitance in carbon nanotube network thin-film transistors

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Choi, B.; Choi, S.; Lee, J.; Lee, J.; Jeon, M.; Lee, Y.; Han, J.; Lee, J.; Kim, D. M.; Kim, D. H.; Kim, S.; Choi, S.-J.

    2016-07-01

    The interface trap density in single-walled carbon nanotube (SWNT) network thin-film transistors (TFTs) is a fundamental and important parameter for assessing the electronic performance of TFTs. However, the number of studies on the extraction of interface trap densities, particularly in SWNT TFTs, has been insufficient. In this work, we propose an efficient technique for extracting the energy-dependent interface traps in SWNT TFTs. From the measured dispersive, frequency-dependent capacitance-voltage (C-V) characteristics, the dispersive-free, frequency-independent C-V curve was obtained, thus enabling the extraction and analysis of the interface trap density, which was found to be approximately 8.2 × 1011 eV-1 cm-2 at the valence band edge. The frequency-independent C-V curve also allows further extraction of the quantum capacitance in the SWNT network without introducing any additional fitting process or parameters. We found that the extracted value of the quantum capacitance in SWNT networks is lower than the theoretical value in aligned SWNTs due to the cross point of SWNTs on the SWNT network. Therefore, the method proposed in this work indicates that the C-V measurement is a powerful tool for obtaining deep physical insights regarding the electrical performance of SWNT TFTs.

  17. Wireless thin film transistor based on micro magnetic induction coupling antenna

    PubMed Central

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-01-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT). PMID:26691929

  18. Coffee-Ring Defined Short Channels for Inkjet-Printed Metal Oxide Thin-Film Transistors.

    PubMed

    Li, Yuzhi; Lan, Linfeng; Xiao, Peng; Sun, Sheng; Lin, Zhenguo; Song, Wei; Song, Erlong; Gao, Peixiong; Wu, Weijing; Peng, Junbiao

    2016-08-01

    Short-channel electronic devices several micrometers in length are difficult to implement by direct inkjet printing due to the limitation of position accuracy of the common inkjet printer system and the spread of functional ink on substrates. In this report, metal oxide thin-film transistors (TFTs) with channel lengths of 3.5 ± 0.7 μm were successfully fabricated with a common inkjet printer without any photolithography steps. Hydrophobic CYTOP coffee stripes, made by inkjet-printing and plasma-treating processes, were utilized to define the channel area of TFTs with channel lengths as short as ∼3.5 μm by dewetting the inks of the source/drain (S/D) precursors. Furthermore, by introduction of an ultrathin layer of PVA to modify the S/D surfaces, the spreading of precursor ink of the InOx semiconductor layer was well-controlled. The inkjet-printed short-channel TFTs exhibited a maximum mobility of 4.9 cm(2) V(-1) s(-1) and an on/off ratio of larger than 10(9). This approach of fabricating short-channel TFTs by inkjet printing will promote the large-area fabrication of short-channel TFTs in a cost-effective manner. PMID:27420373

  19. Localized Tail States and Electron Mobility in Amorphous ZnON Thin Film Transistors

    PubMed Central

    Lee, Sungsik; Nathan, Arokia; Ye, Yan; Guo, Yuzheng; Robertson, John

    2015-01-01

    The density of localized tail states in amorphous ZnON (a-ZnON) thin film transistors (TFTs) is deduced from the measured current-voltage characteristics. The extracted values of tail state density at the conduction band minima (Ntc) and its characteristic energy (kTt) are about 2 × 1020 cm−3eV−1 and 29 meV, respectively, suggesting trap-limited conduction prevails at room temperature. Based on trap-limited conduction theory where these tail state parameters are considered, electron mobility is accurately retrieved using a self-consistent extraction method along with the scaling factor ‘1/(α + 1)’ associated with trapping events at the localized tail states. Additionally, it is found that defects, e.g. oxygen and/or nitrogen vacancies, can be ionized under illumination with hv ≫ Eg, leading to very mild persistent photoconductivity (PPC) in a-ZnON TFTs. PMID:26304606

  20. SEMICONDUCTOR DEVICES: A process simplification scheme for fabricating CMOS polycrystalline-Si thin film transistors

    NASA Astrophysics Data System (ADS)

    Miin-Horng, Juang; Chia-Wei, Chang; Der-Chih, Shye; Chuan-Chou, Hwang; Jih-Liang, Wang; Sheng-Liang, Jang

    2010-06-01

    A process simplification scheme for fabricating CMOS poly-Si thin-film transistors (TFTs) has been proposed, which employs large-angle-tilt-implantation of dopant through a gate sidewall spacer (LATITS). By this LATITS scheme, a lightly doped drain region under the oxide spacer is formed by low-dose tilt implantation of phosphorus (or boron) dopant through the spacer, and then the n+-source/drain (n+-S/D) (or p+-S/D) region is formed via using the same photo-mask layer during CMOS integration. For both n-TFT and p-TFT devices, as compared to the sample with conventional single n+-S/D (or p+-S/D) structure, the LATITS scheme can cause an obviously smaller leakage current, due to more gradual dopant distribution and thus smaller electric field. In addition, the resultant on-state currents only show slight degradation for the LATITS scheme. As a result, by the LATITS scheme, CMOS poly-Si TFT devices with an on/off current ratio well above 8 orders may be achieved without needing extra photo-mask layers during CMOS integration.

  1. Sensitivity of the threshold voltage of organic thin-film transistors to light and water

    SciTech Connect

    Feng, Cong; Marinov, Ognian; Deen, M. Jamal; Selvaganapathy, Ponnambalam Ravi; Wu, Yiliang

    2015-05-14

    Analyses of extensive experiments with organic thin-film transistors (OTFTs) indicate that the threshold voltage V{sub T} of an OTFT has a temporal differential sensitivity. In particular, V{sub T} changes initially by changing the light illumination intensity or making/removing a contact of water with the organic semiconductor. Keeping the conditions stationary, then the initial shift of V{sub T} diminishes, since the time dependence of V{sub T} gradually recovers the OTFT to the state before applying the change in the environmental conditions. While still causing a differential and time-variant shift of V{sub T}, the deionized water does not have a dramatic impact on OTFTs that use the polymer DKPP-βT (diketopyrrolopyrrole β-unsubstituted quaterthiophene) as the active semiconductor material. Observations for the impact of water are made from experiments with an OTFT that has a microfluidic channel on the top the electrical channel, with the water in the microfluidic channel in direct contact with the electrical channel of the OTFT. This arrangement of electrical and microfluidic channels is a novel structure of the microfluidic OTFT, suitable for sensing applications of liquid analytes by means of organic electronics.

  2. Effect of hydrogen on dynamic charge transport in amorphous oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Taeho; Nam, Yunyong; Hur, Ji-Hyun; Park, Sang-Hee Ko; Jeon, Sanghun

    2016-08-01

    Hydrogen in zinc oxide based semiconductors functions as a donor or a defect de-activator depending on its concentration, greatly affecting the device characteristics of oxide thin-film transistors (TFTs). Thus, controlling the hydrogen concentration in oxide semiconductors is very important for achieving high mobility and minimizing device instability. In this study, we investigated the charge transport dynamics of the amorphous semiconductor InGaZnO at various hydrogen concentrations as a function of the deposition temperature of the gate insulator. To examine the nature of dynamic charge trapping, we employed short-pulse current‑voltage and transient current‑time measurements. Among various examined oxide devices, that with a high hydrogen concentration exhibits the best performance characteristics, such as high saturation mobility (10.9 cm2 v‑1 s‑1), low subthreshold slope (0.12 V/dec), and negligible hysteresis, which stem from low defect densities and negligible transient charge trapping. Our finding indicates that hydrogen atoms effectively passivate the defects in subgap states of the bulk semiconductor, minimizing the mobility degradation and threshold voltage instability. This study indicates that hydrogen plays a useful role in TFTs by improving the device performance and stability.

  3. Universal diffusion-limited injection and the hook effect in organic thin-film transistors

    PubMed Central

    Liu, Chuan; Huseynova, Gunel; Xu, Yong; Long, Dang Xuan; Park, Won-Tae; Liu, Xuying; Minari, Takeo; Noh, Yong-Young

    2016-01-01

    The general form of interfacial contact resistance was derived for organic thin-film transistors (OTFTs) covering various injection mechanisms. Devices with a broad range of materials for contacts, semiconductors, and dielectrics were investigated and the charge injections in staggered OTFTs was found to universally follow the proposed form in the diffusion-limited case, which is signified by the mobility-dependent injection at the metal-semiconductor interfaces. Hence, real ohmic contact can hardly ever be achieved in OTFTs with low carrier concentrations and mobility, and the injection mechanisms include thermionic emission, diffusion, and surface recombination. The non-ohmic injection in OTFTs is manifested by the generally observed hook shape of the output conductance as a function of the drain field. The combined theoretical and experimental results show that interfacial contact resistance generally decreases with carrier mobility, and the injection current is probably determined by the surface recombination rate, which can be promoted by bulk-doping, contact modifications with charge injection layers and dopant layers, and dielectric engineering with high-k dielectric materials. PMID:27440253

  4. Electric Field-aided Selective Activation for Indium-Gallium-Zinc-Oxide Thin Film Transistors

    PubMed Central

    Lee, Heesoo; Chang, Ki Soo; Tak, Young Jun; Jung, Tae Soo; Park, Jeong Woo; Kim, Won-Gi; Chung, Jusung; Jeong, Chan Bae; Kim, Hyun Jae

    2016-01-01

    A new technique is proposed for the activation of low temperature amorphous InGaZnO thin film transistor (a-IGZO TFT) backplanes through application of a bias voltage and annealing at 130 °C simultaneously. In this ‘electrical activation’, the effects of annealing under bias are selectively focused in the channel region. Therefore, electrical activation can be an effective method for lower backplane processing temperatures from 280 °C to 130 °C. Devices fabricated with this method exhibit equivalent electrical properties to those of conventionally-fabricated samples. These results are analyzed electrically and thermodynamically using infrared microthermography. Various bias voltages are applied to the gate, source, and drain electrodes while samples are annealed at 130 °C for 1 hour. Without conventional high temperature annealing or electrical activation, current-voltage curves do not show transfer characteristics. However, electrically activated a-IGZO TFTs show superior electrical characteristics, comparable to the reference TFTs annealed at 280 °C for 1 hour. This effect is a result of the lower activation energy, and efficient transfer of electrical and thermal energy to a-IGZO TFTs. With this approach, superior low-temperature a-IGZO TFTs are fabricated successfully. PMID:27725695

  5. Fabrication and Characteristics of High Mobility InSnZnO Thin Film Transistors.

    PubMed

    Choi, Pyungho; Lee, Junki; Park, Hyoungsun; Baek, Dohyun; Lee, Jaehyeong; Yi, Junsin; Kim, Sangsoo; Choi, Byoungdeog

    2016-05-01

    In this paper, we describe the fabrication of thin film transistors (TFTs) with amorphous indium-tin-zinc-oxide (ITZO) as the active material. A transparent ITZO channel layer was formed under an optimized oxygen partial pressure (OPP (%) = O2/(Ar + O2)) and subsequent annealing process. The electrical properties exhibited by this device include field-effect mobility (μ(eff)), sub-threshold swing (SS), and on/off current ratio (I(ON/OFF)) values of 28.97 cm2/V x s, 0.2 V/decade, and 2.64 x 10(7), respectively. The average transmittance values for each OPP condition in the visible range were greater than 80%. The positive gate bias stress resulted in a positive threshold voltage (V(th)) shift in the transfer curves and degraded the parameters μ(eff) and SS. These phenomena originated from electron trapping from the ITZO channel layer into the oxide/ITZO interface trap sites. PMID:27483823

  6. Wireless thin film transistor based on micro magnetic induction coupling antenna.

    PubMed

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-01-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the 'internet of things' (IoT). PMID:26691929

  7. Temperature-dependent charge injection and transport in pentacene thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Dong Wook; Shin, Hyunji; Park, Ji-Ho; Park, Jaehoon; Choi, Jong Sun

    2015-11-01

    The electrical characteristics of p-channel pentacene thin-film transistors (TFTs) were analyzed at different operating temperatures ranging from 253 to 353 K. An improvement in the drain current and field-effect mobility of the pentacene TFTs is observed with increasing temperature. From the Arrhenius plots of field-effect mobility extracted at various temperatures, a lower activation energy of 99.34 meV was obtained when the device is operating in the saturation region. Such observation is ascribed to the thermally activated hole transport through the pentacene grain boundaries. On the other hand, it was found that the Au/pentacene contact significantly affects the TFTs electrical characteristics in the linear region, which resulted in a higher activation energy. The activation energy based on the linear field-effect mobility, which increased from 344.61 to 444.70 meV with decreasing temperature, implies the charge-injection-limited electrical behavior of pentacene TFTs at low temperatures. The thermally induced electrical characteristic variations in pentacene TFTs can thus be studied through the temperature dependence of the charge injection and transport processes.

  8. A tone analyzer based on a piezoelectric polymer and organic thin film transistors.

    PubMed

    Hsu, Yu-Jen; Kymissis, Ioannis

    2012-12-01

    A tone analyzer is demonstrated using a distributed resonator architecture on a tensioned piezoelectric polyvinyledene diuoride (PVDF) sheet. This sheet is used as both the resonator and detection element. Two architectures are demonstrated; one uses distributed, directly addressed elements as a proof of concept, and the other integrates organic thin film transistor-based transimpedance amplifiers directly with the PVDF to convert the piezoelectric charge signal into a current signal. The PVDF sheet material is instrumented along its length, and the amplitude response at 15 sites is recorded and analyzed as a function of the frequency of excitation. The determination of the dominant component of an incoming tone is demonstrated using linear system decomposition of the time-averaged response of the sheet and is performed without any time domain analysis. This design allows for the determination of the spectral composition of a sound using the mechanical signal processing provided by the amplitude response and eliminates the need for time-domain downstream signal processing of the incoming signal. PMID:23231112

  9. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

    SciTech Connect

    Ahn, Cheol Hyoun; Hee Kim, So; Gu Yun, Myeong; Koun Cho, Hyung

    2014-12-01

    In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.

  10. High performance p-type NiOx thin-film transistor by Sn doping

    NASA Astrophysics Data System (ADS)

    Lin, Tengda; Li, Xiuling; Jang, Jin

    2016-06-01

    Major obstacles towards power efficient complementary electronics employing oxide thin-film transistors (TFTs) lie in the lack of equivalent well performing p-channel devices. Here, we report a significant performance enhancement of solution-processed p-type nickel oxide (NiOx) TFTs by introducing Sn dopant. The Sn-doped NiOx (Sn-NiOx) TFTs annealed at 280 °C demonstrate substantially improved electrical performances with the increase in the on/off current ratio (Ion/Ioff) by ˜100 times, field-effect mobility (μlin) by ˜3 times, and the decrease in subthreshold swing by half, comparing with those of pristine NiOx TFTs. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that Sn atoms tend to substitute Ni sites and induce more amorphous phase. A decrease in density of states in the gap of NiOx by Sn doping and the shift of Fermi level (EF) into the midgap lead to the improvements of TFT performances. As a result, Sn-NiOx can be a promising material for the next-generation, oxide-based electronics.

  11. Effect of hydrogen on dynamic charge transport in amorphous oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Taeho; Nam, Yunyong; Hur, Ji-Hyun; Park, Sang-Hee Ko; Jeon, Sanghun

    2016-08-01

    Hydrogen in zinc oxide based semiconductors functions as a donor or a defect de-activator depending on its concentration, greatly affecting the device characteristics of oxide thin-film transistors (TFTs). Thus, controlling the hydrogen concentration in oxide semiconductors is very important for achieving high mobility and minimizing device instability. In this study, we investigated the charge transport dynamics of the amorphous semiconductor InGaZnO at various hydrogen concentrations as a function of the deposition temperature of the gate insulator. To examine the nature of dynamic charge trapping, we employed short-pulse current-voltage and transient current-time measurements. Among various examined oxide devices, that with a high hydrogen concentration exhibits the best performance characteristics, such as high saturation mobility (10.9 cm2 v-1 s-1), low subthreshold slope (0.12 V/dec), and negligible hysteresis, which stem from low defect densities and negligible transient charge trapping. Our finding indicates that hydrogen atoms effectively passivate the defects in subgap states of the bulk semiconductor, minimizing the mobility degradation and threshold voltage instability. This study indicates that hydrogen plays a useful role in TFTs by improving the device performance and stability.

  12. Synergistic approach to high-performance oxide thin film transistors using a bilayer channel architecture.

    PubMed

    Yu, Xinge; Zhou, Nanjia; Smith, Jeremy; Lin, Hui; Stallings, Katie; Yu, Junsheng; Marks, Tobin J; Facchetti, Antonio

    2013-08-28

    We report here a bilayer metal oxide thin film transistor concept (bMO TFT) where the channel has the structure: dielectric/semiconducting indium oxide (In2O3) layer/semiconducting indium gallium oxide (IGO) layer. Both semiconducting layers are grown from solution via a low-temperature combustion process. The TFT mobilities of bottom-gate/top-contact bMO TFTs processed at T = 250 °C are ~5tmex larger (~2.6 cm(2)/(V s)) than those of single-layer IGO TFTs (~0.5 cm(2)/(V s)), reaching values comparable to single-layer combustion-processed In2O3 TFTs (~3.2 cm(2)/(V s)). More importantly, and unlike single-layer In2O3 TFTs, the threshold voltage of the bMO TFTs is ~0.0 V, and the current on/off ratio is significantly enhanced to ~1 × 10(8) (vs ~1 × 10(4) for In2O3). The microstructure and morphology of the In2O3/IGO bilayers are analyzed by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, revealing the polycrystalline nature of the In2O3 layer and the amorphous nature of the IGO layer. This work demonstrates that solution-processed metal oxides can be implemented in bilayer TFT architectures with significantly enhanced performance. PMID:23876148

  13. Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection

    PubMed Central

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Gao, Xike; Di, Chong-an; Zhu, Daoben

    2015-01-01

    The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa−1, a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications. PMID:25872157

  14. Fully Solution-Processed and Foldable Metal-Oxide Thin-Film Transistor.

    PubMed

    Lee, Su Jeong; Ko, Jieun; Nam, Ki-Ho; Kim, Taehee; Lee, Sang Hoon; Kim, Jung Han; Chae, Gee Sung; Han, Hs; Kim, Youn Sang; Myoung, Jae-Min

    2016-05-25

    Flexible and foldable thin-film transistors (TFTs) have been widely studied with the objective of achieving high-performance and low-cost flexible TFTs for next-generation displays. In this study, we introduced the fabrication of foldable TFT devices with excellent mechanical stability, high transparency, and high performance by a fully solution process including PI, YOx, In2O3, SWCNTs, IL-PVP, and Ag NWs. The fabricated fully solution-processed TFTs showed a higher transmittance above 86% in the visible range. Additionally, the charge-carrier mobility and Ion/Ioff ratio of them were 7.12 ± 0.43 cm(2)/V·s and 5.53 ± 0.82 × 10(5) at a 3 V low voltage operating, respectively. In particular, the fully solution-processed TFTs showed good electrical characteristics under tensile strain with 1 mm bending and even extreme folding up to a strain of 26.79%. Due to the good compatibility of each component layer, it maintained the charge-carrier mobility over 79% of initial devices after 5,000 cycles of folding test in both the parallel and perpendicular direction with a bending radius of 1 mm. These results show the potential of the fully solution-processed TFTs as flexible TFTs for a next generation devices because of the robust mechanical flexibility, transparency, and high electrical performance of it. PMID:27120010

  15. Universal diffusion-limited injection and the hook effect in organic thin-film transistors.

    PubMed

    Liu, Chuan; Huseynova, Gunel; Xu, Yong; Long, Dang Xuan; Park, Won-Tae; Liu, Xuying; Minari, Takeo; Noh, Yong-Young

    2016-01-01

    The general form of interfacial contact resistance was derived for organic thin-film transistors (OTFTs) covering various injection mechanisms. Devices with a broad range of materials for contacts, semiconductors, and dielectrics were investigated and the charge injections in staggered OTFTs was found to universally follow the proposed form in the diffusion-limited case, which is signified by the mobility-dependent injection at the metal-semiconductor interfaces. Hence, real ohmic contact can hardly ever be achieved in OTFTs with low carrier concentrations and mobility, and the injection mechanisms include thermionic emission, diffusion, and surface recombination. The non-ohmic injection in OTFTs is manifested by the generally observed hook shape of the output conductance as a function of the drain field. The combined theoretical and experimental results show that interfacial contact resistance generally decreases with carrier mobility, and the injection current is probably determined by the surface recombination rate, which can be promoted by bulk-doping, contact modifications with charge injection layers and dopant layers, and dielectric engineering with high-k dielectric materials. PMID:27440253

  16. Photomodulation of InGaZnO thin film transistors with interfacial silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Jiin; Cho, Jae Eun; Lee, Hyeon-Mo; Park, Jin-Seong; Kang, Seong Jun

    2016-11-01

    Silver nanoparticles (Ag NPs) were inserted between indium gallium zinc oxide (IGZO) and a gate insulator to enhance the generation of plasmonic photocurrent with the illumination of visible light. Ag NPs were formed on a silicon dioxide gate insulator using a thermal evaporator and a post-annealing process. Then, an amorphous IGZO active channel layer was deposited on the Ag NPs using a sputter system. The prepared Ag NPs effectively absorbed a wide wavelength range of visible light due to plasmon effects. The IGZO thin film transistors (TFTs) with interfacial Ag NPs showed a large photocurrent due to the strong coupling between localized plasmons and electrical carriers in the active channel region of the TFTs. The prepared device showed good modulation behavior under visible light even though IGZO has a wide band gap. The results indicate that interfacial Ag NPs enabled the photomodulation of IGZO TFTs when exposed to a periodic signal of low-energy visible light. This work demonstrates a useful way to develop visible-light phototransistors based on a wide band gap semiconductor and plasmonic Ag NPs.

  17. Mechanical Flexibility of Zinc Oxide Thin-Film Transistors Prepared by Transfer Printing Method

    NASA Astrophysics Data System (ADS)

    Eun, K. T.; Hwang, W. J.; Sharma, B. K.; Ahn, J. H.; Lee, Y. K.; Choa, S. H.

    In the present study, we demonstrate the performance of Zinc oxide thin film transistors (ZnO TFTs) array subjected to the strain under high bending test and the reliability of TFTs was confirmed for the bending fatigue test of 2000 cycles. Initially, ZnO TFTs were fabricated on Si substrate and subsequently transferred on flexible PET substrate using transfer printing process. It was observed that when the bending radius reached ≥ 11 mm then cracks start to initiate first at SiO2 bridges, acting as interconnecting layers among individual TFT. Whatever the strain is applied to the devices, it is almost equivalently adopted by the SiO2 bridges, as they are relatively weak compared to rest of the part. The initial cracking of destructed SiO2 bridge leads to the secondary cracks to the ITO electrodes upon further increment of bending radius. Numerical simulation suggested that the strain of SiO2 layer reached to fracture level of 0.55% which was concentrated at the edge of SiO2 bridge layer. It also suggests that the round shape of SiO2 bridge can be more fruitful to compensate the stress concentration and to prevent failure of device.

  18. Coffee-Ring Defined Short Channels for Inkjet-Printed Metal Oxide Thin-Film Transistors.

    PubMed

    Li, Yuzhi; Lan, Linfeng; Xiao, Peng; Sun, Sheng; Lin, Zhenguo; Song, Wei; Song, Erlong; Gao, Peixiong; Wu, Weijing; Peng, Junbiao

    2016-08-01

    Short-channel electronic devices several micrometers in length are difficult to implement by direct inkjet printing due to the limitation of position accuracy of the common inkjet printer system and the spread of functional ink on substrates. In this report, metal oxide thin-film transistors (TFTs) with channel lengths of 3.5 ± 0.7 μm were successfully fabricated with a common inkjet printer without any photolithography steps. Hydrophobic CYTOP coffee stripes, made by inkjet-printing and plasma-treating processes, were utilized to define the channel area of TFTs with channel lengths as short as ∼3.5 μm by dewetting the inks of the source/drain (S/D) precursors. Furthermore, by introduction of an ultrathin layer of PVA to modify the S/D surfaces, the spreading of precursor ink of the InOx semiconductor layer was well-controlled. The inkjet-printed short-channel TFTs exhibited a maximum mobility of 4.9 cm(2) V(-1) s(-1) and an on/off ratio of larger than 10(9). This approach of fabricating short-channel TFTs by inkjet printing will promote the large-area fabrication of short-channel TFTs in a cost-effective manner.

  19. Effect of hydrogen on dynamic charge transport in amorphous oxide thin film transistors.

    PubMed

    Kim, Taeho; Nam, Yunyong; Hur, Ji-Hyun; Park, Sang-Hee Ko; Jeon, Sanghun

    2016-08-12

    Hydrogen in zinc oxide based semiconductors functions as a donor or a defect de-activator depending on its concentration, greatly affecting the device characteristics of oxide thin-film transistors (TFTs). Thus, controlling the hydrogen concentration in oxide semiconductors is very important for achieving high mobility and minimizing device instability. In this study, we investigated the charge transport dynamics of the amorphous semiconductor InGaZnO at various hydrogen concentrations as a function of the deposition temperature of the gate insulator. To examine the nature of dynamic charge trapping, we employed short-pulse current-voltage and transient current-time measurements. Among various examined oxide devices, that with a high hydrogen concentration exhibits the best performance characteristics, such as high saturation mobility (10.9 cm(2) v(-1) s(-1)), low subthreshold slope (0.12 V/dec), and negligible hysteresis, which stem from low defect densities and negligible transient charge trapping. Our finding indicates that hydrogen atoms effectively passivate the defects in subgap states of the bulk semiconductor, minimizing the mobility degradation and threshold voltage instability. This study indicates that hydrogen plays a useful role in TFTs by improving the device performance and stability. PMID:27363543

  20. Impact of universal mobility law on polycrystalline organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Raja, Munira; Donaghy, David; Myers, Robert; Eccleston, Bill

    2012-10-01

    We have developed novel analytical models for polycrystalline organic thin-film transistor (OTFT) by employing new concepts on the charge carrier injection to polysilicon thin-films. The models, also incorporate the effect of contact resistance associated with the poor ohmic nature of the contacts. The drain current equations of the OTFT, both in the quasi-diffusion and quasi-drift regimes, predict temperature dependencies on essential material and device parameters. Interestingly, under the drift regime, the polycrystalline OTFT model reveals similar power dependencies on the applied voltages, to those of purely disordered model developed by utilizing the universal mobility law (UML). Such similarities are not thought to be coincidental since the effect of gate voltage on surface potential is influenced by the Fermi level pinning in the grain boundary. Nonetheless, the best fits on the data of 6,13-bis(tri-isopropylsilylethynyl) OTFTs are attained with the proposed polycrystalline rather than the disordered model, particularly at low gate voltages where the diffusive component is dominant. Moreover, in order to understand the effect of grain boundaries, we devise a relationship for the dependency of the effective mobility on carrier concentration, assuming a crystalline region to be in direct contact with a disordered region. Interestingly, we find a similar dependency as the UML in purely disordered materials, which further signifies the conduction to be limited by the grain boundaries. Subsequently, an analytical model for the variation of the effective mobility with gate voltage is established. Such models are vital in assisting the development of more accurate designs of the novel organic circuits.

  1. Tips pentacene crystal alignment for improving performance of solution processed organic thin film transistors

    NASA Astrophysics Data System (ADS)

    He, Zhengran

    A newly-developed p-type organic semiconductor 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene) demonstrates various advantages such as high mobility, air stability and solution processibility, but at the same time its application is restricted by major issues, such as crystal misorientation and performance variation of organic thin-film transistors (OTFTs). This dissertation demonstrates several different approaches to address these issues. As a result, both crystal orientation and areal coverage can be effectively improved, leading to an enhancement of average mobility and performance consistency of OTFTs. Chapter 1 presents an introduction and background of this dissertation. Chapter 2 explores the usage of inorganic silica nanoparticles to manipulate the morphology of TIPS pentacene thin films and the performance of solution-processed organic OTFTs. The resultant drop-cast films yield improved morphological uniformity at ~10% SiO2 loading, which also leads to a 3-fold increase in average mobility and nearly 4-times reduction in the ratio of standard deviation of mobility (μStdev) to average mobility (μAvg). The experimental results suggest that the SiO2 nanoparticles mostly aggregate at TIPS pentacene grain boundaries, and that 10% nanoparticle concentration effectively reduces the undesirable crystal misorientation without considerably compromising TIPS pentacene crystallinity. Chapter 3 discusses the utilization of air flow to effectively reduce the TIPS pentacene crystal anisotropy and enhance performance consistency in OTFTs. Under air-flow navigation (AFN), TIPS pentacene forms thin films with improved crystal orientation and increased areal coverage, which subsequently lead to a four-fold increase of average hole mobility and one order of magnitude enhancement in performance consistency. Chapter 4 investigates the critical roles of lateral and vertical phase separation in the performance of the next-generation organic and hybrid electronic

  2. Characterizing p-channel thin film transistors using ZnO/hydrated polyvinyl alcohol as the conducting channel

    SciTech Connect

    Liau, Leo Chau-Kuang Hsu, Tzu-Hsien; Lo, Pei-Hsuan

    2014-08-11

    We report the characteristics of p-channel thin film transistors (p-TFTs) with ZnO/hydrated polyvinyl alcohol (PVA) (ZnO/PVA) conducting channels. The metal-oxide-semiconductor structure of the p-TFTs was composed of indium tin oxide (ITO)/SiO{sub 2}/ZnO/PVA layers. The TFT was assembled using PVA gel, which was glued to ITO substrates patterned to form source and drain electrodes. The ZnO/PVA composite film acted as an effective conducting film because of the chemisorption reaction at the film interface where free electrons can be generated. The formation of the conducting channel was also affected by V{sub G} applied to the TFT. The ZnO/PVA-based TFTs demonstrated p-channel transistor performance, shown by current-voltage (I-V) data analysis. The electrical parameters of the device were evaluated, including the on/off ratio (∼10{sup 3}), threshold voltage (V{sub th}, −1 V), and subthreshold swing (−2.2 V/dec). The PVA/ZnO-based p-TFTs were fabricated using simple and cost-effective approaches instead of doping methods.

