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Sample records for nanotube field-effect transistors

  1. Hysteresis modeling in ballistic carbon nanotube field-effect transistors.

    PubMed

    Liu, Yian; Moura, Mateus S; Costa, Ademir J; de Almeida, Luiz Alberto L; Paranjape, Makarand; Fontana, Marcio

    2014-01-01

    Theoretical models are adapted to describe the hysteresis effects seen in the electrical characteristics of carbon nanotube field-effect transistors. The ballistic transport model describes the contributions of conduction energy sub-bands over carbon nanotube field-effect transistor drain current as a function of drain-source and gate-source voltages as well as other physical parameters of the device. The limiting-loop proximity model, originally developed to understand magnetic hysteresis, is also utilized in this work. The curves obtained from our developed model corroborate well with the experimentally derived hysteretic behavior of the transistors. Modeling the hysteresis behavior will enable designers to reliably use these effects in both analog and memory applications. PMID:25187698

  2. Hysteresis modeling in ballistic carbon nanotube field-effect transistors

    PubMed Central

    Liu, Yian; Moura, Mateus S; Costa, Ademir J; de Almeida, Luiz Alberto L; Paranjape, Makarand; Fontana, Marcio

    2014-01-01

    Theoretical models are adapted to describe the hysteresis effects seen in the electrical characteristics of carbon nanotube field-effect transistors. The ballistic transport model describes the contributions of conduction energy sub-bands over carbon nanotube field-effect transistor drain current as a function of drain-source and gate-source voltages as well as other physical parameters of the device. The limiting-loop proximity model, originally developed to understand magnetic hysteresis, is also utilized in this work. The curves obtained from our developed model corroborate well with the experimentally derived hysteretic behavior of the transistors. Modeling the hysteresis behavior will enable designers to reliably use these effects in both analog and memory applications. PMID:25187698

  3. MoS{sub 2} nanotube field effect transistors

    SciTech Connect

    Strojnik, M. E-mail: dragan.mihailovic@ijs.si; Mrzel, A.; Buh, J.; Strle, J.; Kovic, A.; Mihailovic, D. E-mail: dragan.mihailovic@ijs.si

    2014-09-15

    We report on electric field effects on electron transport in multi-walled MoS{sub 2} nanotubes (NTs), fabricated using a two-step synthesis method from Mo{sub 6}S{sub x}I{sub 9-x} nanowire bundle precursors. Transport properties were measured on 20 single nanotube field effect transistor (FET) devices, and compared with MoS{sub 2} layered crystal devices prepared using identical fabrication techniques. The NTs exhibited mobilities of up to 0.014 cm{sup 2}V{sup −1}s{sup −1} and an on/off ratio of up to 60. As such they are comparable with previously reported WS{sub 2} nanotube FETs, but materials defects and imperfections apparently limit their performance compared with multilayer MoS{sub 2} FETs with similar number of layers.

  4. Enhanced shot noise in carbon nanotube field-effect transistors

    SciTech Connect

    Betti, A.; Fiori, G.; Iannaccone, G.

    2009-12-21

    We predict shot noise enhancement in defect-free carbon nanotube field-effect transistors through a numerical investigation based on the self-consistent solution of the Poisson and Schroedinger equations within the nonequilibrium Green's functions formalism, and on a Monte Carlo approach to reproduce injection statistics. Noise enhancement is due to the correlation between trapping of holes from the drain into quasibound states in the channel and thermionic injection of electrons from the source, and can lead to an appreciable Fano factor of 1.22 at room temperature.

  5. Directed Assembly of Single Wall Carbon Nanotube Field Effect Transistors.

    PubMed

    Penzo, Erika; Palma, Matteo; Chenet, Daniel A; Ao, Geyou; Zheng, Ming; Hone, James C; Wind, Shalom J

    2016-02-23

    The outstanding electronic properties of single wall carbon nanotubes (SWCNTs) have made them prime candidates for future nanoelectronics technologies. One of the main obstacles to the implementation of advanced SWCNT electronics to date is the inability to arrange them in a manner suitable for complex circuits. Directed assembly of SWCNT segments onto lithographically patterned and chemically functionalized substrates is a promising way to organize SWCNTs in topologies that are amenable to integration for advanced applications, but the placement and orientational control required have not yet been demonstrated. We have developed a technique for assembling length sorted and chirality monodisperse DNA-wrapped SWCNT segments on hydrophilic lines patterned on a passivated oxidized silicon substrate. Placement of individual SWCNT segments at predetermined locations was achieved with nanometer accuracy. Three terminal electronic devices, consisting of a single SWCNT segment placed either beneath or on top of metallic source/drain electrodes were fabricated. Devices made with semiconducting nanotubes behaved as typical p-type field effect transistors (FETs), whereas devices made with metallic nanotubes had a finite resistance with little or no gate modulation. This scalable, high resolution approach represents an important step forward toward the potential implementation of complex SWCNT devices and circuits. PMID:26807948

  6. Fabrication of Carbon Nanotube Field Effect Transistors Using Plasma-Enhanced Chemical Vapor Deposition Grown Nanotubes

    NASA Astrophysics Data System (ADS)

    Ohnaka, Hirofumi; Kojima, Yoshihiro; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2006-06-01

    Single-walled carbon nanotubes are grown using grid-inserted plasma-enhanced chemical vapor deposition (PECVD). The field effect transistor operation was confirmed using the PECVD grown carbon nanotubes (CNTs). The preferential growth of the semiconducting nanotubes was confirmed in the grid-inserted PECVD by measuring current-voltage (I-V) characteristics of the devices. Based on the measurement of the electrical breakdown of the metallic CNTs, the probability of growing the semiconducting nanotubes has been estimated to be more than 90%.

  7. Analysis of long-channel nanotube field-effect-transistors (NT FETs)

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation provides an analysis of long-channel nanotube (NT) field effect transistors (FET) from NASA's Ames Research Center. The structure of such a transistor including the electrode contact, 1D junction, and the planar junction is outlined. Also mentioned are various characteristics of a nanotube tip-equipped scanning tunnel microscope (STM).

  8. Self aligned hysteresis free carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Shlafman, M.; Tabachnik, T.; Shtempluk, O.; Razin, A.; Kochetkov, V.; Yaish, Y. E.

    2016-04-01

    Hysteresis phenomenon in the transfer characteristics of carbon nanotube field effect transistor (CNT FET) is being considered as the main obstacle for successful realization of electronic devices based on CNTs. In this study, we prepare four kinds of CNTFETs and explore their hysteretic behavior. Two kinds of devices comprise on-surface CNTs (type I) and suspended CNTs (type II) with thin insulating layer underneath and a single global gate which modulates the CNT conductance. The third and fourth types (types III and IV) consist of suspended CNT over a metallic local gate underneath, where for type IV the local gate was patterned self aligned with the source and drain electrodes. The first two types of devices, i.e., type I and II, exhibit substantial hysteresis which increases with scanning range and sweeping time. Under high vacuum conditions and moderate electric fields ( |E |>4 ×106 V /cm ), the hysteresis for on-surface devices cannot be eliminated, as opposed to suspended devices. Interestingly, type IV devices exhibit no hysteresis at all at ambient conditions, and from the different roles which the global and local gates play for the four types of devices, we could learn about the hysteresis mechanism of this system. We believe that these self aligned hysteresis free FETs will enable the realization of different electronic devices and sensors based on CNTs.

  9. Short Channel Field-Effect-Transistors with Inkjet-Printed Semiconducting Carbon Nanotubes.

    PubMed

    Jang, Seonpil; Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2015-11-01

    Short channel field-effect-transistors with inkjet-printed semiconducting carbon nanotubes are fabricated using a novel strategy to minimize material consumption, confining the inkjet droplet into the active channel area. This fabrication approach is compatible with roll-to-roll processing and enables the formation of high-performance short channel device arrays based on inkjet printing. PMID:26312458

  10. Electrostatic Simulation of Charge Trapping in Carbon Nanotube Vertical Organic Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Crawford, Jennifer; Rinzler, Andrew; Hershfield, Selman

    The carbon nanotube vertical organic field effect transistor is a vertical sequence consisting of a gate electrode, gate dielectric, thin nanotube network source electrode, organic semiconducting channel and finally the drain electrode. The drain current is modulated by the gate voltage which varies a Schottky barrier between source and channel layers. Hysteresis in the current-voltage characteristic has been observed when a electret charge trapping layer is placed between the nanotube source and the gate dielectric. We provide a model for charge injection into a trapping layer placed in contact with the carbon nanotube film and solve self-consistently for the electrostatics and the occupancy of the traps. For a range of applied gate voltages the simulations demonstrate hysteresis of the carbon nanotubes' charge as a result of the electric field produced by the trapped charge. This affects the current by modulating the Schottky barrier. This work was supported by the NSF Grant DMR-1461019.

  11. Si/Ge hetero-structure nanotube tunnel field effect transistor

    SciTech Connect

    Hanna, A. N.; Hussain, M. M.

    2015-01-07

    We discuss the physics of conventional channel material (silicon/germanium hetero-structure) based transistor topology mainly core/shell (inner/outer) gated nanotube vs. gate-all-around nanowire architecture for tunnel field effect transistor application. We show that nanotube topology can result in higher performance through higher normalized current when compared to nanowire architecture at V{sub dd} = 1 V due to the availability of larger tunneling cross section and lower Shockley-Reed-Hall recombination. Both architectures are able to achieve sub 60 mV/dec performance for more than five orders of magnitude of drain current. This enables the nanotube configuration achieving performance same as the nanowire architecture even when V{sub dd} is scaled down to 0.5 V.

  12. In vitro detection of biological molecules using carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Briman, Mikhail Borisovich

    The operation and the stability of different types of carbon nanotube field-effect transistors in the liquid buffer are investigated. The effects of environmental parameters of aqueous solutions such as pH and the ionic-strength on the device parameters are also reported. Another set of experiments carried out in the electrolyte showed that number fluctuations are the most likely source of low frequency electrical noise found in the devices. Finally, charge transfer was found to be the dominant effect in the mechanism of nanotube-protein interactions.

  13. Room-temperature single charge sensitivity in carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Peng, H. B.; Hughes, M. E.; Golovchenko, J. A.

    2006-12-01

    Electrical current fluctuation studies are reported for coaxial p-type and n-type single-wall carbon nanotube field-effect transistors (FETs). Abrupt discrete switching of the source-drain current is observed at room temperature. The authors attribute these random telegraph signals to charge fluctuating electron traps near the FET conduction channels. Evolution of the current-switching behavior associated with the occupancy of individual electron traps is demonstrated and analyzed statistically. The result strongly indicates room temperature single charge sensitivity in carbon nanotube FETs, which may offer potential applications for single molecule sensors based on suitably prepared FET devices.

  14. Ultrasensitive Detection of DNA Hybridization Using Carbon Nanotube Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Maehashi, Kenzo; Matsumoto, Kazuhiko; Kerman, Kagan; Takamura, Yuzuru; Tamiya, Eiichi

    2004-12-01

    We have sensitively detected DNA hybridization using carbon nanotube field-effect transistors (CNTFETs) in real time. Amino modified peptide nucleic acid (PNA) oligonucleotides at 5' end were covalently immobilized onto the Au surface of the back gate. For 11-mer PNA oligonucletide probe, full-complementary DNA with concentration as low as 6.8 fM solution could be effectively detected. Our CNTFET-based biochip is a promising candidate for the development of an integrated, high-throughput, multiplexed DNA biosensor for medical, forensic and environmental diagnostics.

  15. Fabrication process of carbon nanotube field effect transistors using atomic layer deposition passivation for biosensors.

    PubMed

    Nakashima, Yasuhiro; Ohno, Yutaka; Kishimoto, Shigeru; Okochi, Mina; Honda, Hiroyuki; Mizutani, Takashi

    2010-06-01

    Fabrication process of the carbon nanotube (CNT) field effect transistors (FETs) for biosensors was studied. Atomic layer deposition (ALD) of HfO2 was applied to the deposition of the passivation/gate insulator film. The CNT-FETs did not show the drain current degradation after ALD passivation even though the passivation by Si3N4 deposited by plasma-enhanced chemical vapor deposition (PECVD) resulted in a significant drain current decrease. This indicates the advantage of the present ALD technique in terms of the damage suppression. The biosensing operation was confirmed using thus fabricated CNT-FETs. PMID:20355371

  16. Selective functionalization and loading of biomolecules in crystalline silicon nanotube field-effect-transistors

    NASA Astrophysics Data System (ADS)

    Kwon, Soonshin; Chen, Zack C. Y.; Noh, Hyunwoo; Lee, Ju Hun; Liu, Hang; Cha, Jennifer N.; Xiang, Jie

    2014-06-01

    Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm2 V-1 s-1 in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length.Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm2 V-1 s-1 in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length. Electronic supplementary information (ESI) available: Modelling (Fig. S1) and

  17. Polymer-Sorted Semiconducting Carbon Nanotube Networks for High-Performance Ambipolar Field-Effect Transistors

    PubMed Central

    2014-01-01

    Efficient selection of semiconducting single-walled carbon nanotubes (SWNTs) from as-grown nanotube samples is crucial for their application as printable and flexible semiconductors in field-effect transistors (FETs). In this study, we use atactic poly(9-dodecyl-9-methyl-fluorene) (a-PF-1-12), a polyfluorene derivative with asymmetric side-chains, for the selective dispersion of semiconducting SWNTs with large diameters (>1 nm) from plasma torch-grown SWNTs. Lowering the molecular weight of the dispersing polymer leads to a significant improvement of selectivity. Combining dense semiconducting SWNT networks deposited from an enriched SWNT dispersion with a polymer/metal-oxide hybrid dielectric enables transistors with balanced ambipolar, contact resistance-corrected mobilities of up to 50 cm2·V–1·s–1, low ohmic contact resistance, steep subthreshold swings (0.12–0.14 V/dec) and high on/off ratios (106) even for short channel lengths (<10 μm). These FETs operate at low voltages (<3 V) and show almost no current hysteresis. The resulting ambipolar complementary-like inverters exhibit gains up to 61. PMID:25493421

  18. Polymer-sorted semiconducting carbon nanotube networks for high-performance ambipolar field-effect transistors.

    PubMed

    Schiessl, Stefan P; Fröhlich, Nils; Held, Martin; Gannott, Florentina; Schweiger, Manuel; Forster, Michael; Scherf, Ullrich; Zaumseil, Jana

    2015-01-14

    Efficient selection of semiconducting single-walled carbon nanotubes (SWNTs) from as-grown nanotube samples is crucial for their application as printable and flexible semiconductors in field-effect transistors (FETs). In this study, we use atactic poly(9-dodecyl-9-methyl-fluorene) (a-PF-1-12), a polyfluorene derivative with asymmetric side-chains, for the selective dispersion of semiconducting SWNTs with large diameters (>1 nm) from plasma torch-grown SWNTs. Lowering the molecular weight of the dispersing polymer leads to a significant improvement of selectivity. Combining dense semiconducting SWNT networks deposited from an enriched SWNT dispersion with a polymer/metal-oxide hybrid dielectric enables transistors with balanced ambipolar, contact resistance-corrected mobilities of up to 50 cm(2)·V(-1)·s(-1), low ohmic contact resistance, steep subthreshold swings (0.12-0.14 V/dec) and high on/off ratios (10(6)) even for short channel lengths (<10 μm). These FETs operate at low voltages (<3 V) and show almost no current hysteresis. The resulting ambipolar complementary-like inverters exhibit gains up to 61. PMID:25493421

  19. Intrinsic memory function of carbon nanotube-based ferroelectric field-effect transistor.

    PubMed

    Fu, Wangyang; Xu, Zhi; Bai, Xuedong; Gu, Changzhi; Wang, Enge

    2009-03-01

    We demonstrate the intrinsic memory function of ferroelectric field-effect transistors (FeFETs) based on an integration of individual single-walled carbon nanotubes (SWCNTs) and epitaxial ferroelectric films. In contrast to the previously reported "charge-storage" CNT-FET memories, whose operations are haunted by a lack of control over the "charge traps", the present CNT-FeFETs exhibit a well-defined memory hysteresis loop induced by the reversible remnant polarization of the ferroelectric films. Large memory windows approximately 4 V, data retention time up to 1 week, and ultralow power consumption (energy per bit) of femto-joule, are highlighted in this report. Further simulations and experimental results show that the memory device is valid under operation voltage less than 1 V due to an electric-field enhancement effect induced by the ultrathin SWCNTs. PMID:19206218

  20. Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistor

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The threshold voltages of a carbon-nanotube (CNT) field-effect transistor (FET) are studied. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, and this makes the device characteristics quite unique. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and inversion and accumulation threshold voltages (V(sub Ti), and V(sub Ta)) are derived. V(sub Ti) of the CNTFETs has a much stronger doping dependence than that of the metal-oxide- semiconductor FETs, while V(sub Ta) of both devices depends weakly on doping with the same functional form.