  3. Vapor-phase molecular layer deposition of self-assembled multilayers for organic thin-film transistor.

    PubMed

    Lee, Byoung H; Lee, Kwang H; Im, Seongil; Sung, Myung M

    2009-12-01

    We report a vapor-phase molecular layer deposition (MLD) of self-assembled multilayer thin films for organic thin-film transistor. In the present MLD process, alkylsiloxane self-assembled multilayers (SAMs) were grown under vacuum by repeated sequential adsorptions of C=C-terminated alkylsilane and aluminum hydroxide with ozone activation. The MLD method is a self-controlled layer-by-layer growth process, and is perfectly compatible with the atomic layer deposition (ALD) method. The SAMs films prepared exhibited good mechanical flexibility and stability, excellent insulating properties, and relatively high dielectric capacitances of 374 nF/cm2 with a high dielectric strength of 4 MV/cm. They were then used as a 12 nm-thick dielectric for pentacene-based thin-film transistors (TFTs), which showed a maximum field effect mobility of 0.57 cm2/V s, operating at -4 V with an on/off current ratio of approximately 10(3).

  4. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    PubMed

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes.

  5. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    PubMed

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes. PMID:27267545

  6. Fabrication of air-stable n-type carbon nanotube thin-film transistors on flexible substrates using bilayer dielectrics

    NASA Astrophysics Data System (ADS)

    Li, Guanhong; Li, Qunqing; Jin, Yuanhao; Zhao, Yudan; Xiao, Xiaoyang; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

    2015-10-01

    Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed charges in the ALD layer. The key advantage of the method is the relatively low temperature (120 or 90 °C) required here for the ALD process because we need not employ this step to totally remove the absorbates on the SWNTs. This advantage facilitates the integration of both p-type and n-type transistors through a simple lift off process and compact CMOS inverters were demonstrated. We also demonstrated that the doping of SWNTs in the channel plays a more important role than the Schottky barriers at the metal contacts in carbon nanotube thin-film transistors, unlike the situation in individual SWNT-based transistors.Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed

  7. Passivated graphene transistors fabricated on a millimeter-sized single-crystal graphene film prepared with chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lin, Meng-Yu; Wang, Cheng-Hung; Chang, Shu-Wei; Lee, Si-Chen; Lin, Shih-Yen

    2015-07-01

    In this work, we first investigate the effects of partial pressures and flow rates of precursors on the single-crystal graphene growth using chemical vapor depositions on copper foils. These factors are shown to be critical to the growth rate, seeding density and size of graphene single crystals. The prepared graphene films in millimeter sizes are then bubbling transferred to silicon-dioxide/silicon substrates for high-mobility graphene transistor fabrications. After high-temperature annealing and hexamethyldisilazane passivation, the water attachment is removed from the graphene channel. The elimination of uncontrolled doping and enhancement of carrier mobility accompanied by these procedures indicate that they are promising for fabrications of graphene transistors.

  8. Improvement of properties of an ambipolar organic field-effect transistor by using a singlet biradicaloid film

    NASA Astrophysics Data System (ADS)

    Yamane, Wataru; Koike, Harunobu; Chikamatsu, Masayuki; Kubo, Takashi; Nishiuchi, Tomohiko; Kanai, Kaname

    2016-01-01

    We have improved the properties of ambipolar organic field-effect transistors by chemically treating the source and drain electrodes with a vacuum-deposited biradicaloid film. Biradicaloid was a diphenyl derivative of s-indacenodiphenalene (Ph2-IDPL). An alkane thiol self-assembled monolayer (SAM) was used as an insulator buffer layer at the Ph2-IDPL/electrode interface to prevent off-current. We confirmed the transport level alignment at the Ph2-IDPL/SAM/electrode interface by ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. Although Ph2-IDPL transistors containing the SAM showed a higher on/off ratio or mobility than a previously reported device without the buffer layer, there was a trade-off between on/off ratio and mobility. Our results suggest that biradical molecules are promising candidates for use in low-power inverters.

  9. Extended-gate field-effect transistor (EG-FET) with molecularly imprinted polymer (MIP) film for selective inosine determination.

    PubMed

    Iskierko, Zofia; Sosnowska, Marta; Sharma, Piyush Sindhu; Benincori, Tiziana; D'Souza, Francis; Kaminska, Izabela; Fronc, Krzysztof; Noworyta, Krzysztof

    2015-12-15

    A novel recognition unit of chemical sensor for selective determination of the inosine, renal disfunction biomarker, was devised and prepared. For that purpose, inosine-templated molecularly imprinted polymer (MIP) film was deposited on an extended-gate field-effect transistor (EG-FET) signal transducing unit. The MIP film was prepared by electrochemical polymerization of bis(bithiophene) derivatives bearing cytosine and boronic acid substituents, in the presence of the inosine template and a thiophene cross-linker. After MIP film deposition, the template was removed, and was confirmed by UV-visible spectroscopy. Subsequently, the film composition was characterized by spectroscopic techniques, and its morphology and thickness were determined by AFM. The finally MIP film-coated extended-gate field-effect transistor (EG-FET) was used for signal transduction. This combination is not widely studied in the literature, despite the fact that it allows for facile integration of electrodeposited MIP film with FET transducer. The linear dynamic concentration range of the chemosensor was 0.5-50 μM with inosine detectability of 0.62 μM. The obtained detectability compares well to the levels of the inosine in body fluids which are in the range 0-2.9 µM for patients with diagnosed diabetic nephropathy, gout or hyperuricemia, and can reach 25 µM in certain cases. The imprinting factor for inosine, determined from piezomicrogravimetric experiments with use of the MIP film-coated quartz crystal resonator, was found to be 5.5. Higher selectivity for inosine with respect to common interferents was also achieved with the present molecularly engineered sensing element. The obtained analytical parameters of the devised chemosensor allow for its use for practical sample measurements.

  10. Effect of Al2O3 insulator thickness on the structural integrity of amorphous indium-gallium-zinc-oxide based thin film transistors.

    PubMed

    Kim, Hak-Jun; Hwang, In-Ju; Kim, Youn-Jea

    2014-12-01

    The current transparent oxide semiconductors (TOSs) technology provides flexibility and high performance. In this study, multi-stack nano-layers of TOSs were designed for three-dimensional analysis of amorphous indium-gallium-zinc-oxide (a-IGZO) based thin film transistors (TFTs). In particular, the effects of torsional and compressive stresses on the nano-sized active layers such as the a-IGZO layer were investigated. Numerical simulations were carried out to investigate the structural integrity of a-IGZO based TFTs with three different thicknesses of the aluminum oxide (Al2O3) insulator (δ = 10, 20, and 30 nm), respectively, using a commercial code, COMSOL Multiphysics. The results are graphically depicted for operating conditions. PMID:25971080

  11. A low-temperature polycrystalline-silicon thin-film transistor micro-manipulation array with indium tin oxide micro-coils and real-time detection

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Yang; Huang, Chien-Yu; Lin, Chrong-Jung; King, Ya-Chin

    2009-12-01

    This study proposes an array for a bio-handling system consisting of microcoils on top of photodetectors fabricated by low-temperature polycrystalline-silicon thin-film transistor (LTPS-TFT) technology on a glass substrate. Using magnetic beads as the medium, the proposed system can simultaneously monitor and manipulate micrometer-sized bio-samples. In a manipulation system based on magnetic force, photo-detecting is a reliable method, immune to the interference caused by electromagnetic fields. Under 480 lux ambient white light, the sensor can detect a microbead as small as 23 µm in diameter with detectable output difference. It provides a new, easier way for handling samples on a small chip.

  12. Alumina nanoparticle/polymer nanocomposite dielectric for flexible amorphous indium-gallium-zinc oxide thin film transistors on plastic substrate with superior stability

    SciTech Connect

    Lai, Hsin-Cheng; Pei, Zingway; Jian, Jyun-Ruri; Tzeng, Bo-Jie

    2014-07-21

    In this study, the Al{sub 2}O{sub 3} nanoparticles were incorporated into polymer as a nono-composite dielectric for used in a flexible amorphous Indium-Gallium-Zinc Oxide (a-IGZO) thin-film transistor (TFT) on a polyethylene naphthalate substrate by solution process. The process temperature was well below 100 °C. The a-IGZO TFT exhibit a mobility of 5.13 cm{sup 2}/V s on the flexible substrate. After bending at a radius of 4 mm (strain = 1.56%) for more than 100 times, the performance of this a-IGZO TFT was nearly unchanged. In addition, the electrical characteristics are less altered after positive gate bias stress at 10 V for 1500 s. Thus, this technology is suitable for use in flexible displays.

  13. Sputtering technology in solid film lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Potential and present sputtering technology is discussed as it applies to the deposition of solid film lubricants particularly MoS2, WS2, and PTFE. Since the sputtered films are very thin, the selection of the sputtering parameters and substrate condition is very critical as reflected by the lubricating properties. It was shown with sputtered MoS2 films that the lubricating characteristics are directly affected by the selected sputtering parameters (power density, pressure, sputter etching, dc-biasing, etc.) and the substrate temperature, chemistry, topography and the environmental conditions during the friction tests. Electron microscopy and other surface sensitive analytical techniques illustrate the resulting changes in sputtered MoS2 film morphology and chemistry which directly influence the film adherence and frictional properties.

  14. Low temperature thin film transistors with hollow cathode plasma-assisted atomic layer deposition based GaN channels

    SciTech Connect

    Bolat, S. E-mail: aokyay@ee.bilkent.edu.tr; Tekcan, B.; Ozgit-Akgun, C.; Biyikli, N.; Okyay, A. K. E-mail: aokyay@ee.bilkent.edu.tr

    2014-06-16

    We report GaN thin film transistors (TFT) with a thermal budget below 250 °C. GaN thin films are grown at 200 °C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3 nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (I{sub ON}/I{sub OFF}) of 10{sup 3} and sub-threshold swing of 3.3 V/decade. The entire TFT device fabrication process temperature is below 250 °C, which is the lowest process temperature reported for GaN based transistors, so far.

  15. Effect of Ta addition of co-sputtered amorphous tantalum indium zinc oxide thin film transistors with bias stability.

    PubMed

    Son, Dae-Ho; Kim, Dae-Hwan; Park, Si-Nae; Sung, Shi-Joon; Kang, Jin-Kyu

    2014-11-01

    In this work, we have fabricated thin film transistors (TFTs) using amorphous tantalum indium zinc oxide (a-TaInZnO) channels by the co-sputtering process. The effects of incorporating tantalum on the InZnO material were investigated using Hall-effect measurement results, and electrical characteristics. We also found that the carrier densities of thin films and the transistor on-off currents were greatly influenced by the composition of tantalum addition. Ta ions have strong affinity to oxygen and so suppress the formation of free electron carriers inthin films; they play an important role in enhancing the electrical characteristic due to their high oxygen bonding ability. The electrical characteristics of the optimized TFTs shows a field effect mobility of 3.67 cm2 V(-1) s(-1), a threshold voltage of 1.28 V, an on/off ratio of 1.1 x 10(8), and a subthreshold swing of 480 mV/dec. Under gate bias stress conditions, the TaInZnO TFTs showed lower shift in threshold voltage shifts. PMID:25958492

  16. Flexible low-voltage polymer thin-film transistors using supercritical CO2-deposited ZrO2 dielectrics.

    PubMed

    Wei, Qingshuo; You, Eunyoung; Hendricks, Nicholas R; Briseno, Alejandro L; Watkins, James J

    2012-05-01

    The fabrication of low-voltage flexible organic thin film transistors using zirconia (ZrO(2)) dielectric layers prepared via supercritical fluid deposition was studied. Continuous, single-phase films of approximately 30 nm thick ZrO(2) were grown on polyimide (PI)/aluminum (Al) substrates at 250 °C via hydrolysis of tetrakis(2,2,6,6-tetramethyl-3,5-heptane-dionato) zirconium in supercritical carbon dioxide. This dielectric layer showed a high areal capacitance of 317 nF cm(-2) at 1 kHz and a low leakage current of 1.8 × 10(-6) A cm(-2) at an applied voltage of -3 V. By using poly(3-hexylthiophene) (P3HT) as a semiconductor, we have fabricated flexible thin film transistors operating at V(DS) = -0.5 V and V(G) in a range from 0.5 V to -4 V, with on/off ratios on the order of 1 × 10(3) and mobility values higher than 0.1 cm(2)/(V s).

  17. High-power microwave LDMOS transistors for wireless data transmission technologies (Review)

    SciTech Connect

    Kuznetsov, E. V. Shemyakin, A. V.

    2010-12-15

    The fields of the application, structure, fabrication, and packaging technology of high-power microwave LDMOS transistors and the main advantages of these devices were analyzed. Basic physical parameters and some technology factors were matched for optimum device operation. Solid-state microwave electronics has been actively developed for the last 10-15 years. Simultaneously with improvement of old devices, new devices and structures are actively being adopted and developed and new semiconductor materials are being commercialized. Microwave LDMOS technology is in demand in such fields as avionics, civil and military radars, repeaters, base stations of cellular communication systems, television and broadcasting transmitters, and transceivers for high-speed wireless computer networks (promising Wi-Fi and Wi-Max standards).

  18. Metal-oxide based transparent conductive oxides and thin film transistors for flexible electronics

    NASA Astrophysics Data System (ADS)

    Indluru, Anil

    The object of this study is to investigate and improve the performance/stability of the flexible thin film transistors (TFTs) and to study the properties of metal oxide transparent conductive oxides for wide range of flexible electronic applications. Initially, a study has been done to improve the conductivity of ITO (indium tin oxide) films on PEN (p olyethylene naphthalate) by inserting a thin layer of silver layer between two ITO layers. The multilayer with an optimum Ag mid-layer thickness, of 8 nm, exhibited excellent photopic average transmittance (˜ 88 %), resistivity (˜ 2.7 x 10-5 micro-cm.) and has the best Hackee figure of merit (41.0 x 10-3 O -1). The electrical conduction is dominated by two different scattering mechanisms depending on the thickness of the Ag mid-layer. Optical transmission is explained by scattering losses and absorption of light due to inter-band electronic transitions. A systematic study was carried out to improve the performance/stability of the TFTs on PEN. The performance and stability of a-Si:H and a-IZO (amorphous indium zinc oxide) TFTs were improved by performing a systematic low temperature (150 °C) anneals for extended times. For 96 hours annealed a-Si:H TFTs, the sub-threshold slope and off-current were reduced by a factor ˜ 3 and by 2 orders of magnitude, respectively when compared to unannealed a-Si:H TFTs. For a-IZO TFTs, 48 hours of annealing is found to be the optimum time for the best performance and elevated temperature stability. These devices exhibit saturation mobility varying between 4.5--5.5 cm2/V-s, ION/IOFF ratio was 10 6 and a sub-threshold swing variation of 1--1.25 V/decade. An in-depth study on the mechanical and electromechanical stress response on the electrical properties of the a-IZO TFTs has also been investigated. Finally, the a-Si:H TFTs were exposed to gamma radiation to examine their radiation resistance. The interface trap density (Nit) values range from 5 to 6 x 1011 cm-2 for only electrical

  19. Testing of flexible InGaZnO-based thin-film transistors under mechanical strain

    NASA Astrophysics Data System (ADS)

    Münzenrieder, N. S.; Cherenack, K. H.; Tröster, G.

    2011-08-01

    Thin-film transistors (TFTs) fabricated on flexible plastic substrates are an integral part of future flexible large-area electronic devices like displays and smart textiles. Devices for such applications require stable electrical performance under electrical stress and also during applied mechanical stress induced by bending of the flexible substrate. Mechanical stress can be tensile or compressive strain depending on whether the TFT is located outside or inside of the bending plane. Especially the impact of compressive bending on TFT performance is hard to measure, because the device is covered with the substrate in this case. We present a method which allows us to continuously measure the electrical performance parameters of amorphous Indium-Gallium-Zinc Oxide (a-IGZO) based TFTs exposed to arbitrary compressive and tensile bending radii. To measure the influence of strain on a TFT it is attached and electrically connected to a flexible carrier foil, which afterwards is fastened to two plates in our bending tester. The bending radius can be adjusted by changing the distance between these plates. Thus it is possible to apply bending radii in the range between a totally flat substrate and ≈1 mm, corresponding to a strain of ≈3.5%. The tested bottom-gate TFTs are especially designed for use with our bending tester and fabricated on 50 μm thick flexible Kapton® E polyimide substrates. To show the different application areas of our bending method we characterized our TFTs while they are bent to different tensile and compressive bending radii. These measurements show that the field effect mobilities and threshold voltages of the tested a-IGZO TFTs are nearly, but not absolutely, stable under applied strain, compared to the initial values the mobilities shift by ≈3.5% in the tensile case and ≈-1.5% in the compressive one, at a bending radius of 8 mm. We also measured the influence of repeated bending (2500 cycles over ≈70 h), where a shift of the

  20. High-performance n-channel organic thin-film transistor based on naphthalene diimide.

    PubMed

    Dey, Anamika; Kalita, Anamika; Krishnan Iyer, Parameswar

    2014-08-13

    A conjugated molecule comprising 1,4,5,8-naphthalene diimide (NDI) substituted with two octadecylamine (OD) chains has been synthesized (NDI-OD2) in a single step from commercial materials, and its organic thin-film transistor (OTFT) devices on glass substrate have been studied using poly(vinyl alcohol) (PVA) gate dielectric material. Although we utilized the PVA dielectric without any intermediate buffer layer or PVA cross-linkers, excellent electron mobility as high as ∼1.0 cm(2)V(-1) s(-1) are obtained. This NDI-OD2 molecule exhibits comparable optical (Eg(UV) ∼3.1 eV) and electrochemical band gaps (Eg(CV) ∼3.02 eV) with a lowest unoccupied molecular orbital (LUMO) energy levels of ∼3.3 eV. When processed by solution method, this material forms rod-shaped crystalline microstructures, whereas, when thermally deposited, it assumes the formation of smooth 2D films. The chemical as well as physical properties and theoretical calculations of NDI-OD2 have been studied and the effect of the C-18 alkyl chain unit has been discussed. The OTFT consisting of NDI-OD2 exhibits excellent performance parameters such as high electron mobility (μe) and Ion-to-Ioff ratio. After demonstrating the high performance of NDI-OD2-based TFT devices fabricated with biocompatible PVA dielectric, we have also demonstrated that these devices can be degraded because of the presence of this PVA dielectric when exposed to a high-moisture environment. The systematic degradation of the device activity in a controlled way within 10 days of exposure (>80% moisture) is also presented here. In this study, a conceptually important feature and futuristic aspect that the n-channel TFT devices can also be biodegraded irreversibly is demonstrated. This concept of developing a low cost and biodegradable OTFT device with biocompatible PVA dielectric with excellent electron mobility is expected to have diverse applications in disposable electronic tags, biomedical devices, and food industry packing

  1. Two-Dimensional Van der Waals Materials for Thin Film Transistor Applications

    NASA Astrophysics Data System (ADS)

    George, Aaron Scott

    Research on two-dimensional nanomaterials has become a topic of considerable interest since the pioneering work experimentally introducing the two-dimensional carbon allotrope of graphene in 2004. The atomically thin hexagonally arranged carbon crystal structure has offered the opportunity for numerous studies in condensed matter physics and materials science, revealing new phenomenon and remarkable properties. Graphene has excellent chemical and mechanical stability, allowing researchers to probe the properties of graphene in a wide variety of applications and in contact with a wide variety of materials. Ballistic transport of graphene at room temperature suggests that graphene would be poised to enter in to a wide variety of microelectronic application; vii however, synthesis methods and surface effects have so far limited the widespread use of graphene. Additionally, the absence of electronic band gap in graphene, classifying it as a "semi-metal", limits the use of graphene to areas other than logic applications. In this work, fabrication methods for the improved synthesis graphene and selected two-dimensional transition metal dichalcogenides, molybdenum disulfide and tungsten disulfide, are presented for thin film transistor applications. First, the introduction of thin film zwitterionic polymer interlayers in graphene devices is outlined as a means to reduce the contact resistance between metal contacts and the underlying graphene layer. Second, a self-assembly nanoscale lithography process utilizing diblock copolymer templates as an etching mask directly on the surface of graphene is shown as a method to introduce a band gap in graphene due to quantum confinement effects. The third chapter applies to another class of two-dimensional materials, transition metal dichalcogenides, which, unlike graphene, can exhibit suitable electronic band structures for logic applications. When the thickness of these transition metal dichalcogenides is reduced to a single

  2. Solution-Processed Organic Thin-Film Transistor Array for Active-Matrix Organic Light-Emitting Diode

    NASA Astrophysics Data System (ADS)

    Harada, Chihiro; Hata, Takuya; Chuman, Takashi; Ishizuka, Shinichi; Yoshizawa, Atsushi

    2013-05-01

    We developed a 3-in. organic thin-film transistor (OTFT) array with an ink-jetted organic semiconductor. All layers except electrodes were fabricated by solution processes. The OTFT performed well without hysteresis, and the field-effect mobility in the saturation region was 0.45 cm2 V-1 s-1, the threshold voltage was 3.3 V, and the on/off current ratio was more than 106. We demonstrated a 3-in. active-matrix organic light-emitting diode (AMOLED) display driven by the OTFT array. The display could provide clear moving images. The peak luminance of the display was 170 cd/m2.

  3. Low-Voltage InGaZnO Thin Film Transistors with Small Sub-Threshold Swing.

    PubMed

    Cheng, C H; Chou, K I; Hsu, H H

    2015-02-01

    We demonstrate a low-voltage driven, indium-gallium-zinc oxide thin-film transistor using high-κ LaAlO3 gate dielectric. A low VT of 0.42 V, very small sub-threshold swing of 68 mV/dec, field-effect mobility of 4.1 cm2/Ns and low operation voltage of 1.4 V were reached simultaneously in LaAlO3/IGZO TFT device. This low-power and small SS TFT has the potential for fast switching speed and low power applications. PMID:26353677

  4. The influence of the SiO{sub 2} interlayer on transfer characteristic in tin oxide thin film transistor

    SciTech Connect

    Kim, Woong-Sun; Moon, Yeon-Keon; Kim, Kyung-Taek; Park, Jong-Wan

    2011-12-23

    In this article, we report the fabrication on SnO{sub 2} thin film transistors (TFTs) fabricated by DC sputtering system. SnO{sub 2} based TFTs have been reported previously, and all the TFTs operate depletion-mode, requiring the application of a gate voltage to turn it off. In contrast to previously reports, the SnO{sub 2} TFT reported herein operates as an enhancement-mode device, requiring the application of a gate voltage to turn the device on. Furthermore, we introduce an hafnium-tin oxide (HfSnO) semiconductor materials that have been developed for use as p-channel TFTs.

  5. Observation of electric potential in organic thin-film transistor by bias-applied hard X-ray photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Watanabe, Takeshi; Tada, Keisuke; Yasuno, Satoshi; Oji, Hiroshi; Yoshimoto, Noriyuki; Hirosawa, Ichiro

    2016-03-01

    The effect of gate voltage on electric potential in a pentacene (PEN) layer was studied by hard X-ray photoelectron spectroscopy under a bias voltage. It was observed that applying a negative gate voltage substantially increases the width of a C 1s peak. This suggested that injected and accumulated carriers in an organic thin film transistor channel modified the potential depth profile in PEN. It was also observed that the C 1s kinetic energy tends to increase monotonically with threshold voltage.

  6. Bias-illumination stress effect in thin film transistors with a nitrogen low-doped IZO active layer

    NASA Astrophysics Data System (ADS)

    Cheremisin, Alexander B.; Kuznetsov, Sergey N.; Stefanovich, Genrikh B.

    2016-10-01

    The effect of ZnO and IZO moderate nitridation on the performance of thin film transistors (TFTs) has been studied by methods of transfer and capacitance-voltage characteristics, isochronal annealing and computer modeling. Layers of ZnO:N and IZO:N were prepared by reactive sputtering. It is shown that nitridation of the ZnO matrix up to a concentration of 9 at.% results in the deterioration of transistor parameters. However, nitridation of the IZO matrix does not impair a transistor’s static parameters and also provides enhanced performance reproducibility. An additional positive effect is manifested in the electrical stress stability of transistor characteristics at negative bias and positive bias in darkness. Negative bias illumination stress (NBIS) of IZO:N structures also causes TFTs’ degradation similar to that for IGZO devices. However, our observations of the NBIS effect have revealed the following important features. Holes trapped under NBIS could not be neutralized by electrons in the channel in the accumulation regime, thus indicating negligible interaction between positively-charged defects and the conduction band. In addition, trapped holes’ depopulation was performed by thermal activation with an isochronal annealing method. An activation energy of ˜0.8 eV was revealed which is interpreted as the energy level of defects above the valence-band maximum. The specified features do not correlate with the assumption of the key role of oxygen vacancies in NBIS that is extensively presented in literature.

  7. A flexible organic active matrix circuit fabricated using novel organic thin film transistors and organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Heredia, G.; González, L. A.; Alshareef, H. N.; Gnade, B. E.; Quevedo-López, M.

    2010-11-01

    We present an active matrix circuit fabricated on plastic (polyethylene naphthalene, PEN) and glass substrates using organic thin film transistors and organic capacitors to control organic light-emitting diodes (OLEDs). The basic circuit is fabricated using two pentacene-based transistors and a capacitor using a novel aluminum oxide/parylene stack (Al2O3/parylene) as the dielectric for both the transistor and the capacitor. We report that our circuit can deliver up to 15 µA to each OLED pixel. To achieve 200 cd m-2 of brightness a 10 µA current is needed; therefore, our approach can initially deliver 1.5× the required current to drive a single pixel. In contrast to parylene-only devices, the Al2O3/parylene stack does not fail after stressing at a field of 1.7 MV cm-1 for >10 000 s, whereas 'parylene only' devices show breakdown at approximately 1000 s. Details of the integration scheme are presented.

  8. Enhanced carrier mobility of multilayer MoS2 thin-film transistors by Al2O3 encapsulation

    NASA Astrophysics Data System (ADS)

    Kim, Seong Yeoul; Park, Seonyoung; Choi, Woong

    2016-10-01

    We report the effect of Al2O3 encapsulation on the carrier mobility and contact resistance of multilayer MoS2 thin-film transistors by statistically investigating 70 devices with SiO2 bottom-gate dielectric. After Al2O3 encapsulation by atomic layer deposition, calculation based on Y-function method indicates that the enhancement of carrier mobility from 24.3 cm2 V-1 s-1 to 41.2 cm2 V-1 s-1 occurs independently from the reduction of contact resistance from 276 kΩ.μm to 118 kΩ.μm. Furthermore, contrary to the previous literature, we observe a negligible effect of thermal annealing on contact resistance and carrier mobility during the atomic layer deposition of Al2O3. These results demonstrate that Al2O3 encapsulation is a useful method of improving the carrier mobility of multilayer MoS2 transistors, providing important implications on the application of MoS2 and other two-dimensional materials into high-performance transistors.

  9. Low-voltage-operated organic one-time programmable memory using printed organic thin-film transistors and antifuse capacitors.

    PubMed

    Jung, Soon-Won; Na, Bock Soon; Park, Chan Woo; Koo, Jae Bon

    2014-11-01

    We demonstrate an organic one-time programmable memory cell formed entirely at plastic-compatible temperatures. All the processes are performed at below 130 degrees C. Our memory cell consists of a printed organic transistor and an organic capacitor. Inkjet-printed organic transistors are fabricated by using high-k polymer dielectric blends comprising poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] and poly(methyl methacrylate) (PMMA) for low-voltage operation. P(NDI2OD-T2) transistors have a high field-effect mobility of 0.2 cm2/Vs and a low operation gate voltage of less than 10 V. The operation voltage effectively decreases owing to the high permittivity of the P(VDF-TrFE):PMMA blended film. The data in the memory cell are programmed by electrically breaking the organic capacitor. The organic capacitor acts like an antifuse capacitor, because it is initially open, and it becomes permanently short-circuited by applying a high voltage. The organic memory cells are programmed with 4 V, and they are read out with 2 V. The memory data are read out by sensing the current in the memory cell. The printed organic one-time programmable memory is suitable for applications storing small amount of data, such as low-cost radio-frequency identification (RFID) tag.

  10. Optically and electrically driven organic thin film transistors with diarylethene photochromic channel layers.

    PubMed

    Hayakawa, Ryoma; Higashiguchi, Kenji; Matsuda, Kenji; Chikyow, Toyohiro; Wakayama, Yutaka

    2013-05-01

    We achieved drain-current switching of diarylethene-channel field-effect transistors with light- and electric-field effects. The drain current was reversibly changed by alternating ultraviolet and visible light irradiation. Stress is placed on the fact that the on/off ratio realized by light irradiation was 1 × 10(2) (1 × 10(4)%) and this value is much larger than those in other photochromism-based transistors. These results indicate that the drain current was effectively controlled by light irradiation. Furthermore, the on and off states modulated by light were maintained without light irradiation even after 1 week, exhibiting that our transistor works as an optical memory. We clarified that the light-driven modulation can be attributed to the transformation in the π-conjugation system accompanied by photoisomerization. These findings have the potential to attain high-performance optoelectrical organic devices including optical sensors, optical memory, and photoswitching transistors.