  1. Floating-gated memory based on carbon nanotube field-effect transistors with Si floating dots

    NASA Astrophysics Data System (ADS)

    Seike, Kohei; Fujii, Yusuke; Ohno, Yasuhide; Maehashi, Kenzo; Inoue, Koichi; Matsumoto, Kazuhiko

    2014-01-01

    We have fabricated a carbon nanotube field-effect transistor (CNTFET)-based nonvolatile memory device with Si floating dots. The electrical characteristics of this memory device were compared with those of devices with a HfO2 charge storage layer or Au floating dots. For a sweep width of 6 V, the memory window of the devices with the Si floating dots increased twofold as compared with that of the devices with the HfO2 layer. Moreover, the retention characteristics revealed that, for the device with the Au floating dots, the off-state had almost the same current as the on-state at the 400th s. However, the devices with the Si floating dots had longer-retention characteristics. The results indicate that CNTFET-based devices with Si floating dots are promising candidates for low-power consumption nonvolatile memory devices.

  2. Performance analysis of junctionless carbon nanotube field effect transistors using NEGF formalism

    NASA Astrophysics Data System (ADS)

    Barbastegan, Saber; Shahhoseini, Ali

    2016-04-01

    This paper presents the simulation study of a junctionless carbon nanotube field effect transistor (JL-CNTFET) and a comparison is made with the conventional CNTFET using the atomistic scale simulation, within the non-equilibrium Green’s function (NEGF) formalism. In order to have a comprehensive analysis, both analog and digital parameters of the device are studied. Results have shown that JL-CNTFET with respect to C-CNTFET shows slightly higher ION/IOFF ratio about two times larger than that of C-CNTFET, smaller electric field along channel more than three order of magnitude and reduced tunneling current about 100 times. In addition, the investigation of analog properties of both devices has exhibited that junctionless structure has a transconductance about two times and an intrinsic gain of 15 dB larger than C-CNTFET in same bias condition which makes JL-CNTFET a promising candidate for low voltage analog applications.

  3. Suspended single-walled carbon-nanotube field-effect transistor for gas sensing application

    NASA Astrophysics Data System (ADS)

    Wada, Yukiko; Fujita, Yoshihiro; Takei, Kuniharu; Arie, Takayuki; Akita, Seiji

    2015-06-01

    We investigate the pressure dependence of transfer characteristics of suspended single-walled carbon-nanotube field-effect transistors. We find that the gate bias around the charge neutral point with low drain current is appropriate for gas sensing application, while the high gate bias condition with high drain current that induces Joule heating in the suspended region for the desorption of the adsorbed molecules is preferable for the vacuum gauge application based on the heat exchange surrounding gas molecules, where the temperature at the suspended channel is investigated based on the simple one-dimensional heat transport model. We also revealed that the pressure dependence of the channel conductance at the gate bias around the charge neutral point can be explained by the Langmuir isotherm.

  4. A measurement technique for circumventing hysteresis and conductance drift in carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Tunnell, Andrew; Ballarotto, Vincent; Cumings, John

    2014-01-01

    We present a measurement protocol that effectively eliminates both the hysteresis and the temporal drift typically observed in the channel conductance of single-walled carbon nanotube field-effect transistors (SWNT FETs) during the application of gate voltages. Before each resistance measurement, the gate is first stepped through a series of alternating positive and negative voltages to produce a neutral charge distribution within the device. This process is highly effective at removing the hysteresis in the channel conductance, and time-dependent measurements further demonstrate that the drain current is stable and single-valued, independent of the prior measurement history. The effectiveness of this method can be understood within the Preisach hysteresis model, which we demonstrate as a useful framework to predict the observed results.

  5. A measurement technique for circumventing hysteresis and conductance drift in carbon nanotube field-effect transistors.

    PubMed

    Tunnell, Andrew; Ballarotto, Vincent; Cumings, John

    2014-01-31

    We present a measurement protocol that effectively eliminates both the hysteresis and the temporal drift typically observed in the channel conductance of single-walled carbon nanotube field-effect transistors (SWNT FETs) during the application of gate voltages. Before each resistance measurement, the gate is first stepped through a series of alternating positive and negative voltages to produce a neutral charge distribution within the device. This process is highly effective at removing the hysteresis in the channel conductance, and time-dependent measurements further demonstrate that the drain current is stable and single-valued, independent of the prior measurement history. The effectiveness of this method can be understood within the Preisach hysteresis model, which we demonstrate as a useful framework to predict the observed results. PMID:24394672

  6. Sensing Reversible Protein–Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors

    PubMed Central

    2015-01-01

    We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor’s response at various ionic strengths was analyzed. Furthermore, protein “fingerprints” of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS). PMID:25126155

  7. Single-molecule measurements of proteins using carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Sims, Patrick Craig

    Single-walled carbon nanotube (SWCNT) field-effect transistors (FETs) provide a promising platform for investigating proteins at the single-molecule level. Recently, we have demonstrated that SWCNT FETs have sufficient sensitivity and bandwidth to monitor the conformational motions and processivity of an individual T4 lysozyme molecule. This is accomplished by functionalizing a SWCNT FET device with a single protein and measuring the conductance versus time through the device as it is submerged in an electrolyte solution. To generalize this approach for the study of a wide variety of proteins at the single-molecule level, this dissertation investigates the conjugation process to determine and isolate the key parameters involved in functionalizing a SWCNT with a single protein, the physical basis for transducing conformational motion of a protein into an electrical signal, and finally, the general application of the technique to monitor the binary and ternary complex formation of cAMP-dependent protein kinase (PKA).

  8. Modeling and simulation of carbon nanotube field effect transistor and its circuit application

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Saini, Dinesh Kumar; Agarwal, Dinesh; Aggarwal, Sajal; Khosla, Mamta; Raj, Balwinder

    2016-07-01

    The carbon nanotube field effect transistor (CNTFET) is modelled for circuit application. The model is based on the transport mechanism and it directly relates the transport mechanism with the chirality. Also, it does not consider self consistent equations and thus is used to develop the HSPICE compatible circuit model. For validation of the model, it is applied to the top gate CNTFET structure and the MATLAB simulation results are compared with the simulations of a similar structure created in NanoTCAD ViDES. For demonstrating the circuit compatibility of the model, two circuits viz. inverter and SRAM are designed and simulated in HSPICE. Finally, SRAM performance metrics are compared with those of device simulations from Nano TCAD ViDES.

  9. Synthesized multiwall MoS{sub 2} nanotube and nanoribbon field-effect transistors

    SciTech Connect

    Fathipour, S. Ajoy, A.; Vishwanath, S.; Rouvimov, S.; Xing, H. G.; Jena, D.; Seabaugh, A.; Remskar, M.; Varlec, A.; Yan, R.; Hwang, W. S.

    2015-01-12

    We report on the fabrication and characterization of synthesized multiwall MoS{sub 2} nanotube (NT) and nanoribbon (NR) field-effect transistors (FETs). The MoS{sub 2} NTs and NRs were grown by chemical transport, using iodine as a transport agent. Raman spectroscopy confirms the material as unambiguously MoS{sub 2} in NT, NR, and flake forms. Transmission electron microscopy was used to observe cross sections of the devices after electrical measurements and these were used in the interpretation of the electrical measurements, allowing the estimation of the current density. The NT and NR FETs demonstrate n-type behavior, with ON/OFF current ratios exceeding 10{sup 3}, and with current densities of 1.02 μA/μm and 0.79 μA/μm at V{sub DS} = 0.3 V and V{sub BG} = 1 V, respectively. Photocurrent measurements conducted on a MoS{sub 2} NT FET revealed short-circuit photocurrent of tens of nanoamps under an excitation optical power of 78 μW and 488 nm wavelength, which corresponds to a responsivity of 460 μA/W. A long channel transistor model was used to model the common-source characteristics of MoS{sub 2} NT and NR FETs and was shown to be consistent with the measured data.

  10. Synthesized multiwall MoS2 nanotube and nanoribbon field-effect transistors

    NASA Astrophysics Data System (ADS)

    Fathipour, S.; Remskar, M.; Varlec, A.; Ajoy, A.; Yan, R.; Vishwanath, S.; Rouvimov, S.; Hwang, W. S.; Xing, H. G.; Jena, D.; Seabaugh, A.

    2015-01-01

    We report on the fabrication and characterization of synthesized multiwall MoS2 nanotube (NT) and nanoribbon (NR) field-effect transistors (FETs). The MoS2 NTs and NRs were grown by chemical transport, using iodine as a transport agent. Raman spectroscopy confirms the material as unambiguously MoS2 in NT, NR, and flake forms. Transmission electron microscopy was used to observe cross sections of the devices after electrical measurements and these were used in the interpretation of the electrical measurements, allowing the estimation of the current density. The NT and NR FETs demonstrate n-type behavior, with ON/OFF current ratios exceeding 103, and with current densities of 1.02 μA/μm and 0.79 μA/μm at VDS = 0.3 V and VBG = 1 V, respectively. Photocurrent measurements conducted on a MoS2 NT FET revealed short-circuit photocurrent of tens of nanoamps under an excitation optical power of 78 μW and 488 nm wavelength, which corresponds to a responsivity of 460 μA/W. A long channel transistor model was used to model the common-source characteristics of MoS2 NT and NR FETs and was shown to be consistent with the measured data.

  11. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET

    PubMed Central

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  12. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET.

    PubMed

    Tan, Michael Loong Peng; Lentaris, Georgios; Amaratunga Aj, Gehan

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  13. Enzyme assays using sensor arrays based on ion-selective carbon nanotube field-effect transistors.

    PubMed

    Melzer, K; Bhatt, V Deep; Jaworska, E; Mittermeier, R; Maksymiuk, K; Michalska, A; Lugli, P

    2016-10-15

    In the fields of clinical diagnostics and point-of-care diagnosis as well as food and environmental monitoring there is a high demand for reliable high-throughput, rapid and highly sensitive assays for a simultaneous detection of several analytes in complex and low-volume samples. Sensor platforms based on solution-processable electrolyte-gated carbon nanotube field-effect transistors (CNT-FETs) are a simple and cost-effective alternative for conventional assays. In this work we demonstrate a selective as well as direct detection of the products of an enzyme-substrate interaction, here the for metabolic processes important urea-urease system, with sensors based on spray-coated CNT-FETs. The selective and direct detection is achieved by immobilizing the enzyme urease via certain surface functionalization techniques on the sensor surface and further modifying the active interfaces with polymeric ion-selective membranes as well as pH-sensitive layers. Thereby, we can avoid the generally applied approach for a field-effect based detection of enzyme reactions via detecting changes in the pH value due to an on-going enzymatic reaction and directly detect selectively the products of the enzymatic conversion. Thus, we can realize a buffering-capacity independent monitoring of changes in the substrate concentration. PMID:27140308

  14. Strain on field effect transistors with single–walled–carbon nanotube network on flexible substrate

    SciTech Connect

    Kim, T. G.; Kim, U. J.; Lee, E. H.; Hwang, J. S.; Hwang, S. W. E-mail: sangsig@korea.ac.kr; Kim, S. E-mail: sangsig@korea.ac.kr

    2013-12-07

    We have systematically analyzed the effect of strain on the electrical properties of flexible field effect transistors with a single-walled carbon nanotube (SWCNT) network on a polyethersulfone substrate. The strain was applied and estimated at the microscopic scale (<1 μm) by using scanning electron microscope (SEM) equipped with indigenously designed special bending jig. Interestingly, the strain estimated at the microscopic scale was found to be significantly different from the strain calculated at the macroscopic scale (centimeter-scale), by a factor of up to 4. Further in-depth analysis using SEM indicated that the significant difference in strain, obtained from two different measurement scales (microscale and macroscale), could be attributed to the formation of cracks and tears in the SWCNT network, or at the junction of SWCNT network and electrode during the strain process. Due to this irreversible morphological change, the electrical properties, such as on current level and field effect mobility, lowered by 14.3% and 4.6%, respectively.

  15. Demonstration of high current carbon nanotube enabled vertical organic field effect transistors at industrially relevant voltages

    NASA Astrophysics Data System (ADS)

    McCarthy, Mitchell

    The display market is presently dominated by the active matrix liquid crystal display (LCD). However, the active matrix organic light emitting diode (AMOLED) display is argued to become the successor to the LCD, and is already beginning its way into the market, mainly in small size displays. But, for AMOLED technology to become comparable in market share to LCD, larger size displays must become available at a competitive price with their LCD counterparts. A major issue preventing low-cost large AMOLED displays is the thin-film transistor (TFT) technology. Unlike the voltage driven LCD, the OLEDs in the AMOLED display are current driven. Because of this, the mature amorphous silicon TFT backplane technology used in the LCD must be upgraded to a material possessing a higher mobility. Polycrystalline silicon and transparent oxide TFT technologies are being considered to fill this need. But these technologies bring with them significant manufacturing complexity and cost concerns. Carbon nanotube enabled vertical organic field effect transistors (CN-VFETs) offer a unique solution to this problem (now known as the AMOLED backplane problem). The CN-VFET allows the use of organic semiconductors to be used for the semiconductor layer. Organics are known for their low-cost large area processing compatibility. Although the mobility of the best organics is only comparable to that of amorphous silicon, the CN-VFET makes up for this by orienting the channel vertically, as opposed to horizontally (like in conventional TFTs). This allows the CN-VFET to achieve sub-micron channel lengths without expensive high resolution patterning. Additionally, because the CN-VFET can be easily converted into a light emitting transistor (called the carbon nanotube enabled vertical organic light emitting transistor---CN-VOLET) by essentially stacking an OLED on top of the CN-VFET, more potential benefits can be realized. These potential benefits include, increased aperture ratio, increased OLED

  16. Functionalized carbon nanotube field effect transistors for chemical and biological sensing

    NASA Astrophysics Data System (ADS)

    Chen, Michelle Hsiu-Yu

    Specific, sensitive, reproducible, and rapid detection of chemical and biological species is crucial for the environment, disease diagnosis, and even homeland security. Owing to the miniature size, large surface to volume ratio, high electrical conductivity, and compatibility with dense array fabrication, carbon nanotubes are excellent candidates for sensing application. In this thesis we present nanosealed chemical and biological sensors based on functionalized single-walled carbon nanotube field effect transistors (SWNT-FETs). For chemical sensors, single stranded DNA/RNA serve as the chemical recognition sites and SWNT-FETs as the electronic readout components. Non-covalent functionalization of SWNT-FETs with DNA/RNA resulted in current changes when exposed to gaseous analytes, whereas the bare nanotube devices show no detectable change. The sensor responses differ in sign and magnitude depending both on the type of gaseous analyte and the sequence of DNA/RNA being used. DNA/RNA functionalized SWNT-FET gas sensors possess rapid recovery and self-regenerating ability, which could lead to realization of large arrays for sensitive electronic olfaction and disease diagnosis. For biological sensors, we present proof-of-concept experiments for developing highly sensitive and last-response miniaturized SWNT-FET biosensors for electrically detecting adenovirus using ligand-receptor-protein specificity. SWNTs are mildly oxidized to form carboxylic groups on the surfaces without compromising the electronic integrity of the nanotubes. Then the human coxsackievirus and adenovirus receptor (CAR) is covalently functionalized onto the nanotube surface via diimide-activated amidation process. Upon exposure of the device to adenovirus protein, Ad12 Knob (Knob), specific binding of Knob to CAR decreases the current that flows through the SWNT-FET device. For control experiment, the CAR-SWNT device is exposed to YieF, which is a virus protein that does not bind specifically to CAR

  17. The Effect of Hydrophobin Protein on Conductive Properties of Carbon Nanotube Field-Effect Transistors: First Study on Sensing Mechanism.