  11. Fabrication of assembled ZnO/TiO2 heterojunction thin film transistors using solution processing technique

    NASA Astrophysics Data System (ADS)

    Liau, Leo Chau-Kuang; Lin, Yun-Guo

    2015-01-01

    Ceramic-based metal-oxide-semiconductor (MOS) field-effect thin film transistors (TFTs), which were assembled by ZnO and TiO2 heterojunction films coated using solution processing technique, were fabricated and characterized. The fabrication of the device began with the preparation of ZnO and TiO2 films by spin coating. The ZnO and TiO2 films that were stacked together and annealed at 450 °C were characterized as a p-n junction diode. Two types of the devices, p-channel and n-channel TFTs, were produced using different assemblies of ZnO and TiO2 films. Results show that the p-channel TFTs (p-TFTs) and n-channel TFTs (n-TFTs) using the assemblies of ZnO and TiO2 films were demonstrated by source-drain current vs. drain voltage (IDS-VDS) measurements. Several electronic properties of the p- and n- TFTs, such as threshold voltage (Vth), on-off ratio, channel mobility, and subthreshold swing (SS), were determined by current-voltage (I-V) data analysis. The ZnO/TiO2-based TFTs can be produced using solution processing technique and an assembly approach.

  12. Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer

    NASA Astrophysics Data System (ADS)

    Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

    2016-02-01

    Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (+/-2 V) and subthreshold swing (SS) (122-161 mV dec-1), high effective mobility (up to 17.6-37.7 cm2 V-1 s-1) and high on/off ratio (104-107). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption.Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge

  13. Study on Preparation of High-k Organic-Inorganic Thin Film for Organic-Inorganic Thin Film Transistor Gate Dielectric Application

    NASA Astrophysics Data System (ADS)

    Lee, Wen-Hsi; Liu, Chao-Te; Lee, Ying-Chieh

    2012-06-01

    A simple solution-based deposition technique combined with spin-coating is a plausible way to prepare ultra-thin organic-inorganic nanocomposite films. In this study, we describe the spin-coating deposition of a colloidal nanoparticle suspension to obtain an ultra-thin organic-inorganic composite film as a gate insulator for organic thin film transistor (O-TFT) application. To obtain a homogenous organic-inorganic composite film, well-dispersed TiO2 nanoparticles in γ-butyrolactone and polyimide are important; therefore, several dispersants were assessed on the basis of the measurement of the rheological behavior of slurries. The thickness of the organic-inorganic composite film is mainly determined by the speed of spin-coating and viscosity of slurries. An approximately 4000-Å-thick nanocomposite film with homogeneous distribution of TiO2 nanoparticles in polyimide and low roughness was obtained after curing at 200 °C, resulting in a low leakage current density of the nano-composite film, when less than 2 vol % TiO2 nanoparticles were well dispersed in polyimide slurry. The dielectric constant of the organic-inorganic nanocomposite increases with increasing TiO2 content in polyimide, being situated in the range between 4 and 5.

  14. Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer.

    PubMed

    Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

    2016-02-28

    Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (±2 V) and subthreshold swing (SS) (122-161 mV dec(-1)), high effective mobility (up to 17.6-37.7 cm(2) V(-1) s(-1)) and high on/off ratio (10(4)-10(7)). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption. PMID:26847814

  15. High electron mobility thin-film transistors based on Ga{sub 2}O{sub 3} grown by atmospheric ultrasonic spray pyrolysis at low temperatures

    SciTech Connect

    Thomas, Stuart R. E-mail: thomas.anthopoulos@imperial.ac.uk; Lin, Yen-Hung; Faber, Hendrik; Anthopoulos, Thomas D. E-mail: thomas.anthopoulos@imperial.ac.uk; Adamopoulos, George; Sygellou, Labrini; Stratakis, Emmanuel; Pliatsikas, Nikos; Patsalas, Panos A.

    2014-09-01

    We report on thin-film transistors based on Ga{sub 2}O{sub 3} films grown by ultrasonic spray pyrolysis in ambient atmosphere at 400–450 °C. The elemental, electronic, optical, morphological, structural, and electrical properties of the films and devices were investigated using a range of complementary characterisation techniques, whilst the effects of post deposition annealing at higher temperature (700 °C) were also investigated. Both as-grown and post-deposition annealed Ga{sub 2}O{sub 3} films are found to be slightly oxygen deficient, exceptionally smooth and exhibit a wide energy bandgap of ∼4.9 eV. Transistors based on as-deposited Ga{sub 2}O{sub 3} films show n-type conductivity with the maximum electron mobility of ∼2 cm{sup 2}/V s.

  16. Film Style and Technology in the Thirties

    ERIC Educational Resources Information Center

    Salt, Barry

    1976-01-01

    Examines various formal stylistic features of cinema in the 1930's and the relationship of these features to the technological developments of the period. Available from: Film Quarterly, University of California Press, Berkeley, CA 94702. Subscription Rates: $6.00, per year; $10.80, two years; single copies, $1.50. (MH)

  17. Development, Demonstration, and Device Physics of Fet-Accessed One-Transistor Gallium Arsenide Dynamic Memory Technologies

    NASA Astrophysics Data System (ADS)

    Neudeck, Philip Gerold

    The introduction of digital GaAs into modern high -speed computing systems has led to an increasing demand for high-density memory in these GaAs technologies. To date, most of the memory development efforts in GaAs have been directed toward four- and six-transistor static RAM's, which consume substantial chip area and dissipate much static power resulting in limited single-chip GaAs storage capacities. As it has successfully done in silicon, a one-transistor dynamic RAM approach could alleviate these problems making higher density GaAs memories possible. This dissertation discusses theoretical and experimental work that presents the possibility for a high-speed, low-power, one-transistor dynamic RAM technology in GaAs. The two elements of the DRAM cell, namely the charge storage capacitor and the access field-effect transistor have been studied in detail. Isolated diode junction charge storage capacitors have demonstrated 30 minutes of storage time at room temperature with charge densities comparable to those obtained in planar silicon DRAM capacitors. GaAs JFET and MESFET technologies have been studied, and with careful device design and choice of proper operating voltages experimental results show that both can function as acceptable access transistors. One-transistor MESFET- and JFET-accessed DRAM cells have been fabricated and operated at room temperature and above with a standby power dissipation that is only a small fraction of the power dissipated by the best commercial GaAs static RAM cells. A 2 x 2 bit demonstration array was built and successfully operated at room temperature to demonstrate the addressable read/write capability of this new technology.

  18. Suppression of photo-bias induced instability for amorphous indium tungsten oxide thin film transistors with bi-layer structure

    NASA Astrophysics Data System (ADS)

    Liu, Po-Tsun; Chang, Chih-Hsiang; Chang, Chih-Jui

    2016-06-01

    This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO2 backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliability of device under NBTIS.

  19. Dual Input AND Gate Fabricated From a Single Channel Poly (3-Hexylthiophene) Thin Film Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    Pinto, N. J.; Perez, R.; Mueller, C. H.; Theofylaktos, N.; Miranda, F. A.

    2006-01-01

    A regio-regular poly (3-hexylthiophene) (RRP3HT) thin film transistor having a split-gate architecture has been fabricated on a doped silicon/silicon nitride substrate and characterized. This device demonstrates AND logic functionality. The device functionality was controlled by applying either 0 or -10 V to each of the gate electrodes. When -10 V was simultaneously applied to both gates, the device was conductive (ON), while any other combination of gate voltages rendered the device resistive (OFF). The p-type carrier charge mobility was about 5x10(exp -4) per square centimeter per V-sec. The low mobility is attributed to the sharp contours of the RRP3HT film due to substrate non-planarity. A significant advantage of this architecture is that AND logic devices with multiple inputs can be fabricated using a single RRP3HT channel with multiple gates.

  20. Low-voltage and hysteresis-free organic thin-film transistors employing solution-processed hybrid bilayer gate dielectrics

    SciTech Connect

    Ha, Tae-Jun

    2014-07-28

    This study presents a promising approach to realize low-voltage (<3 V) organic thin-film transistors (OTFTs) exhibiting improved electrical and optical stability. Such device performance results from the use of solution-processed hybrid bilayer gate dielectrics consisting of zirconium dioxide (high-k dielectric) and amorphous fluoropolymer, CYTOP{sup ®} (low-k dielectric). Employing a very thin amorphous fluoropolymer film reduces interfacial defect-states by repelling water molecules and other aqueous chemicals from an organic semiconductor active layer due to the hydrophobic surface-property. The chemically clean interface, stemming from decrease in density of trap states improves all the key device properties such as field-effect mobility, threshold voltage, and sub-threshold swing. Furthermore, degradation by electrical bias-stress and photo-induced hysteresis were suppressed in OTFTs employing hybrid bilayer gate dielectrics.

  1. Flexible logic circuits based on top-gate thin film transistors with printed semiconductor carbon nanotubes and top electrodes

    NASA Astrophysics Data System (ADS)

    Xu, Weiwei; Liu, Zhen; Zhao, Jianwen; Xu, Wenya; Gu, Weibing; Zhang, Xiang; Qian, Long; Cui, Zheng

    2014-11-01

    In this report printed thin film transistors and logic circuits on flexible substrates are reported. The top-gate thin film transistors were made of the sorted semiconducting single-walled carbon nanotubes (sc-SWCNTs) ink as channel material and printed silver lines as top electrodes and interconnect. 5 nm HfOx thin films pre-deposited on PET substrates by atomic layer deposition (ALD) act as the adhesion layers to significantly improve the immobilization efficiency of sc-SWCNTs and environmental stability. The immobilization mechanism was investigated in detail. The flexible partially-printed top-gate SWCNT TFTs display ambipolar characteristics with slightly strong p-type when using 50 nm HfOx thin films as dielectric layer, as well as the encapsulation layer by atomic layer deposition (ALD) at 120 °C. The hole mobility, on/off ratio and subthreshold swing (SS) are ~46.2 cm2 V-1 s-1, 105 and 109 mV per decade, respectively. Furthermore, partially-printed TFTs show small hysteresis, low operating voltage (2 V) and high stability in air. Flexible partially-printed inverters show good performance with voltage gain up to 33 with 1.25 V supply voltage, and can work at 10 kHz. The frequency of flexible partially-printed five-stage ring oscillators can reach 1.7 kHz at supply voltages of 2 V with per stage delay times of 58.8 μs. This work paves a way to achieve printed SWCNT advanced logic circuits and systems on flexible substrates.In this report printed thin film transistors and logic circuits on flexible substrates are reported. The top-gate thin film transistors were made of the sorted semiconducting single-walled carbon nanotubes (sc-SWCNTs) ink as channel material and printed silver lines as top electrodes and interconnect. 5 nm HfOx thin films pre-deposited on PET substrates by atomic layer deposition (ALD) act as the adhesion layers to significantly improve the immobilization efficiency of sc-SWCNTs and environmental stability. The immobilization mechanism

  2. Low-temperature processable amorphous In-W-O thin-film transistors with high mobility and stability

    SciTech Connect

    Kizu, Takio; Aikawa, Shinya; Mitoma, Nobuhiko; Shimizu, Maki; Gao, Xu; Lin, Meng-Fang; Tsukagoshi, Kazuhito; Nabatame, Toshihide

    2014-04-14

    Thin-film transistors (TFTs) with a high stability and a high field-effect mobility have been achieved using W-doped indium oxide semiconductors in a low-temperature process (∼150 °C). By incorporating WO{sub 3} into indium oxide, TFTs that were highly stable under a negative bias stress were reproducibly achieved without high-temperature annealing, and the degradation of the field-effect mobility was not pronounced. This may be due to the efficient suppression of the excess oxygen vacancies in the film by the high dissociation energy of the bond between oxygen and W atoms and to the different charge states of W ions.

  3. Hysteresis of pentacene thin-film transistors and inverters with cross-linked poly(4-vinylphenol) gate dielectrics

    NASA Astrophysics Data System (ADS)

    Lim, Sang Chul; Kim, Seong Hyun; Koo, Jae Bon; Lee, Jung Hun; Ku, Chan Hoe; Yang, Yong Suk; Zyung, Taehyoung

    2007-04-01

    The authors report the effects of hydroxyl groups (OH bonds) on the electrical reliabilities of pentacene organic thin-film transistors (OTFTs) with poly-4-vinylphenol (PVP) gate dielectrics. PVP gate dielectric films mixed with different concentrations of methylated poly(melamine-co-formaldehyde) (MMF) were fabricated, and experiments on the hysteresis behavior of the OTFT device were conducted. Pentacene TFTs with the PVP (MMF 0wt.%) exhibited a large hysteresis, while in the PVP (MMF 125wt.%), nearly no hysteresis was observed. Large hysteresis observed in OTFT devices was confirmed to be strongly related to the hydroxyl groups existing inside of the polymeric dielectrics and could reduced by the decrease of OH group.

  4. Transparent and flexible thin-film transistors with channel layers composed of sintered HgTe nanocrystals.

    PubMed

    Jang, Jaewon; Cho, Kyoungah; Lee, Sang Heon; Kim, Sangsig

    2008-01-01

    Transparent and flexible thin film transistors (TFTs) with channel layers composed of sintered HgTe nanocrystals were fabricated on top of UV/ozone treated plastic substrates and their electrical properties were characterized. A representative TFT with a channel layer composed of sintered HgTe nanocrystals revealed typical p-type characteristics, an on/off current ratio of ∼10(3) and a field-effect mobility of 4.1 cm(2) V(-1) s(-1). When the substrate was bent until the bending radius of the substrate reached 2.4 cm, which corresponded to a strain of 0.83% that the HgTe thin film experienced, the TFT exhibited an on/off current ratio of ∼10(3) and a field-effect mobility of 4.0 cm(2) V(-1) s(-1).

  5. Threshold voltage manipulation of ZnO-graphene oxide hybrid thin film transistors via Au nanoparticles doping

    NASA Astrophysics Data System (ADS)

    Song, Wooseok; Kim, Ki Woong; Kim, Seong Jun; Min, Bok Ki; Rang Lim, Yi; Myung, Sung; Lee, Sun Sook; Lim, Jongsun; An, Ki-Seok

    2015-12-01

    In order to fabricate a complementary inverter, precise control of the threshold voltages for n-type semiconductor based thin film transistors (TFTs) is highly required. Here we provided a facile methodology for controlling the threshold voltage of ZnO-based TFTs. Chemically-derived graphene oxide (GO) and Au-decorated GO (Au-GO) flakes were hybridized with solution-processed ZnO thin films to control electron injection determined by the workfunction difference between ZnO and GO or Au-GO. As a result, the threshold voltages for the ZnO, GO/ZnO, and Au-GO/ZnO TFTs were 24 ± 3 V, -11 ± 4 V, and 63 ± 5 V, respectively, which determine depletion or enhancement mode TFTs without any significant change in the field effect mobility and on/off ratio.

  6. Photo-modulated thin film transistor based on dynamic charge transfer within quantum-dots-InGaZnO interface

    SciTech Connect

    Liu, Xiang; Yang, Xiaoxia; Liu, Mingju; Tao, Zhi; Wei, Lei Li, Chi Zhang, Xiaobing; Wang, Baoping; Dai, Qing; Nathan, Arokia

    2014-03-17

    The temporal development of next-generation photo-induced transistor across semiconductor quantum dots and Zn-related oxide thin film is reported in this paper. Through the dynamic charge transfer in the interface between these two key components, the responsibility of photocurrent can be amplified for scales of times (∼10{sup 4} A/W 450 nm) by the electron injection from excited quantum dots to InGaZnO thin film. And this photo-transistor has a broader waveband (from ultraviolet to visible light) optical sensitivity compared with other Zn-related oxide photoelectric device. Moreover, persistent photoconductivity effect can be diminished in visible waveband which lead to a significant improvement in the device's relaxation time from visible illuminated to dark state due to the ultrafast quenching of quantum dots. With other inherent properties such as integrated circuit compatible, low off-state current and high external quantum efficiency resolution, it has a great potential in the photoelectric device application, such as photodetector, phototransistor, and sensor array.

  7. Reduction of the interfacial trap density of indium-oxide thin film transistors by incorporation of hafnium and annealing process

    SciTech Connect

    Lin, Meng-Fang E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Gao, Xu; Mitoma, Nobuhiko; Kizu, Takio; Ou-Yang, Wei; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya; Nabatame, Toshihide

    2015-01-15

    The stable operation of transistors under a positive bias stress (PBS) is achieved using Hf incorporated into InO{sub x}-based thin films processed at relatively low temperatures (150 to 250 °C). The mobilities of the Hf-InO{sub x} thin-film transistors (TFTs) are higher than 8 cm{sup 2}/Vs. The TFTs not only have negligible degradation in the mobility and a small shift in the threshold voltage under PBS for 60 h, but they are also thermally stable at 85 °C in air, without the need for a passivation layer. The Hf-InO{sub x} TFT can be stable even annealed at 150 °C for positive bias temperature stability (PBTS). A higher stability is achieved by annealing the TFTs at 250 °C, originating from a reduction in the trap density at the Hf-InO{sub x}/gate insulator interface. The knowledge obtained here will aid in the realization of stable TFTs processed at low temperatures.

  8. Addition of ferrocene controls polymorphism and enhances charge mobilities in poly(3-hexylthiophene) thin-film transistors

    NASA Astrophysics Data System (ADS)

    Smith, Brandon; Clark, Michael; Grieco, Christopher; Larsen, Alec; Asbury, John; Gomez, Enrique

    2015-03-01

    Crystalline organic molecules often exhibit the ability to form multiple crystal structures depending on the processing conditions. Exploiting this polymorphism to optimize molecular orbital overlap between adjacent molecules within the unit lattice of conjugated polymers is an approach to enhance charge transport within the material. We have demonstrated the formation of tighter π- π stacking poly(3-hexylthiophene-2,5-diyl) polymorphs in films spin coated from ferrocene-containing solutions using grazing incident X-ray diffraction. As a result, we found that the addition of ferrocene to casting solutions yields thin-film transistors which exhibit significantly higher source-drain current and charge mobilities than neat polymer devices. Insights gleaned from ferrocene/poly(3-hexylthiophene) mixtures can serve as a template for selection and optimization of next generation small molecule/polymer systems possessing greater baseline charge mobilities. Ultimately, the development of such techniques to enhance the characteristics of organic transistors without imparting high costs or loss of advantageous properties will be a critical factor determining the future of organic components within the electronics market.

  9. High-performance calcium-doped zinc oxide thin-film transistors fabricated on glass at low temperature

    NASA Astrophysics Data System (ADS)

    Yu, Wen; Han, Dedong; Cui, Guodong; Cong, Yingying; Dong, Junchen; Zhang, Xiaomi; Zhang, Xing; Wang, Yi; Zhang, Shengdong

    2016-04-01

    High-performance calcium-doped zinc oxide thin-film transistors (Ca-ZnO TFTs) have been successfully fabricated on transparent glass at low temperature by RF magnetron sputtering. To study the effects of calcium doping on zinc oxide thin-film transistors, the characteristics of Ca-ZnO TFTs and ZnO TFTs are compared and analyzed in detail from different perspectives, including electrical performance, surface morphology, and crystal structure of the material. The results suggest that the incorporation of calcium element can decrease the root-mean-square roughness of the material, suppress growth of a columnar structure, and improve device performance. The TFTs with Ca-ZnO active layer exhibit excellent electrical properties with the saturation mobility (μsat) of 147.1 cm2 V-1 s-1, threshold voltage (V t) of 2.91 V, subthreshold slope (SS) of 0.271 V/dec, and I on/I off ratio of 2.34 × 108. In addition, we also study the uniformity of the devices. The experimental results show that the Ca-ZnO TFTs possess good uniformity, which is important for large-area application.

  10. Thin Film Transistor Gas Sensors Incorporating High-Mobility Diketopyrrolopyrole-Based Polymeric Semiconductor Doped with Graphene Oxide.

    PubMed

    Cheon, Kwang Hee; Cho, Jangwhan; Kim, Yun-Hi; Chung, Dae Sung

    2015-07-01

    In this work, we fabricated a diketopyrrolopyrole-based donor-acceptor copolymer composite film. This is a high-mobility semiconductor component with a functionalized-graphene-oxide (GO) gas-adsorbing dopant, used as an active layer in gas-sensing organic-field-effect transistor (OFET) devices. The GO content of the composite film was carefully controlled so that the crystalline orientation of the semiconducting polymer could be conserved, without compromising its gas-adsorbing ability. The resulting optimized device exhibited high mobility (>1 cm(2) V(-1) s(-1)) and revealed sensitive response during programmed exposure to various polar organic molecules (i.e., ethanol, acetone, and acetonitrile). This can be attributed to the high mobility of polymeric semiconductors, and also to their high surface-to-volume ratio of GO. The operating mechanism of the gas sensing GO-OFET is fully discussed in conjunction with charge-carrier trap theory. It was found that each transistor parameter (e.g., mobility, threshold voltage), responds independently to each gas molecule, which enables high selectivity of GO-OFETs for various gases. Furthermore, we also demonstrated practical GO-OFET devices that operated at low voltage (<1.5 V), and which successfully responded to gas exposure.

  11. Thin Film Transistor Gas Sensors Incorporating High-Mobility Diketopyrrolopyrole-Based Polymeric Semiconductor Doped with Graphene Oxide.

    PubMed

    Cheon, Kwang Hee; Cho, Jangwhan; Kim, Yun-Hi; Chung, Dae Sung

    2015-07-01

    In this work, we fabricated a diketopyrrolopyrole-based donor-acceptor copolymer composite film. This is a high-mobility semiconductor component with a functionalized-graphene-oxide (GO) gas-adsorbing dopant, used as an active layer in gas-sensing organic-field-effect transistor (OFET) devices. The GO content of the composite film was carefully controlled so that the crystalline orientation of the semiconducting polymer could be conserved, without compromising its gas-adsorbing ability. The resulting optimized device exhibited high mobility (>1 cm(2) V(-1) s(-1)) and revealed sensitive response during programmed exposure to various polar organic molecules (i.e., ethanol, acetone, and acetonitrile). This can be attributed to the high mobility of polymeric semiconductors, and also to their high surface-to-volume ratio of GO. The operating mechanism of the gas sensing GO-OFET is fully discussed in conjunction with charge-carrier trap theory. It was found that each transistor parameter (e.g., mobility, threshold voltage), responds independently to each gas molecule, which enables high selectivity of GO-OFETs for various gases. Furthermore, we also demonstrated practical GO-OFET devices that operated at low voltage (<1.5 V), and which successfully responded to gas exposure. PMID:26068504

  12. Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method

    NASA Astrophysics Data System (ADS)

    Yuan, Yongbo; Giri, Gaurav; Ayzner, Alexander L.; Zoombelt, Arjan P.; Mannsfeld, Stefan C. B.; Chen, Jihua; Nordlund, Dennis; Toney, Michael F.; Huang, Jinsong; Bao, Zhenan

    2014-01-01

    Organic semiconductors with higher carrier mobility and better transparency have been actively pursued for numerous applications, such as flat-panel display backplane and sensor arrays. The carrier mobility is an important figure of merit and is sensitively influenced by the crystallinity and the molecular arrangement in a crystal lattice. Here we describe the growth of a highly aligned meta-stable structure of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) from a blended solution of C8-BTBT and polystyrene by using a novel off-centre spin-coating method. Combined with a vertical phase separation of the blend, the highly aligned, meta-stable C8-BTBT films provide a significantly increased thin film transistor hole mobility up to 43 cm2 Vs-1 (25 cm2 Vs-1 on average), which is the highest value reported to date for all organic molecules. The resulting transistors show high transparency of >90% over the visible spectrum, indicating their potential for transparent, high-performance organic electronics.

  13. Polaron and ion diffusion in a poly(3-hexylthiophene) thin-film transistor gated with polymer electrolyte dielectric

    NASA Astrophysics Data System (ADS)

    Mills, T.; Kaake, L. G.; Zhu, X.-Y.

    2009-04-01

    Electrolytes are finding applications as dielectric materials in low-voltage organic thin-film transistors (OTFT). The presence of mobile ions in these materials (polymer electrolytes or ion gels) gives rise to very high capacitance (>10 μF/cm2) and thus low transistor turn-on voltage. In order to establish fundamental limits in switching speeds of electrolyte gated OFETs, we carry out in situ optical spectroscopy measurement of a poly(3-hexylthiophene) (P3HT) OTFT gated with a LiClO4:poly(ethyleneoxide) (PEO) dielectric. Based on spectroscopic signatures of molecular vibrations and polaron transitions, we quantitatively determine charge carrier concentration and diffusion constants. We find two distinctively different regions: at V G≥-1.5 V, drift-diffusion (parallel to the semiconductor/dielectric interface) of hole-polarons in P3HT controls charging of the device; at V G<-1.5 V, electrochemical doping of the entire P3HT film occurs and charging is controlled by drift/diffusion (perpendicular to the interface) of ClO4 - counter ions into the polymer semiconductor.

  14. Toward Active-Matrix Lab-On-A-Chip: Programmable Electrofluidic control Enaled by Arrayed Oxide Thin Film Transistors

    SciTech Connect

    Noh, Joo Hyon; Noh, Jiyong; Kreit, Eric; Heikenfeld, Jason; Rack, Philip D

    2012-01-01

    Agile micro- and nano-fluidic control is critical to numerous life science and chemical science synthesis as well as kinetic and thermodynamic studies. To this end, we have demonstrated the use of thin film transistor arrays as an active matrix addressing method to control an electrofluidic array. Because the active matrix method minimizes the number of control lines necessary (m + n lines for the m x n element array), the active matrix addressing method integrated with an electrofluidic platform can be a significant breakthrough for complex electrofluidic arrays (increased size or resolution) with enhanced function, agility and programmability. An amorphous indium gallium zinc oxide (a-IGZO) semiconductor active layer is used because of its high mobility of 1-15 cm{sup 2} V{sup -1} s{sup -1}, low-temperature processing and transparency for potential spectroscopy and imaging. Several electrofluidic functionalities are demonstrated using a simple 2 x 5 electrode array connected to a 2 x 5 IGZO thin film transistor array with the semiconductor channel width of 50 {mu}m and mobility of 6.3 cm{sup 2} V{sup -1} s{sup -1}. Additionally, using the TFT device characteristics, active matrix addressing schemes are discussed as the geometry of the electrode array can be tailored to act as a storage capacitor element. Finally, requisite material and device parameters are discussed in context with a VGA scale active matrix addressed electrofluidic platform.

  15. Analysis of subthreshold slope of fully depleted amorphous In-Ga-Zn-O thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kawamura, Tetsufumi; Uchiyama, Hiroyuki; Saito, Shinichi; Wakana, Hironori; Mine, Toshiyuki; Hatano, Mutsuko

    2015-01-01

    The behavior of the subthreshold slope (SS) of fully depleted (FD) amorphous In-Ga-Zn-O (a-InGaZnO) thin-film transistors (TFTs), which are n-type accumulation mode metal-oxide-semiconductor transistors, was analyzed. Thermal desorption spectra revealed that annealing was necessary to desorb H2 and H2O from the a-InGaZnO films for the FD mode operation along with small SS. Our experimental results indicated that the SS (a) increases with the increase in the thickness of the a-InGaZnO channel layer, (b) increases with the decrease in the oxygen partial pressure during the sputtering of the a-InGaZnO, (c) increases linearly with the increase in the thickness of the gate insulator, and (d) increases linearly with the increase in the temperature of the TFT. A theoretical equation that explains these results was derived by using the relations between the variations in the voltages applied to the electrodes and variations in the surface potentials derived from the charge conservation law. It was assumed during the derivation of the equation that the potential in the channel layer is the lowest along the back surface in the subthreshold region and most of the current flows there.

  16. High-Quality Solution-Processed Silicon Oxide Gate Dielectric Applied on Indium Oxide Based Thin-Film Transistors.

    PubMed

    Jaehnike, Felix; Pham, Duy Vu; Anselmann, Ralf; Bock, Claudia; Kunze, Ulrich

    2015-07-01

    A silicon oxide gate dielectric was synthesized by a facile sol-gel reaction and applied to solution-processed indium oxide based thin-film transistors (TFTs). The SiOx sol-gel was spin-coated on highly doped silicon substrates and converted to a dense dielectric film with a smooth surface at a maximum processing temperature of T = 350 °C. The synthesis was systematically improved, so that the solution-processed silicon oxide finally achieved comparable break downfield strength (7 MV/cm) and leakage current densities (<10 nA/cm(2) at 1 MV/cm) to thermally grown silicon dioxide (SiO2). The good quality of the dielectric layer was successfully proven in bottom-gate, bottom-contact metal oxide TFTs and compared to reference TFTs with thermally grown SiO2. Both transistor types have field-effect mobility values as high as 28 cm(2)/(Vs) with an on/off current ratio of 10(8), subthreshold swings of 0.30 and 0.37 V/dec, respectively, and a threshold voltage close to zero. The good device performance could be attributed to the smooth dielectric/semiconductor interface and low interface trap density. Thus, the sol-gel-derived SiO2 is a promising candidate for a high-quality dielectric layer on many substrates and high-performance large-area applications. PMID:26039187

  17. Optical density measurement of thin-film transistor liquid crystal display by a monochrome light-emitting diode.

    PubMed

    Tzu, Fu-Ming; Chou, Jung-Hua

    2009-06-10

    A new method using a monochromatic light-emitting diode (LED) to measure the optical density (OD) of the black matrix of thin-film transistor liquid crystal display (LCD) is developed in this study. The measured results show that the average OD difference is within 1% between the proposed 3 W monochromatic LED and the currently adopted 100 W quartz halogen lamp. On the other hand, the monochromatic LED reduces the boosting time by 40% in establishing the baseline database. The 3sigma standard deviation of the OD of the test samples is from 0.1% to 0.6% for the LED, whereas it is from 0.5% to 1.2% for the halogen lamp. Using standard glass samples, the monochromatic LED demonstrates accuracy within 1.58%, better than that of the quartz halogen lamp. Therefore, it can substitute for the quartz halogen lamp currently used in the thin-film transistor LCD industry for OD measurement of the black matrix layer, as it is faster, is more accurate, is more reliable, and consumes less power. PMID:19516356

  18. Novel organic semiconductors and dielectric materials for high performance and low-voltage organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Yoon, Myung-Han

    Two novel classes of organic semiconductors based on perfluoroarene/arene-modified oligothiophenes and perfluoroacyl/acyl-derivatized quaterthiophens are developed. The frontier molecular orbital energies of these compounds are studied by optical spectroscopy and electrochemistry while solid-state/film properties are investigated by thermal analysis, x-ray diffraction, and scanning electron microscopy. Organic thin film transistors (OTFTs) performance parameters are discussed in terms of the interplay between semiconductor molecular energetics and film morphologies/microstructures. For perfluoroarene-thiophene oligomer systems, majority charge carrier type and mobility exhibit a strong correlation with the regiochemistry of perfluoroarene incorporation. In quaterthiophene-based semiconductors, carbonyl-functionalization allows tuning of the majority carrier type from p-type to ambipolar and to n-type. In situ conversion of a p-type semiconducting film to n-type film is also demonstrated. Very thin self-assembled or spin-on organic dielectric films have been integrated into OTFTs to achieve 1 - 2 V operating voltages. These new dielectrics are deposited either by layer-by-layer solution phase deposition of molecular precursors or by spin-coating a mixture of polymer and crosslinker, resulting in smooth and virtually pinhole-free thin films having exceptionally large capacitances (300--700 nF/cm2) and low leakage currents (10 -9 - 10-7 A/cm2). These organic dielectrics are compatible with various vapor- or solution-deposited p- and n-channel organic semiconductors. Furthermore, it is demonstrated that spin-on crosslinked-polymer-blend dielectrics can be employed for large-area/patterned electronics, and complementary inverters. A general approach for probing semiconductor-dielectric interface effects on OTFT performance parameters using bilayer gate dielectrics is presented. Organic semiconductors having p-, n-type, or ambipolar majority charge carriers are grown on

  19. Electrical dependence on the chemical composition of the gate dielectric in indium gallium zinc oxide thin-film transistors

    SciTech Connect

    Tari, Alireza Lee, Czang-Ho; Wong, William S.

    2015-07-13

    Bottom-gate thin-film transistors were fabricated by depositing a 50 nm InGaZnO (IGZO) channel layer at 150 °C on three separate gate dielectric films: (1) thermal SiO{sub 2}, (2) plasma-enhanced chemical-vapor deposition (PECVD) SiN{sub x}, and (3) a PECVD SiO{sub x}/SiN{sub x} dual-dielectric. X-ray photoelectron and photoluminescence spectroscopy showed the V{sub o} concentration was dependent on the hydrogen concentration of the underlying dielectric film. IGZO films on SiN{sub x} (high V{sub o}) and SiO{sub 2} (low V{sub o}) had the highest and lowest conductivity, respectively. A PECVD SiO{sub x}/SiN{sub x} dual-dielectric layer was effective in suppressing hydrogen diffusion from the nitride layer into the IGZO and resulted in higher resistivity films.

  20. 7-Octenyltrichrolosilane/trimethyaluminum hybrid dielectrics fabricated by molecular-atomic layer deposition on ZnO thin film transistors

    NASA Astrophysics Data System (ADS)

    Huang, Jie; Lee, Mingun; Lucero, Antonio T.; Cheng, Lanxia; Ha, Min-Woo; Kim, Jiyoung

    2016-06-01

    We demonstrate the fabrication of 7-octenytrichlorosilane (7-OTS)/trimethylaluminum (TMA) organic-inorganic hybrid films using molecular-atomic layer deposition (MALD). The properties of 7-OTS/TMA hybrid films are extensively investigated using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and electrical measurements. Our results suggest that uniform and smooth amorphous hybrid thin films with excellent insulating properties are obtained using the MALD process. Films have a relatively high dielectric constant of approximately 5.0 and low leakage current density. We fabricate zinc oxide (ZnO) based thin film transistors (TFTs) using 7-OTS/TMA hybrid material as a back gate dielectric with the top ZnO channel layer deposited in-situ via MALD. The ZnO TFTs exhibit a field effect mobility of approximately 0.43 cm2 V-1 s-1, a threshold voltage of approximately 1 V, and an on/off ratio of approximately 103 under low voltage operation (from -3 to 9 V). This work demonstrates an organic-inorganic hybrid gate dielectric material potentially useful in flexible electronics application.

  1. Air-stable solution-processed n-channel organic thin film transistors with polymer-enhanced morphology

    SciTech Connect

    He, Zhengran; Shaik, Shoieb; Bi, Sheng; Li, Dawen; Chen, Jihua

    2015-05-04

    N,N′-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN{sub 2}) is an n-type semiconductor exhibiting high electron mobility and excellent air stability. However, the reported electron mobility based on spin-coated PDIF-CN{sub 2} film is much lower than the value of PDIF-CN{sub 2} single crystals made from vapor phase deposition, indicating significant room for mobility enhancement. In this study, various insulating polymers, including poly(vinyl alcohol), poly(methyl methacrylate) (PMMA), and poly(alpha-methylstyrene) (PαMS), are pre-coated on silicon substrate aiming to enhance the morphology of the PDIF-CN{sub 2} thin film, thereby improving the charge transport and air stability. Atomic force microscopy images reveal that with the pre-deposition of PαMS or PMMA polymers, the morphology of the PDIF-CN{sub 2} polycrystalline films is optimized in semiconducting crystal connectivity, domain size, and surface roughness, which leads to significant improvement of organic thin-film transistor (OTFT) performance. Particularly, an electron mobility of up to 0.55 cm{sup 2}/V s has been achieved from OTFTs based on the PDIF-CN{sub 2} film with the pre-deposition of PαMS polymer.

  2. AFM, ellipsometry, XPS and TEM on ultra-thin oxide/polymer nanocomposite layers in organic thin film transistors.

    PubMed

    Fian, A; Haase, A; Stadlober, B; Jakopic, G; Matsko, N B; Grogger, W; Leising, G

    2008-03-01

    Here we report on the fabrication and characterization of ultra-thin nanocomposite layers used as gate dielectric in low-voltage and high-performance flexible organic thin film transistors (oTFTs). Reactive sputtered zirconia layers were deposited with low thermal exposure of the substrate and the resulting porous oxide films with high leakage currents were spin-coated with an additional layer of poly-alpha-methylstyrene (P alphaMS). After this treatment a strong improvement of the oTFT performance could be observed; leakage currents could be eliminated almost completely. In ellipsometric studies a higher refractive index of the ZrO(2)/P alphaMS layers compared to the "as sputtered" zirconia films could be detected without a significant enhancement of the film thickness. Atomic force microscopy (AFM) measurements of the surface topography clearly showed a surface smoothing after the P alphaMS coating. Further studies with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) also indicated that the polymer definitely did not form an extra layer. The polymer chains rather (self-)assemble in the nano-scaled interspaces of the porous oxide film giving an oxide-polymer "nanocomposite" with a high oxide filling grade resulting in high dielectric constants larger than 15. The dielectric strength of more than 1 MV cm(-1) is in good accordance with the polymer-filled interspaces. PMID:17952415

  3. Li-Assisted Low-Temperature Phase Transitions in Solution-Processed Indium Oxide Films for High-Performance Thin Film Transistor

    NASA Astrophysics Data System (ADS)

    Nguyen, Manh-Cuong; Jang, Mi; Lee, Dong-Hwi; Bang, Hyun-Jun; Lee, Minjung; Jeong, Jae Kyeong; Yang, Hoichang; Choi, Rino

    2016-04-01

    Lithium (Li)-assisted indium oxide (In2O3) thin films with ordered structures were prepared on solution-processed zirconium oxide (ZrO2) gate dielectrics by spin-casting and thermally annealing hydrated indium nitrate solutions with different Li nitrate loadings. It was found that the Li-assisted In precursor films on ZrO2 dielectrics could form crystalline structures even at processing temperatures (T) below 200 °C. Different In oxidation states were observed in the Li-doped films, and the development of such states was significantly affected by both temperature and the mol% of Li cations, [Li+]/([In3+] + [Li+]), in the precursor solutions. Upon annealing the Li-assisted precursor films below 200 °C, metastable indium hydroxide and/or indium oxyhydroxide phases were formed. These phases were subsequently transformed into crystalline In2O3 nanostructures after thermal dehydration and oxidation. Finally, an In2O3 film doped with 13.5 mol% Li+ and annealed at 250 °C for 1 h exhibited the highest electron mobility of 60 cm2 V‑1 s‑1 and an on/off current ratio above 108 when utilized in a thin film transistor.

  4. Li-Assisted Low-Temperature Phase Transitions in Solution-Processed Indium Oxide Films for High-Performance Thin Film Transistor

    PubMed Central

    Nguyen, Manh-Cuong; Jang, Mi; Lee, Dong-Hwi; Bang, Hyun-Jun; Lee, Minjung; Jeong, Jae Kyeong; Yang, Hoichang; Choi, Rino

    2016-01-01

    Lithium (Li)-assisted indium oxide (In2O3) thin films with ordered structures were prepared on solution-processed zirconium oxide (ZrO2) gate dielectrics by spin-casting and thermally annealing hydrated indium nitrate solutions with different Li nitrate loadings. It was found that the Li-assisted In precursor films on ZrO2 dielectrics could form crystalline structures even at processing temperatures (T) below 200 °C. Different In oxidation states were observed in the Li-doped films, and the development of such states was significantly affected by both temperature and the mol% of Li cations, [Li+]/([In3+] + [Li+]), in the precursor solutions. Upon annealing the Li-assisted precursor films below 200 °C, metastable indium hydroxide and/or indium oxyhydroxide phases were formed. These phases were subsequently transformed into crystalline In2O3 nanostructures after thermal dehydration and oxidation. Finally, an In2O3 film doped with 13.5 mol% Li+ and annealed at 250 °C for 1 h exhibited the highest electron mobility of 60 cm2 V−1 s−1 and an on/off current ratio above 108 when utilized in a thin film transistor. PMID:27121951

  5. Composite films of oxidized multiwall carbon nanotube and poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) as a contact electrode for transistor and inverter devices.

    PubMed

    Yun, Dong-Jin; Rhee, Shi-Woo

    2012-02-01

    Composite films of multiwall carbon nanotube (MWNT)/poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) were prepared by spin-coating a mixture solution. The effect of the MWNT loading and the MWNT oxidation, with acid solution or ultraviolet (UV)-ozone treatment, on the film properties such as surface roughness, work function, surface energy, optical transparency and conductivity were studied. Also pentacene thin film transistors and inverters were made with these composite films as a contact metal and the device characteristics were measured. The oxidation of MWNT reduced the conductivity of MWNT/PEDOT:PSS composite film but increased the work function and transparency. UV-ozone treated MWNT/PEDOT:PSS composite film showed higher conductivity (14000 Ω/□) and work function (4.9 eV) than acid-oxidized MWNT/PEDOT:PSS composite film and showed better performance as a source/drain electrode in organic thin film transistor (OTFT) than other types of MWNT/PEDOT:PSS composite films. Hole injection barrier of the UV-ozone treated MWNT/PEDOT:PSS composite film with pentacene was significantly lower than any other films because of the higher work function. PMID:22264140

  6. Origin of mobility enhancement by chemical treatment of gate-dielectric surface in organic thin-film transistors: Quantitative analyses of various limiting factors in pentacene thin films

    NASA Astrophysics Data System (ADS)

    Matsubara, R.; Sakai, Y.; Nomura, T.; Sakai, M.; Kudo, K.; Majima, Y.; Knipp, D.; Nakamura, M.

    2015-11-01

    For the better performance of organic thin-film transistors (TFTs), gate-insulator surface treatments are often applied. However, the origin of mobility increase has not been well understood because mobility-limiting factors have not been compared quantitatively. In this work, we clarify the influence of gate-insulator surface treatments in pentacene thin-film transistors on the limiting factors of mobility, i.e., size of crystal-growth domain, crystallite size, HOMO-band-edge fluctuation, and carrier transport barrier at domain boundary. We quantitatively investigated these factors for pentacene TFTs with bare, hexamethyldisilazane-treated, and polyimide-coated SiO2 layers as gate dielectrics. By applying these surface treatments, size of crystal-growth domain increases but both crystallite size and HOMO-band-edge fluctuation remain unchanged. Analyzing the experimental results, we also show that the barrier height at the boundary between crystal-growth domains is not sensitive to the treatments. The results imply that the essential increase in mobility by these surface treatments is only due to the increase in size of crystal-growth domain or the decrease in the number of energy barriers at domain boundaries in the TFT channel.

  7. Effect of Nickel Concentration on Bias Reliability and Thermal Stability of Thin-Film Transistors Fabricated by Ni-Metal-Induced Crystallization

    NASA Astrophysics Data System (ADS)

    Lai, Ming-Hui; Sermon Wu, YewChung; Huang, Jung-Jie

    2012-01-01

    Ni-metal-induced crystallization (MIC) of amorphous Si (α-Si) has been employed to fabricate low-temperature polycrystalline silicon (poly-Si) thin-film transistors (TFTs). Although the high leakage current is a major issue in the performance of conventional MIC-TFTs since Ni contamination induces deep-level state traps, it can be greatly improved by using well-known technologies to reduce Ni contamination. However, for active-matrix organic light-emitting diode (AMOLED) display applications, the bias reliability and thermal stability are major concerns especially when devices are operated under a hot carrier condition and in a high-temperature environment. It will be interesting to determine how the bias reliability and thermal stability are affected by the reduction of Ni concentration. In the study, the effect of Ni concentration on bias reliability and thermal stability was investigated. We found that a device exhibited high immunity against hot-carrier stress and elevated temperatures. These findings demonstrated that reducing the Ni concentration in MIC films was also beneficial for bias reliability and thermal stability.

  8. Progress of p-channel bottom-gate poly-Si thin-film transistor by nickel silicide seed-induced lateral crystallization

    NASA Astrophysics Data System (ADS)

    Lee, Sol Kyu; Seok, Ki Hwan; Park, Jae Hyo; Kim, Hyung Yoon; Chae, Hee Jae; Jang, Gil Su; Lee, Yong Hee; Han, Ji Su; Joo, Seung Ki

    2016-06-01

    Excimer laser annealing (ELA) is known to be the most common crystallization technology for the fabrication of low-temperature polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) in the mass production industry. This technology, however, cannot be applied to bottom-gate (BG) TFTs, which are well developed for the liquid-crystal display (LCD) back-planes, because strong laser energy of ELA can seriously damage the other layers. Here, we propose a novel high-performance BG poly-Si TFT using Ni silicide seed-induced lateral crystallization (SILC). The SILC technology renders it possible to ensure low damage in the layers, smooth surface, and longitudinal large grains in the channel. It was observed that the electrical properties exhibited a steep subthreshold slope of 110 mV/dec, high field-effect mobility of 304 cm2/Vsec, high I on/ I off ratio of 5.9 × 107, and a low threshold voltage of -3.9 V.

  9. Water-Mediated Photochemical Treatments for Low-Temperature Passivation of Metal-Oxide Thin-Film Transistors.

    PubMed

    Heo, Jae Sang; Jo, Jeong-Wan; Kang, Jingu; Jeong, Chan-Yong; Jeong, Hu Young; Kim, Sung Kyu; Kim, Kwanpyo; Kwon, Hyuck-In; Kim, Jaekyun; Kim, Yong-Hoon; Kim, Myung-Gil; Park, Sung Kyu

    2016-04-27

    The low-temperature electrical passivation of an amorphous oxide semiconductor (AOS) thin-film transistor (TFT) is achieved by a deep ultraviolet (DUV) light irradiation-water treatment-DUV irradiation (DWD) method. The water treatment of the first DUV-annealed amorphous indium-gallium-zinc-oxide (a-IGZO) thin film is likely to induce the preferred adsorption of water molecules at the oxygen vacancies and leads to subsequent hydroxide formation in the bulk a-IGZO films. Although the water treatment initially degraded the electrical performance of the a-IGZO TFTs, the second DUV irradiation on the water-treated devices may enable a more complete metal-oxygen-metal lattice formation while maintaining low oxygen vacancies in the oxide films. Overall, the stable and dense metal-oxygen-metal (M-O-M) network formation could be easily achieved at low temperatures (below 150 °C). The successful passivation of structural imperfections in the a-IGZO TFTs, such as hydroxyl group (OH-) and oxygen vacancies, mainly results in the enhanced electrical performances of the DWD-processed a-IGZO TFTs (on/off current ratio of 8.65 × 10(9), subthreshold slope of 0.16 V/decade, an average mobility of >6.94 cm(2) V(-1) s(-1), and a bias stability of ΔVTH < 2.5 V), which show more than a 30% improvement over the simple DUV-treated a-IGZO TFTs.

  10. Water-Mediated Photochemical Treatments for Low-Temperature Passivation of Metal-Oxide Thin-Film Transistors.

    PubMed

    Heo, Jae Sang; Jo, Jeong-Wan; Kang, Jingu; Jeong, Chan-Yong; Jeong, Hu Young; Kim, Sung Kyu; Kim, Kwanpyo; Kwon, Hyuck-In; Kim, Jaekyun; Kim, Yong-Hoon; Kim, Myung-Gil; Park, Sung Kyu

    2016-04-27

    The low-temperature electrical passivation of an amorphous oxide semiconductor (AOS) thin-film transistor (TFT) is achieved by a deep ultraviolet (DUV) light irradiation-water treatment-DUV irradiation (DWD) method. The water treatment of the first DUV-annealed amorphous indium-gallium-zinc-oxide (a-IGZO) thin film is likely to induce the preferred adsorption of water molecules at the oxygen vacancies and leads to subsequent hydroxide formation in the bulk a-IGZO films. Although the water treatment initially degraded the electrical performance of the a-IGZO TFTs, the second DUV irradiation on the water-treated devices may enable a more complete metal-oxygen-metal lattice formation while maintaining low oxygen vacancies in the oxide films. Overall, the stable and dense metal-oxygen-metal (M-O-M) network formation could be easily achieved at low temperatures (below 150 °C). The successful passivation of structural imperfections in the a-IGZO TFTs, such as hydroxyl group (OH-) and oxygen vacancies, mainly results in the enhanced electrical performances of the DWD-processed a-IGZO TFTs (on/off current ratio of 8.65 × 10(9), subthreshold slope of 0.16 V/decade, an average mobility of >6.94 cm(2) V(-1) s(-1), and a bias stability of ΔVTH < 2.5 V), which show more than a 30% improvement over the simple DUV-treated a-IGZO TFTs. PMID:27035796

  11. Annealing-free high-mobility diketopyrrolopyrrole-quaterthiophene copolymer for solution-processed organic thin film transistors.

    PubMed

    Li, Yuning; Sonar, Prashant; Singh, Samarendra P; Soh, Mui Siang; van Meurs, Martin; Tan, Jozel

    2011-02-23

    A donor-acceptor polymer semiconductor, PDQT, comprising diketopyrrolopyrrole (DPP) and β-unsubstituted quaterthiophene (QT) for organic thin film transistors (OTFTs) is reported. This polymer forms ordered layer-by-layer lamellar packing with an edge-on orientation in thin films even without thermal annealing. The strong intermolecular interactions arising from the fused aromatic DPP moiety and the DPP-QT donor-acceptor interaction facilitate the spontaneous self-assembly of the polymer chains into close proximity and form a large π-π overlap, which are favorable for intermolecular charge hopping. The well-interconnected crystalline grains form efficient intergranular charge transport pathways. The desirable chemical, electronic, and morphological structures of PDQT bring about high hole mobility of up to 0.97 cm(2)/(V·s) in OTFTs with polymer thin films annealed at a mild temperature of 100 °C and similarly high mobility of 0.89 cm(2)/(V·s) for polymer thin films even without thermal annealing.

  12. Easily processable highly ordered Langmuir-Blodgett films of quaterthiophene disiloxane dimer for monolayer organic field-effect transistors.

    PubMed

    Sizov, Alexey S; Anisimov, Daniil S; Agina, Elena V; Borshchev, Oleg V; Bakirov, Artem V; Shcherbina, Maxim A; Grigorian, Souren; Bruevich, Vladimir V; Chvalun, Sergei N; Paraschuk, Dmitry Yu; Ponomarenko, Sergei A

    2014-12-23

    Self-assembly of highly soluble water-stable tetramethyldisiloxane-based dimer of α,α'-dialkylquaterthiophene on the water-air interface was investigated by Langmuir, grazing incidence X-ray diffraction, and X-ray reflectivity techniques. The conditions for formation of very homogeneous crystalline monolayer Langmuir-Blodgett (LB) films of the oligomer were found. Monolayer organic field-effect transistors (OFETs) based on these LB films as a semiconducting layer showed hole mobilities up to 3 × 10(-3) cm(2)/(V s), on-off ratio of 10(5), small hysteresis, and high long-term stability. The electrical performance of the LB films studied is close to that for the same material in the bulk or in the monolayer OFETs prepared from water vapor sensitive chlorosilyl derivatives of quaterthiophene by self-assembling from solution. These findings show high potential of disiloxane-based LB films in monolayer OFETs for large-area organic electronics.

  13. Impact of the cation composition on the electrical performance of solution-processed zinc tin oxide thin-film transistors.

    PubMed

    Kim, Yoon Jang; Oh, Seungha; Yang, Bong Seob; Han, Sang Jin; Lee, Hong Woo; Kim, Hyuk Jin; Jeong, Jae Kyeong; Hwang, Cheol Seong; Kim, Hyeong Joon

    2014-08-27

    This study examined the structural, chemical, and electrical properties of solution-processed (Zn,Sn)O3 (ZTO) films with various Sn/[Zn+Sn] ratios for potential applications to large-area flat panel displays. ZTO films with a Zn-rich composition had a polycrystalline wurtzite structure. On the other hand, the Sn-rich ZTO films exhibited a rutile structure, where the Zn atom was speculated to replace the Sn site, thereby acting as an acceptor. In the intermediate composition regions (Sn/[Zn+Sn] ratio from 0.28 to 0.48), the ZTO films had an amorphous structure, even after annealing at 450 °C. The electrical transport properties and photobias stability of ZTO thin film transistors (TFTs) were also examined according to the Sn/[Zn+Sn] ratio. The optimal transport property of ZTO TFT was observed for the device with an amorphous structure at a Sn/[Zn+Sn] ratio of 0.48. The mobility, threshold voltage, subthreshold swing, and on/off current ratio were 4.3 cm(2)/(V s), 0 V, 0.4 V/decade, and 4.1 × 10(7), respectively. In contrast, the device performance for the ZTO TFTs with either a higher or lower Sn concentration suffered from low mobility and a high off-state current, respectively. The photoelectrical stress measurements showed that the photobias stability of the ZTO TFTs was improved substantially when the ZTO semiconducting films had a lower oxygen vacancy concentration and an amorphous structure. The relevant rationale is discussed based on the phototransition and subsequent migration mechanism from neutral to positively charged oxygen vacancies. PMID:25090286

  14. Gate insulator effects on the electrical performance of ZnO thin film transistor on a polyethersulphone substrate.

    PubMed

    Lee, Jae-Kyu; Choi, Duck-Kyun

    2012-07-01

    Low temperature processing for fabrication of transistor backplane is a cost effective solution while fabrication on a flexible substrate offers a new opportunity in display business. Combination of both merits is evaluated in this investigation. In this study, the ZnO thin film transistor on a flexible Polyethersulphone (PES) substrate is fabricated using RF magnetron sputtering. Since the selection and design of compatible gate insulator is another important issue to improve the electrical properties of ZnO TFT, we have evaluated three gate insulator candidates; SiO2, SiNx and SiO2/SiNx. The SiO2 passivation on both sides of PES substrate prior to the deposition of ZnO layer was effective to enhance the mechanical and thermal stability. Among the fabricated devices, ZnO TFT employing SiNx/SiO2 stacked gate exhibited the best performance. The device parameters of interest are extracted and the on/off current ratio, field effect mobility, threshold voltage and subthreshold swing are 10(7), 22 cm2/Vs, 1.7 V and 0.4 V/decade, respectively.

  15. High mobility bottom gate InGaZnO thin film transistors with SiO{sub x} etch stopper

    SciTech Connect

    Kim, Minkyu; Jeong, Jong Han; Lee, Hun Jung; Ahn, Tae Kyung; Shin, Hyun Soo; Park, Jin-Seong; Jeong, Jae Kyeong; Mo, Yeon-Gon; Kim, Hye Dong

    2007-05-21

    The authors report on the fabrication of thin film transistors (TFTs), which use an amorphous indium gallium zinc oxide (a-IGZO) channel, by rf sputtering at room temperature and for which the channel length and width are patterned by photolithography and dry etching. To prevent plasma damage to the active channel, a 100-nm-thick SiO{sub x} layer deposited by plasma enhanced chemical vapor deposition was adopted as an etch stopper structure. The a-IGZO TFT (W/L=10 {mu}m/50 {mu}m) fabricated on glass exhibited a high field-effect mobility of 35.8 cm{sup 2}/V s, a subthreshold gate swing value of 0.59 V/decade, a thrseshold voltage of 5.9 V, and an I{sub on/off} ratio of 4.9x10{sup 6}, which is acceptable for use as the switching transistor of an active-matrix TFT backplane.

  16. Enhanced Sensitivity of Gas Sensor Based on Poly(3-hexylthiophene) Thin-Film Transistors for Disease Diagnosis and Environment Monitoring.

    PubMed

    Cavallari, Marco R; Izquierdo, José E E; Braga, Guilherme S; Dirani, Ely A T; Pereira-da-Silva, Marcelo A; Rodríguez, Estrella F G; Fonseca, Fernando J

    2015-01-01

    Electronic devices based on organic thin-film transistors (OTFT) have the potential to supply the demand for portable and low-cost gadgets, mainly as sensors for in situ disease diagnosis and environment monitoring. For that reason, poly(3-hexylthiophene) (P3HT) as the active layer in the widely-used bottom-gate/bottom-contact OTFT structure was deposited over highly-doped silicon substrates covered with thermally-grown oxide to detect vapor-phase compounds. A ten-fold organochloride and ammonia sensitivity compared to bare sensors corroborated the application of this semiconducting polymer in sensors. Furthermore, P3HT TFTs presented approximately three-order higher normalized sensitivity than any chemical sensor addressed herein. The results demonstrate that while TFTs respond linearly at the lowest concentration values herein, chemical sensors present such an operating regime mostly above 2000 ppm. Simultaneous alteration of charge carrier mobility and threshold voltage is responsible for pushing the detection limit down to units of ppm of ammonia, as well as tens of ppm of alcohol or ketones. Nevertheless, P3HT transistors and chemical sensors could compose an electronic nose operated at room temperature for a wide range concentration evaluation (1-10,000 ppm) of gaseous analytes. Targeted analytes include not only biomarkers for diseases, such as uremia, cirrhosis, lung cancer and diabetes, but also gases for environment monitoring in food, cosmetic and microelectronics industries.

  17. Temperature-dependent bias-stress-induced electrical instability of amorphous indium-gallium-zinc-oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Qian, Hui-Min; Yu, Guang; Lu, Hai; Wu, Chen-Fei; Tang, Lan-Feng; Zhou, Dong; Ren, Fang-Fang; Zhang, Rong; Zheng, You-Liao; Huang, Xiao-Ming

    2015-07-01

    The time and temperature dependence of threshold voltage shift under positive-bias stress (PBS) and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. It is found that the time dependence of threshold voltage shift can be well described by a stretched exponential equation in which the time constant τ is found to be temperature dependent. Based on Arrhenius plots, an average effective energy barrier Eτstress = 0.72 eV for the PBS process and an average effective energy barrier Eτrecovery = 0.58 eV for the recovery process are extracted respectively. A charge trapping/detrapping model is used to explain the threshold voltage shift in both the PBS and the recovery process. The influence of gate bias stress on transistor performance is one of the most critical issues for practical device development. Project supported by the National Basic Research Program of China (Grant Nos. 2011CB301900 and 2011CB922100) and the Priority Academic Program Development of Jiangsu Higher Education Institutions, China

  18. The influence of interfacial defects on fast charge trapping in nanocrystalline oxide-semiconductor thin film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Taeho; Hur, Jihyun; Jeon, Sanghun

    2016-05-01

    Defects in oxide semiconductors not only influence the initial device performance but also affect device reliability. The front channel is the major carrier transport region during the transistor turn-on stage, therefore an understanding of defects located in the vicinity of the interface is very important. In this study, we investigated the dynamics of charge transport in a nanocrystalline hafnium-indium-zinc-oxide thin-film transistor (TFT) by short pulse I-V, transient current and 1/f noise measurement methods. We found that the fast charging behavior of the tested device stems from defects located in both the front channel and the interface, following a multi-trapping mechanism. We found that a silicon-nitride stacked hafnium-indium-zinc-oxide TFT is vulnerable to interfacial charge trapping compared with silicon-oxide counterpart, causing significant mobility degradation and threshold voltage instability. The 1/f noise measurement data indicate that the carrier transport in a silicon-nitride stacked TFT device is governed by trapping/de-trapping processes via defects in the interface, while the silicon-oxide device follows the mobility fluctuation model.