    PubMed

    Yotprayoonsakl, Peerapong; Szilvay, Géza R; Laaksonen, Päivi; Linder, Markus B; Ahlskog, Markus

    2015-03-01

    Hydrophobin is a surface active protein having both hydrophobic and hydrophilic functional domains which has previously been used for functionalization and solubilization of graphene and carbon nanotubes. In this work, field-effect transistors based on single nanotubes have been employed for electronic detection of hydrophobin protein in phosphate buffer solution. Individual nanotubes, single- and multiwalled, are characterized by atomic force microscopy after being immersed in protein solution, showing a relatively dense coverage with hydrophobin. We have studied aspects such as nanotube length (0.3-1.2 µm) and the hysteresis effect in the gate voltage dependent conduction. When measured in ambient condition after the exposure to hydrophobin, the resistance increase has a strong dependence on the nanotube length, which we ascribe to mobility degradation and localization effects. The change could be exceptionally large when measured in-situ in solution and at suitable gate voltage conditions, which is shown to relate to the different mechanism behind the hysteresis effect. PMID:26413623

  18. Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistors

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2002-01-01

    The threshold voltages of a carbon nanotube (CNT) field-effect transistor (FET) are derived and compared with those of the metal oxide-semiconductor (MOS) FETs. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, which is the CNT diameter direction, and this makes the CNTFET characteristics quite different from those in MOSFETs. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and it is shown that the familiar relations are still valid because of the macroscopic number of states available in the CNTs. This is in sharp contrast to the cases of quantum dots. Using these relations, we derive an inversion threshold voltage V(sub Ti) and an accumulation threshold voltage V(sub Ta) as a function of the Fermi level E(sub F) in the channel, where E(sub F) is a measure of channel doping. V(sub Ti) of the CNTFETs has a much stronger dependence than that of MOSFETs, while V(sub Ta)s of both CNTFETs and MOSFETs depend quite weakly on E(sub F) with the same functional form. This means the transition from normally-off mode to normally-on mode is much sharper in CNTFETs as the doping increases, and this property has to be taken into account in circuit design.

  19. Compact model for ballistic MOSFET-like carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Abdolkader, Tarek M.; Fikry, Wael

    2016-01-01

    In this work, a compact model for MOSFET-like ballistic carbon nanotube field-effect transistors (CNFETs) is presented. The model is based on calculating the charge and surface potential on the top of the barrier between source and drain using closed-form analytical formulae. The formula for the surface potential is obtained by merging two simplified expressions obtained in two extreme cases (very low and very high gate bias). Two fitting parameters are introduced whose values are extracted by best fitting model results with numerically calculated ones. The model has a continuous derivative and thus it is SPICE-compatible. Accuracy of the model is compared to previous analytical model presented in the literature with numerical results taken as a reference. Proposed model proves to give less relative error over a wide range of gate biases, and for a drain bias up to 0.5 V. In addition, the model enables the calculation of quantum and gate capacitance analytically reproducing the negative capacitance behaviour known in CNFETs.

  20. Fabrication and characterization of junctionless carbon nanotube field effect transistor for cholesterol detection

    SciTech Connect

    Barik, Md. Abdul Dutta, Jiten Ch.

    2014-08-04

    We have reported fabrication and characterization of polyaniline (PANI)/zinc oxide (ZnO) membrane-based junctionless carbon nanotube field effect transistor deposited on indium tin oxide glass plate for the detection of cholesterol (0.5–22.2 mM). Cholesterol oxidase (ChOx) has been immobilized on the PANI/ZnO membrane by physical adsorption technique. Electrical response has been recorded using digital multimeter (Agilent 3458A) in the presence of phosphate buffer saline of 50 mM, pH 7.0, and 0.9% NaCl contained in a glass pot. The results of response studies for cholesterol reveal linearity as 0.5–16.6 mM and improved sensitivity of 60 mV/decade in good agreement with Nernstian limit ∼59.2 mV/decade. The life time of this sensor has been found up to 5 months and response time of 1 s. The limit of detection with regression coefficient (r) ∼ 0.998 and Michaelis-Menten constant (K{sub m}) were found to be ∼0.25 and 1.4 mM, respectively, indicating high affinity of ChOx to cholesterol. The results obtained in this work show negligible interference with glucose and urea.

  1. Single-Wall Carbon Nanotube Field Effect Transistors with Non-Volatile Memory Operation

    NASA Astrophysics Data System (ADS)

    Sakurai, Tatsuya; Yoshimura, Takeshi; Akita, Seiji; Fujimura, Norifumi; Nakayama, Yoshikazu

    2006-10-01

    We describe the fabrication and electrical characteristics of single-wall carbon-nanotubes field-effect transistors (CNT-FETs) with a non-volatile memory function using ferroelectric thin films as gate insulators. The ferroelectric-gate CNT-FETs were fabricated using single-wall CNTs synthesized from alcohol by catalytic chemical vapor deposition and sol-gel derived PbZr0.5Ti0.5O3 thin films. The ferroelectric-gate CNT-FETs showed modulation of the drain current with the gate voltage and the threshold voltage shift (memory window) on the drain current-gate voltage characteristics. Moreover, the memory window was saturated around 1.1 V as the gate voltage sweeping range increased. These results indicate that carriers in CNTs are controlled by spontaneous polarization of the ferroelectric films. Because ferroelectrics exhibit complex couplings between their electrical, structural, mechanical, thermal, and optical properties, and because CNTs have unique mechanical and electrical properties, ferroelectric-gate CNT-FETs offer promise as potentially useful nanoelectronics devices not only for non-volatile memory elements but also for high-sensitivity sensors.

  2. Advantages of flattened electrode in bottom contact single-walled carbon nanotube field-effect transistor

    SciTech Connect

    Setiadi, Agung; Akai-Kasaya, Megumi Saito, Akira; Kuwahara, Yuji

    2014-09-01

    We fabricated single-walled carbon nanotube (SWNT) field-effect transistor (FET) devices on flattened electrodes, in which there are no height difference between metal electrodes and the substrate. SWNT-FET fabricated using bottom contact technique have some advantages, such that the SWNTs are free from electron irradiation, have direct contact with the desired metal electrodes, and can be functionalized before or after deposition. However, the SWNTs can be bent at the contact point with the metal electrodes leading to a different electrical characteristic of the devices. The number of SWNT direct junctions in short channel length devices is drastically increased by the use of flattened electrodes due to strong attractive interaction between SWNT and the substrate. The flattened electrodes show a better balance between their hole and electron mobility compared to that of the non-flattened electrodes, that is, ambipolar FET characteristic. It is considered that bending of the SWNTs in the non-flattened electrode devices results in a higher Schottky barrier for the electrons.

  3. Fabrication and characterization of junctionless carbon nanotube field effect transistor for cholesterol detection

    NASA Astrophysics Data System (ADS)

    Barik, Md. Abdul; Dutta, Jiten Ch.

    2014-08-01

    We have reported fabrication and characterization of polyaniline (PANI)/zinc oxide (ZnO) membrane-based junctionless carbon nanotube field effect transistor deposited on indium tin oxide glass plate for the detection of cholesterol (0.5-22.2 mM). Cholesterol oxidase (ChOx) has been immobilized on the PANI/ZnO membrane by physical adsorption technique. Electrical response has been recorded using digital multimeter (Agilent 3458A) in the presence of phosphate buffer saline of 50 mM, pH 7.0, and 0.9% NaCl contained in a glass pot. The results of response studies for cholesterol reveal linearity as 0.5-16.6 mM and improved sensitivity of 60 mV/decade in good agreement with Nernstian limit ˜59.2 mV/decade. The life time of this sensor has been found up to 5 months and response time of 1 s. The limit of detection with regression coefficient (r) ˜ 0.998 and Michaelis-Menten constant (Km) were found to be ˜0.25 and 1.4 mM, respectively, indicating high affinity of ChOx to cholesterol. The results obtained in this work show negligible interference with glucose and urea.

  4. Highly Uniform Carbon Nanotube Field-Effect Transistors and Medium Scale Integrated Circuits.

    PubMed

    Chen, Bingyan; Zhang, Panpan; Ding, Li; Han, Jie; Qiu, Song; Li, Qingwen; Zhang, Zhiyong; Peng, Lian-Mao

    2016-08-10

    Top-gated p-type field-effect transistors (FETs) have been fabricated in batch based on carbon nanotube (CNT) network thin films prepared from CNT solution and present high yield and highly uniform performance with small threshold voltage distribution with standard deviation of 34 mV. According to the property of FETs, various logical and arithmetical gates, shifters, and d-latch circuits were designed and demonstrated with rail-to-rail output. In particular, a 4-bit adder consisting of 140 p-type CNT FETs was demonstrated with higher packing density and lower supply voltage than other published integrated circuits based on CNT films, which indicates that CNT based integrated circuits can reach to medium scale. In addition, a 2-bit multiplier has been realized for the first time. Benefitted from the high uniformity and suitable threshold voltage of CNT FETs, all of the fabricated circuits based on CNT FETs can be driven by a single voltage as small as 2 V. PMID:27459084

  5. Solution-processed single-walled carbon nanotube field effect transistors and bootstrapped inverters for disintegratable, transient electronics

    SciTech Connect

    Jin, Sung Hun E-mail: jhl@snu.ac.kr Shin, Jongmin; Cho, In-Tak; Lee, Jong-Ho E-mail: jhl@snu.ac.kr; Han, Sang Youn; Lee, Dong Joon; Lee, Chi Hwan; Rogers, John A. E-mail: jhl@snu.ac.kr

    2014-07-07

    This paper presents materials, device designs, and physical/electrical characteristics of a form of nanotube electronics that is physically transient, in the sense that all constituent elements dissolve and/or disperse upon immersion into water. Studies of contact effects illustrate the ability to use water soluble metals such as magnesium for source/drain contacts in nanotube based field effect transistors. High mobilities and on/off ratios in transistors that use molybdenum, silicon nitride, and silicon oxide enable full swing characteristics for inverters at low voltages (∼5 V) and with high gains (∼30). Dissolution/disintegration tests of such systems on water soluble sheets of polyvinyl alcohol demonstrate physical transience within 30 min.

  6. Detection of the Odor Signature of Ovarian Cancer using DNA-Decorated Carbon Nanotube Field Effect Transistor Arrays

    NASA Astrophysics Data System (ADS)

    Kehayias, Christopher; Kybert, Nicholas; Yodh, Jeremy; Johnson, A. T. Charlie

    Carbon nanotubes are low-dimensional materials that exhibit remarkable chemical and bio-sensing properties and have excellent compatibility with electronic systems. Here, we present a study that uses an electronic olfaction system based on a large array of DNA-carbon nanotube field effect transistors vapor sensors to analyze the VOCs of blood plasma samples collected from patients with malignant ovarian cancer, patients with benign ovarian lesions, and age-matched healthy subjects. Initial investigations involved coating each CNT sensor with single-stranded DNA of a particular base sequence. 10 distinct DNA oligomers were used to functionalize the carbon nanotube field effect transistors, providing a 10-dimensional sensor array output response. Upon performing a statistical analysis of the 10-dimensional sensor array responses, we showed that blood samples from patients with malignant cancer can be reliably differentiated from those of healthy control subjects with a p-value of 3 x 10-5. The results provide preliminary evidence that the blood of ovarian cancer patients contains a discernable volatile chemical signature that can be detected using DNA-CNT nanoelectronic vapor sensors, a first step towards a minimally invasive electronic diagnostic technology for ovarian cancer.

  7. High-performance carbon-nanotube-based complementary field-effect-transistors and integrated circuits with yttrium oxide

    SciTech Connect

    Liang, Shibo; Zhang, Zhiyong Si, Jia; Zhong, Donglai; Peng, Lian-Mao

    2014-08-11

    High-performance p-type carbon nanotube (CNT) transistors utilizing yttrium oxide as gate dielectric are presented by optimizing oxidization and annealing processes. Complementary metal-oxide-semiconductor (CMOS) field-effect-transistors (FETs) are then fabricated on CNTs, and the p- and n-type devices exhibit symmetrical high performances, especially with low threshold voltage near to zero. The corresponding CMOS CNT inverter is demonstrated to operate at an ultra-low supply voltage down to 0.2 V, while displaying sufficient voltage gain, high noise margin, and low power consumption. Yttrium oxide is proven to be a competitive gate dielectric for constructing high-performance CNT CMOS FETs and integrated circuits.

  8. Microwave field effect transistor

    NASA Technical Reports Server (NTRS)

    Huang, Ho-Chung (Inventor)

    1989-01-01

    Electrodes of a high power, microwave field effect transistor are substantially matched to external input and output networks. The field effect transistor includes a metal ground plane layer, a dielectric layer on the ground plane layer, a gallium arsenide active region on the dielectric layer, and substantially coplanar spaced source, gate, and drain electrodes having active segments covering the active region. The active segment of the gate electrode is located between edges of the active segments of the source and drain electrodes. The gate and drain electrodes include inactive pads remote from the active segments. The pads are connected directly to the input and output networks. The source electrode is connected to the ground plane layer. The space between the electrodes and the geometry of the electrodes extablish parasitic shunt capacitances and series inductances that provide substantial matches between the input network and the gate electrode and between the output network and the drain electrode. Many of the devices are connected in parallel and share a common active region, so that each pair of adjacent devices shares the same source electrodes and each pair of adjacent devices shares the same drain electrodes. The gate electrodes for the parallel devices are formed by a continuous stripe that extends between adjacent devices and is connected at different points to the common gate pad.

  9. Carbon nanotube based field-effect transistors: merits and fundamental limits

    NASA Astrophysics Data System (ADS)

    Peng, Lian-Mao

    The development of even more powerful computer systems are made possible by scaling of CMOS transistors, and this simple process has afforded continuous improvement in both the device switch time and integration density. However, CMOS scaling has become very difficult at the 22-nm node and unlikely to be rewarding beyond the 14-nm node. Among other new approaches, carbon nanotube devices are emerging as the most promising technique with unique properties that are ideal for nanoelectronics. In particular, perfect n-type and p-type contacts are now available for controlled injection of electrons into the conduction band and holes into the valence band of the CNT, paving the way for a doping free fabrication of CNT based ballistic CMOS, high performance optoelectronic devices, and integrated circuits. These results will be compared with data projected for Si CMOS toward the end of the roadmap at 2026, as well as with those thermodynamic and quantum limits.

  10. Solution-Processed Carbon Nanotube and Chemically Synthesized Graphene Nanoribbon Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Bennett, Patrick Bryce

    Carbon nanotubes (CNTs) possess great potential as high performance semiconducting channels due to their one-dimensional nature, extremely high mobility, and their demonstrated ability to transport electrons ballistically in transistors. However, the presence of metallic CNTs in CNT films and arrays represents a major impediment towards large-scale integration. Methods of solution purification have demonstrated partial success in metallic CNT removal, although their effects on device performance are unknown. While this problem may be solvable, new synthesis techniques have recently resulted in the creation of high-density films of graphene nanoribbons (GNRs) with atomically smooth edges, uniform widths, and uniform band structure. These may ultimately supplant CNTs in device applications due to their theoretically similar, but uniform electronic properties. This work aims to study the effects of purification of semiconducting CNTs in thin film transistors (TFTs) and to develop methods to increase device performance when metallic CNTs are present. Devices consisting of large networks of CNTs as well as short channel, single CNT devices are characterized to determine the effects of solution processing on CNTs themselves. Short channel, bottom-up GNR devices are fabricated to compare their performance to CNT transistors. The first half of this dissertation describes the methods of integrating CNTs from various sources into transistors. Growth and transfer are described, as well as methods of creating aqueous suspensions for solution processing. Development of novel surfactant materials based on biomimetic polymers used to suspend CNTs in solution are reported and characterized. Methods of deposition out of solution and onto insulating substrates are covered. Device fabrication from start to finish is detailed, with the subtleties of processing required to produce sub 10-nm channel length devices explained. The second half reports devices produced via these techniques

  11. Contact and channel resistances of ballistic and non-ballistic carbon-nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Park, Jong-Myeon; Hong, Shin-Nam

    2016-01-01

    Recently, many research has been conducted on the carbon-nanotube field-effect transistors (CNFETs) in expectation that the CNFETs could replace metal-oxide-semiconductor field-effect transistors (MOSFETs) in the sub-10-nm era. In consideration of both ballistic conduction and nonballistic conduction, including elastic scattering, optical phonon scattering, and acoustic phonon scattering, this paper presents the simulated dependence of the coaxially-gated single-walled semiconducting CNFET characteristics on the contact and the channel lengths. When the contact length was longer than 100 nm, the CNFETs showed a constant minimal value of the contact resistance. In this case, the saturated drain current was higher than that of CNFETs with a shorter contact length. When the channel was longer than 600 nm, the channel resistance was significantly increased due to acoustic phonon scattering. When the channel was shorter than 200 - 250 nm with optical scattering, acoustic scattering or all three scattering mechanisms taken into account, the contact resistance began to become larger than channel resistance.

  12. Superconducting Field-Effect Transistors

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul; Romanofsky, Robert R.; Tabib-Azar, Massood

    1995-01-01

    Devices offer switching speeds greater than semiconducting counterparts. High-Tc superconducting field-effect transistors (SUPEFETs) investigated for use as electronic switches in delay-line-type microwave phase shifters. Resemble semiconductor field-effect transistors in some respects, but their operation based on different principle; namely, electric-field control of transition between superconductivity and normal conductivity.

  13. Probing Biological Processes on Supported Lipid Bilayers with Single-Walled Carbon Nanotube Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose Manuel; Craighead, Harold; McEuen, Paul

    2006-03-01

    We have formed supported lipid bilayers (SLBs) by small unilamellar vesicle fusion on substrates containing single-walled carbon nanotube field-effect transistors (SWNT-FETs). We are able to detect the self-assembly of SLBs electrically with SWNT-FETs since their threshold voltages are shifted by this event. The SLB fully covers the NT surface and lipid molecules can diffuse freely in the bilayer surface across the NT. To study the interactions of important biological entities with receptors imbedded within the membrane, we have also integrated a membrane protein, GT1b ganglioside, in the bilayer. While bare gangliosides can diffuse freely across the NT, interestingly the NT acts as a diffusion barrier for the gangliosides when they are bound with tetanus toxin. This experiment opens the possibility of using SWNT-FETs as biosensors for label-free detection.

  14. Unipolar p-type single-walled carbon nanotube field-effect transistors using TTF-TCNQ as the contact material.

    PubMed

    Xian, Xiaojun; Yan, Kai; Zhou, Wei; Jiao, Liying; Wu, Zhongyun; Liu, Zhongfan

    2009-12-16

    We demonstrate herein that organic metal tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) can serve as an ideal material for source and drain electrodes to build unipolar p-type single-walled carbon nanotube (SWNTs) field-effect transistors (FETs). SWNTs were synthesized by the chemical vapor deposition (CVD) method on silicon wafer and then TTF-TCNQ was deposited by thermal evaporation through a shadow mask to form the source and drain contacts. An SiO2 layer served as the gate dielectric and Si was used as the backgate. Transfer characteristics show that these TTF-TCNQ contacted devices are Schottky barrier transistors just like conventional metal contacted SWNT-FETs. The most interesting characteristic of these SWNT transistors is that all devices demonstrate the unipolar p-type transport behavior. This behavior originates from the unique crystal structure and physical properties of TTF-TCNQ and this device may have potential applications in carbon nanotube electronics. PMID:19923654

  15. Unipolar p-type single-walled carbon nanotube field-effect transistors using TTF-TCNQ as the contact material

    NASA Astrophysics Data System (ADS)

    Xian, Xiaojun; Yan, Kai; Zhou, Wei; Jiao, Liying; Wu, Zhongyun; Liu, Zhongfan

    2009-12-01

    We demonstrate herein that organic metal tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) can serve as an ideal material for source and drain electrodes to build unipolar p-type single-walled carbon nanotube (SWNTs) field-effect transistors (FETs). SWNTs were synthesized by the chemical vapor deposition (CVD) method on silicon wafer and then TTF-TCNQ was deposited by thermal evaporation through a shadow mask to form the source and drain contacts. An SiO2 layer served as the gate dielectric and Si was used as the backgate. Transfer characteristics show that these TTF-TCNQ contacted devices are Schottky barrier transistors just like conventional metal contacted SWNT-FETs. The most interesting characteristic of these SWNT transistors is that all devices demonstrate the unipolar p-type transport behavior. This behavior originates from the unique crystal structure and physical properties of TTF-TCNQ and this device may have potential applications in carbon nanotube electronics.

  16. Direct growth of horizontally aligned carbon nanotubes between electrodes and its application to field-effect transistors.

    PubMed

    Hayashi, Yasuhiko; Jang, B; Iijima, T; Tokunaga, T; Hayashi, A; Tanemura, M; Amaratunga, G A J

    2011-12-01

    This paper presents direct growth of horizontally-aligned carbon nanotubes (CNTs) between two predefined various inter-spacing up to tens of microns of electrodes (pads) and its use as CNT field-effect transistors (CNT-FETs). Using the conventional photolithography technique followed by thin film evaporation and lift off, the catalytic electrodes (pads) were prepared, consisting of Pt, Al and Fe triple layers on SiO2/Si substrate. The grown CNTs were horizontally-aligned across the catalytic electrodes on the modified gold image furnace hot stage (thermal CVD) at 800 degrees C by using an alcohol vapor as the carbon source. Scanning and transmission electron microcopies (SEM/TEM) were used to observe the structure, growth direction and density of CNTs, while Raman spectrum analysis was used to indicate the degree of amorphous impurity and diameter of CNTs. Both single- and multi-wall CNTs with diameters of 1.1-2.2 nm were obtained and the CNT density was controlled by thickness of Fe catalytic layer. Following horizontally-aligned growth of CNTs, the electrical properties of back-gate CNT-FETs were measured and showd p-type conduction behaviors of FET. PMID:22409045

  17. Carbon nanotube feedback-gate field-effect transistor: suppressing current leakage and increasing on/off ratio.

    PubMed

    Qiu, Chenguang; Zhang, Zhiyong; Zhong, Donglai; Si, Jia; Yang, Yingjun; Peng, Lian-Mao

    2015-01-27

    Field-effect transistors (FETs) based on moderate or large diameter carbon nanotubes (CNTs) usually suffer from ambipolar behavior, large off-state current and small current on/off ratio, which are highly undesirable for digital electronics. To overcome these problems, a feedback-gate (FBG) FET structure is designed and tested. This FBG FET differs from normal top-gate FET by an extra feedback-gate, which is connected directly to the drain electrode of the FET. It is demonstrated that a FBG FET based on a semiconducting CNT with a diameter of 1.5 nm may exhibit low off-state current of about 1 × 10(-13) A, high current on/off ratio of larger than 1 × 10(8), negligible drain-induced off-state leakage current, and good subthreshold swing of 75 mV/DEC even at large source-drain bias and room temperature. The FBG structure is promising for CNT FETs to meet the standard for low-static-power logic electronics applications, and could also be utilized for building FETs using other small band gap semiconductors to suppress leakage current. PMID:25545108

  18. Role of hybridization on the Schottky barrier height of carbon nanotube field effect transistors

    NASA Astrophysics Data System (ADS)

    Casterman, D.; de Souza, M. M.; Tahraoui, A.; Durkan, C.; Milne, W. I.

    2009-03-01

    The impact of hybridization on the Schottky barrier height (SBH) for holes at a metal/nanotube contact is investigated using ab initio density-functional theory. For small diameters, the impact of hybridization is a deviation of the SBH in comparison to that calculated using the “ 1/d ” rule, where d is the diameter of the carbon nanotube (CNT). In the hybridization region, the SBH reduces with chiral angle, suggesting that CNTs in this region may well be suited to microelectronic applications due to small SBH and large band gaps. Hybridization also causes a difference between the effective mass of electrons and holes, supposed to be identical within the tight-binding approximation. A strongly patterned behavior of the effective mass dependent on chirality and diameter is also reported here.

  19. Highly sensitive potassium-doped polypyrrole/carbon nanotube-based enzyme field effect transistor (ENFET) for cholesterol detection.

    PubMed

    Barik, Md Abdul; Sarma, Manoj Kumar; Sarkar, C R; Dutta, Jiten Ch

    2014-10-01

    Highly sensitive potassium (K)-doped carbon nanotube (CNT) and polypyrrole (PPy) nanocomposite membrane-based enzyme field effect transistor (ENFET) has been fabricated on indium tin oxide (ITO) for detection of cholesterol. P-type graphene has been deposited as substrate on ITO glass electrochemically. N-type graphene has been deposited in source and drain regions. Zirconium dioxide (ZrO2) has been deposited on the channel region as gate insulator. K/PPy/CNT composite has been deposited as sensing membrane on the top of ZrO2 layer; 1 μl of cholesterol oxidase (ChOx) has been immobilized on K/PPy/CNT membrane via physical adsorption technique. The response of K/PPy/CNT/FET has been studied using Agilent 3458A digital multimeter in presence of phosphate buffer saline (PBS) of 50 mM, pH 7.0 and 0.9 % NaCl contained in a glass pot. During measurement, 20 μl cholesterol solutions (0.5 to 25 mM) were poured into the pot through micropipette each time. It has been found that K/PPy/CNT/FET has linearly varied from 0.5 to 20 mM. The sensitivity of this FET has been found to be ~400 μA/mM/mm(2) with regression coefficient (r) ~ 0.998. The proposed ENFET has response time of 1 s and stability up to 6 months. The experiment has been repeated 10 times, and only 2.0 % output variation has been observed. The limit of detection (LoD) and Michaelis-Menten constant (K m) were found to be ~1.4 and 2.5 mM, respectively. The results obtained in this work show negligible interference (3.7 %) with uric acid, glucose and urea. PMID:25005579

  20. Polyfluorene-sorted, carbon nanotube array field-effect transistors with increased current density and high on/off ratio.

    PubMed

    Brady, Gerald J; Joo, Yongho; Wu, Meng-Yin; Shea, Matthew J; Gopalan, Padma; Arnold, Michael S

    2014-11-25

    Challenges in eliminating metallic from semiconducting single-walled carbon nanotubes (SWCNTs) and in controlling their alignment have limited the development of high-performance SWCNT-based field-effect transistors (FETs). We recently pioneered an approach for depositing aligned arrays of ultra-high-purity semiconducting SWCNTs, isolated using polyfluorene derivatives, called dose-controlled floating evaporative self-assembly. Here, we tailor FETs fabricated from these arrays to achieve on-conductance (G(on)) per width and an on-off ratio (G(on)/G(off)) of 261 μS/μm and 2 × 10(5), respectively, for a channel length (L(ch)) of 240 nm and 116 μS/μm and 1 × 10(6), respectively, for an L(ch) of 1 μm. We demonstrate 1400× greater G(on)/G(off) than SWCNT FETs fabricated by other methods, at comparable G(on) per width of ∼250 μS/μm and 30-100× greater G(on) per width at comparable G(on)/G(off) of 10(5)-10(7). The average G(on) per tube reaches 5.7 ± 1.4 μS at a packing density of 35 tubes/μm for L(ch) in the range 160-240 nm, limited by contact resistance. These gains highlight the promise of using ultra-high-purity semiconducting SWCNTs with controlled alignment for next-generation semiconductor electronics. PMID:25383880

  1. Mobilities in ambipolar field effect transistors based on single-walled carbon nanotube network and formed on a gold nanoparticle template

    SciTech Connect

    Wongsaeng, Chalao; Singjai, Pisith

    2014-04-07

    Ambipolar field effect transistors based on a single-walled carbon nanotube (SWNT) network formed on a gold nanoparticle (AuNP) template with polyvinyl alcohol as a gate insulator were studied by measuring the current–gate voltage characteristics. It was found that the mobilities of holes and electrons increased with increasing AuNP number density. The disturbances in the flow pattern of the carbon feedstock in the chemical vapor deposition growth that were produced by the AuNP geometry, resulted in the differences in the crystallinity and the diameter, as well as the changes in the degree of the semiconductor behavior of the SWNTs.

  2. Band-to-band tunneling in a carbon nanotube metal-oxide-semiconductor field-effect transistor is dominated by phonon-assisted tunneling.