  19. Enhanced Sensitivity of Gas Sensor Based on Poly(3-hexylthiophene) Thin-Film Transistors for Disease Diagnosis and Environment Monitoring

    PubMed Central

    Cavallari, Marco R.; Izquierdo, José E. E.; Braga, Guilherme S.; Dirani, Ely A. T.; Pereira-da-Silva, Marcelo A.; Rodríguez, Estrella F. G.; Fonseca, Fernando J.

    2015-01-01

    Electronic devices based on organic thin-film transistors (OTFT) have the potential to supply the demand for portable and low-cost gadgets, mainly as sensors for in situ disease diagnosis and environment monitoring. For that reason, poly(3-hexylthiophene) (P3HT) as the active layer in the widely-used bottom-gate/bottom-contact OTFT structure was deposited over highly-doped silicon substrates covered with thermally-grown oxide to detect vapor-phase compounds. A ten-fold organochloride and ammonia sensitivity compared to bare sensors corroborated the application of this semiconducting polymer in sensors. Furthermore, P3HT TFTs presented approximately three-order higher normalized sensitivity than any chemical sensor addressed herein. The results demonstrate that while TFTs respond linearly at the lowest concentration values herein, chemical sensors present such an operating regime mostly above 2000 ppm. Simultaneous alteration of charge carrier mobility and threshold voltage is responsible for pushing the detection limit down to units of ppm of ammonia, as well as tens of ppm of alcohol or ketones. Nevertheless, P3HT transistors and chemical sensors could compose an electronic nose operated at room temperature for a wide range concentration evaluation (1–10,000 ppm) of gaseous analytes. Targeted analytes include not only biomarkers for diseases, such as uremia, cirrhosis, lung cancer and diabetes, but also gases for environment monitoring in food, cosmetic and microelectronics industries. PMID:25912354

  20. Enhanced Sensitivity of Gas Sensor Based on Poly(3-hexylthiophene) Thin-Film Transistors for Disease Diagnosis and Environment Monitoring.

    PubMed

    Cavallari, Marco R; Izquierdo, José E E; Braga, Guilherme S; Dirani, Ely A T; Pereira-da-Silva, Marcelo A; Rodríguez, Estrella F G; Fonseca, Fernando J

    2015-01-01

    Electronic devices based on organic thin-film transistors (OTFT) have the potential to supply the demand for portable and low-cost gadgets, mainly as sensors for in situ disease diagnosis and environment monitoring. For that reason, poly(3-hexylthiophene) (P3HT) as the active layer in the widely-used bottom-gate/bottom-contact OTFT structure was deposited over highly-doped silicon substrates covered with thermally-grown oxide to detect vapor-phase compounds. A ten-fold organochloride and ammonia sensitivity compared to bare sensors corroborated the application of this semiconducting polymer in sensors. Furthermore, P3HT TFTs presented approximately three-order higher normalized sensitivity than any chemical sensor addressed herein. The results demonstrate that while TFTs respond linearly at the lowest concentration values herein, chemical sensors present such an operating regime mostly above 2000 ppm. Simultaneous alteration of charge carrier mobility and threshold voltage is responsible for pushing the detection limit down to units of ppm of ammonia, as well as tens of ppm of alcohol or ketones. Nevertheless, P3HT transistors and chemical sensors could compose an electronic nose operated at room temperature for a wide range concentration evaluation (1-10,000 ppm) of gaseous analytes. Targeted analytes include not only biomarkers for diseases, such as uremia, cirrhosis, lung cancer and diabetes, but also gases for environment monitoring in food, cosmetic and microelectronics industries. PMID:25912354

  1. Solution-Processed Flexible Fluorine-doped Indium Zinc Oxide Thin-Film Transistors Fabricated on Plastic Film at Low Temperature

    PubMed Central

    Seo, Jin-Suk; Jeon, Jun-Hyuck; Hwang, Young Hwan; Park, Hyungjin; Ryu, Minki; Park, Sang-Hee Ko; Bae, Byeong-Soo

    2013-01-01

    Transparent flexible fluorine-doped indium zinc oxide (IZO:F) thin-film transistors (TFTs) were demonstrated using the spin-coating method of the metal fluoride precursor aqueous solution with annealing at 200°C for 2 hrs on polyethylene naphthalate films. The proposed thermal evolution mechanism of metal fluoride aqueous precursor solution examined by thermogravimetric analysis and Raman spectroscopy can easily explain oxide formation. The chemical composition analysed by XPS confirms that the fluorine was doped in the thin films annealed below 250°C. In the IZO:F thin films, a doped fluorine atom substitutes for an oxygen atom generating a free electron or occupies an oxygen vacancy site eliminating an electron trap site. These dual roles of the doped fluorine can enhance the mobility and improve the gate bias stability of the TFTs. Therefore, the transparent flexible IZO:F TFT shows a high mobility of up to 4.1 cm2/V·s and stable characteristics under the various gate bias and temperature stresses. PMID:23803977

  2. The effect of Ta doping in polycrystalline TiO{sub x} and the associated thin film transistor properties

    SciTech Connect

    Ok, Kyung-Chul Park, Yoseb Park, Jin-Seong E-mail: jsparklime@hanyang.ac.kr; Chung, Kwun-Bum E-mail: jsparklime@hanyang.ac.kr

    2013-11-18

    Tantalum (Ta) is suggested to act as an electron donor and crystal phase stabilizer in titanium oxide (TiO{sub x}). A transition occurs from an amorphous state to a crystalline phase at an annealing temperature above 300 °C in a vacuum ambient. As the annealing temperature increases from 300 °C to 450 °C, the mobility increases drastically from 0.07 cm{sup 2}/Vs to 0.61 cm{sup 2}/Vs. The remarkable enhancement of thin film transistor performance is suggested to be due to the splitting of Ti 3d band orbitals as well as the increase in Ta{sup 5+} ions that can act as electron donors.

  3. Solution-grown small-molecule organic semiconductor with enhanced crystal alignment and areal coverage for organic thin film transistors

    DOE PAGES

    Bi, Sheng; He, Zhengran; Chen, Jihua; Li, Dawen

    2015-07-24

    Drop casting of small-molecule organic semiconductors typically forms crystals with random orientation and poor areal coverage, which leads to significant performance variations of organic thin-film transistors (OTFTs). In this study, we utilize the controlled evaporative self-assembly (CESA) method combined with binary solvent system to control the crystal growth. A small-molecule organic semiconductor,2,5-Di-(2-ethylhexyl)-3,6-bis(5"-n-hexyl-2,2',5',2"]terthiophen-5-yl)-pyrrolo[3,4-c]pyrrole-1,4-dione (SMDPPEH), is used as an example to demonstrate the effectiveness of our approach. By optimizing the double solvent ratios, well-aligned SMDPPEH crystals with significantly improved areal coverage were achieved. As a result, the SMDPPEH based OTFTs exhibit a mobility of 1.6 × 10-2 cm2/V s, which is themore » highest mobility from SMDPPEH ever reported.« less

  4. Static and low frequency noise characterization of N-type random network of carbon nanotubes thin film transistors

    NASA Astrophysics Data System (ADS)

    Joo, Min-Kyu; Mouis, Mireille; Jeon, Dae-Young; Kim, Gyu-Tae; Kim, Un Jeong; Ghibaudo, Gérard

    2013-10-01

    Static and low frequency noise (LFN) characterizations in two-dimensional (2D) N-type random network thin film transistors (RN-TFTs) based on single-walled carbon nanotubes were presented. For the electrical parameter extraction, the Y-function method was used to suppress the series resistance (Rsd) influence. The gate-to-channel capacitance (Cgc) was directly measured by the split capacitance-to-voltage method and compared to 2D metal-plate capacitance model (C2D). In addition, to account for the percolation-dominated 2D RN-TFTs, a numerical percolation simulation was performed. LFN measurements were also carried out and the results were well interpreted by the carrier number and correlated mobility fluctuation model. Finally, one-dimensional (1D) cylindrical analytical capacitance based model (C1D) was suggested and applied to provide better consistency between all electrical parameters based on experimental and simulation results.

  5. A New Low Temperature Polycrystalline Silicon Thin Film Transistor Pixel Circuit for Active Matrix Organic Light Emitting Diode

    NASA Astrophysics Data System (ADS)

    Ching-Lin Fan,; Yi-Yan Lin,; Jyu-Yu Chang,; Bo-Jhang Sun,; Yan-Wei Liu,

    2010-06-01

    This study presents one novel compensation pixel design and driving method for active matrix organic light-emitting diode (AMOLED) displays that use low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) with a voltage feed-back method and the simulation results are proposed and verified by SPICE simulator. The measurement and simulation of LTPS TFT characteristics demonstrate the good fitting result. The proposed circuit consists of four TFTs and two capacitors with an additional signal line. The error rates of OLED anode voltage variation are below 0.3% under the threshold voltage deviation of driving TFT (Δ VTH = ± 0.33 V). The simulation results show that the pixel design can improve the display image non-uniformity by compensating the threshold voltage deviation of driving TFT and the degradation of OLED threshold voltage at the same time.

  6. A New Low Temperature Polycrystalline Silicon Thin Film Transistor Pixel Circuit for Active Matrix Organic Light Emitting Diode

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Lin, Yi-Yan; Chang, Jyu-Yu; Sun, Bo-Jhang; Liu, Yan-Wei

    2010-06-01

    This study presents one novel compensation pixel design and driving method for active matrix organic light-emitting diode (AMOLED) displays that use low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) with a voltage feed-back method and the simulation results are proposed and verified by SPICE simulator. The measurement and simulation of LTPS TFT characteristics demonstrate the good fitting result. The proposed circuit consists of four TFTs and two capacitors with an additional signal line. The error rates of OLED anode voltage variation are below 0.3% under the threshold voltage deviation of driving TFT (ΔVTH = ±0.33 V). The simulation results show that the pixel design can improve the display image non-uniformity by compensating the threshold voltage deviation of driving TFT and the degradation of OLED threshold voltage at the same time.

  7. Combustion-process derived comparable performances of Zn-(In:Sn)-O thin-film transistors with a complete miscibility

    SciTech Connect

    Jiang, Qingjun; Lu, Jianguo Cheng, Jipeng; Sun, Rujie; Feng, Lisha; Dai, Wen; Yan, Weichao; Ye, Zhizhen; Li, Xifeng

    2014-09-29

    Amorphous zinc-indium-tin oxide (a-ZITO) thin-film transistors (TFTs) have been prepared using a low-temperature combustion process, with an emphasis on complete miscibility of In and Sn contents. The a-ZITO TFTs were comparatively studied in detail, especially for the working stability. The a-ZITO TFTs all exhibited acceptable and excellent behaviors from Sn-free TFTs to In-free TFTs. The obtained a-ZTO TFTs presented a field-effect mobility of 1.20 cm{sup 2} V{sup −1} s{sup −1}, an on/off current ratio of 4.89 × 10{sup 6}, and a long-term stability under positive bias stress, which are comparable with those of the a-ZIO TFTs. The In-free a-ZTO TFTs are very potential for electrical applications with a low cost.

  8. Investigation of channel width-dependent threshold voltage variation in a-InGaZnO thin-film transistors

    SciTech Connect

    Liu, Kuan-Hsien; Chou, Wu-Ching; Chang, Ting-Chang; Wu, Ming-Siou; Hung, Yi-Syuan; Sze, Simon M.; Hung, Pei-Hua; Chu, Ann-Kuo; Hsieh, Tien-Yu; Yeh, Bo-Liang

    2014-03-31

    This Letter investigates abnormal channel width-dependent threshold voltage variation in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. Unlike drain-induced source barrier lowering effect, threshold voltage increases with increasing drain voltage. Furthermore, the wider the channel, the larger the threshold voltage observed. Because of the surrounding oxide and other thermal insulating material and the low thermal conductivity of the IGZO layer, the self-heating effect will be pronounced in wider channel devices and those with a larger operating drain bias. To further clarify the physical mechanism, fast IV measurement is utilized to demonstrate the self-heating induced anomalous channel width-dependent threshold voltage variation.

  9. Investigation of channel width-dependent threshold voltage variation in a-InGaZnO thin-film transistors

    NASA Astrophysics Data System (ADS)

    Liu, Kuan-Hsien; Chang, Ting-Chang; Wu, Ming-Siou; Hung, Yi-Syuan; Hung, Pei-Hua; Hsieh, Tien-Yu; Chou, Wu-Ching; Chu, Ann-Kuo; Sze, Simon M.; Yeh, Bo-Liang

    2014-03-01

    This Letter investigates abnormal channel width-dependent threshold voltage variation in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. Unlike drain-induced source barrier lowering effect, threshold voltage increases with increasing drain voltage. Furthermore, the wider the channel, the larger the threshold voltage observed. Because of the surrounding oxide and other thermal insulating material and the low thermal conductivity of the IGZO layer, the self-heating effect will be pronounced in wider channel devices and those with a larger operating drain bias. To further clarify the physical mechanism, fast IV measurement is utilized to demonstrate the self-heating induced anomalous channel width-dependent threshold voltage variation.

  10. High Mobility and Stability of Thin-Film Transistors Using Silicon-Doped Amorphous Indium Tin Oxide Semiconductors

    NASA Astrophysics Data System (ADS)

    Seo, T. W.; Kim, Hyun-Suk; Lee, Kwang-Ho; Chung, Kwun-Bum; Park, Jin-Seong

    2014-09-01

    We report the fabrication of high-performance thin-film transistors (TFTs) with an amorphous silicon indium tin oxide ( a-SITO) channel, which was deposited by cosputtering a silicon dioxide and an indium tin oxide target. The effect of the silicon doping on the device performance and stability of the a-SITO TFTs was investigated. The field-effect mobility and stability under positive bias stress of the a-SITO TFTs with optimized Si content (0.22 at.% Si) dramatically improved to 28.7 cm2/Vs and 1.5 V shift of threshold voltage, respectively, compared with the values (0.72 cm2/Vs and 8.9 V shift) for a-SITO TFTs with 4.22 at.% Si. The role of silicon in a-SITO TFTs is discussed based on various physical and chemical analyses, including x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, and spectroscopic ellipsometry measurements.

  11. Recovery from ultraviolet-induced threshold voltage shift in indium gallium zinc oxide thin film transistors by positive gate bias

    SciTech Connect

    Liu, P.; Chen, T. P.; Li, X. D.; Wong, J. I.; Liu, Z.; Liu, Y.; Leong, K. C.

    2013-11-11

    The effect of short-duration ultraviolet (UV) exposure on the threshold voltage (V{sub th}) of amorphous indium gallium zinc oxide thin film transistors (TFTs) and its recovery characteristics were investigated. The V{sub th} exhibited a significant negative shift after UV exposure. The V{sub th} instability caused by UV illumination is attributed to the positive charge trapping in the dielectric layer and/or at the channel/dielectric interface. The illuminated devices showed a slow recovery in threshold voltage without external bias. However, an instant recovery can be achieved by the application of positive gate pulses, which is due to the elimination of the positive trapped charges as a result of the presence of a large amount of field-induced electrons in the interface region.

  12. Metal-induced crystallization of amorphous zinc tin oxide semiconductors for high mobility thin-film transistors

    NASA Astrophysics Data System (ADS)

    Hwang, Ah Young; Kim, Sang Tae; Ji, Hyuk; Shin, Yeonwoo; Jeong, Jae Kyeong

    2016-04-01

    Transition tantalum induced crystallization of amorphous zinc tin oxide (a-ZTO) was observed at low temperature annealing of 300 °C. Thin-film transistors (TFTs) with an a-ZTO channel layer exhibited a reasonable field-effect mobility of 12.4 cm2/V s, subthreshold swing (SS) of 0.39 V/decade, threshold voltage (VTH) of 1.5 V, and ION/OFF ratio of ˜107. A significant improvement in the field-effect mobility (up to ˜33.5 cm2/V s) was achieved for crystallized ZTO TFTs: this improvement was accomplished without compromising the SS, VTH, or ION/OFF ratio due to the presence of a highly ordered microstructure.

  13. Defect generation in amorphous-indium-gallium-zinc-oxide thin-film transistors by positive bias stress at elevated temperature

    SciTech Connect

    Um, Jae Gwang; Mativenga, Mallory; Jang, Jin; Migliorato, Piero

    2014-04-07

    We report on the generation and characterization of a hump in the transfer characteristics of amorphous indium gallium zinc-oxide thin-film transistors by positive bias temperature stress. The hump depends strongly on the gate bias stress at 100 °C. Due to the hump, the positive shift of the transfer characteristic in deep depletion is always smaller that in accumulation. Since, the latter shift is twice the former, with very good correlation, we conclude that the effect is due to creation of a double acceptor, likely to be a cation vacancy. Our results indicate that these defects are located near the gate insulator/active layer interface, rather than in the bulk. Migration of donor defects from the interface towards the bulk may also occur under PBST at 100 °C.

  14. Subgap states in p-channel tin monoxide thin-film transistors from temperature-dependent field-effect characteristics

    NASA Astrophysics Data System (ADS)

    Jeong, Chan-Yong; Lee, Daeun; Han, Young-Joon; Choi, Yong-Jin; Kwon, Hyuck-In

    2015-08-01

    This paper experimentally investigates the subgap density of states (DOS) in p-type tin monoxide (SnO) thin-film transistors (TFTs) for the first time by using temperature-dependent field-effect measurements. As the temperature increases, the turn-on voltage moves in the positive direction, and the off-current and subthreshold slope continuously increase. We found that the conductivity of the SnO TFT obeys the Meyer-Neldel (MN) rule with a characteristic MN parameter of 28.6 eV-1 in the subthreshold region, from which we successfully extracted the subgap DOS by combing the field-effect method and the MN relation. The extracted subgap DOS from fabricated p-type SnO TFTs are exponentially distributed in energy, and exhibit around two orders of magnitude higher values compared to those of the n-type amorphous indium-gallium-zinc oxide TFTs.

  15. Characterization of solution processed, p-doped films using hole-only devices and organic field-effect transistors

    SciTech Connect

    Swensen, James S.; Wang, Liang; Rainbolt, James E.; Koech, Phillip K.; Polikarpov, Evgueni; Gaspar, Daniel J.; Padmaperuma, Asanga B.

    2012-12-01

    We report a solution-processed approach for a p-type doped hole transport layer in organic light emitting devices (OLEDs). UV-vis-NIR absorption spectra identified the charge transfer between the donor and acceptor in the solution processed doped films. Single carrier device and field-effect transistor were utilized as test vehicles to study the charge transport property and extract important parameters such as bulk mobile carrier concentration and mobility. OLEDs with p-type doped hole transport layer showed significant improvement in power efficiency up to 30% at the optimal doping ratio. This approach has the great potential to reduce the power consumption for OLED solid state lighting while lowering the cost and boosting the throughput of its manufacturing.

  16. Thermal Characteristics of Amorphous Indium-Gallium-Zinc-Oxide and Graphite in Display Panel Based Thin Film Transistors.

    PubMed

    Kim, Hak-Jun; Kim, Youn-Jea

    2015-11-01

    One of the important design factors in the smart electronic industry is proper heat treatment of the display panel. In order to improve the heat transfer performance of display panels, we analyzed a three-dimensional model of multi-stack layers of the thin film transistors (TFTs). In particular, we numerically investigated the thermal barrier effects of active layers having different material properties of a-IGZO (isotropy) and graphite (anisotropy). We calculated the temperature distribution on the display panel with each active layer, using the commercial code, COMSOL Multiphysics. We graphically depict comparative results of the thermal characteristics between a-IGZO and graphite with the stacked structure of the TFTs. PMID:26726627

  17. Top-gate zinc tin oxide thin-film transistors with high bias and environmental stress stability

    SciTech Connect

    Fakhri, M.; Theisen, M.; Behrendt, A.; Görrn, P.; Riedl, T.

    2014-06-23

    Top gated metal-oxide thin-film transistors (TFTs) provide two benefits compared to their conventional bottom-gate counterparts: (i) The gate dielectric may concomitantly serve as encapsulation layer for the TFT channel. (ii) Damage of the dielectric due to high-energetic particles during channel deposition can be avoided. In our work, the top-gate dielectric is prepared by ozone based atomic layer deposition at low temperatures. For ultra-low gas permeation rates, we introduce nano-laminates of Al{sub 2}O{sub 3}/ZrO{sub 2} as dielectrics. The resulting TFTs show a superior environmental stability even at elevated temperatures. Their outstanding stability vs. bias stress is benchmarked against bottom-gate devices with encapsulation.

  18. Thickness dependent low-frequency noise characteristics of a-InZnO thin-film transistors under light illumination

    SciTech Connect

    Choi, Hyun-Sik; Jeon, Sanghun

    2014-01-13

    The influence of illumination on the electrical characteristics of amorphous indium–zinc oxide (a-IZO) thin-film transistors (TFTs) has been investigated. The electrical properties are found to depend significantly on the active thickness (T{sub IZO}) of the a-IZO TFT. The active thickness is seen to play a major role in the carrier transport mechanism. Based on the carrier fluctuation model, the low-frequency noise (LFN) characteristics of a-IZO devices of varying thicknesses were evaluated before as well as after illumination. Similar to the results of DC and capacitance–voltage (C–V) measurements, the LFN characteristics too show that the light-induced carrier transport becomes significantly enhanced for relatively thick (T{sub IZO} ≥ 60 nm) a-IZO devices.

  19. Electrical stress-induced instability of amorphous indium-gallium-zinc oxide thin-film transistors under bipolar ac stress

    SciTech Connect

    Lee, Sangwon; Jeon, Kichan; Park, Jun-Hyun; Kim, Sungchul; Kong, Dongsik; Kim, Dong Myong; Kim, Dae Hwan; Kim, Sangwook; Kim, Sunil; Hur, Jihyun; Park, Jae Chul; Song, Ihun; Kim, Chang Jung; Park, Youngsoo; Jung, U-In

    2009-09-28

    Bipolar ac stress-induced instability of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors is comparatively investigated with that under a positive dc gate bias stress. While the positive dc gate bias stress-induced threshold voltage shift ({delta}V{sub T}) is caused by the charge trapping into the interface/gate dielectric as reported in previous works, the dominant mechanism of the ac stress-induced {delta}V{sub T} is observed to be due to the increase in the acceptorlike deep states of the density of states (DOS) in the a-IGZO active layer. Furthermore, it is found that the variation of deep states in the DOS makes a parallel shift in the I{sub DS}-V{sub GS} curve with an insignificant change in the subthreshold slope, as well as the deformation of the C{sub G}-V{sub G} curves.

  20. Solution-grown small-molecule organic semiconductor with enhanced crystal alignment and areal coverage for organic thin film transistors

    SciTech Connect

    Bi, Sheng; He, Zhengran; Chen, Jihua; Li, Dawen

    2015-07-24

    Drop casting of small-molecule organic semiconductors typically forms crystals with random orientation and poor areal coverage, which leads to significant performance variations of organic thin-film transistors (OTFTs). In this study, we utilize the controlled evaporative self-assembly (CESA) method combined with binary solvent system to control the crystal growth. A small-molecule organic semiconductor,2,5-Di-(2-ethylhexyl)-3,6-bis(5"-n-hexyl-2,2',5',2"]terthiophen-5-yl)-pyrrolo[3,4-c]pyrrole-1,4-dione (SMDPPEH), is used as an example to demonstrate the effectiveness of our approach. By optimizing the double solvent ratios, well-aligned SMDPPEH crystals with significantly improved areal coverage were achieved. As a result, the SMDPPEH based OTFTs exhibit a mobility of 1.6 × 10-2 cm2/V s, which is the highest mobility from SMDPPEH ever reported.

  1. Origin of degradation phenomenon under drain bias stress for oxide thin film transistors using IGZO and IGO channel layers.

    PubMed

    Bak, Jun Yong; Kang, Youngho; Yang, Shinhyuk; Ryu, Ho-Jun; Hwang, Chi-Sun; Han, Seungwu; Yoon, Sung-Min

    2015-01-20

    Top-gate structured thin film transistors (TFTs) using In-Ga-Zn-O (IGZO) and In-Ga-O (IGO) channel compositions were investigated to reveal a feasible origin for degradation phenomenon under drain bias stress (DBS). DBS-driven instability in terms of V(TH) shift, deviation of the SS value, and increase in the on-state current were detected only for the IGZO-TFT, in contrast to the IGO-TFT, which did not demonstrate V(TH) shift. These behaviors were visually confirmed via nanoscale transmission electron microscopy and energy-dispersive x-ray spectroscopy observations. To understand the degradation mechanism, we performed ab initio molecular dynamic simulations on the liquid phases of IGZO and IGO. The diffusivities of Ga and In atoms were enhanced in IGZO, confirming the degradation mechanism to be increased atomic diffusion.

  2. Low power low temperature poly-Si thin-film transistor shift register with DC-type output driver

    NASA Astrophysics Data System (ADS)

    Song, Seok-Jeong; Kim, Byung Hoon; Jang, Jin; Nam, Hyoungsik

    2015-09-01

    This paper demonstrates a low power DC-type low temperature poly-Si (LTPS) thin-film transistor (TFT) shift register that consists of nine TFTs and one bootstrapping capacitor. The proposed circuit connects large size pull-up TFTs of output drivers to positive supply instead of alternating clock signals in order to reduce substantially the power consumption of clock drivers. The SPICE simulation ensures that the variable overlap intervals can be programmed by the delay between clock signals and the overall power consumption of a DC-type circuit can be reduced to 45% of an AC-type one for a full-HD display. The operation of a proposed structure is also verified with a fabricated 16-stage gate driver.

  3. Light-induced hysteresis and recovery behaviors in photochemically activated solution-processed metal-oxide thin-film transistors

    SciTech Connect

    Jo, Jeong-Wan; Park, Sung Kyu E-mail: skpark@cau.ac.kr; Kim, Yong-Hoon E-mail: skpark@cau.ac.kr

    2014-07-28

    In this report, photo-induced hysteresis, threshold voltage (V{sub T}) shift, and recovery behaviors in photochemically activated solution-processed indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) are investigated. It was observed that a white light illumination caused negative V{sub T} shift along with creation of clockwise hysteresis in electrical characteristics which can be attributed to photo-generated doubly ionized oxygen vacancies at the semiconductor/gate dielectric interface. More importantly, the photochemically activated IGZO TFTs showed much reduced overall V{sub T} shift compared to thermally annealed TFTs. Reduced number of donor-like interface states creation under light illumination and more facile neutralization of ionized oxygen vacancies by electron capture under positive gate potential are claimed to be the origin of the less V{sub T} shift in photochemically activated TFTs.

  4. Charge transport study of high mobility polymer thin-film transistors based on thiophene substituted diketopyrrolopyrrole copolymers.

    PubMed

    Ha, Tae-Jun; Sonar, Prashant; Dodabalapur, Ananth

    2013-06-28

    In this paper, we report on the device physics and charge transport characteristics of high-mobility dual-gated polymer thin-film transistors with active semiconductor layers consisting of thiophene flanked DPP with thienylene-vinylene-thienylene (PDPP-TVT) alternating copolymers. Room temperature mobilities in these devices are high and can exceed 2 cm(2) V(-1) s(-1). Steady-state and non-quasi-static measurements have been performed to extract key transport parameters and velocity distributions of charge carriers in this copolymer. Charge transport in this polymer semiconductor can be explained using a Multiple-Trap-and-Release or Monroe-type model. We also compare the activation energy vs. field-effect mobility in a few important polymer semiconductors to gain a better understanding of transport of DPP systems and make appropriate comparisons.

  5. Conducting glasses recovered from thin film transistor liquid crystal display wastes for dye-sensitized solar cell cathodes.

    PubMed

    Chen, C-C; Chang, F-C; Peng, C Y; Wang, H Paul

    2015-01-01

    Transparent conductive glasses such as thin film transistor (TFT) array and colour filter glasses were recovered from the TFT-liquid crystal display panel wastes by dismantling and sonic cleaning. Noble metals (i.e. platinum (Pt)) and indium tin oxide (ITO) are generally used in the cathode of a dye-sensitized solar cell (DSSC). To reduce the DSSC cost, Pt was replaced with nano nickel-encapsulated carbon-shell (Ni@C) nanoparticles, which were prepared by carbonization of Ni²⁺-β-cyclodextrin at 673 K for 2 h. The recovered conductive glasses were used in the DSSC electrodes in the substitution of relatively expensive ITO. Interestingly, the efficiency of the DSSC having the Ni@C-coated cathode is as high as 2.54%. Moreover, the cost of the DSSC using the recovered materials can be reduced by at least 24%. PMID:25399759

  6. Conducting glasses recovered from thin film transistor liquid crystal display wastes for dye-sensitized solar cell cathodes.

    PubMed

    Chen, C-C; Chang, F-C; Peng, C Y; Wang, H Paul

    2015-01-01

    Transparent conductive glasses such as thin film transistor (TFT) array and colour filter glasses were recovered from the TFT-liquid crystal display panel wastes by dismantling and sonic cleaning. Noble metals (i.e. platinum (Pt)) and indium tin oxide (ITO) are generally used in the cathode of a dye-sensitized solar cell (DSSC). To reduce the DSSC cost, Pt was replaced with nano nickel-encapsulated carbon-shell (Ni@C) nanoparticles, which were prepared by carbonization of Ni²⁺-β-cyclodextrin at 673 K for 2 h. The recovered conductive glasses were used in the DSSC electrodes in the substitution of relatively expensive ITO. Interestingly, the efficiency of the DSSC having the Ni@C-coated cathode is as high as 2.54%. Moreover, the cost of the DSSC using the recovered materials can be reduced by at least 24%.