    PubMed

    Koswatta, Siyuranga O; Lundstrom, Mark S; Nikonov, Dmitri E

    2007-05-01

    Band-to-band tunneling (BTBT) devices have recently gained a lot of interest due to their potential for reducing power dissipation in integrated circuits. We have performed extensive simulations for the BTBT operation of carbon nanotube metal-oxide-semiconductor field-effect transistors (CNT-MOSFETs) using the nonequilibrium Green's function formalism for both ballistic and dissipative quantum transport. In comparison with recently reported experimental data (J. Am. Chem. Soc. 2006, 128, 3518-3519), we have obtained strong evidence that BTBT in CNT-MOSFETs is dominated by optical phonon assisted inelastic transport, which can have important implications on the transistor characteristics. It is shown that, under large biasing conditions, two-phonon scattering may also become important. PMID:17388638

  3. Ambipolar phosphorene field effect transistor.

    PubMed

    Das, Saptarshi; Demarteau, Marcel; Roelofs, Andreas

    2014-11-25

    In this article, we demonstrate enhanced electron and hole transport in few-layer phosphorene field effect transistors (FETs) using titanium as the source/drain contact electrode and 20 nm SiO2 as the back gate dielectric. The field effect mobility values were extracted to be ∼38 cm(2)/Vs for electrons and ∼172 cm(2)/Vs for the holes. On the basis of our experimental data, we also comprehensively discuss how the contact resistances arising due to the Schottky barriers at the source and the drain end effect the different regime of the device characteristics and ultimately limit the ON state performance. We also propose and implement a novel technique for extracting the transport gap as well as the Schottky barrier height at the metal-phosphorene contact interface from the ambipolar transfer characteristics of the phosphorene FETs. This robust technique is applicable to any ultrathin body semiconductor which demonstrates symmetric ambipolar conduction. Finally, we demonstrate a high gain, high noise margin, chemical doping free, and fully complementary logic inverter based on ambipolar phosphorene FETs. PMID:25329532

  4. Simultaneous Improvement of Hole and Electron Injection in Organic Field-effect Transistors by Conjugated Polymer-wrapped Carbon Nanotube Interlayers.

    PubMed

    Lee, Seung-Hoon; Khim, Dongyoon; Xu, Yong; Kim, Juhwan; Park, Won-Tae; Kim, Dong-Yu; Noh, Yong-Young

    2015-01-01

    Efficient charge injection is critical for flexible organic electronic devices such as organic light-emitting diodes (OLEDs) and field-effect transistors (OFETs). Here, we investigated conjugated polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWNTs) as solution-processable charge-injection layers in ambipolar organic field-effect transistors with poly(thienylenevinylene-co-phthalimide)s. The interlayers were prepared using poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) or poly(9,9-dioctylfluorene) (PFO) to wrap s-SWNTs. In the contact-limited ambipolar OFETs, the interlayer led to significantly lower contact resistance (Rc) and increased mobilities for both holes and electrons. The resulting PTVPhI-Eh OFETs with PFO-wrapped s-SWNT interlayers showed very well-balanced ambipolar transport properties with a hole mobility of 0.5 cm(2)V(-1)S(-1) and an electron mobility of 0.5 cm(2)V(-1)S(-1) in linear regime. In addition, the chirality of s-SWNTs and kind of wrapping of conjugated polymers are not critical to improving charge-injection properties. We found that the improvements caused by the interlayer were due to the better charge injection at the metal/organic semiconductor contact interface and the increase in the charge concentration through a detailed examination of charge transport with low-temperature measurements. Finally, we successfully demonstrated complementary ambipolar inverters incorporating the interlayers without excessive patterning. PMID:26001198

  5. Simultaneous Improvement of Hole and Electron Injection in Organic Field-effect Transistors by Conjugated Polymer-wrapped Carbon Nanotube Interlayers

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hoon; Khim, Dongyoon; Xu, Yong; Kim, Juhwan; Park, Won-Tae; Kim, Dong-Yu; Noh, Yong-Young

    2015-05-01

    Efficient charge injection is critical for flexible organic electronic devices such as organic light-emitting diodes (OLEDs) and field-effect transistors (OFETs). Here, we investigated conjugated polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWNTs) as solution-processable charge-injection layers in ambipolar organic field-effect transistors with poly(thienylenevinylene-co-phthalimide)s. The interlayers were prepared using poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) or poly(9,9-dioctylfluorene) (PFO) to wrap s-SWNTs. In the contact-limited ambipolar OFETs, the interlayer led to significantly lower contact resistance (Rc) and increased mobilities for both holes and electrons. The resulting PTVPhI-Eh OFETs with PFO-wrapped s-SWNT interlayers showed very well-balanced ambipolar transport properties with a hole mobility of 0.5 cm2V-1S-1 and an electron mobility of 0.5 cm2V-1S-1 in linear regime. In addition, the chirality of s-SWNTs and kind of wrapping of conjugated polymers are not critical to improving charge-injection properties. We found that the improvements caused by the interlayer were due to the better charge injection at the metal/organic semiconductor contact interface and the increase in the charge concentration through a detailed examination of charge transport with low-temperature measurements. Finally, we successfully demonstrated complementary ambipolar inverters incorporating the interlayers without excessive patterning.

  6. Individual SWCNT based ionic field effect transistor

    NASA Astrophysics Data System (ADS)

    Pang, Pei; He, Jin; Park, Jae Hyun; Krstic, Predrag; Lindsay, Stuart

    2011-03-01

    Here we report that the ionic current through a single-walled carbon nanotube (SWCNT) can be effectively gated by a perpendicular electrical field from a top gate electrode, working as ionic field effect transistor. Both our experiment and simulation confirms that the electroosmotic current (EOF) is the main component in the ionic current through the SWCNT and is responsible for the gating effect. We also studied the gating efficiency as a function of solution concentration and pH and demonstrated that the device can work effectively in the physiological relevant condition. This work opens the door to use CNT based nanofluidics for ion and molecule manipulation. This work was supported by the DNA Sequencing Technology Program of the National Human Genome Research Institute (1RC2HG005625-01, 1R21HG004770-01), Arizona Technology Enterprises and the Biodesign Institute.

  7. The effect of local polarized domains of ferroelectric P(VDF/TrFE) copolymer thin film on a carbon nanotube field-effect transistor.

    PubMed

    Nishio, Taichi; Miyato, Yuji; Kobayashi, Kei; Ishida, Kenji; Matsushige, Kazumi; Yamada, Hirofumi

    2008-01-23

    We produced local polarized domains of ferroelectric P(VDF/TrFE) copolymer thin films on a carbon nanotube field-effect transistor (CN-FET) channel by atomic force microscopy (AFM). The drain current versus gate voltage (I(d)-V(g)) curves measured after forming the local polarized domains showed a shift in the threshold voltages. We also found that the amount of the shifts in the threshold voltages gradually decreased during the measurement of this characteristic over 100 h after forming the polarized domains. The mechanisms of the shifts in the threshold voltages and their decreasing behaviour were explained in terms of the excessive charges that were induced upon the formation of the polarized domains. PMID:21817562

  8. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, Albert G.; Drummond, Timothy J.; Robertson, Perry J.; Zipperian, Thomas E.

    1995-01-01

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits.

  9. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, A.G.; Drummond, T.J.; Robertson, P.J.; Zipperian, T.E.

    1995-12-26

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits. 10 figs.

  10. CADAT field-effect-transistor simulator

    NASA Technical Reports Server (NTRS)

    1981-01-01

    CADAT field-effect transistor simulator (FETSIM) analyzes dc and transient behavior of metal-oxide-semiconductor (MOS) circuits. Both N-MOS and P-MOS transistor configurations in either bulk of silicon-on-sapphire (SOS) technology and almost any combination of R/C elements are analyzed.

  11. Influence of redox molecules on the electronic conductance of single-walled carbon nanotube field-effect transistors: application to chemical and biological sensing.

    PubMed

    Boussaad, Salah; Diner, Bruce A; Fan, Janine

    2008-03-26

    In an effort to develop sensitive nanoscale devices for chemical and biological sensing, we have examined, using liquid gating, the conductance of semiconducting single-walled carbon nanotube-based field-effect transistors (SWCNT-FETs) in the presence of redox mediators. As examples, redox couples K3Fe(CN)6/K4Fe(CN)6 and K2IrCl6/K3IrCl6 are shown to modulate the SWCNT-FET conductance in part through their influence via the electrolyte gate on the electrostatic potential of the solution, as described by Larrimore et al. (Nano Lett. 2006, 6, 3129-1333) and in part through electron transfer between the redox mediators and the nanotubes. In the latter case, the rate of electron transfer is determined by the difference in chemical potential between the redox mediator and the SWCNTs and by the concentrations of the oxidized and reduced forms of the redox couple. Furthermore, these devices can detect the activity of redox enzymes through their sensitivity to the change in oxidation state of the enzyme substrate. An example is given for the blue copper oxidase, Trametes versicolor laccase, in which the rate of change of the SWCNT device conductance is linearly proportional to the rate of oxidation of the substrate 10-(2-hydroxyethyl)phenoxazine, varied over 2 orders of magnitude by the laccase concentration in the picomolar range. The behavior described in this work provides a highly sensitive means with which to do chemical and biological sensing using SWCNTs that is different from the amperometric, capacitive, and field-effect type sensing methods previously described in the literature for this material. PMID:18321094

  12. Carbon nanomaterials: controlled growth and field-effect transistor biosensors

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Na; Hu, Ping-An

    2012-03-01

    Carbon nanostructures, including carbon nanotubes (CNTs) and graphene, have been studied extensively due to their special structures, excellent electrical properties and high chemical stability. With the development of nanotechnology and nanoscience, various methods have been developed to synthesize CNTs/graphene and to assemble them into microelectronic/sensor devices. In this review, we mainly demonstrate the latest progress in synthesis of CNTs and graphene and their applications in field-effect transistors (FETs) for biological sensors.

  13. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, J.C.; Shul, R.J.

    1999-02-02

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  14. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C.; Shul, Randy J.

    1999-01-01

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  15. Investigation of light doping and hetero gate dielectric carbon nanotube tunneling field-effect transistor for improved device and circuit-level performance

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Sun, Yuan; Wang, Huan; Xu, Hongsong; Xu, Min; Jiang, Sitao; Yue, Gongshu

    2016-03-01

    We perform a comparative study (both for device and circuit simulations) of three carbon nanotube tunneling field-effect transistor (CNT-TFET) designs: high-K gate dielectric TFETs (HK-TFETs), hetero gate dielectric TFETs (HTFETs) and a novel CNT-TFET-based combination of light doping and hetero gate dielectric TFETs (LD-HTFETs). At device level, the effects of channel and gate dielectric engineering on the switching and high-frequency characteristics for CNT-TFET have been theoretically investigated using a quantum kinetic model. This model is based on two-dimensional non-equilibrium Green’s functions solved self-consistently with Poisson’s equations. It is revealed that the proposed LD-HTFET structure can significantly reduce leakage current, enhance control ability of the gate on the channel, improve the switching speed, and is more suitable for use in low-power, high-frequency circuits. At circuit level, using HSPICE with look-up table-based Verilog-A models, the performance and reliability of CNT-TFET logic gate circuits is evaluated on the basis of power consumption, average delay, stability, energy consumption and power-delay product (PDP). Simulation results indicate that, compared to a traditional CNT-TFET-based circuit, the one based on LD-HTFET has a significantly better performance (static noise margin, energy, delay, PDP). It is also observed that our proposed design exhibits better robustness under different operational conditions by considering power supply voltage and temperature variations. Our results may be useful for designing and optimizing CNTFET devices and circuits.

  16. A silicon nanocrystal tunnel field effect transistor

    SciTech Connect

    Harvey-Collard, Patrick; Drouin, Dominique; Pioro-Ladrière, Michel

    2014-05-12

    In this work, we demonstrate a silicon nanocrystal Field Effect Transistor (ncFET). Its operation is similar to that of a Tunnelling Field Effect Transistor (TFET) with two barriers in series. The tunnelling barriers are fabricated in very thin silicon dioxide and the channel in intrinsic polycrystalline silicon. The absence of doping eliminates the problem of achieving sharp doping profiles at the junctions, which has proven a challenge for large-scale integration and, in principle, allows scaling down the atomic level. The demonstrated ncFET features a 10{sup 4} on/off current ratio at room temperature, a low 30 pA/μm leakage current at a 0.5 V bias, an on-state current on a par with typical all-Si TFETs and bipolar operation with high symmetry. Quantum dot transport spectroscopy is used to assess the band structure and energy levels of the silicon island.

  17. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-02-01

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending.

  18. Hysteresis modeling in graphene field effect transistors

    SciTech Connect

    Winters, M.; Rorsman, N.; Sveinbjörnsson, E. Ö.

    2015-02-21

    Graphene field effect transistors with an Al{sub 2}O{sub 3} gate dielectric are fabricated on H-intercalated bilayer graphene grown on semi-insulating 4H-SiC by chemical vapour deposition. DC measurements of the gate voltage v{sub g} versus the drain current i{sub d} reveal a severe hysteresis of clockwise orientation. A capacitive model is used to derive the relationship between the applied gate voltage and the Fermi energy. The electron transport equations are then used to calculate the drain current for a given applied gate voltage. The hysteresis in measured data is then modeled via a modified Preisach kernel.

  19. Functional organic field-effect transistors.

    PubMed

    Guo, Yunlong; Yu, Gui; Liu, Yunqi

    2010-10-25

    Functional organic field-effect transistors (OFETs) have attracted increasing attention in the past few years due to their wide variety of potential applications. Research on functional OFETs underpins future advances in organic electronics. In this review, different types of functional OFETs including organic phototransistors, organic memory FETs, organic light emitting FETs, sensors based on OFETs and other functional OFETs are introduced. In order to provide a comprehensive overview of this field, the history, current status of research, main challenges and prospects for functional OFETs are all discussed. PMID:20853375

  20. Pressure Sensitive Insulated Gate Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Suminto, James Tjan-Meng

    A pressure sensitive insulated gate field effect transistor has been developed. The device is an elevated gate field-effect-transistor. It consists of a p-type silicon substrate in which two n^+ region, the source and drain, are formed. The gate electrode is a metal film sandwiched in an insulated micro-diaphragm resembling a pill-box which covers the gate oxide, drain, and source. The space between the gate electrode and the oxide is vacuum or an air-gap. When pressure is applied on the diaphragm it deflects and causes a change in the gate capacitance, and thus modulates the conductance of the channel between source and drain. A general theory dealing with the characteristic of this pressure sensitive insulated gate field effect transistor has been derived, and the device fabricated. The fabrication process utilizes the standard integrated circuit fabrication method. It features a batch fabrication of field effect devices followed by the batch fabrication of the deposited diaphragm on top of each field effect device. The keys steps of the diaphragm fabrication are the formation of spacer layer, formation of the diaphragm layer, and the subsequent removal of the spacer layer. The chip size of the device is 600 μm x 1050 mum. The diaphragm size is 200 μm x 200 mum. Characterization of the device has been performed. The current-voltage characteristics with pressure as parameters have been demonstrated and the current-pressure transfer curves obtained. They show non-linear characteristics as those of conventional capacitive pressure sensors. The linearity of threshold voltage versus pressure transfer curves has been demonstrated. The temperature effect on the device performances has been tested. The temperature coefficient of threshold voltage, rather than the electron mobility, has dominated the temperature coefficient of the device. Two temperature compensation schemes have been tested: one method is by connecting two identical PSIGFET in a differential amplifier

  1. Tantalum Disulfide Ionic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Yu, Yijun; Yang, Fangyuan; Lu, Xiu Fang; Yan, Ya Jun; Cho, Y. H.; Ma, Liguo; Niu, Xiaohai; Kim, Sejoong; Son, Yong-Woo; Feng, Donglai; Li, Shiyan; Cheong, Sang-Wook; Chen, Xian Hui; Zhang, Yuanbo

    2015-03-01

    The ability to tune material properties using gate electric field is at the heart of the modern electronic technology. Electrolyte gating has recently emerged as an important technique to reach extremely high surface charge carrier concentration in a variety of materials through the formation of electric double layer (EDL) at the sample surface. Here we demonstrate a new mechanism of electrolyte gating that modulates the volumetric carrier density by gate-controlled intercalation in layered materials. We fabricate field-effect transistors (referred to as ionic field-effect transistor, iFET) based on transition metal dichalcogenides 1T-TaS2 and 2H-TaS2. The unprecedented large doping induces dramatic changes in the transport properties of the sample, including CDW phase transitions, superconductivity and metal-to-insulator transitions. The controllable and reversible intercalation of different ion spices into layered materials opens up new possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.