  7. Synthesis and characterization of a new poly(octathiophene) based copolymer for organic thin-film transistor.

    PubMed

    Yun, Hui-Jun; Park, Jong-Man; Jeon, Chan Woo; Nam, Sang Yong; Shin, Sung-Chul; Hwang, Jaeyoung; Kim, Yun-Hi

    2014-08-01

    A new poly(octathiophene) based copolymer was designed and synthesized by the palladium catalyzed Suzuki coupling reaction. The structure of the newly obtained copolymer was confirmed by 1H-NMR and IR. The number-average molecular weight (M(n)) of the polymer was 36,000 with a poly-dispersity index of 1.15. The polymer has good solubility in common solvents such as chloroform, toluene, chlorobenzene, dichlorobenzene and tetrahydrofuran at room temperature. The optical, thermal and electrochemical properties of the polymer were characterized by UV-vis absorption, TGA and DSC and cyclovoltametry, respectively. A thin film transistor using the new polymer as an organic semiconductor was found to exhibit typical p-channel FET characteristics with a hole mobility of 5 x 10(-4) cm2/Vs. PMID:25936032

  8. Electrothermal Annealing (ETA) Method to Enhance the Electrical Performance of Amorphous-Oxide-Semiconductor (AOS) Thin-Film Transistors (TFTs).

    PubMed

    Kim, Choong-Ki; Kim, Eungtaek; Lee, Myung Keun; Park, Jun-Young; Seol, Myeong-Lok; Bae, Hagyoul; Bang, Tewook; Jeon, Seung-Bae; Jun, Sungwoo; Park, Sang-Hee K; Choi, Kyung Cheol; Choi, Yang-Kyu

    2016-09-14

    An electro-thermal annealing (ETA) method, which uses an electrical pulse of less than 100 ns, was developed to improve the electrical performance of array-level amorphous-oxide-semiconductor (AOS) thin-film transistors (TFTs). The practicality of the ETA method was experimentally demonstrated with transparent amorphous In-Ga-Zn-O (a-IGZO) TFTs. The overall electrical performance metrics were boosted by the proposed method: up to 205% for the trans-conductance (gm), 158% for the linear current (Ilinear), and 206% for the subthreshold swing (SS). The performance enhancement were interpreted by X-ray photoelectron microscopy (XPS), showing a reduction of oxygen vacancies in a-IGZO after the ETA. Furthermore, by virtue of the extremely short operation time (80 ns) of ETA, which neither provokes a delay of the mandatory TFTs operation such as addressing operation for the display refresh nor demands extra physical treatment, the semipermanent use of displays can be realized. PMID:27552134

  9. Artificial DNA nanostructure detection using solution-processed In-Ga-Zn-O thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Si Joon; Kim, Byeonghoon; Jung, Joohye; Yoon, Doo Hyun; Lee, Junwye; Park, Sung Ha; Kim, Hyun Jae

    2012-03-01

    A method for detecting artificial DNA using solution-processed In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) was developed. The IGZO TFT had a field-effect mobility (μFET) of 0.07 cm2/Vs and an on-current (Ion) value of about 2.68 μA. A dry-wet method was employed to immobilize double-crossover (DX) DNA onto the IGZO surface. After DX DNA immobilization, significant decreases in μFET (0.02 cm2/Vs) and Ion (0.247 μA) and a positive shift of threshold voltage were observed. These results were attributed to the negatively charged phosphate groups on the DNA backbone, which generated electrostatic interactions in the TFT device.

  10. Competitive device performance of low-temperature and all-solution-processed metal-oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Min; Kim, Chi Wan; Heo, Jae-Seok; Na, Hyungil; Lee, Jung Eun; Park, Chang Bum; Bae, Jong-Uk; Kim, Chang-Dong; Jun, Myungchul; Hwang, Yong Kee; Meyers, Stephen T.; Grenville, Andrew; Keszler, Douglas A.

    2011-12-01

    In this Letter, we described a solution-processed indium-gallium-zinc oxide thin-film transistors (TFTs) with a solution-processed aluminum oxide phosphate gate dielectric, fabricated at a maximum annealing temperature under 350 °C to be applicable to conventional fabrication process of flat-panel displays (FPDs). The solution-processed TFTs exhibited competitive device characteristics under 350 °C, including a field-effect mobility of 4.50 cm2/Vs, an on-to-off current ratio of ˜109, a threshold voltage of 2.34 V, and a subthreshold gate swing of 0.46 V/dec, making them applicable to the future backplane of FPDs.

  11. High Performance Bottom-Gate-Type Amorphous InGaZnO Flexible Transparent Thin-Film Transistors Deposited on PET Substrates at Low Temperature

    NASA Astrophysics Data System (ADS)

    Lee, Hsin-Ying; Ye, Wan-Yi; Lin, Yung-Hao; Lou, Li-Ren; Lee, Ching-Ting

    2014-01-01

    The InGaZnO channel layer of bottom-gate-type flexible transparent thin-film transistors was deposited on polyethylene terephthalate substrates using a magnetron radio frequency cosputter system with a single InGaZnO target. The composition of the InGaZnO channel layer was controlled by sputtering at various Ar/O2 gas ratios. A 15-nm-thick SiO y insulator film was used to passivate the InGaZnO channel layer. Much better performances of the passivated devices were obtained, which verified the passivation function. To study the bending stability of the resulting flexible transparent thin-film transistors, a stress test with a bending radius of 1.17 cm for 1,500 s was carried out, which showed a variation in the effective filed-effect mobility and the threshold voltage of the unpassivated and passivated devices being maintained within 10 and 8%, respectively.

  12. High-temperature performance of MoS{sub 2} thin-film transistors: Direct current and pulse current-voltage characteristics

    SciTech Connect

    Jiang, C.; Samnakay, R.; Balandin, A. A.; Rumyantsev, S. L.; Shur, M. S.

    2015-02-14

    We report on fabrication of MoS{sub 2} thin-film transistors (TFTs) and experimental investigations of their high-temperature current-voltage characteristics. The measurements show that MoS{sub 2} devices remain functional to temperatures of at least as high as 500 K. The temperature increase results in decreased threshold voltage and mobility. The comparison of the direct current (DC) and pulse measurements shows that the direct current sub-linear and super-linear output characteristics of MoS{sub 2} thin-films devices result from the Joule heating and the interplay of the threshold voltage and mobility temperature dependences. At temperatures above 450 K, a kink in the drain current occurs at zero gate voltage irrespective of the threshold voltage value. This intriguing phenomenon, referred to as a “memory step,” was attributed to the slow relaxation processes in thin films similar to those in graphene and electron glasses. The fabricated MoS{sub 2} thin-film transistors demonstrated stable operation after two months of aging. The obtained results suggest new applications for MoS{sub 2} thin-film transistors in extreme-temperature electronics and sensors.

  13. Performance Enhancement of ZITO Thin-Film Transistors via Graphene Bridge Layer by Sol-Gel Combustion Process.

    PubMed

    Zhang, Jianhua; Dong, Panpan; Gao, Yana; Sheng, Chenhang; Li, Xifeng

    2015-11-01

    In this article, we reported the stacked structure zinc-indium-tin oxide (ZITO) thin-film transistors (TFTs) with graphene nanosheets (GNSs) prepared by solution process. GNSs were used as bridge layer between dual-ZITO layers. The transmission of stacked ZITO/GNSs/ZITO films are more than 80% in the visible region and the resistivity of ZITO films with GNSs bridge layer decreased from 502.9 to 13.4 Ω cm. The solution-processed TFT devices with GNSs bridge layer exhibited a desirable characteristic with a subthreshold slope of 0.25 V/dec and current on-off ratio of 1 × 10(7), and the saturation filed effect mobility is improved to 45.9 cm(2)V(-1)s(-1), which exceeds the mobility values of the pristine ZITO TFTs by one order. These results demonstrate the solution-processed ZITO/GNSs/ZITO TFTs maybe make a further step to achieve high-performance TFTs and show the potential for next-generation applications. PMID:26473579

  14. ZnO thin film transistors and electronic connections for adjustable x-ray mirrors: SMART-X telescope

    NASA Astrophysics Data System (ADS)

    Johnson-Wilke, R. L.; Wilke, R. H. T.; Wallace, M.; Ramirez, J. I.; Prieskorn, Z.; Nikoleyczik, J.; Cotroneo, V.; Allured, R.; Schwartz, D. A.; McMuldroch, S.; Reid, P. B.; Burrows, D. N.; Jackson, T. N.; Trolier-McKinstry, S.

    2014-09-01

    The proposed SMART-X telescope consists of a pixelated array of a piezoelectric lead zirconate titanate (PZT) thin film deposited on flexible glass substrates. These cells or pixels are used to actively control the overall shape of the mirror surface. It is anticipated that the telescope will consist of 8,000 mirror panels with 400-800 cells on each panel. This creates an enormous number (6.4 million) of traces and contacts needed to address the PZT. In order to simplify the design, a row/column addressing scheme using ZnO thin film transistors (TFTs) is proposed. In addition, connection of the gate and drain lines on the mirror segment to an external supply via a flexible cable was investigated through use of an anisotropic conductive film (ACF). This paper outlines the design of the ZnO TFTs, use of ACF for bonding, and describes a specially designed electronics box with associated software to address the desired cells.

  15. Electrolysis-induced protonation of VO2 thin film transistor for the metal-insulator phase modulation

    NASA Astrophysics Data System (ADS)

    Katase, Takayoshi; Endo, Kenji; Ohta, Hiromichi

    2016-02-01

    Compared to state-of-the-art modulation techniques, protonation is the most ideal to control the electrical and optical properties of transition metal oxides (TMOs) due to its intrinsic non-volatile operation. However, the protonation of TMOs is not typically utilized for solid-state devices because of imperative high-temperature annealing treatment in hydrogen source. Although one solution for room temperature (RT) protonation of TMOs is liquid-phase electrochemistry, it is unsuited for practical purposes due to liquid-leakage problem. Herein we demonstrate solid-state RT-protonation of vanadium dioxide (VO2), which is a well-known thermochromic TMO. We fabricated the three terminal thin-film-transistor structure on an insulating VO2 film using a water-infiltrated nanoporous glass, which serves as a solid electrolyte. For gate voltage application, water electrolysis and protonation/deprotonation of VO2 film surface occurred, leading to reversible metal-insulator phase conversion of ~11-nm-thick VO2 layer. The protonation was clearly accompanied by the structural change from an insulating monoclinic to a metallic tetragonal phase. Present results offer a new route for the development of electro-optically active solid-state devices with TMO materials by engineering RT protonation.

  16. Performance Enhancement of ZITO Thin-Film Transistors via Graphene Bridge Layer by Sol-Gel Combustion Process.

    PubMed

    Zhang, Jianhua; Dong, Panpan; Gao, Yana; Sheng, Chenhang; Li, Xifeng

    2015-11-01

    In this article, we reported the stacked structure zinc-indium-tin oxide (ZITO) thin-film transistors (TFTs) with graphene nanosheets (GNSs) prepared by solution process. GNSs were used as bridge layer between dual-ZITO layers. The transmission of stacked ZITO/GNSs/ZITO films are more than 80% in the visible region and the resistivity of ZITO films with GNSs bridge layer decreased from 502.9 to 13.4 Ω cm. The solution-processed TFT devices with GNSs bridge layer exhibited a desirable characteristic with a subthreshold slope of 0.25 V/dec and current on-off ratio of 1 × 10(7), and the saturation filed effect mobility is improved to 45.9 cm(2)V(-1)s(-1), which exceeds the mobility values of the pristine ZITO TFTs by one order. These results demonstrate the solution-processed ZITO/GNSs/ZITO TFTs maybe make a further step to achieve high-performance TFTs and show the potential for next-generation applications.

  17. Plasmon-enhanced photocurrent of Ge-doped InGaO thin film transistors using silver nanoparticles

    SciTech Connect

    Park, Si Jin; Lee, Sang Moo; Kang, Seong Jun; Lee, Kwang-Ho; Park, Jin-Seong

    2015-03-15

    Germanium-doped indium-gallium oxide (GIGO) thin film transistors (TFTs) decorated with silver (Ag) nanoparticles (NPs) were prepared to study the plasmon effect. GIGO films of various thicknesses were deposited on SiO{sub 2}/Si substrates, and Ag NPs (∼25 nm in diameter) were formed using a thermal evaporator and a postannealing process. The Ag NPs effectively absorbed light in the wavelength range of 500 and 600 nm, which corresponds to the plasmonic effect. Due to the plasmon resonance of Ag NPs, a significantly enhanced photocurrent was observed on the devices. The current increased by 348% with exposure to light when the Ag NPs were formed at the interface between the 10-nm-thick GIGO film and SiO{sub 2} substrate. The increased photocurrent revealed the presence of strong coupling between the localized plasmon and electrical carrier of the devices. The results show that the photocurrent of GIGO TFTs can be greatly enhanced when the plasmonic Ag NPs are located in the channel region of the devices.

  18. Effect of the gate metal work function on water-gated ZnO thin-film transistor performance

    NASA Astrophysics Data System (ADS)

    Singh, Mandeep; Yusuf Mulla, Mohammad; Vittoria Santacroce, Maria; Magliulo, Maria; Di Franco, Cinzia; Manoli, Kyriaki; Altamura, Davide; Giannini, Cinzia; Cioffi, Nicola; Palazzo, Gerardo; Scamarcio, Gaetano; Torsi, Luisa

    2016-07-01

    ZnO thin films, prepared using a printing-compatible sol-gel method involving a thermal treatment below 400 °C, are proposed as active layers in water-gated thin-film transistors (WG-TFTs). The thin-film structure and surface morphology reveal the presence of contiguous ZnO crystalline (hexagonal wurtzite) with isotropic nano-grains as large as 10 nm characterized by a preferential orientation along the a-axis. The TFT devices are gated through a droplet of deionized water by means of electrodes characterized by different work functions. The high capacitance of the electrolyte allowed operation below 0.5 V. While the Ni, Pd, Au and Pt gate electrodes are electrochemically stable in the inspected potential range, electrochemical activity is revealed for the W one. Such an occurrence leads to an increase of capacitance (and current), which is ascribed to a high output current from the dissolution of a lower capacitance W-oxide layer. The environmental stability of the ZnO WG-TFTs is quite good over a period of five months.

  19. Amorphous ZnAlSnO thin-film transistors by a combustion solution process for future displays

    SciTech Connect

    Jiang, Qingjun; Feng, Lisha; Wu, Chuanjia; Sun, Rujie; Lu, Bin; Ye, Zhizhen; Lu, Jianguo; Li, Xifeng

    2015-02-02

    A combustion solution method was developed to fabricate amorphous ZnAlSnO (a-ZATO) for thin-film transistors (TFTs). The properties of a-ZATO films and behaviors of a-ZATO TFTs were studied in detail. An appropriate Al content in the matrix could suppress the formation of oxygen vacancies efficiently and achieve densely amorphous films. The a-ZATO TFTs exhibited acceptable performances, with an on/off current ratio of ∼10{sup 6}, field-effect mobility of 2.33 cm{sup 2}·V{sup −1}·S{sup −1}, threshold voltage of 2.39 V, and subthreshold swing of 0.52 V/decade at an optimal Al content (0.5). The relation between on- and off-resistance of the ZATO TFT was also within the range expected for fast switching devices. More importantly, the introduced Al with an appropriate content had the ability to evidently enhance the device long-term stability under working bias stress and storage durations. The obtained indium- and gallium-free a-ZATO TFTs are very promising for the next-generation displays.

  20. Hole mobility modulation of solution-processed nickel oxide thin-film transistor based on high-k dielectric

    NASA Astrophysics Data System (ADS)

    Liu, Ao; Liu, Guoxia; Zhu, Huihui; Shin, Byoungchul; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

    2016-06-01

    Solution-processed p-type oxide semiconductors have recently attracted increasing interests for the applications in low-cost optoelectronic devices and low-power consumption complementary metal-oxide-semiconductor circuits. In this work, p-type nickel oxide (NiOx) thin films were prepared using low-temperature solution process and integrated as the channel layer in thin-film transistors (TFTs). The electrical properties of NiOx TFTs, together with the characteristics of NiOx thin films, were systematically investigated as a function of annealing temperature. By introducing aqueous high-k aluminum oxide (Al2O3) gate dielectric, the electrical performance of NiOx TFT was improved significantly compared with those based on SiO2 dielectric. Particularly, the hole mobility was found to be 60 times enhancement, quantitatively from 0.07 to 4.4 cm2/V s, which is mainly beneficial from the high areal capacitance of the Al2O3 dielectric and high-quality NiOx/Al2O3 interface. This simple solution-based method for producing p-type oxide TFTs is promising for next-generation oxide-based electronic applications.

  1. Atomic layer deposition of aluminum oxide films for carbon nanotube network transistor passivation.

    PubMed

    Grigoras, Kestutis; Zavodchikova, Marina Y; Nasibulin, Albert G; Kauppinen, Esko I; Ermolov, Vladimir; Franssila, Sami

    2011-10-01

    Ultra-thin (2-5 nm thick) aluminum oxide layers were grown on non-functionalized individual single walled carbon nanotubes (SWCNT) and their bundles by atomic layer deposition (ALD) technique in order to investigate the mechanism of the coating process. Transmission electron microscopy (TEM) was used to examine the uniformity and conformality of the coatings grown at different temperatures (80 degrees C or 220 degrees C) and with different precursors for oxidation (water and ozone). We found that bundles of SWCNTs were coated continuously, but at the same time, bare individual nanotubes remained uncoated. The successful coating of bundles was explained by the formation of interstitial pores between the individual SWCNTs constituting the bundle, where the precursor molecules can adhere, initiating the layer growth. Thicker alumina layers (20-35 nm thick) were used for the coating of bottom-gated SWCNT-network based field effect transistors (FETs). ALD layers, grown at different conditions, were found to influence the performance of the SWCNT-network FETs: low temperature ALD layers caused the ambipolarity of the channel and pronounced n-type conduction, whereas high temperature ALD processes resulted in hysteresis suppression in the transfer characteristics of the SWCNT transistors and preserved p-type conduction. Fixed charges in the ALD layer have been considered as the main factor influencing the conduction change of the SWCNT network based transistors.

  2. Low-temperature, solution-processed ZrO2:B thin film: a bifunctional inorganic/organic interfacial glue for flexible thin-film transistors.

    PubMed

    Park, Jee Ho; Oh, Jin Young; Han, Sun Woong; Lee, Tae Il; Baik, Hong Koo

    2015-03-01

    A solution-processed boron-doped peroxo-zirconium oxide (ZrO2:B) thin film has been found to have multifunctional characteristics, providing both hydrophobic surface modification and a chemical glue layer. Specifically, a ZrO2:B thin film deposited on a hydrophobic layer becomes superhydrophilic following ultraviolet-ozone (UVO) treatment, whereas the same treatment has no effect on the hydrophobicity of the hydrophobic layer alone. Investigation of the ZrO2:B/hydrophobic interface layer using angle-resolved X-ray photoelectron spectroscopy (AR XPS) confirmed it to be chemically bonded like glue. Using the multifunctional nature of the ZrO2:B thin film, flexible amorphous indium oxide (In2O3) thin-film transistors (TFTs) were subsequently fabricated on a polyimide substrate along with a ZrO2:B/poly-4-vinylphenol (PVP) dielectric. An aqueous In2O3 solution was successfully coated onto the ZrO2:B/PVP dielectric, and the surface and chemical properties of the PVP and ZrO2:B thin films were analyzed by contact angle measurement, atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The surface-engineered PVP dielectric was found to have a lower leakage current density (Jleak) of 4.38 × 10(-8) A/cm(2) at 1 MV/cm, with no breakdown behavior observed up to a bending radius of 5 mm. In contrast, the electrical characteristics of the flexible amorphous In2O3 TFT such as on/off current ratio (Ion/off) and electron mobility remained similar up to 10 mm of bending without degradation, with the device being nonactivated at a bending radius of 5 mm. These results suggest that ZrO2:B thin films could be used for low-temperature, solution-processed surface-modified flexible devices. PMID:25664940

  3. Low-temperature, solution-processed ZrO2:B thin film: a bifunctional inorganic/organic interfacial glue for flexible thin-film transistors.

    PubMed

    Park, Jee Ho; Oh, Jin Young; Han, Sun Woong; Lee, Tae Il; Baik, Hong Koo

    2015-03-01

    A solution-processed boron-doped peroxo-zirconium oxide (ZrO2:B) thin film has been found to have multifunctional characteristics, providing both hydrophobic surface modification and a chemical glue layer. Specifically, a ZrO2:B thin film deposited on a hydrophobic layer becomes superhydrophilic following ultraviolet-ozone (UVO) treatment, whereas the same treatment has no effect on the hydrophobicity of the hydrophobic layer alone. Investigation of the ZrO2:B/hydrophobic interface layer using angle-resolved X-ray photoelectron spectroscopy (AR XPS) confirmed it to be chemically bonded like glue. Using the multifunctional nature of the ZrO2:B thin film, flexible amorphous indium oxide (In2O3) thin-film transistors (TFTs) were subsequently fabricated on a polyimide substrate along with a ZrO2:B/poly-4-vinylphenol (PVP) dielectric. An aqueous In2O3 solution was successfully coated onto the ZrO2:B/PVP dielectric, and the surface and chemical properties of the PVP and ZrO2:B thin films were analyzed by contact angle measurement, atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The surface-engineered PVP dielectric was found to have a lower leakage current density (Jleak) of 4.38 × 10(-8) A/cm(2) at 1 MV/cm, with no breakdown behavior observed up to a bending radius of 5 mm. In contrast, the electrical characteristics of the flexible amorphous In2O3 TFT such as on/off current ratio (Ion/off) and electron mobility remained similar up to 10 mm of bending without degradation, with the device being nonactivated at a bending radius of 5 mm. These results suggest that ZrO2:B thin films could be used for low-temperature, solution-processed surface-modified flexible devices.

  4. A light-stimulated synaptic transistor with synaptic plasticity and memory functions based on InGaZnOx-Al2O3 thin film structure

    NASA Astrophysics Data System (ADS)

    Li, H. K.; Chen, T. P.; Liu, P.; Hu, S. G.; Liu, Y.; Zhang, Q.; Lee, P. S.

    2016-06-01

    In this work, a synaptic transistor based on the indium gallium zinc oxide (IGZO)-aluminum oxide (Al2O3) thin film structure, which uses ultraviolet (UV) light pulses as the pre-synaptic stimulus, has been demonstrated. The synaptic transistor exhibits the behavior of synaptic plasticity like the paired-pulse facilitation. In addition, it also shows the brain's memory behaviors including the transition from short-term memory to long-term memory and the Ebbinghaus forgetting curve. The synapse-like behavior and memory behaviors of the transistor are due to the trapping and detrapping processes of the holes, which are generated by the UV pulses, at the IGZO/Al2O3 interface and/or in the Al2O3 layer.

  5. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-01

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10-5 of on/off ratio and ~8 cm2 V-1 s-1 of field effect mobility.

  6. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition.

    PubMed

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-22

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10(-5) of on/off ratio and approximately 8 cm2 V(-1) s(-1) of field effect mobility. PMID:19567966

  7. Metallic oxide switches using thick film technology

    NASA Technical Reports Server (NTRS)

    Patel, D. N.; Williams, L., Jr.

    1974-01-01

    Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

  8. Low-Temperature Solution Processing of Amorphous Metal Oxide Semiconductors for High-Performance Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Hennek, Jonathan W.

    The growing field of large-area flexible electronics presents the need for amorphous materials with electrical performances superior to amorphous hydrogenated silicon (a-Si:H). Metal oxide semiconductors show great promise in thin film transistors (TFTs) due to their high electron mobility (micro, 1--100 cm2V-1s-1), mechanical flexibility, and electrical stability. However, most oxide semiconductor fabrication still relies on expensive, inflexible and energy intensive vacuum deposition methods. To overcome these limitations, my thesis work has focused on developing low-temperature solution processing routes to functional metal oxide materials. In Chapter 2, we demonstrate an optimized "ink" and printing process for inkjet patterning of amorphous indium gallium zinc oxide (a-IGZO) and investigate the effects of device structure on derived electron mobility. Bottom-gate top-contact (BGTC) TFTs are fabricated and shown to exhibit electron mobilities comparable to a-Si:H. Furthermore, a record micro of 2.5 cm 2V-1s-1 is demonstrated for bottom-gate bottom-contact (BGBC) TFTs. The mechanism underlying such impressive performance is investigated using transmission line techniques, and it is shown that the semiconductor-source/drain electrode interface contact resistance is nearly an order of magnitude lower for BGBC transistors versus BGTC devices. In Chapter 3, we report the implementation of amorphous indium yttrium oxide (a-IYO) as a TFT semiconductor for the first time. Amorphous and polycrystalline IYO films are grown via a low-temperature solution process utilizing exothermic "combustion" precursors. Precursor transformation and the IYO films are analyzed by DTA, TGA, XRD, AFM, XPS, and optical transmission, revealing efficient conversion to the metal-oxide lattice, and smooth, transparent films. a-IYO TFTs fabricated with a hybrid nanodielectric exhibit impressive electron mobilities of 7.3 cm2V-1s-1 (Tanneal = 300 °C) and 5.0 cm2V-1s -1 (Tanneal = 250 °C) for 2

  9. Multi-level interconnects for heterojunction bipolar transistor integrated circuit technologies

    SciTech Connect

    Patrizi, G.A.; Lovejoy, M.L.; Schneider, R.P. Jr.; Hou, H.Q.; Enquist, P.M.

    1995-12-31

    Heterojunction bipolar transistors (HBTs) are mesa structures which present difficult planarization problems in integrated circuit fabrication. The authors report a multilevel metal interconnect technology using Benzocyclobutene (BCB) to implement high-speed, low-power photoreceivers based on InGaAs/InP HBTs. Processes for patterning and dry etching BCB to achieve smooth via holes with sloped sidewalls are presented. Excellent planarization of 1.9 {micro}m mesa topographies on InGaAs/InP device structures is demonstrated using scanning electron microscopy (SEM). Additionally, SEM cross sections of both the multi-level metal interconnect via holes and the base emitter via holes required in the HBT IC process are presented. All via holes exhibit sloped sidewalls with slopes of 0.4 {micro}m/{micro}m to 2 {micro}m/{micro}m which are needed to realize a robust interconnect process. Specific contact resistances of the interconnects are found to be less than 6 {times} 10{sup {minus}8} {Omega}cm{sup 2}. Integrated circuits utilizing InGaAs/InP HBTs are fabricated to demonstrate the applicability and compatibility of the multi-level interconnect technology with integrated circuit processing.

  10. Low-voltage Organic Thin Film Transistors (OTFTs) with Solution-processed High-k Dielectric cum Interface Engineering

    NASA Astrophysics Data System (ADS)

    Su, Yaorong

    Although impressive progress has been made in improving the performance of organic thin film transistors (OTFTs), the high operation voltage resulting from the low gate areal capacitance of traditional SiO 2 remains a severe limitation that hinders OTFTs' development in practical applications. In this regard, developing new materials with high- k characteristics at low cost is of great scientific and technological importance in the area of both academia and industry. In this thesis, we first describe a simple solution-based method to fabricate a high-k bilayer Al2Oy/TiOx (ATO) dielectric system at low temperature. Then the dielectric properties of the ATO are characterized and discussed in detail. Furthermore, by employing the high-k ATO as gate dielectric, low-voltage copper phthalocyanine (CuPc) based OTFTs are successfully developed. Interestingly, the obtained low-voltage CuPc TFT exhibits outstanding electrical performance, which is even higher than the device fabricated on traditional low-k SiO2. The above results seem to be contradictory to the reported results due to the fact that high-k usually shows adverse effect on the device performance. This abnormal phenomenon is then studied in detail. Characterization on the initial growth shows that the CuPc molecules assemble in a "rod-like" nano crystal with interconnected network on ATO, which probably promotes the charge carrier transport, whereas, they form isolated small islands with amorphous structure on SiO2. In addition, a better metal/organic contact is observed on ATO, which benefits the charge carrier injection. Our studies suggest that the low-temperature, solution-processed high-k ATO is a promising candidate for fabrication of high-performance, low-voltage OTFTs. Furthermore, it is well known that the properties of the dielectric/semiconductor and electrode/semiconductor interfaces are crucial in controlling the electrical properties of OTFTs. Hence, investigation the effects of interfaces

  11. Thickness scaling of atomic-layer-deposited HfO2 films and their application to wafer-scale graphene tunnelling transistors

    PubMed Central

    Jeong, Seong-Jun; Gu, Yeahyun; Heo, Jinseong; Yang, Jaehyun; Lee, Chang-Seok; Lee, Min-Hyun; Lee, Yunseong; Kim, Hyoungsub; Park, Seongjun; Hwang, Sungwoo

    2016-01-01

    The downscaling of the capacitance equivalent oxide thickness (CET) of a gate dielectric film with a high dielectric constant, such as atomic layer deposited (ALD) HfO2, is a fundamental challenge in achieving high-performance graphene-based transistors with a low gate leakage current. Here, we assess the application of various surface modification methods on monolayer graphene sheets grown by chemical vapour deposition to obtain a uniform and pinhole-free ALD HfO2 film with a substantially small CET at a wafer scale. The effects of various surface modifications, such as N-methyl-2-pyrrolidone treatment and introduction of sputtered ZnO and e-beam-evaporated Hf seed layers on monolayer graphene, and the subsequent HfO2 film formation under identical ALD process parameters were systematically evaluated. The nucleation layer provided by the Hf seed layer (which transforms to the HfO2 layer during ALD) resulted in the uniform and conformal deposition of the HfO2 film without damaging the graphene, which is suitable for downscaling the CET. After verifying the feasibility of scaling down the HfO2 thickness to achieve a CET of ~1.5 nm from an array of top-gated metal-oxide-graphene field-effect transistors, we fabricated graphene heterojunction tunnelling transistors with a record-low subthreshold swing value of <60 mV/dec on an 8″ glass wafer. PMID:26861833

  12. Fabrication of Zinc Oxide Transparent Thin-Film Transistor with ZrO2 Insulating Layer by Sol-Gel Method

    NASA Astrophysics Data System (ADS)

    Ohya, Yutaka; Kume, Takashi; Ban, Takayuki

    2005-04-01

    A thin-film transistor consisting of a ZnO active layer and a ZrO2 insulating layer was fabricated on a tin-doped indium oxide sputtered glass substrate as well as on a SiO2/Si wafer. The ZnO and ZrO2 layers were deposited by a sol-gel, dip-coating procedure. The resultant ZrO2 layer was about 150 nm thick and the ZnO layer 70 nm thick. The ZnO layer consisted of a single-grain thickness while the ZrO2 layer consisted of about 10 nm grains and was rather porous. The multilayered film consisting of ZnO/ZrO2/ITO/glass was transparent with 60-85% transmittance in the visible region and exhibited characteristics of a field-effect transistor. The multilayered film of the ZnO/ZrO2/SiO2/Si wafer was also examined and the behavior of the thin-film transistor was confirmed. The ZrO2 layer deposited on the SiO2/Si wafer minimized leakage through the insulating layer.