  2. Field-effect transistors (2nd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Bocharov, L. N.

    The design, principle of operation, and principal technical characteristics of field-effect transistors produced in the USSR are described. Problems related to the use of field-effect transistors in various radioelectronic devices are examined, and tables of parameters and mean statistical characteristics are presented for the main types of field-effect transistors. Methods for calculating various circuit components are discussed and illustrated by numerical examples.

  3. Antiferromagnetic Spin Wave Field-Effect Transistor.

    PubMed

    Cheng, Ran; Daniels, Matthew W; Zhu, Jian-Gang; Xiao, Di

    2016-01-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale. PMID:27048928

  4. Antiferromagnetic Spin Wave Field-Effect Transistor

    NASA Astrophysics Data System (ADS)

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-04-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale.

  5. Polycrystalline silicon ion sensitive field effect transistors

    NASA Astrophysics Data System (ADS)

    Yan, F.; Estrela, P.; Mo, Y.; Migliorato, P.; Maeda, H.; Inoue, S.; Shimoda, T.

    2005-01-01

    We report the operation of polycrystalline silicon ion sensitive field effect transistors. These devices can be fabricated on inexpensive disposable substrates such as glass or plastics and are, therefore, promising candidates for low cost single-use intelligent multisensors. In this work we have developed an extended gate structure with a Si3N4 sensing layer. Nearly ideal pH sensitivity (54mV /pH) and stable operation have been achieved. Temperature effects have been characterized. A penicillin sensor has been fabricated by functionalizing the sensing area with penicillinase. The sensitivity to penicillin G is about 10mV/mM, in solutions with concentration lower than the saturation value, which is about 7 mM.

  6. Antiferromagnetic Spin Wave Field-Effect Transistor

    PubMed Central

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-01-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale. PMID:27048928

  7. Antiferromagnetic Spin Wave Field-Effect Transistor

    DOE PAGESBeta

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-04-06

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. In conclusion, our findings open up the exciting possibilitymore » of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale.« less

  8. Contact electrification field-effect transistor.

    PubMed

    Zhang, Chi; Tang, Wei; Zhang, Limin; Han, Changbao; Wang, Zhong Lin

    2014-08-26

    Utilizing the coupled metal oxide semiconductor field-effect transistor and triboelectric nanogenerator, we demonstrate an external force triggered/controlled contact electrification field-effect transistor (CE-FET), in which an electrostatic potential across the gate and source is created by a vertical contact electrification between the gate material and a “foreign” object, and the carrier transport between drain and source can be tuned/controlled by the contact-induced electrostatic potential instead of the traditional gate voltage. With the two contacted frictional layers vertically separated by 80 μm, the drain current is decreased from 13.4 to 1.9 μA in depletion mode and increased from 2.4 to 12.1 μA in enhancement mode at a drain voltage of 5 V. Compared with the piezotronic devices that are controlled by the strain-induced piezoelectric polarization charged at an interface/junction, the CE-FET has greatly expanded the sensing range and choices of materials in conjunction with semiconductors. The CE-FET is likely to have important applications in sensors, human–silicon technology interfacing, MEMS, nanorobotics, and active flexible electronics. Based on the basic principle of the CE-FET, a field of tribotronics is proposed for devices fabricated using the electrostatic potential created by triboelectrification as a “gate” voltage to tune/control charge carrier transport in conventional semiconductor devices. By the three-way coupling among triboelectricity, semiconductor, and photoexcitation, plenty of potentially important research fields are expected to be explored in the near future. PMID:25119657

  9. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

    PubMed Central

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-01-01

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending. PMID:26846587

  10. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

    DOE PAGESBeta

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-02-05

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under variousmore » bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (insitu STM-TEM). Ultimately, as suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending.« less

  11. Compact model for switching characteristics of graphene field effect transistor

    NASA Astrophysics Data System (ADS)

    Sreenath, R.; Bala Tripura Sundari, B.

    2016-04-01

    The scaling of CMOS transistors has resulted in intensified short channel effects, indicating that CMOS has reached its physical limits. Alternate non silicon based materials namely carbon based graphene, carbon nanotubes are being explored for usability as channel and interconnect material due to their established higher mobility and robustness. This paper presents a drift-diffusion based circuit simulatable Verilog-A compact model of graphene field effect transistor (GFET) for channel length of 100nm.The focus is on the development of simulatable device model in Verilog A based on intrinsic parameters and obtain the current, high cutoff frequency and use the model into circuit level simulations to realize an inverter and a 3-stage ring oscillator using Synopsys HSPICE. The applications are so chosen that their switching characteristics enable the determination of the RF frequency ranges of operation that the model can achieve when used in digital applications and also to compare its performance with existing CMOS model. The GFET's switching characteristics and power consumption were found to be better than similarly sized CMOS operating at same range of voltages. The basic frequency of operation in the circuit is of significant importance so as to use the model in other applications at RF and in future for millimeter wave applications. The frequency of operation at circuit level is found to be 1.1GHz at 100nm which is far higher than the existing frequency of 245 MHz reported at 500nm using AlN.

  12. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors.

    PubMed

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L; Banyai, Douglas; Savaikar, Madhusudan A; Jaszczak, John A; Yap, Yoke Khin

    2016-01-01

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending. PMID:26846587

  13. Noise characteristics of single-walled carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-01

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors.

  14. Noise characteristics of single-walled carbon nanotube network transistors.

    PubMed

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-16

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors. PMID:21828739

  15. Ambipolar transistors based on random networks of WS2 nanotubes

    NASA Astrophysics Data System (ADS)

    Sugahara, Mitsunari; Kawai, Hideki; Yomogida, Yohei; Maniwa, Yutaka; Okada, Susumu; Yanagi, Kazuhiro

    2016-07-01

    WS2 nanotubes are rolled multiwalled nanotubes made of a layered material, tungsten disulfide. Their fibril structures enable the fabrication of random network films; however, these films are nonconducting, and thus have not been used for electronic applications. Here, we demonstrate that carrier injection into WS2 networks using an electrolyte gating approach could cause these networks to act as semiconducting channels. We clarify the Raman characteristics of WS2 nanotubes under electrolyte gating and confirm the feasibility of the injection of electrons and holes. We reveal ambipolar behaviors of the WS2 nanotube networks in field-effect transistor setups with electrolyte gating.

  16. Gate protective device for insulated gate field-effect transistors

    NASA Technical Reports Server (NTRS)

    Sunshine, R. A.

    1972-01-01

    Device, which protects insulated gate field-effect transistors, improves reliability through utilization of layers of conductive material on top of each alternating semiconductor material region. Separation of layers is necessary to prevent shorting out junctions between alternating regions.

  17. A Field-Effect Transistor (FET) model for ASAP

    NASA Technical Reports Server (NTRS)

    Ming, L.

    1965-01-01

    The derivation of the circuitry of a field effect transistor (FET) model, the procedure for adapting the model to automated statistical analysis program (ASAP), and the results of applying ASAP on this model are described.

  18. I-V Characteristics of a Ferroelectric Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Ho, Fat Duen

    1999-01-01

    There are many possible uses for ferroelectric field effect transistors.To understand their application, a fundamental knowledge of their basic characteristics must first be found. In this research, the current and voltage characteristics of a field effect transistor are described. The effective gate capacitance and charge are derived from experimental data on an actual FFET. The general equation for a MOSFET is used to derive the internal characteristics of the transistor: This equation is modified slightly to describe the FFET characteristics. Experimental data derived from a Radiant Technologies FFET is used to calculate the internal transistor characteristics using fundamental MOSFET equations. The drain current was measured under several different gate and drain voltages and with different initial polarizations on the ferroelectric material in the transistor. Two different polarization conditions were used. One with the gate ferroelectric material polarized with a +9.0 volt write pulse and one with a -9.0 volt pulse.

  19. From transistor to nanotube

    NASA Astrophysics Data System (ADS)

    Boudenot, Jean-Claude

    2008-01-01

    We present here the main steps in the evolution of the transistor, since the tremendous invention of such a device and the introduction of the integrated circuit. We will then recall the main steps of Moore's law development. Nanotechnology began at the very beginning of the 21st century. Two aspects are presented in this article: the first, called 'More Moore', consists in continuing the laws of scale up to the physical limits; the second aspect, called 'beyond CMOS' explores new concepts such as spintronics, moletronics, nanotronics and other types of molecular electronics. To cite this article: J.-C. Boudenot, C. R. Physique 9 (2008).

  20. Spin field effect transistors with ultracold atoms.

    PubMed

    Vaishnav, J Y; Ruseckas, Julius; Clark, Charles W; Juzeliūnas, Gediminas; Juzelŭnas, Gediminas

    2008-12-31

    We propose a method of constructing cold atom analogs of the spintronic device known as the Datta-Das transistor (DDT), which, despite its seminal conceptual role in spintronics, has never been successfully realized with electrons. We propose two alternative schemes for an atomic DDT, both of which are based on the experimental setup for tripod stimulated Raman adiabatic passage. Both setups involve atomic beams incident on a series of laser fields mimicking the relativistic spin-orbit coupling for electrons that is the operating mechanism of the DDT. PMID:19437649

  1. Sandwich double gate vertical tunneling field-effect transistor

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhang, Wen-hao; Yu, Cheng-hao; Cao, Fei

    2016-05-01

    In this work, a sandwich vertical tunnel field effect transistor (SDG-VTFET) is presented and studied. Since the dominant carrier tunneling of SDG-VFET occurs in a direction that is in line with the gate field, high ON-state current and steep subthreshold slope are observed. Comparisons between SDG-VFET and double gate tunnel field effect transistor are made to clarify advantages of SDG-VTFET. The simulation results of our work show that SDG-VTFET has stronger gate control, steeper subthreshold slope and higher ON-state current. The device plays a promising candidate for future low power circuit applications.

  2. An anion sensor based on an organic field effect transistor.

    PubMed

    Minami, Tsuyoshi; Minamiki, Tsukuru; Tokito, Shizuo

    2015-06-11

    We propose an organic field effect transistor (OFET)-based sensor design as a new and innovative platform for anion detection. OFETs could be fabricated on low-cost plastic film substrates using printing technologies, suggesting that OFETs can potentially be applied to practical supramolecular anion sensor devices in the near future. PMID:25966040

  3. Radiation tolerant silicon nitride insulated gate field effect transistors

    NASA Technical Reports Server (NTRS)

    Newman, P. A.

    1969-01-01

    Metal-Insulated-Semiconductor Field Effect Transistor /MISFET/ device uses a silicon nitride passivation layer over a thin silicon oxide layer to enhance the radiation tolerance. It is useful in electronic systems exposed to space radiation environment or the effects of nuclear weapons.

  4. Multiplexer uses insulated gate-field effect transistors

    NASA Technical Reports Server (NTRS)

    Gussow, S. S.

    1967-01-01

    Small lightweight multiplexer incorporates IG-FETs /Insulated Gate-Field Effect Transistors/ for all digital logic functions, including the internally generated 3.6-kHz clock. It consists of 30 primary channels, each of which is sampled 120 times per second.

  5. Improved Field-Effect Transistor Equations for Computer Simulation.

    ERIC Educational Resources Information Center

    Kidd, Richard; Ardini, James

    1979-01-01

    Presents a laboratory experiment that was developed to acquaint physics students with field-effect transistor characteristics and circuits. Computer-drawn curves supplementing student laboratory exercises can be generated to provide more permanent, usable data than those taken from a curve tracer. (HM)

  6. Carbon nanotube electrodes in organic transistors.

    PubMed

    Valitova, Irina; Amato, Michele; Mahvash, Farzaneh; Cantele, Giovanni; Maffucci, Antonio; Santato, Clara; Martel, Richard; Cicoira, Fabio

    2013-06-01

    The scope of this Minireview is to provide an overview of the recent progress on carbon nanotube electrodes applied to organic thin film transistors. After an introduction on the general aspects of the charge injection processes at various electrode-semiconductor interfaces, we discuss the great potential of carbon nanotube electrodes for organic thin film transistors and the recent achievements in the field. PMID:23639944

  7. Porous-Floating-Gate Field-Effect Transistor

    NASA Technical Reports Server (NTRS)

    Thakoor, Anilkumar P.; Moopenn, Alexander W.; Lambe, John J.

    1990-01-01

    Porous-floating-gate, "vertical" field-effect transistor proposed as programmable analog memory device especially suitable for use in electronic neural networks. Analog value of electrical conductance of device represents synaptic weight (strength of synaptic connection) repeatedly modified by application of suitable writing or erasing voltage. Suited for hardware implementations of massively parallel neural-network architectures for two important reasons: vertical transistor structure requires only two external electrodes, and use of tailored amorphous semiconductors provides choice of very wide range of low conductivity values, dictated by overall power dissipation requirements in massively parallel neural-network circuits.

  8. Transit-time spin field-effect transistor

    NASA Astrophysics Data System (ADS)

    Appelbaum, Ian; Monsma, Douwe J.

    2007-06-01

    The authors propose and analyze a four-terminal metal-semiconductor device that uses hot-electron transport through thin ferromagnetic films to inject and detect a charge-coupled spin current transported through the conduction band of an arbitrary semiconductor. This provides the possibility of realizing a spin field-effect transistor in Si using electrostatic transit-time control of coherent spin precession in a perpendicular magnetic field.

  9. A scheme for a topological insulator field effect transistor

    NASA Astrophysics Data System (ADS)

    Vali, Mehran; Dideban, Daryoosh; Moezi, Negin

    2015-05-01

    We propose a scheme for a topological insulator field effect transistor. The idea is based on the gate voltage control of the Dirac fermions in a ferromagnetic topological insulator channel with perpendicular magnetization connecting to two metallic topological insulator leads. Our theoretical analysis shows that the proposed device displays a switching effect with high on/off current ratio and a negative differential conductance with a good peak to valley ratio.

  10. TOPICAL REVIEW: Organic field-effect transistors using single crystals

    NASA Astrophysics Data System (ADS)

    Hasegawa, Tatsuo; Takeya, Jun

    2009-04-01

    Organic field-effect transistors using small-molecule organic single crystals are developed to investigate fundamental aspects of organic thin-film transistors that have been widely studied for possible future markets for 'plastic electronics'. In reviewing the physics and chemistry of single-crystal organic field-effect transistors (SC-OFETs), the nature of intrinsic charge dynamics is elucidated for the carriers induced at the single crystal surfaces of molecular semiconductors. Materials for SC-OFETs are first reviewed with descriptions of the fabrication methods and the field-effect characteristics. In particular, a benchmark carrier mobility of 20-40 cm2 Vs-1, achieved with thin platelets of rubrene single crystals, demonstrates the significance of the SC-OFETs and clarifies material limitations for organic devices. In the latter part of this review, we discuss the physics of microscopic charge transport by using SC-OFETs at metal/semiconductor contacts and along semiconductor/insulator interfaces. Most importantly, Hall effect and electron spin resonance (ESR) measurements reveal that interface charge transport in molecular semiconductors is properly described in terms of band transport and localization by charge traps.