  13. Rapid low-temperature processing of metal-oxide thin film transistors with combined far ultraviolet and thermal annealing

    SciTech Connect

    Leppäniemi, J. Ojanperä, K.; Kololuoma, T.; Huttunen, O.-H.; Majumdar, H.; Alastalo, A.; Dahl, J.; Tuominen, M.; Laukkanen, P.

    2014-09-15

    We propose a combined far ultraviolet (FUV) and thermal annealing method of metal-nitrate-based precursor solutions that allows efficient conversion of the precursor to metal-oxide semiconductor (indium zinc oxide, IZO, and indium oxide, In{sub 2}O{sub 3}) both at low-temperature and in short processing time. The combined annealing method enables a reduction of more than 100 °C in annealing temperature when compared to thermally annealed reference thin-film transistor (TFT) devices of similar performance. Amorphous IZO films annealed at 250 °C with FUV for 5 min yield enhancement-mode TFTs with saturation mobility of ∼1 cm{sup 2}/(V·s). Amorphous In{sub 2}O{sub 3} films annealed for 15 min with FUV at temperatures of 180 °C and 200 °C yield TFTs with low-hysteresis and saturation mobility of 3.2 cm{sup 2}/(V·s) and 7.5 cm{sup 2}/(V·s), respectively. The precursor condensation process is clarified with x-ray photoelectron spectroscopy measurements. Introducing the FUV irradiation at 160 nm expedites the condensation process via in situ hydroxyl radical generation that results in the rapid formation of a continuous metal-oxygen-metal structure in the film. The results of this paper are relevant in order to upscale printed electronics fabrication to production-scale roll-to-roll environments.

  14. Furan Substituted Diketopyrrolopyrrole and Thienylenevinylene Based Low Band Gap Copolymer for High Mobility Organic Thin Film Transistors

    SciTech Connect

    Sonar, Prashant; Zhuo, Jing-Mei; Zhao, Li-Hong; Lim, Kai-Ming; Chen, Jihua; Rondinone, Adam Justin; Singh, Samarendra; Chua, Lay-Lay; Ho, Peter; Dodabalapur, Ananth

    2012-01-01

    A novel solution processable donor-acceptor (D-A) based low band gap polymer semiconductor poly{l_brace}3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thienylenevinylene{r_brace} (PDPPF-TVT), was designed and synthesized by a Pd-catalyzed Stille coupling route. An electron deficient furan based diketopyrrolopyrrole (DPP) block and electron rich thienylenevinylene (TVT) donor moiety were attached alternately in the polymer backbone. The polymer exhibited good solubility, film forming ability and thermal stability. The polymer exhibits wide absorption bands from 400 nm to 950 nm (UV-vis-NIR region) with absorption maximum centered at 782 nm in thin film. The optical band gap (E{sub g}{sup opt}) calculated from the polymer film absorption onset is around 1.37 eV. The {pi}-energy band level (ionization potential) calculated by photoelectron spectroscopy in air (PESA) for PDPPF-TVT is around 5.22 eV. AFM and TEM analyses of the polymer reveal nodular terrace morphology with optimized crystallinity after 200 C thermal annealing. This polymer exhibits p-channel charge transport characteristics when used as the active semiconductor in organic thin-film transistor (OTFT) devices. The highest hole mobility of 0.13 cm{sup 2} V{sup -1} s{sup -1} is achieved in bottom gate and top-contact OTFT devices with on/off ratios in the range of 10{sup 6}-10{sup 7}. This work reveals that the replacement of thiophene by furan in DPP copolymers exhibits such a high mobility, which makes DPP furan a promising block for making a wide range of promising polymer semiconductors for broad applications in organic electronics.

  15. Amorphous indium-tin-zinc oxide films deposited by magnetron sputtering with various reactive gases: Spatial distribution of thin film transistor performance

    SciTech Connect

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki

    2015-01-12

    This work presents the spatial distribution of electrical characteristics of amorphous indium-tin-zinc oxide film (a-ITZO), and how they depend on the magnetron sputtering conditions using O{sub 2}, H{sub 2}O, and N{sub 2}O as the reactive gases. Experimental results show that the electrical properties of the N{sub 2}O incorporated a-ITZO film has a weak dependence on the deposition location, which cannot be explained by the bombardment effect of high energy particles, and may be attributed to the difference in the spatial distribution of both the amount and the activity of the reactive gas reaching the substrate surface. The measurement for the performance of a-ITZO thin film transistor (TFT) also suggests that the electrical performance and device uniformity of a-ITZO TFTs can be improved significantly by the N{sub 2}O introduction into the deposition process, where the field mobility reach to 30.8 cm{sup 2} V{sup –1} s{sup –1}, which is approximately two times higher than that of the amorphous indium-gallium-zinc oxide TFT.

  16. A study of optical and electronic properties of organic thin film transistors based on naphthalenetetracarboxylic diimide derivatives

    NASA Astrophysics Data System (ADS)

    Yang, Dongxing

    The optical properties of spin cast thin films of N,N'-bis(3-phenoxy-3-phenoxy-phenoxy)-1,4,5,8-naphthalene-tetracarboxylic diimide (NDA-n2) and N,N'-bis(3-phenoxy-phenoxy)-1,4,5,8-naphthalene-tetracarboxylic diimide (NDA-n1) were investigated using spectroscopic ellipsometry (SE) complimented by optical absorption spectroscopy in the visible-near UV optical range and atomic force microscopy (AFM) for surface roughness. A combination of Tauc-Lorentzian and Gaussian oscillators model was used to fit the measurements obtained from SE. Film roughness results were also evaluated in the optical model using Bruggman Effective Medium Approximation (BEMA). The effect of different spin deposit conditions including spin speed, concentration of solution and deposition ambient on the NDA's film thickness, surface roughness, optical properties and optical anisotropy have been investigated. No anisotropy has been found for the spin cast film and moderate temperature annealing in high vacuum leads to film densification. Organic thin film transistors (OTFT's) were fabricated with NDA's as the active semiconductor layer, silicon dioxide (SiO2) as the gate dielectric, heavily doped silicon as the substrate, and vacuum evaporated gold lines as the source and drain contacts. The electronic properties were characterized using a custom built probe station. The custom probe station was automated with software program written in LabVIEW(TM). NDA's yielded a P-channel device. From transfer characteristic and turn-on plot, the charge mobility was calculated which was in the range of about 10 -2 cm2 V-1 s-1. Various post fabrication processes were carried out to optimize the device performance. Bottom contact configuration has shown higher charge mobility than top contact in this study. Moderate temperature annealing in high vacuum has improved the device mobility by several orders, yielding evidence for a hopping mechanism for charge transport in NDA's. The high mobility of NDA-n1 compared

  17. Single ion conducting, polymerized ionic liquid triblock copolymer films: high capacitance electrolyte gates for n-type transistors.

    PubMed

    Choi, Jae-Hong; Xie, Wei; Gu, Yuanyan; Frisbie, C Daniel; Lodge, Timothy P

    2015-04-01

    There has been impressive progress in the fabrication and characterization of p-type organic electrolyte-gated transistors (EGTs). Unfortunately, despite the importance of n-type organic transistors for complementary circuits, fewer investigations have focused on developing electrolytes as gate dielectrics for n-type organic semiconductors. Here, we present a novel single ion conductor, a polymerized ionic liquid (PIL) triblock copolymer (PS-PIL-PS) composed of styrene (PS) and 1-[(2-acryloyloxy)ethyl]-3-butylimidazolium bis(trifluoromethylsulfonyl)imide (PIL), that conducts only the TFSI anion. This triblock copolymer acts as a gate dielectric to allow low-voltage n-type organic EGT operation. Impedance characterization of PS-PIL-PS reveals that there are three polarization regions: (1) dipolar relaxation, (2) ion migration, and (3) electric double layer (EDL) formation. These polarization regions are controlled by film thickness, and rapid EDL formation can be obtained in thinner polyelectrolyte films. In particular, a 500 nm-thick polyelectrolyte film exhibits a large capacitance of ∼1 μF/cm(2) at 10 kHz. Employing this single ion conducting PIL triblock copolymer as the gate insulator, we achieved low voltage operation (<1 V supply) of poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) n-type organic EGTs (electron mobility of ∼0.008 cm(2)/(V·s) and ON/OFF current ratio of ∼2 × 10(3)) by preventing electrochemical doping. Furthermore, the recognition that the performance of n-type organic EGTs is diminished by 3D electrochemical doping suggests that it may be necessary to have a unipolar electrolyte to gate n-type organic semiconductors. Finally, we highlight that the use of PIL block copolymer electrolytes as gate insulators opens unique opportunities to explore the role of ion penetration in n-type organic EGTs by tuning the extent of electrochemical doping.

  18. Effect of Pentacene-dielectric Affinity on Pentacene Thin Film Growth Morphology in Organic Field-effect Transistors

    SciTech Connect

    S Kim; M Jang; H Yang; C Park

    2011-12-31

    Organic field-effect transistors (OFETs) are fabricated by depositing a thin film of semiconductor on the functionalized surface of a SiO{sub 2} dielectric. The chemical and morphological structures of the interface between the semiconductor and the functionalized dielectric are critical for OFET performance. We have characterized the effect of the affinity between semiconductor and functionalized dielectric on the properties of the semiconductor-dielectric interface. The crystalline microstructure/nanostructure of the pentacene semiconductor layers, grown on a dielectric substrate that had been functionalized with either poly(4-vinyl pyridine) or polystyrene (to control hydrophobicity), and grown under a series of substrate temperatures and deposition rates, were characterized by X-ray diffraction, photoemission spectroscopy, and atomic force microscopy. By comparing the morphological features of the semiconductor thin films with the device characteristics (field-effect mobility, threshold voltage, and hysteresis) of the OFET devices, the effect of affinity-driven properties on charge modulation, charge trapping, and charge carrier transport could be described.

  19. Modulation of superconducting critical temperature in niobium film by using all-solid-state electric-double-layer transistor

    SciTech Connect

    Tsuchiya, Takashi E-mail: TERABE.Kazuya@nims.go.jp; Moriyama, Satoshi; Terabe, Kazuya E-mail: TERABE.Kazuya@nims.go.jp; Aono, Masakazu

    2015-07-06

    An all-solid-state electric-double-layer transistor (EDLT) was fabricated for electrical modulation of the superconducting critical temperature (T{sub c}) of Nb film epitaxially grown on α-Al{sub 2}O{sub 3} (0001) single crystal. In an experiment, T{sub c} was modulated from 8.33 to 8.39 K while the gate voltage (V{sub G}) was varied from 2.5 to −2.5 V. The specific difference of T{sub c} for the applied V{sub G} was 12 mK/V, which is larger than that of an EDLT composed of ionic liquid. A T{sub c} enhancement of 300 mK was found at the Li{sub 4}SiO{sub 4}/Nb film interface and is attributed to an increase in density of states near the Fermi level due to lattice constant modulation. This solid electrolyte gating method should enable development of practical superconducting devices highly compatible with other electronic devices.

  20. Facile Routes To Improve Performance of Solution-Processed Amorphous Metal Oxide Thin Film Transistors by Water Vapor Annealing.

    PubMed

    Park, Won-Tae; Son, Inyoung; Park, Hyun-Woo; Chung, Kwun-Bum; Xu, Yong; Lee, Taegweon; Noh, Yong-Young

    2015-06-24

    Here, we report on a simple and high-rate oxidization method for producing solution-based compound mixtures of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) metal-oxide semiconductors (MOS) for thin-film transistor (TFT) applications. One of the issues for solution-based MOS fabrication is how to sufficiently oxidize the precursor in order to achieve high performance. As the oxidation rate of solution processing is lower than vacuum-based deposition such as sputtering, devices using solution-processed MOS exhibit relatively poorer performance. Therefore, we propose a method to prepare the metal-oxide precursor upon exposure to saturated water vapor in a closed volume for increasing the oxidization efficiency without requiring additional oxidizing agent. We found that the hydroxide rate of the MOS film exposed to water vapor is lower than when unexposed (≤18%). Hence, we successfully fabricated oxide TFTs with high electron mobility (27.9 cm(2)/V·s) and established a rapid process (annealing at 400 °C for 5 min) that is much shorter than the conventional as-deposited long-duration annealing (at 400 °C for 1 h) whose corresponding mobility is even lower (19.2 cm(2)/V·s). PMID:26043206

  1. A Comparison of Photo-Induced Hysteresis Between Hydrogenated Amorphous Silicon and Amorphous IGZO Thin-Film Transistors.

    PubMed

    Ha, Tae-Jun; Cho, Won-Ju; Chung, Hong-Bay; Koo, Sang-Mo

    2015-09-01

    We investigate photo-induced instability in thin-film transistors (TFTs) consisting of amorphous indium-gallium-zinc-oxide (a-IGZO) as active semiconducting layers by comparing with hydrogenated amorphous silicon (a-Si:H). An a-IGZO TFT exhibits a large hysteresis window in the illuminated measuring condition but no hysteresis window in the dark condition. On the contrary, a large hysteresis window measured in the dark condition in a-Si:H was not observed in the illuminated condition. Even though such materials possess the structure of amorphous phase, optical responses or photo instability in TFTs looks different from each other. Photo-induced hysteresis results from initially trapped charges at the interface between semiconductor and dielectric films or in the gate dielectric which possess absorption energy to interact with deep trap-states and affect the movement of Fermi energy level. In order to support our claim, we also perform CV characteristics in photo-induced hysteresis and demonstrate thermal-activated hysteresis. We believe that this work can provide important information to understand different material systems for optical engineering which includes charge transport and band transition. PMID:26716230

  2. Tailoring indium oxide nanocrystal synthesis conditions for air-stable high-performance solution-processed thin-film transistors.

    PubMed

    Swisher, Sarah L; Volkman, Steven K; Subramanian, Vivek

    2015-05-20

    Semiconducting metal oxides (ZnO, SnO2, In2O3, and combinations thereof) are a uniquely interesting family of materials because of their high carrier mobilities in the amorphous and generally disordered states, and solution-processed routes to these materials are of particular interest to the printed electronics community. Colloidal nanocrystal routes to these materials are particularly interesting, because nanocrystals may be formulated with tunable surface properties into stable inks, and printed to form devices in an additive manner. We report our investigation of an In2O3 nanocrystal synthesis for high-performance solution-deposited semiconductor layers for thin-film transistors (TFTs). We studied the effects of various synthesis parameters on the nanocrystals themselves, and how those changes ultimately impacted the performance of TFTs. Using a sintered film of solution-deposited In2O3 nanocrystals as the TFT channel material, we fabricated devices that exhibit field effect mobility of 10 cm(2)/(V s) and an on/off current ratio greater than 1 × 10(6). These results outperform previous air-stable nanocrystal TFTs, and demonstrate the suitability of colloidal nanocrystal inks for high-performance printed electronics.

  3. Electronic Structure of Low-Temperature Solution-Processed Amorphous Metal Oxide Semiconductors for Thin-Film Transistor Applications

    PubMed Central

    Socratous, Josephine; Banger, Kulbinder K; Vaynzof, Yana; Sadhanala, Aditya; Brown, Adam D; Sepe, Alessandro; Steiner, Ullrich; Sirringhaus, Henning

    2015-01-01

    The electronic structure of low temperature, solution-processed indium–zinc oxide thin-film transistors is complex and remains insufficiently understood. As commonly observed, high device performance with mobility >1 cm2 V−1 s−1 is achievable after annealing in air above typically 250 °C but performance decreases rapidly when annealing temperatures ≤200 °C are used. Here, the electronic structure of low temperature, solution-processed oxide thin films as a function of annealing temperature and environment using a combination of X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and photothermal deflection spectroscopy is investigated. The drop-off in performance at temperatures ≤200 °C to incomplete conversion of metal hydroxide species into the fully coordinated oxide is attributed. The effect of an additional vacuum annealing step, which is beneficial if performed for short times at low temperatures, but leads to catastrophic device failure if performed at too high temperatures or for too long is also investigated. Evidence is found that during vacuum annealing, the workfunction increases and a large concentration of sub-bandgap defect states (re)appears. These results demonstrate that good devices can only be achieved in low temperature, solution-processed oxides if a significant concentration of acceptor states below the conduction band minimum is compensated or passivated by shallow hydrogen and oxygen vacancy-induced donor levels. PMID:26190964

  4. Transport Properties of Anatase-TiO2 Polycrystalline-Thin-Film Field-Effect Transistors with Electrolyte Gate Layers

    NASA Astrophysics Data System (ADS)

    Horita, Ryohei; Ohtani, Kyosuke; Kai, Takahiro; Murao, Yusuke; Nishida, Hiroya; Toya, Taku; Seo, Kentaro; Sakai, Mio; Okuda, Tetsuji

    2013-11-01

    We have fabricated anatase-TiO2 polycrystalline-thin-film field-effect transistors (FETs) with poly(vinyl alcohol) (PVA), ion-liquid (IL), and ion-gel (IG) gate layers, and have tried to improve the response to gate voltage by varying the concentration of mobile ions in these electrolyte gate layers. The increase in the concentration of mobile ions by doping NaOH into the PVA gate layer or reducing the gelator in the IG gate layer markedly increases the drain-source current and reduces the driving gate voltage, which show that the mobile ions in the PVA, IL, and IG gate layers cause the formation of electric double layers (EDLs), which act as nanogap capacitors. In these TiO2-EDL-FETs, the slow formation of EDLs and the oxidation reaction at the interface between the surface of the TiO2 film and the electrolytes cause unideal FET properties. In the optimized IL and IG TiO2-EDL-FETs, the driving gate voltage is less than 1 V and the ON/OFF ratios of the transfer characteristics are about 1×104 at RT, and the nearly metallic state is realized at the interface purely by applying a gate voltage.

  5. Low-temperature processable inherently photosensitive polyimide as a gate insulator for organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Pyo, Seungmoon; Son, Hyunsam; Choi, Kil-Yeong; Yi, Mi Hye; Hong, Sung Kwon

    2005-03-01

    We have fabricated organic thin-film transistors (OTFTs) on polyethersulfone substrate using low-temperature processable, inherently photosensitive polyimide as the gate insulator and pentacene as the active material. The polyimide was prepared through two-step reaction. The polyimide precursor, poly(amic acid), was prepared from a dianhydride and aromatic diamine through a polycondensation reaction, and subsequently converted to its corresponding polyimide by a chemical imidization. Photolithographic properties of the polyimide are investigated. The pattern resolution of the cured polyimide was about 50μm. The pentacene OTFTs with the patterned polyimide were obtained with a carrier mobility of 0.1cm2/Vs and ION/IOFF of 5×105. The OTFT characteristics are discussed in more detail with respect to the electrical properties of the photosensitive polyimide thin film. This low-temperature photopatternable polyimide paves the way for the easy and low-cost fabrication of OTFT arrays without expensive and complicated photolithography and dry etching processes.

  6. A mixed solution-processed gate dielectric for zinc-tin oxide thin-film transistor and its MIS capacitance

    PubMed Central

    Kim, Hunho; Kwack, Young-Jin; Yun, Eui-Jung; Choi, Woon-Seop

    2016-01-01

    Solution-processed gate dielectrics were fabricated with the combined ZrO2 and Al2O3 (ZAO) in the form of mixed and stacked types for oxide thin film transistors (TFTs). ZAO thin films prepared with double coatings for solid gate dielectrics were characterized by analytical tools. For the first time, the capacitance of the oxide semiconductor was extracted from the capacitance-voltage properties of the zinc-tin oxide (ZTO) TFTs with the combined ZAO dielectrics by using the proposed metal-insulator-semiconductor (MIS) structure model. The capacitance evolution of the semiconductor from the TFT model structure described well the threshold voltage shift observed in the ZTO TFT with the ZAO (1:2) gate dielectric. The electrical properties of the ZTO TFT with a ZAO (1:2) gate dielectric showed low voltage driving with a field effect mobility of 37.01 cm2/Vs, a threshold voltage of 2.00 V, an on-to-off current ratio of 1.46 × 105, and a subthreshold slope of 0.10 V/dec. PMID:27641430

  7. Fabrication and characterization of p+-i-p+ type organic thin film transistors with electrodes of highly doped polymer

    NASA Astrophysics Data System (ADS)

    Tadaki, Daisuke; Ma, Teng; Zhang, Jinyu; Iino, Shohei; Hirano-Iwata, Ayumi; Kimura, Yasuo; Rosenberg, Richard A.; Niwano, Michio

    2016-04-01

    Organic thin film transistors (OTFTs) have been explored because of their advantageous features such as light-weight, flexible, and large-area. For more practical application of organic electronic devices, it is very important to realize OTFTs that are composed only of organic materials. In this paper, we have fabricated p+-i-p+ type of OTFTs in which an intrinsic (i) regioregular poly (3-hexylthiophene) (P3HT) layer is used as the active layer and highly doped p-type (p+) P3HT is used as the source and drain electrodes. The 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) was used as the p-type dopant. A fabricating method of p+-i-p+ OTFTs has been developed by using SiO2 and aluminum films as capping layers for micro-scaled patterning of the p+-P3HT electrodes. The characteristics of the OTFTs were examined using the photoelectron spectroscopy and electrical measurements. We demonstrated that the fabricated p+-i-p+ OTFTs work with carrier injection through a built-in potential at p+/i interfaces. We found that the p+-i-p+ OTFTs exhibit better FET characteristics than the conventional P3HT-OTFT with metal (Au) electrodes, indicating that the influence of a carrier injection barrier at the interface between the electrode and the active layer was suppressed by replacing the metal electrodes with p+-P3HT layers.

  8. A Comparison of Photo-Induced Hysteresis Between Hydrogenated Amorphous Silicon and Amorphous IGZO Thin-Film Transistors.

    PubMed

    Ha, Tae-Jun; Cho, Won-Ju; Chung, Hong-Bay; Koo, Sang-Mo

    2015-09-01

    We investigate photo-induced instability in thin-film transistors (TFTs) consisting of amorphous indium-gallium-zinc-oxide (a-IGZO) as active semiconducting layers by comparing with hydrogenated amorphous silicon (a-Si:H). An a-IGZO TFT exhibits a large hysteresis window in the illuminated measuring condition but no hysteresis window in the dark condition. On the contrary, a large hysteresis window measured in the dark condition in a-Si:H was not observed in the illuminated condition. Even though such materials possess the structure of amorphous phase, optical responses or photo instability in TFTs looks different from each other. Photo-induced hysteresis results from initially trapped charges at the interface between semiconductor and dielectric films or in the gate dielectric which possess absorption energy to interact with deep trap-states and affect the movement of Fermi energy level. In order to support our claim, we also perform CV characteristics in photo-induced hysteresis and demonstrate thermal-activated hysteresis. We believe that this work can provide important information to understand different material systems for optical engineering which includes charge transport and band transition.

  9. Tailoring indium oxide nanocrystal synthesis conditions for air-stable high-performance solution-processed thin-film transistors.

    PubMed

    Swisher, Sarah L; Volkman, Steven K; Subramanian, Vivek

    2015-05-20

    Semiconducting metal oxides (ZnO, SnO2, In2O3, and combinations thereof) are a uniquely interesting family of materials because of their high carrier mobilities in the amorphous and generally disordered states, and solution-processed routes to these materials are of particular interest to the printed electronics community. Colloidal nanocrystal routes to these materials are particularly interesting, because nanocrystals may be formulated with tunable surface properties into stable inks, and printed to form devices in an additive manner. We report our investigation of an In2O3 nanocrystal synthesis for high-performance solution-deposited semiconductor layers for thin-film transistors (TFTs). We studied the effects of various synthesis parameters on the nanocrystals themselves, and how those changes ultimately impacted the performance of TFTs. Using a sintered film of solution-deposited In2O3 nanocrystals as the TFT channel material, we fabricated devices that exhibit field effect mobility of 10 cm(2)/(V s) and an on/off current ratio greater than 1 × 10(6). These results outperform previous air-stable nanocrystal TFTs, and demonstrate the suitability of colloidal nanocrystal inks for high-performance printed electronics. PMID:25915094

  10. A mixed solution-processed gate dielectric for zinc-tin oxide thin-film transistor and its MIS capacitance.

    PubMed

    Kim, Hunho; Kwack, Young-Jin; Yun, Eui-Jung; Choi, Woon-Seop

    2016-01-01

    Solution-processed gate dielectrics were fabricated with the combined ZrO2 and Al2O3 (ZAO) in the form of mixed and stacked types for oxide thin film transistors (TFTs). ZAO thin films prepared with double coatings for solid gate dielectrics were characterized by analytical tools. For the first time, the capacitance of the oxide semiconductor was extracted from the capacitance-voltage properties of the zinc-tin oxide (ZTO) TFTs with the combined ZAO dielectrics by using the proposed metal-insulator-semiconductor (MIS) structure model. The capacitance evolution of the semiconductor from the TFT model structure described well the threshold voltage shift observed in the ZTO TFT with the ZAO (1:2) gate dielectric. The electrical properties of the ZTO TFT with a ZAO (1:2) gate dielectric showed low voltage driving with a field effect mobility of 37.01 cm(2)/Vs, a threshold voltage of 2.00 V, an on-to-off current ratio of 1.46 × 10(5), and a subthreshold slope of 0.10 V/dec. PMID:27641430

  11. A mixed solution-processed gate dielectric for zinc-tin oxide thin-film transistor and its MIS capacitance

    NASA Astrophysics Data System (ADS)

    Kim, Hunho; Kwack, Young-Jin; Yun, Eui-Jung; Choi, Woon-Seop

    2016-09-01

    Solution-processed gate dielectrics were fabricated with the combined ZrO2 and Al2O3 (ZAO) in the form of mixed and stacked types for oxide thin film transistors (TFTs). ZAO thin films prepared with double coatings for solid gate dielectrics were characterized by analytical tools. For the first time, the capacitance of the oxide semiconductor was extracted from the capacitance-voltage properties of the zinc-tin oxide (ZTO) TFTs with the combined ZAO dielectrics by using the proposed metal-insulator-semiconductor (MIS) structure model. The capacitance evolution of the semiconductor from the TFT model structure described well the threshold voltage shift observed in the ZTO TFT with the ZAO (1:2) gate dielectric. The electrical properties of the ZTO TFT with a ZAO (1:2) gate dielectric showed low voltage driving with a field effect mobility of 37.01 cm2/Vs, a threshold voltage of 2.00 V, an on-to-off current ratio of 1.46 × 105, and a subthreshold slope of 0.10 V/dec.

  12. National solar technology roadmap: Film-silicon PV

    SciTech Connect

    Keyes, Brian

    2007-06-01

    Silicon photovoltaic (PV) technologies are addressed in two different technology roadmaps: Film-Silicon PV and Wafer-Silicon PV. This Film-Silicon PV roadmap applies to all silicon-film technologies that rely on a supporting substrate such as glass, polymer, aluminum, stainless steel, or metallurgical-grade silicon. Such devices typically use amorphous, nanocrystalline, fine-grained polycrystalline, or epitaxial silicon layers that are 1–20 μm thick.

  13. Overview and Challenges of Thin Film Solar Electric Technologies

    SciTech Connect

    Ullal, H. S.

    2008-12-01

    In this paper, we report on the significant progress made worldwide by thin-film solar cells, namely, amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). Thin-film photovoltaic (PV) technology status is also discussed in detail. In addition, R&D and technology challenges in all three areas are elucidated. The worldwide estimated projection for thin-film PV technology production capacity announcements are estimated at more than 5000 MW by 2010.

  14. Characterization of bias induced metastability of amorphous silicon thin film transistor based passive pixel sensor switch and its impact on biomedical x-ray imaging application

    NASA Astrophysics Data System (ADS)

    Sultana, Afrin; Safavian, N.; Izadi, M. H.; Karim, K. S.; Rowlands, J. A.