  11. Lead iodide perovskite light-emitting field-effect transistor

    PubMed Central

    Chin, Xin Yu; Cortecchia, Daniele; Yin, Jun; Bruno, Annalisa; Soci, Cesare

    2015-01-01

    Despite the widespread use of solution-processable hybrid organic–inorganic perovskites in photovoltaic and light-emitting applications, determination of their intrinsic charge transport parameters has been elusive due to the variability of film preparation and history-dependent device performance. Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors. Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport. Under balanced ambipolar carrier injection, gate-dependent electroluminescence is also observed from the transistor channel, with spectra revealing the tetragonal to orthorhombic phase transition. This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature. PMID:26108967

  12. Lead iodide perovskite light-emitting field-effect transistor.

    PubMed

    Chin, Xin Yu; Cortecchia, Daniele; Yin, Jun; Bruno, Annalisa; Soci, Cesare

    2015-01-01

    Despite the widespread use of solution-processable hybrid organic-inorganic perovskites in photovoltaic and light-emitting applications, determination of their intrinsic charge transport parameters has been elusive due to the variability of film preparation and history-dependent device performance. Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors. Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport. Under balanced ambipolar carrier injection, gate-dependent electroluminescence is also observed from the transistor channel, with spectra revealing the tetragonal to orthorhombic phase transition. This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature. PMID:26108967

  13. Lead iodide perovskite light-emitting field-effect transistor

    NASA Astrophysics Data System (ADS)

    Chin, Xin Yu; Cortecchia, Daniele; Yin, Jun; Bruno, Annalisa; Soci, Cesare

    2015-06-01

    Despite the widespread use of solution-processable hybrid organic-inorganic perovskites in photovoltaic and light-emitting applications, determination of their intrinsic charge transport parameters has been elusive due to the variability of film preparation and history-dependent device performance. Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors. Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport. Under balanced ambipolar carrier injection, gate-dependent electroluminescence is also observed from the transistor channel, with spectra revealing the tetragonal to orthorhombic phase transition. This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature.

  14. Exfoliated multilayer MoTe2 field-effect transistors

    NASA Astrophysics Data System (ADS)

    Fathipour, S.; Ma, N.; Hwang, W. S.; Protasenko, V.; Vishwanath, S.; Xing, H. G.; Xu, H.; Jena, D.; Appenzeller, J.; Seabaugh, A.

    2014-11-01

    The properties of multilayer exfoliated MoTe2 field-effect transistors (FETs) on SiO2 were investigated for channel thicknesses from 6 to 44 monolayers (MLs). All transistors showed p-type conductivity at zero back-gate bias. For channel thicknesses of 8 ML or less, the transistors exhibited ambipolar characteristics. ON/OFF current ratio was greatest, 1 × 105, for the transistor with the thinnest channel, 6 ML. Devices showed a clear photoresponse to wavelengths between 510 and 1080 nm at room temperature. Temperature-dependent current-voltage measurements were performed on a FET with 30 layers of MoTe2. When the channel is turned-on and p-type, the temperature dependence is barrier-limited by the Au/Ti/MoTe2 contact with a hole activation energy of 0.13 eV. A long channel transistor model with Schottky barrier contacts is shown to be consistent with the common-source characteristics.

  15. 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

  16. 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.

  17. DNA aptamer functionalized zinc oxide field effect transistors for liquid state selective sensing of small molecules

    NASA Astrophysics Data System (ADS)

    Hagen, Joshua A.; Kim, Sang N.; Bayraktaroglu, Burhan; Kelley-Loughnane, Nancy; Naik, Rajesh R.; Stone, Morley O.

    2010-08-01

    In this work, we show the use of single stranded DNA aptamers as selective biorecognition elements in a sensor based on a field effect transistor (FET) platform. Aptamers are chemically attached to the semiconducting material in the FET through the use of linker molecules and confirmed through atomic force microscopy and positive target detection. Highly selective sensing of a small molecule, riboflavin is shown down to the nano-molar level in zinc oxide FET and micro-molar level in a carbon nanotube FET. High selectivity is determined through the use of negative control target molecules with similar molecular structures as the positive control targets with little to no sensor response. The goal of this work is to develop a sensor platform where biorecognition elements can be used to functionalize an array of transistors for simultaneous sensing of multiple targets in biological fluids.

  18. Semiconducting nanowire field effect transistor for nanoelectronics and nanomechanics

    NASA Astrophysics Data System (ADS)

    Deshmukh, Mandar

    2013-02-01

    Semiconducting nanowire transistors offer an interesting avenue to make fundamentally new device architecture for future switching devices. I will our work to develop a simple fabrication technique for lateral nanowire wrap-gate devices with high capacitive coupling and field-effect mobility using InAs nanowires and also discuss electrical characterization of these devices. Our process uses e-beam lithography with a single resist-spinning step and does not require chemical etching. We measure significantly larger mobility and good sub-threshold characteristics [1]. I will also discuss the applications of using suspended nanowire transistors in studying mechanics and thermal properties of nanostructures as they can be useful in studying a wide variety of physics at the nanoscale. This work is supported by Government of India and partially supported by IBM India.

  19. Vertical Organic Field-Effect Transistors for Integrated Optoelectronic Applications.

    PubMed

    Yu, Hyeonggeun; Dong, Zhipeng; Guo, Jing; Kim, Doyoung; So, Franky

    2016-04-27

    Direct integration of a vertical organic field-effect transistor (VOFET) and an optoelectronic device offers a single stacked, low power optoelectronic VOFET with high aperture ratios. However, a functional optoelectronic VOFET could not be realized because of the difficulty in fabricating transparent source and gate electrodes. Here, we report a VOFET with an on/off ratio up to 10(5) as well as output current saturation by fabricating a transparent gate capacitor consisting of a perforated indium tin oxide (ITO) source electrode, HfO2 gate dielectric, and ITO gate electrode. Effects of the pore size and the pore depth within the porous ITO electrodes on the on/off characteristic of a VOFET are systematically explained in this work. By combining a phosphorescent organic light-emitting diode with an optimized VOFET structure, a vertical organic light-emitting transistor with a luminance on/off ratio of 10(4) can be fabricated. PMID:27082815

  20. Ferroelectric memory element based on thin film field effect transistor

    NASA Astrophysics Data System (ADS)

    Poghosyan, A. R.; Aghamalyan, N. R.; Elbakyan, E. Y.; Guo, R.; Hovsepyan, R. K.

    2013-09-01

    We report the preparation and investigation of ferroelectric field effect transistors (FET) using ZnO:Li films with high field mobility of the charge carriers as a FET channel and as a ferroelectric active element simultaneously. The possibility for using of ferroelectric FET based on the ZnO:Li films in the ZnO:Li/LaB6 heterostructure as a bi-stable memory element for information recording is shown. The proposed ferroelectric memory structure does not manifest a fatigue after multiple readout of once recorded information.

  1. Cryogenetically Cooled Field Effect Transistors for Low-Noise Systems

    NASA Technical Reports Server (NTRS)

    Wollack, Edward J.; Rabin, Douglas M. (Technical Monitor)

    2002-01-01

    Recent tends in the design, fabrication and use of High-Electron-Mobility-Transistors (HEMT) in low noise amplifiers are reviewed. Systems employing these devices have achieved the lowest system noise for wavelengths greater than three millimeters with relatively modest cryogenic cooling requirements in a variety of ground and space based applications. System requirements which arise in employing such devices in imaging applications are contrasted with other leading coherent detector candidates at microwave wavelengths. Fundamental and practical limitations which arise in the context of microwave application of field effect devices at cryogenic temperatures will be discussed from a component and systems point of view.

  2. Cryogenically Cooled Field Effect Transistors for Low-Noise Systems

    NASA Technical Reports Server (NTRS)

    Wollack, Edward J.

    2002-01-01

    Recent tends in the design, fabrication and use of High-Electron-Mobility-Transistors (HEMT) in low noise amplifiers are reviewed. Systems employing these devices have achieved the lowest system noise for wavelengths greater than three millimeters with relatively modest cryogenic cooling requirements in a variety of ground and space based applications. System requirements which arise in employing such devices in imaging applications are contrasted with other leading coherent detector candidates at microwave wavelengths. Fundamental and practical limitations which arise in the context of microwave application of field effect devices at cryogenic temperatures will be discussed from a component and systems point of view.

  3. Experimental realization of a silicon spin field-effect transistor

    NASA Astrophysics Data System (ADS)

    Huang, Biqin; Monsma, Douwe J.; Appelbaum, Ian

    2007-08-01

    A longitudinal electric field is used to control the transit time (through an undoped silicon vertical channel) of spin-polarized electrons precessing in a perpendicular magnetic field. Since an applied voltage determines the final spin direction at the spin detector and hence the output collector current, this comprises a spin field-effect transistor. An improved hot-electron spin injector providing ≈115% magnetocurrent, corresponding to at least ≈37% electron current spin polarization after transport through 10μm undoped single-crystal silicon, is used for maximum current modulation.

  4. Noise in ZnO nanowire field effect transistors.

    PubMed

    Xiong, Hao D; Wang, Wenyong; Suehle, John S; Richter, Curt A; Hong, Woong-Ki; Lee, Takhee

    2009-02-01

    The noise power spectra in ZnO nanowire field effect transistors (FETs) were experimentally investigated and showed a classical 1/f dependence. A Hooge's constant of 5 x 10(-3) was estimated. This value is within the range reported for CMOS FETs with high-k dielectrics, supporting the concept that nanowires can be utilized for future beyond-CMOS electronic applications from the point of view of device noise properties. ZnO FETs measured in a dry O2 environment displayed elevated noise levels compared to in vacuum. At low temperature, random telegraph signals are observed in the drain current. PMID:19441450

  5. Pressure sensing by flexible, organic, field effect transistors

    NASA Astrophysics Data System (ADS)

    Manunza, I.; Sulis, A.; Bonfiglio, A.

    2006-10-01

    A mechanical sensor based on a pentacene field effect transistor has been fabricated. The pressure dependence of the output current has been investigated by applying a mechanical stimulus by means of a pressurized air flow. Experimental results show a reversible current dependence on pressure. Data analysis suggests that variations of threshold voltage, mobility and contact resistance are responsible for current variations. Thanks to the flexibility of the substrate and the low cost of the technology, this device opens the way for flexible mechanical sensors that can be used in a variety of innovative applications such as e-textiles and robotic interfaces.

  6. Ion-Sensitive Field-Effect Transistor for Biological Sensing

    PubMed Central

    Lee, Chang-Soo; Kim, Sang Kyu; Kim, Moonil

    2009-01-01

    In recent years there has been great progress in applying FET-type biosensors for highly sensitive biological detection. Among them, the ISFET (ion-sensitive field-effect transistor) is one of the most intriguing approaches in electrical biosensing technology. Here, we review some of the main advances in this field over the past few years, explore its application prospects, and discuss the main issues, approaches, and challenges, with the aim of stimulating a broader interest in developing ISFET-based biosensors and extending their applications for reliable and sensitive analysis of various biomolecules such as DNA, proteins, enzymes, and cells. PMID:22423205

  7. Hall and field-effect mobilities in few layered p-WSe₂ field-effect transistors.

    PubMed

    Pradhan, N R; Rhodes, D; Memaran, S; Poumirol, J M; Smirnov, D; Talapatra, S; Feng, S; Perea-Lopez, N; Elias, A L; Terrones, M; Ajayan, P M; Balicas, L

    2015-01-01

    Here, we present a temperature (T) dependent comparison between field-effect and Hall mobilities in field-effect transistors based on few-layered WSe2 exfoliated onto SiO2. Without dielectric engineering and beyond a T-dependent threshold gate-voltage, we observe maximum hole mobilities approaching 350 cm(2)/Vs at T = 300 K. The hole Hall mobility reaches a maximum value of 650 cm(2)/Vs as T is lowered below ~150 K, indicating that insofar WSe2-based field-effect transistors (FETs) display the largest Hall mobilities among the transition metal dichalcogenides. The gate capacitance, as extracted from the Hall-effect, reveals the presence of spurious charges in the channel, while the two-terminal sheet resistivity displays two-dimensional variable-range hopping behavior, indicating carrier localization induced by disorder at the interface between WSe2 and SiO2. We argue that improvements in the fabrication protocols as, for example, the use of a substrate free of dangling bonds are likely to produce WSe2-based FETs displaying higher room temperature mobilities, i.e. approaching those of p-doped Si, which would make it a suitable candidate for high performance opto-electronics. PMID:25759288

  8. Ferroelectric Field-Effect Transistor Differential Amplifier Circuit Analysis

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat D.

    2008-01-01

    There has been considerable research investigating the Ferroelectric Field-Effect Transistor (FeFET) in memory circuits. However, very little research has been performed in applying the FeFET to analog circuits. This paper investigates the use of FeFETs in a common analog circuit, the differential amplifier. The two input Metal-Oxide-Semiconductor (MOS) transistors in a general MOS differential amplifier circuit are replaced with FeFETs. Resistors are used in place of the other three MOS transistors. The FeFET model used in the analysis has been previously reported and was based on experimental device data. Because of the FeFET hysteresis, the FeFET differential amplifier has four different operating modes depending on whether the FeFETs are positively or negatively polarized. The FeFET differential amplifier operation in the different modes was analyzed by calculating the amplifier voltage transfer and gain characteristics shown in figures 2 through 5. Comparisons were made between the FeFET differential amplifier and the standard MOS differential amplifier. Possible applications and benefits of the FeFET differential amplifier are discussed.