    2009-02-01

    Active Matrix Flat Panel Imagers (AMFPIs) based on amorphous silicon (a-Si:H) thin film transistor (TFT) array is the most promising technology for large area biomedical x-ray imaging. a-Si:H TFT exhibits a metastable shift in its characteristics when subject to prolonged gate bias that results in a change in its threshold voltage (VΤ) and a corresponding change in ON resistance (RON). If not properly accounted for, the VΤ shift can be a major constraint in imaging applications as it contributes to the fixed pattern noise in the imager. In this work, we investigated the timedependent shift in VΤ (ΔVΤ) of a-Si:H TFTs stressed with the same bipolar pulsed bias used for static (chest radiography, mammography, and static protein crystallography) and real time imaging (low dose fluoroscopy at 15, 30 and 60 frames/second, and dynamic protein crystallography). We used the well known power law model of time dependent ΔVT to estimate the change in RON over time. Our calculation showed that RON can be decreased ~ 0.03 % per frame and ~ 5 % over 10,000 hours at 30 frames/second. We verified the theoretical results with measurement data. The implication of TFT metastability on the performance (NPS, and DQE) of biomedical imagers is discussed.

  15. Fabrication of high-performance ultra-thin-body SnO{sub 2} thin-film transistors using microwave-irradiation post-deposition annealing

    SciTech Connect

    Jo, Kwang-Won; Moon, Sung-Wan; Cho, Won-Ju

    2015-01-26

    We report on the fabrication of high-performance ultra-thin-body (UTB) SnO{sub 2} thin-film transistors (TFTs) using microwave-irradiation post-deposition annealing (PDA) at a low process temperature (<100 °C). We confirm that the electrical characteristics of SnO{sub 2} TFTs become drastically enhanced below a body thickness of 10 nm. The microwave-annealed UTB SnO{sub 2} TFTs with a thickness of 5 nm exhibited increased optical transmittance, as well as remarkable transfer characteristics: a high mobility of 35.4 cm{sup 2} V{sup −1} s{sup −1}, a drain current on/off ratio of 4.5 × 10{sup 7}, a steep subthreshold gate voltage swing of 623 mV/dec, and a clear enhancement-mode behavior. Additionally, the microwave-annealed SnO{sub 2} TFTs exhibited a better positive gate-bias stress/negative gate-bias stress immunity than thermally annealed SnO{sub 2} TFTs. Therefore, the thickness of the UTB SnO{sub 2} TFTs, as well as the microwave-annealing process, are both shown to be essential for transparent and flexible display technology.

  16. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend.

    PubMed

    Leydecker, Tim; Herder, Martin; Pavlica, Egon; Bratina, Gvido; Hecht, Stefan; Orgiu, Emanuele; Samorì, Paolo

    2016-09-01

    Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logic circuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organic memories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well as the number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-film transistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromic diarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bit storage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses. We also report robustness over 70 write-erase cycles and non-volatility exceeding 500 days. The device was implemented on a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics and smart nanodevices.

  17. Density of states of short channel amorphous In-Ga-Zn-O thin-film transistor arrays fabricated using manufacturable processes

    NASA Astrophysics Data System (ADS)

    Kim, Soo Chang; Kim, Young Sun; Kanicki, Jerzy

    2015-05-01

    The effect of temperature on the electrical characteristics of the short channel amorphous In-Ga-Zn-O (a-IGZO) thin-film transistor (TFT) arrays fabricated using manufacturable processes was investigated. This work shows that the fabricated TFT arrays are acceptable and stable enough for manufacturing of the ultra high definition (UHD) active matrix liquid crystal displays in size larger than 55 in. We observed that studied a-IGZO TFT arrays obeyed the Meyer-Neldel (MN) rule over a broad range of gate bias voltages. The MN rule and exponential subgap density of states (DOS) model were combined to extract the DOS distribution for the investigated a-IGZO TFT arrays. The results were consistent with the previous works on single a-IGZO TFTs. This study demonstrates that this method of DOS extraction can be applied to both single devices and arrays, and is reproducible from lab to lab. We believe that this approach of DOS extraction is useful for further development of UHD flat panel display technology.

  18. Scaling and Graphical Transport-Map Analysis of Ambipolar Schottky-Barrier Thin-Film Transistors Based on a Parallel Array of Si Nanowires.

    PubMed

    Jeon, Dae-Young; Pregl, Sebastian; Park, So Jeong; Baraban, Larysa; Cuniberti, Gianaurelio; Mikolajick, Thomas; Weber, Walter M

    2015-07-01

    Si nanowire (Si-NW) based thin-film transistors (TFTs) have been considered as a promising candidate for next-generation flexible and wearable electronics as well as sensor applications with high performance. Here, we have fabricated ambipolar Schottky-barrier (SB) TFTs consisting of a parallel array of Si-NWs and performed an in-depth study related to their electrical performance and operation mechanism through several electrical parameters extracted from the channel length scaling based method. Especially, the newly suggested current-voltage (I-V) contour map clearly elucidates the unique operation mechanism of the ambipolar SB-TFTs, governed by Schottky-junction between NiSi2 and Si-NW. Further, it reveals for the first-time in SB based FETs the important internal electrostatic coupling between the channel and externally applied voltages. This work provides helpful information for the realization of practical circuits with ambipolar SB-TFTs that can be transferred to different substrate technologies and applications.

  19. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend.

    PubMed

    Leydecker, Tim; Herder, Martin; Pavlica, Egon; Bratina, Gvido; Hecht, Stefan; Orgiu, Emanuele; Samorì, Paolo

    2016-09-01

    Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logic circuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organic memories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well as the number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-film transistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromic diarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bit storage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses. We also report robustness over 70 write-erase cycles and non-volatility exceeding 500 days. The device was implemented on a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics and smart nanodevices. PMID:27323302

  20. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend

    NASA Astrophysics Data System (ADS)

    Leydecker, Tim; Herder, Martin; Pavlica, Egon; Bratina, Gvido; Hecht, Stefan; Orgiu, Emanuele; Samorì, Paolo

    2016-09-01

    Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logic circuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organic memories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well as the number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-film transistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromic diarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bit storage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses. We also report robustness over 70 write-erase cycles and non-volatility exceeding 500 days. The device was implemented on a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics and smart nanodevices.

  1. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend

    NASA Astrophysics Data System (ADS)

    Leydecker, Tim; Herder, Martin; Pavlica, Egon; Bratina, Gvido; Hecht, Stefan; Orgiu, Emanuele; Samorì, Paolo

    2016-09-01

    Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logic circuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organic memories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well as the number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-film transistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromic diarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bit storage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses. We also report robustness over 70 write–erase cycles and non-volatility exceeding 500 days. The device was implemented on a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics and smart nanodevices.

  2. Effect of hafnium doping on density of states in dual-target magnetron co-sputtering HfZnSnO thin film transistors

    SciTech Connect

    Huang, Chuan-Xin; Li, Jun Fu, Yi-Zhou; Jiang, Xue-Yin; Zhang, Jian-Hua; Zhang, Zhi-Lin

    2015-11-23

    This study investigates the effect of hafnium doping on the density of states (DOSs) in HfZnSnO thin film transistors fabricated by dual-target magnetron co-sputtering system. The DOSs is extracted by temperature-dependent field-effect measurements, and they decrease from 1.1 × 10{sup 17} to 4.6 × 10{sup 16 }eV/cm{sup 3} with increasing the hafnium concentrations. The behavior of DOSs for the increasing hafnium concentration HfZnSnO thin film transistors can be confirmed by both the reduction of ΔV{sub T} under bias stress and the trapping charges calculated by capacitance voltage measurements. It suggests that the reduction in DOSs due to the hafnium doping is closely related with the bias stability and thermal stability.

  3. Black phosphorus radio-frequency transistors.

    PubMed

    Wang, Han; Wang, Xiaomu; Xia, Fengnian; Wang, Luhao; Jiang, Hao; Xia, Qiangfei; Chin, Matthew L; Dubey, Madan; Han, Shu-jen

    2014-11-12

    Few-layer and thin film forms of layered black phosphorus (BP) have recently emerged as a promising material for applications in high performance nanoelectronics and infrared optoelectronics. Layered BP thin films offer a moderate bandgap of around 0.3 eV and high carrier mobility, which lead to transistors with decent on-off ratios and high on-state current densities. Here, we demonstrate the gigahertz frequency operation of BP field-effect transistors for the first time. The BP transistors demonstrated here show respectable current saturation with an on-off ratio that exceeds 2 × 10(3). We achieved a current density in excess of 270 mA/mm and DC transconductance above 180 mS/mm for hole conduction. Using standard high frequency characterization techniques, we measured a short-circuit current-gain cutoff frequency fT of 12 GHz and a maximum oscillation frequency fmax of 20 GHz in 300 nm channel length devices. BP devices may offer advantages over graphene transistors for high frequency electronics in terms of voltage and power gain due to the good current saturation properties arising from their finite bandgap, thus can be considered as a promising candidate for the future high performance thin film electronics technology for operation in the multi-GHz frequency range and beyond.

  4. A Soluble Dynamic Complex Strategy for the Solution-Processed Fabrication of Organic Thin-Film Transistors of a Boron-Containing Polycyclic Aromatic Hydrocarbon.

    PubMed

    Matsuo, Kyohei; Saito, Shohei; Yamaguchi, Shigehiro

    2016-09-19

    The solution-processed fabrication of thin films of organic semiconductors enables the production of cost-effective, large-area organic electronic devices under mild conditions. The formation/dissociation of a dynamic B-N coordination bond can be used for the solution-processed fabrication of semiconducting films of polycyclic aromatic hydrocarbon (PAH) materials. The poor solubility of a boron-containing PAH in chloroform, toluene, and chlorobenzene was significantly improved by addition of minor amounts (1 wt % of solvent) of pyridine derivatives, as their coordination to the boron atom suppresses the inherent propensity of the PAHs to form π-stacks. Spin-coating solutions of the thus formed Lewis acid-base complexes resulted in the formation of amorphous thin films, which could be converted into polycrystalline films of the boron-containing PAH upon thermal annealing. Organic thin-film transistors prepared by this solution process displayed typical p-type characteristics. PMID:27576306

  5. A Soluble Dynamic Complex Strategy for the Solution-Processed Fabrication of Organic Thin-Film Transistors of a Boron-Containing Polycyclic Aromatic Hydrocarbon.

    PubMed

    Matsuo, Kyohei; Saito, Shohei; Yamaguchi, Shigehiro

    2016-09-19

    The solution-processed fabrication of thin films of organic semiconductors enables the production of cost-effective, large-area organic electronic devices under mild conditions. The formation/dissociation of a dynamic B-N coordination bond can be used for the solution-processed fabrication of semiconducting films of polycyclic aromatic hydrocarbon (PAH) materials. The poor solubility of a boron-containing PAH in chloroform, toluene, and chlorobenzene was significantly improved by addition of minor amounts (1 wt % of solvent) of pyridine derivatives, as their coordination to the boron atom suppresses the inherent propensity of the PAHs to form π-stacks. Spin-coating solutions of the thus formed Lewis acid-base complexes resulted in the formation of amorphous thin films, which could be converted into polycrystalline films of the boron-containing PAH upon thermal annealing. Organic thin-film transistors prepared by this solution process displayed typical p-type characteristics.

  6. Pulsed direct flame deposition and thermal annealing of transparent amorphous indium zinc oxide films as active layers in field effect transistors.

    PubMed

    Kilian, Daniel; Polster, Sebastian; Vogeler, Isabell; Jank, Michael P M; Frey, Lothar; Peukert, Wolfgang

    2014-08-13

    Indium-zinc oxide (IZO) films were deposited via flame spray pyrolysis (FSP) by pulsewise shooting a Si/SiO2 substrate directly into the combustion area of the flame. Based on UV-vis measurements of thin-films deposited on glass substrates, the optimal deposition parameters with respect to low haze values and film thicknesses of around 100 nm were determined. Thermal annealing of the deposited films at temperatures between 300 and 700 °C was carried out and staggered bottom gate thin-film transistors (TFT) were fabricated. The thin films were investigated by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, and room-temperature photoluminescence measurements. The outcome of these investigations lead to two major requirements in order to implement a working TFT: (i) organic residues from the deposition process need to be removed and (ii) the net free charge carrier concentration has to be minimized by controlling the trap states in the semiconductor. The optimal annealing temperature was 300 °C as both requirements are fulfilled best in this case. This leads to field effect transistors with a low hysteresis, a saturation mobility of μSat = 0.1 cm(2)/(V s), a threshold voltage of Vth = -18.9 V, and an Ion/Ioff ratio on the order of 10(7). Depending on thermal treatment, the defect density changes significantly strongly influencing the transfer characteristics of the device. PMID:25029269

  7. The Effects of UV Treatment on Thermal and Plasma-Enhanced Atomic Layer Deposition of ZnO Thin Film Transistor

    SciTech Connect

    Kim, Jae-Min; Kim, Doyoung; Kim, Hyungjun; Lim, S. J.

    2011-12-23

    We investigated the ultraviolet (UV) light photostability of plasma-enhanced and thermal atomic layer deposition of ZnO thin film transistor (TFT). The negative shift of threshold voltage was similarly observed in both cases by UV exposure due to the increment of carrier concentration. Additionally, the transfer curves of TFT using thermal ALD ZnO:N active layer were exhibited recovery characteristics.

  8. High-Mobility Transistors Based on Large-Area and Highly Crystalline CVD-Grown MoSe2 Films on Insulating Substrates.

    PubMed

    Rhyee, Jong-Soo; Kwon, Junyeon; Dak, Piyush; Kim, Jin Hee; Kim, Seung Min; Park, Jozeph; Hong, Young Ki; Song, Won Geun; Omkaram, Inturu; Alam, Muhammad A; Kim, Sunkook

    2016-03-23

    Large-area and highly crystalline CVD-grown multilayer MoSe2 films exhibit a well-defined crystal structure (2H phase) and large grains reaching several hundred micrometers. Multilayer MoSe2 transistors exhibit high mobility up to 121 cm(2) V(-1) s(-1) and excellent mechanical stability. These results suggest that high mobility materials will be indispensable for various future applications such as high-resolution displays and human-centric soft electronics.

  9. Chemical composition and temperature dependent performance of ZnO-thin film transistors deposited by pulsed and continuous spray pyrolysis

    SciTech Connect

    Ortel, Marlis; Balster, Torsten; Wagner, Veit

    2013-12-21

    Zinc oxide thin film transistors (TFTs) deposited by continuous and pulsed spray pyrolysis were investigated to analyze process kinetics which make reduction of process temperature possible. Thus, fluid mechanics, chemical composition, electrical performance, and deposition and annealing temperature were systematically analyzed. It was found that ZnO layers continuously deposited at 360 °C contained zinc oxynitrides, CO{sub 3}, and hydro carbonate groups from pyrolysis of basic zinc acetate. Statistically, every second wurtzite ZnO unit cell contained an impurity atom. The purity and performance of the ZnO-TFTs increased systematically with increasing deposition temperature due to an improved oxidation processes. At 500 °C the zinc to oxygen ratio exceeded a high value of 0.96. Additionally, the ZnO film was not found to be in a stabilized state after deposition even at high temperatures. Introducing additional subsequent annealing steps stabilizes the film and allows the reduction of the overall thermal stress to the substrate. Further improvement of device characteristics was obtained by pulsed deposition which allowed a more effective transport of the by-products and oxygen. A significant reduction of the deposition temperature by 140 °C was achieved compared to the same performance as in continuous deposition mode. The trap density close to the Fermi energy could be reduced by a factor of two to 4 × 10{sup 17} eV{sup −1} cm{sup −3} due to the optimized combustion process on the surface. The optimization of the deposition processes made the fabrication of TFTs with excellent performance possible. The mobility was high and exceeded 12 cm{sup 2}/V s, the subthreshold slope was 0.3 V dec{sup −1}, and an on-set close to the ideal value of 0 V was achieved.

  10. Exploration of maximum count rate capabilities for large-area photon counting arrays based on polycrystalline silicon thin-film transistors

    NASA Astrophysics Data System (ADS)

    Liang, Albert K.; Koniczek, Martin; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua

    2016-03-01

    Pixelated photon counting detectors with energy discrimination capabilities are of increasing clinical interest for x-ray imaging. Such detectors, presently in clinical use for mammography and under development for breast tomosynthesis and spectral CT, usually employ in-pixel circuits based on crystalline silicon - a semiconductor material that is generally not well-suited for economic manufacture of large-area devices. One interesting alternative semiconductor is polycrystalline silicon (poly-Si), a thin-film technology capable of creating very large-area, monolithic devices. Similar to crystalline silicon, poly-Si allows implementation of the type of fast, complex, in-pixel circuitry required for photon counting - operating at processing speeds that are not possible with amorphous silicon (the material currently used for large-area, active matrix, flat-panel imagers). The pixel circuits of two-dimensional photon counting arrays are generally comprised of four stages: amplifier, comparator, clock generator and counter. The analog front-end (in particular, the amplifier) strongly influences performance and is therefore of interest to study. In this paper, the relationship between incident and output count rate of the analog front-end is explored under diagnostic imaging conditions for a promising poly-Si based design. The input to the amplifier is modeled in the time domain assuming a realistic input x-ray spectrum. Simulations of circuits based on poly-Si thin-film transistors are used to determine the resulting output count rate as a function of input count rate, energy discrimination threshold and operating conditions.

  11. A Study on the Fabrication of Organic Thin Film Transistor Sensors using Gravure Printing

    NASA Astrophysics Data System (ADS)

    Hwang, Won-Jin; Hong, Jae-Min; Ju, Byeong-Kwon; Yu, Jae-Woong

    2011-12-01

    Conducting polymer TFT was fabricated with gravure printing technique using a vapor polymerization method. Polyvinyl alcohol (PVA) with excellent film forming characteristics was used as a matrix polymer. After the printing of the oxidant dispersed PVA dissolved in DI water, the vapor polymerization of the pyrrole monomer formed a thin conducting polymer film. The conductivity of the film was dependent on the concentration of the oxidant and the polymerization time. In order to be used for TFT application, the conductivity had to be reduced by controlling the various conditions. The effect of exposure to humidity on TFT signal was studied.

  12. Chemical Gated Field Effect Transistor by Hybrid Integration of One-Dimensional Silicon Nanowire and Two-Dimensional Tin Oxide Thin Film for Low Power Gas Sensor.

    PubMed

    Han, Jin-Woo; Rim, Taiuk; Baek, Chang-Ki; Meyyappan, M

    2015-09-30

    Gas sensors based on metal-oxide-semiconductor transistor with the polysilicon gate replaced by a gas sensitive thin film have been around for over 50 years. These are not suitable for the emerging mobile and wearable sensor platforms due to operating voltages and powers far exceeding the supply capability of batteries. Here we present a novel approach to decouple the chemically sensitive region from the conducting channel for reducing the drive voltage and increasing reliability. This chemically gated field effect transistor uses silicon nanowire for the current conduction channel with a tin oxide film on top of the nanowire serving as the gas sensitive medium. The potential change induced by the molecular adsorption and desorption allows the electrically floating tin oxide film to gate the silicon channel. As the device is designed to be normally off, the power is consumed only during the gas sensing event. This feature is attractive for the battery operated sensor and wearable electronics. In addition, the decoupling of the chemical reaction and the current conduction regions allows the gas sensitive material to be free from electrical stress, thus increasing reliability. The device shows excellent gas sensitivity to the tested analytes relative to conventional metal oxide transistors and resistive sensors.

  13. Chemical Gated Field Effect Transistor by Hybrid Integration of One-Dimensional Silicon Nanowire and Two-Dimensional Tin Oxide Thin Film for Low Power Gas Sensor.

    PubMed

    Han, Jin-Woo; Rim, Taiuk; Baek, Chang-Ki; Meyyappan, M

    2015-09-30

    Gas sensors based on metal-oxide-semiconductor transistor with the polysilicon gate replaced by a gas sensitive thin film have been around for over 50 years. These are not suitable for the emerging mobile and wearable sensor platforms due to operating voltages and powers far exceeding the supply capability of batteries. Here we present a novel approach to decouple the chemically sensitive region from the conducting channel for reducing the drive voltage and increasing reliability. This chemically gated field effect transistor uses silicon nanowire for the current conduction channel with a tin oxide film on top of the nanowire serving as the gas sensitive medium. The potential change induced by the molecular adsorption and desorption allows the electrically floating tin oxide film to gate the silicon channel. As the device is designed to be normally off, the power is consumed only during the gas sensing event. This feature is attractive for the battery operated sensor and wearable electronics. In addition, the decoupling of the chemical reaction and the current conduction regions allows the gas sensitive material to be free from electrical stress, thus increasing reliability. The device shows excellent gas sensitivity to the tested analytes relative to conventional metal oxide transistors and resistive sensors. PMID:26381613

  14. Intense pulsed light induced crystallization of a liquid-crystalline polymer semiconductor for efficient production of flexible thin-film transistors.

    PubMed

    Yang, Hee Yeon; Park, Han-Wool; Kim, Soo Jin; Hong, Jae-Min; Kim, Tae Whan; Kim, Do Hwan; Lim, Jung Ah

    2016-02-14

    Here we demonstrated the split-second crystallization of a liquid-crystalline conjugated polymer semiconductor induced by irradiation with intense pulsed white light (IPWL) for the efficient improvement of electrical properties of flexible thin film transistors. A few seconds of IPWL irradiation of poly(didodecylquaterthiophene-alt-didodecylbithiazole) (PQTBTz-C12) thin films generated heat energy through the photo-thermal effect, leading to the crystallization of PQTBTz-C12 and formation of nodule-like nanostructures. The IPWL-induced crystallization of PQTBTz-C12 resulted in a threefold improvement in the field-effect mobility of thin film transistors compared to as-prepared devices. The conformational change of the PQTBTz-C12 chains was found to be strongly related to the irradiation fluence. As a proof-of-concept, the IPWL treatment was successfully applied to the PQTBTz-C12 layer in flexible transistors based on plastic substrates. The performance of these flexible devices was significantly improved after only 0.6 s of IPWL treatment, without deformation of the plastic substrate. PMID:26795202

  15. Improved contact resistance in ReSe2 thin film field-effect transistors

    NASA Astrophysics Data System (ADS)

    Corbet, Chris M.; Sonde, Sushant S.; Tutuc, Emanuel; Banerjee, Sanjay K.

    2016-04-01

    We report the fabrication and device characteristics of exfoliated, few-layer, ReSe2 field effect transistors (FET) and a method to improve contact resistance by up to three orders of magnitude using ultra-high-vacuum annealing (UHV). Many devices were studied in the absence of light and we found an average contact of 750 Ω . cm after UHV treatment. The median FET metrics were similar to other transition metal dichalcogenides: field effect mobility ˜6.7 cm2/V . s, subthreshold swing ˜1.2 V/decade, and Ion/Ioff ˜ 105. In devices with low Rc current saturation was observed and is attributed to injection limited transport.

  16. Artificial neural systems using memristive synapses and nano-crystalline silicon thin-film transistors

    NASA Astrophysics Data System (ADS)

    Cantley, Kurtis D.

    Future computer systems will not rely solely on digital processing of inputs from well-defined data sets. They will also be required to perform various computational tasks using large sets of ill-defined information from the complex environment around them. The most efficient processor of this type of information known today is the human brain. Using a large number of primitive elements (˜1010 neurons in the neocortex) with high parallel connectivity (each neuron has ˜104 synapses), brains have the remarkable ability to recognize and classify patterns, predict outcomes, and learn from and adapt to incredibly diverse sets of problems. A reasonable goal in the push to increase processing power of electronic systems would thus be to implement artificial neural networks in hardware that are compatible with today's digital processors. This work focuses on the feasibility of utilizing non-crystalline silicon devices in neuromorphic electronics. Hydrogenated amorphous silicon (a-Si:H) nanowire transistors with Schottky barrier source/drain junctions, as well as a-Si:H/Ag resistive switches are fabricated and characterized. In the transistors, it is found that the on-current scales linearly with the effective width W eff of the channel nanowire array down to at least 20 nm. The solid-state electrolyte resistive switches (memristors) are shown to exhibit the proper current-voltage hysteresis. SPICE models of similar devices are subsequently developed to investigate their performance in neural circuits. The resulting SPICE simulations demonstrate spiking properties and synaptic learning rules that are incredibly similar to those in biology. Specifically, the neuron circuits can be designed to mimic the firing characteristics of real neurons, and Hebbian learning rules are investigated. Finally, some applications are presented, including associative learning analogous to the classical conditioning experiments originally performed by Pavlov, and frequency and pattern

  17. Thin Film Technology Development for the Powersphere

    NASA Technical Reports Server (NTRS)

    Simburger, Edward J.; Matsumoto, James H.; Giants, Thomas W.; Garcia, Alexander, III; Liu, Simon; Rawal, Suraj P.; Perry, Alan R.; Marshall, Craig H.; Lin, John K.; Scarborough, Stephen; Curtis, Henry B.

    2003-01-01

    The Aerospace Corporation, NASA Glenn Research Center, Lockheed-Martin, and ILC Dover over the past two years have been engaged in developing a Multifunctional Inflatable Structure for the Powersphere Concept under contract with NASA (NAS3-01115). The Powersphere concept consists of a relatively large spherical solar array, which would be deployed from a microsatellite. The Powersphere structure and the deployment method was patented by the Aerospace Corporation (U.S. Patent Numbers 6,284,966 B 1 and 6,3 18,675). The work on this project has resulted in a number of technological innovations in the state of the art for integrating flexible thin-film solar cells with flex circuit harness technology and inflatable ultraviolet-light-rigidizable structures. The specific power, specific volume, for the Powersphere are presented in Figures 1 and 2 as a function of solar cell technology and efficiency. The Powersphere will enable microsatellite missions across NASA enterprises and DoD missions by providing ample electric power at an affordable cost. The Powersphere design provides attitude-independent electric power and thermal control for an enclosed microsatellite payload. The design is scalable, robust in high radiation environments and provides sufficient electric power to allow the use of electric propulsion. Electric propulsion enables precise positioning of microsatellites which is required for inspectors that would be deployed to inspect the International Space Station, Space Shuttle or large unmanned spacecraft. The Powersphere allows for efficient launch packaging versus deployed volume as shown in Figure 3.

  18. Thin film three-dimensional topological insulator metal-oxide-semiconductor field-effect-transistors: A candidate for sub-10 nm devices

    SciTech Connect

    Akhavan, N. D. Jolley, G.; Umana-Membreno, G. A.; Antoszewski, J.; Faraone, L.

    2014-08-28

    Three-dimensional (3D) topological insulators (TI) are a new state of quantum matter in which surface states reside in the bulk insulating energy bandgap and are protected by time-reversal symmetry. It is possible to create an energy bandgap as a consequence of the interaction between the conduction band and valence band surface states from the opposite surfaces of a TI thin film, and the width of the bandgap can be controlled by the thin film thickness. The formation of an energy bandgap raises the possibility of thin-film TI-based metal-oxide-semiconductor field-effect-transistors (MOSFETs). In this paper, we explore the performance of MOSFETs based on thin film 3D-TI structures by employing quantum ballistic transport simulations using the effective continuous Hamiltonian with fitting parameters extracted from ab-initio calculations. We demonstrate that thin film transistors based on a 3D-TI structure provide similar electrical characteristics compared to a Si-MOSFET for gate lengths down to 10 nm. Thus, such a device can be a potential candidate to replace Si-based MOSFETs in the sub-10 nm regime.

  19. Spatial atmospheric atomic layer deposition of InxGayZnzO for thin film transistors.

    PubMed

    Illiberi, A; Cobb, B; Sharma, A; Grehl, T; Brongersma, H; Roozeboom, F; Gelinck, G; Poodt, P

    2015-02-18

    We have investigated the nucleation and growth of InGaZnO thin films by spatial atmospheric atomic layer deposition. Diethyl zinc (DEZ), trimethyl indium (TMIn), triethyl gallium (TEGa), and water were used as Zn, In, Ga and oxygen precursors, respectively. The vaporized metal precursors have been coinjected in the reactor. The metal composition of InGaZnO has been controlled by varying the TMIn or TEGa flow to the reactor, for a given DEZ flow and exposure time. The morphology of the films changes from polycrystalline, for ZnO and In-doped ZnO, to amorphous for In-rich IZO and InGaZnO. The use of these films as the active channel in TFTs has been demonstrated and the influence of In and Ga cations on the electrical characteristics of the TFTs has been studied.

  20. Design of an Auto-zeroed, Differential, Organic Thin-film Field-effect Transistor Amplifier for Sensor Applications

    NASA Technical Reports Server (NTRS)

    Binkley, David M.; Verma, Nikhil; Crawford, Robert L.; Brandon, Erik; Jackson, Thomas N.

    2004-01-01

    Organic strain gauge and other sensors require high-gain, precision dc amplification to process their low-level output signals. Ideally, amplifiers would be fabricated using organic thin-film field-effect transistors (OTFT's) adjacent to the sensors. However, OTFT amplifiers exhibit low gain and high input-referred dc offsets that must be effectively managed. This paper presents a four-stage, cascaded differential OTFT amplifier utilizing switched capacitor auto-zeroing. Each stage provides a nominal voltage gain of four through a differential pair driving low-impedance active loads, which provide common-mode output voltage control. p-type pentacence OTFT's are used for the amplifier devices and auto-zero switches. Simulations indicate the amplifier provides a nominal voltage gain of 280 V/V and effectively amplifies a 1-mV dc signal in the presence of 500-mV amplifier input-referred dc offset voltages. Future work could include the addition of digital gain calibration and offset correction of residual offsets associated with charge injection imbalance in the differential circuits.