  9. Infrared light gated MoS₂ field effect transistor.

    PubMed

    Fang, Huajing; Lin, Ziyuan; Wang, Xinsheng; Tang, Chun-Yin; Chen, Yan; Zhang, Fan; Chai, Yang; Li, Qiang; Yan, Qingfeng; Chan, H L W; Dai, Ji-Yan

    2015-12-14

    Molybdenum disulfide (MoS₂) as a promising 2D material has attracted extensive attentions due to its unique physical, optical and electrical properties. In this work, we demonstrate an infrared (IR) light gated MoS₂ transistor through a device composed of MoS₂ monolayer and a ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O₃-PbTiO₃ (PMN-PT). With a monolayer MoS₂ onto the top surface of (111) PMN-PT crystal, the drain current of MoS₂ channel can be modulated with infrared illumination and this modulation process is reversible. Thus, the transistor can work as a new kind of IR photodetector with a high IR responsivity of 114%/Wcm⁻². The IR response of MoS₂ transistor is attributed to the polarization change of PMN-PT single crystal induced by the pyroelectric effect which results in a field effect. Our result promises the application of MoS₂ 2D material in infrared optoelectronic devices. Combining with the intrinsic photocurrent feature of MoS₂ in the visible range, the MoS₂ on ferroelectric single crystal may be sensitive to a broadband wavelength of light. PMID:26698982

  10. Graphene field effect transistor without an energy gap.

    PubMed

    Jang, Min Seok; Kim, Hyungjun; Son, Young-Woo; Atwater, Harry A; Goddard, William A

    2013-05-28

    Graphene is a room temperature ballistic electron conductor and also a very good thermal conductor. Thus, it has been regarded as an ideal material for postsilicon electronic applications. A major complication is that the relativistic massless electrons in pristine graphene exhibit unimpeded Klein tunneling penetration through gate potential barriers. Thus, previous efforts to realize a field effect transistor for logic applications have assumed that introduction of a band gap in graphene is a prerequisite. Unfortunately, extrinsic treatments designed to open a band gap seriously degrade device quality, yielding very low mobility and uncontrolled on/off current ratios. To solve this dilemma, we propose a gating mechanism that leads to a hundredfold enhancement in on/off transmittance ratio for normally incident electrons without any band gap engineering. Thus, our saw-shaped geometry gate potential (in place of the conventional bar-shaped geometry) leads to switching to an off state while retaining the ultrahigh electron mobility in the on state. In particular, we report that an on/off transmittance ratio of 130 is achievable for a sawtooth gate with a gate length of 80 nm. Our switching mechanism demonstrates that intrinsic graphene can be used in designing logic devices without serious alteration of the conventional field effect transistor architecture. This suggests a new variable for the optimization of the graphene-based device--geometry of the gate electrode. PMID:23671093

  11. Charge Transport in Hybrid Halide Perovskite Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Jurchescu, Oana

    Hybrid organic-inorganic trihalide perovskite (HTP) materials exhibit a strong optical absorption, tunable band gap, long carrier lifetimes and fast charge carrier transport. These remarkable properties, coupled with their reduced complexity processing, make the HTPs promising contenders for large scale, low-cost thin film optoelectronic applications. But in spite of the remarkable demonstrations of high performance solar cells, light-emitting diodes and field-effect transistor devices, all of which took place in a very short time period, numerous questions related to the nature and dynamics of the charge carriers and their relation to device performance, stability and reliability still remain. This presentation describes the electrical properties of HTPs evaluated from field-effect transistor measurements. The electrostatic gating of provides an unique platform for the study of intrinsic charge transport in these materials, and, at the same time, expand the use of HTPs towards switching electronic devices, which have not been explored previously. We fabricated FETs on SiO2 and polymer dielectrics from spin coating, thermal evaporation and spray deposition and compare their properties. CH3NH3PbI3-xClx can reach balanced electron and hole mobilities of 10 cm2/Vs upon tuning the thin-film microstructure, injection and the defect density at the semiconductor/dielectric interface. The work was performed in collaboration with Yaochuan Mei (Wake Forest University), Chuang Zhang, and Z. Valy Vardeny (University of Utah). The work is supported by ONR Grant N00014-15-1-2943.

  12. 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.

  13. In situ tuning and probing the ambipolar field effect on multiwall carbon nanotubes

    SciTech Connect

    Chen, Li-Ying; Chang, Chia-Seng

    2014-12-15

    We report a method of fabricating ultra-clean and hysteresis-free multiwall carbon nanotube field-effect transistors (CNFETs) inside the ultra-high vacuum transmission electron microscope equipped with a movable gold tip as a local gate. By tailoring the shell structure of the nanotube and varying the drain-source voltage (V{sub ds}), we can tune the electronic characteristic of a multiwall CNFET in situ. We have also found that the Schottky barriers of a multiwall CNFET are generated within the nanotube, but not at the nanotube/electrode contacts, and the barrier height has been derived. We have subsequently demonstrated the ambipolar characteristics of the CNFET with concurrent high-resolution imaging and local gating.

  14. Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

    PubMed

    Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

    2016-04-26

    We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces. PMID:27002483

  15. Polymer electrolyte-gated organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Panzer, Matthew J.

    Contemporary interest in organic semiconductors is driven both by questions regarding the fundamentals of charge transport in these materials and by their potential for flexible, low-cost electronic applications. The key device utilized in these endeavors is the organic field-effect transistor (OFET). Attaining large charge carrier densities in OFETs is desirable for two main reasons. First, because the conductivity in an OFET is proportional to the product of carrier mobility and charge density, increasing charge density levels can boost transistor currents significantly and facilitate low-voltage operation. Additionally, the achievement of carrier densities approaching the twodimensional (2D) molecular density (˜5 x 1014 cm-2) in an organic semiconductor monolayer can enable a variety of fundamental transport experiments. The results summarized in this thesis illustrate that charge densities exceeding 1014 charges/cm2 can be attained in a variety of organic semiconductors by using a solid polymer electrolyte as an OFET dielectric. Polymer electrolytes can provide specific capacitances exceeding 10 muF/cm 2, resulting from the migration of ions within a polymer matrix. By measuring the transient gate displacement current caused by ionic motion in a polymer electrolyte-gated organic field-effect transistor (PEG-FET), large electrostatically-injected charge density values can be calculated; these are typically above 1014 charges/cm2 at gate voltages under 3 V. Negative transconductance at large carrier densities is observed in oligomeric, polymeric, and organic single-crystal semiconductors. This phenomenon is ascribed to charge correlations or a nearly complete filling of the semiconductor transport band with carriers. Polymer semiconductors exhibited the highest performance among PEG-FETs with a top gate architecture. Nearly metallic conductivities (˜1000 S/cm), weak ON current temperature dependences, and large linear mobility values (˜3 cm2/V·s) were

  16. GaN Metal Oxide Semiconductor Field Effect Transistors

    SciTech Connect

    Ren, F.; Pearton, S.J.; Abernathy, C.R.; Baca, A.; Cheng, P.; Shul, R.J.; Chu, S.N.G.; Hong, M.; Lothian, J.R.; Schurman, M.J.

    1999-03-02

    A GaN based depletion mode metal oxide semiconductor field effect transistor (MOSFET) was demonstrated using Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) as the gate dielectric. The MOS gate reverse breakdown voltage was > 35V which was significantly improved from 17V of Pt Schottky gate on the same material. A maximum extrinsic transconductance of 15 mS/mm was obtained at V{sub ds} = 30 V and device performance was limited by the contact resistance. A unity current gain cut-off frequency, f{sub {tau}}, and maximum frequency of oscillation, f{sub max} of 3.1 and 10.3 GHz, respectively, were measured at V{sub ds} = 25 V and V{sub gs} = {minus}20 V.

  17. Electrospun Polyaniline/Polyethylene Oxide Nanofiber Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    Pinto, N. J.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

    2003-01-01

    We report on the observation of field effect transistor (FET) behavior in electrospun camphorsulfonic acid doped polyaniline(PANi)/polyethylene oxide(PE0) nanofibers. Saturation channel currents are observed at surprisingly low source/drain voltages. The hole mobility in the depletion regime is 1.4 x 10(exp -4) sq cm/V s while the 1-D charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating 1-D polymer FET's.

  18. Electric control of spin in monolayer WSe₂ field effect transistors.

    PubMed

    Gong, Kui; Zhang, Lei; Liu, Dongping; Liu, Lei; Zhu, Yu; Zhao, Yonghong; Guo, Hong

    2014-10-31

    We report first-principles theoretical investigations of quantum transport in a monolayer WSe2 field effect transistor (FET). Due to strong spin-orbit interaction (SOI) and the atomic structure of the two-dimensional lattice, monolayer WSe2 has an electronic structure that exhibits Zeeman-like up-down spin texture near the K and K' points of the Brillouin zone. In a FET, the gate electric field induces an extra, externally tunable SOI that re-orients the spins into a Rashba-like texture thereby realizing electric control of the spin. The conductance of FET is modulated by the spin texture, namely by if the spin orientation of the carrier after the gated channel region, matches or miss-matches that of the FET drain electrode. The carrier current I(τ, s) in the FET is labelled by both the valley index and spin index, realizing valleytronics and spintronics in the same device. PMID:25287881

  19. Axial SiGe Heteronanowire Tunneling Field-Effect Transistors

    SciTech Connect

    Le, Son T.; Jannaty, P.; Luo, Xu; Zaslavsky, A.; Perea, Daniel E.; Dayeh, Shadi A.; Picraux, Samuel T.

    2012-10-31

    We present silicon-compatible tri-gated p-Ge/i-Si/n-Si axial heteronanowire tunneling field-effect transistors (TFETs), where on-state tunneling occurs in the Ge drain section, while off-state leakage is dominated by the Si junction in the source. Our TFETs have high ION ~ 2 µA/µm, fully suppressed ambipolarity, and a sub-threshold slope SS ~ 140 mV/decade over 4 decades of current with lowest SS ~ 50 mV/decade. Device operation in the tunneling mode is confirmed by three-dimensional TCAD simulation. Interestingly, in addition to the TFET mode, our devices work as standard nanowire FETs with good ION/IOFF ratio when the source-drain junction is forward-biased. The improved transport in both biasing modes confirms the benefits of utilizing bandgap engineered axial nanowires for enhancing device performance.

  20. Semianalytical quantum model for graphene field-effect transistors

    SciTech Connect

    Pugnaghi, Claudio; Grassi, Roberto Gnudi, Antonio; Di Lecce, Valerio; Gnani, Elena; Reggiani, Susanna; Baccarani, Giorgio

    2014-09-21

    We develop a semianalytical model for monolayer graphene field-effect transistors in the ballistic limit. Two types of devices are considered: in the first device, the source and drain regions are doped by charge transfer with Schottky contacts, while, in the second device, the source and drain regions are doped electrostatically by a back gate. The model captures two important effects that influence the operation of both devices: (i) the finite density of states in the source and drain regions, which limits the number of states available for transport and can be responsible for negative output differential resistance effects, and (ii) quantum tunneling across the potential steps at the source-channel and drain-channel interfaces. By comparison with a self-consistent non-equilibrium Green's function solver, we show that our model provides very accurate results for both types of devices, in the bias region of quasi-saturation as well as in that of negative differential resistance.

  1. Encapsulated graphene field-effect transistors for air stable operation

    SciTech Connect

    Alexandrou, Konstantinos Kymissis, Ioannis; Petrone, Nicholas; Hone, James

    2015-03-16

    In this work, we report the fabrication of encapsulated graphene field effects transistors (GFETs) with excellent air stability operation in ambient environment. Graphene's 2D nature makes its electronics properties very sensitive to the surrounding environment, and thus, non-encapsulated graphene devices show extensive vulnerability due to unintentional hole doping from the presence of water molecules and oxygen limiting their performance and use in real world applications. Encapsulating GFETs with a thin layer of parylene-C and aluminum deposited on top of the exposed graphene channel area resulted in devices with excellent electrical performance stability for an extended period of time. Moisture penetration is reduced significantly and carrier mobility degraded substantially less when compared to non-encapsulated control devices. Our CMOS compatible encapsulation method minimizes the problems of environmental doping and lifetime performance degradation, enabling the operation of air stable devices for next generation graphene-based electronics.

  2. Modeling of Metal-Ferroelectric-Semiconductor Field Effect Transistors

    NASA Technical Reports Server (NTRS)

    Duen Ho, Fat; Macleod, Todd C.

    1998-01-01

    The characteristics for a MFSFET (metal-ferroelectric-semiconductor field effect transistor) is very different than a conventional MOSFET and must be modeled differently. The drain current has a hysteresis shape with respect to the gate voltage. The position along the hysteresis curve is dependent on the last positive or negative polling of the ferroelectric material. The drain current also has a logarithmic decay after the last polling. A model has been developed to describe the MFSFET drain current for both gate voltage on and gate voltage off conditions. This model takes into account the hysteresis nature of the MFSFET and the time dependent decay. The model is based on the shape of the Fermi-Dirac function which has been modified to describe the MFSFET's drain current. This is different from the model proposed by Chen et. al. and that by Wu.

  3. The fundamental downscaling limit of field effect transistors

    SciTech Connect

    Mamaluy, Denis Gao, Xujiao

    2015-05-11

    We predict that within next 15 years a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs) will be reached. Specifically, we show that at room temperatures all FETs, irrespective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths. These findings were confirmed by performing quantum mechanical transport simulations for a variety of 6-, 5-, and 4-nm gate length Si devices, optimized to satisfy high-performance logic specifications by ITRS. Different channel materials and wafer/channel orientations have also been studied; it is found that altering channel-source-drain materials achieves only insignificant increase in switching energy, which overall cannot sufficiently delay the approaching downscaling limit. Alternative possibilities are discussed to continue the increase of logic element densities for room temperature operation below the said limit.

  4. Theoretical study of phosphorene tunneling field effect transistors

    SciTech Connect

    Chang, Jiwon; Hobbs, Chris

    2015-02-23

    In this work, device performances of tunneling field effect transistors (TFETs) based on phosphorene are explored via self-consistent atomistic quantum transport simulations. Phosphorene is an ultra-thin two-dimensional (2-D) material with a direct band gap suitable for TFETs applications. Our simulation shows that phosphorene TFETs exhibit subthreshold slope below 60 mV/dec and a wide range of on-current depending on the transport direction due to highly anisotropic band structures of phosphorene. By benchmarking with monolayer MoTe{sub 2} TFETs, we predict that phosphorene TFETs oriented in the small effective mass direction can yield much larger on-current at the same on-current/off-current ratio than monolayer MoTe{sub 2} TFETs. It is also observed that a gate underlap structure is required for scaling down phosphorene TFETs in the small effective mass direction to suppress the source-to-drain direct tunneling leakage current.

  5. Resolving ambiguities in nanowire field-effect transistor characterization.

    PubMed

    Heedt, Sebastian; Otto, Isabel; Sladek, Kamil; Hardtdegen, Hilde; Schubert, Jürgen; Demarina, Natalia; Lüth, Hans; Grützmacher, Detlev; Schäpers, Thomas

    2015-11-21

    We have modeled InAs nanowires using finite element methods considering the actual device geometry, the semiconducting nature of the channel and surface states, providing a comprehensive picture of charge distribution and gate action. The effective electrostatic gate width and screening effects are taken into account. A pivotal aspect is that the gate coupling to the nanowire is compromised by the concurrent coupling of the gate electrode to the surface/interface states, which provide the vast majority of carriers for undoped nanowires. In conjunction with field-effect transistor (FET) measurements using two gates with distinctly dissimilar couplings, the study reveals the density of surface states that gives rise to a shallow quantum well at the surface. Both gates yield identical results for the electron concentration and mobility only at the actual surface state density. Our method remedies the flaws of conventional FET analysis and provides a straightforward alternative to intricate Hall effect measurements on nanowires. PMID:26482127

  6. Touching polymer chains by organic field-effect transistors

    PubMed Central

    Shao, Wei; Dong, Huanli; Wang, Zhigang; Hu, Wenping

    2014-01-01

    Organic field-effect transistors (OFETs) are used to directly “touch” the movement and dynamics of polymer chains, and then determine Tg. As a molecular-level probe, the conducting channel of OFETs exhibits several unique advantages: 1) it directly detects the motion and dynamics of polymer chain at Tg; 2) it allows the measurement of size effects in ultrathin polymer films (even down to 6 nm), which bridges the gap in understanding effects between surface and interface. This facile and reliable determination of Tg of polymer films and the understanding of polymer chain dynamics guide a new prospect for OFETs besides their applications in organic electronics and casting new light on the fundamental understanding of the nature of polymer chain dynamics. PMID:25227159

  7. `Soft' amplifier circuits based on field-effect ionic transistors

    NASA Astrophysics Data System (ADS)

    Boon, Niels; Olvera de La Cruz, Monica

    Soft materials can be used as building blocks of electronic devices with extraordinary properties. We demonstrate that an ionic analogue of the semiconductor field-effect transistor (FET) could be used for voltage and current amplifiers. Our theoretical model incorporates readily-available soft materials, such as conductive porous membranes and polymer electrolytes to represent a current-gating device that can be integrated in electronic circuits. By means of Nernst-Planck numerical simulations as well as an analytical approach towards expressions that describe steady-state currents, we find that the behavior in response to various input voltages can be categorized into ohmic, sub-threshold, and active modes. This is fully analogous to what is known for semiconductor FETs. Pivotal FET properties such as threshold voltage and transconductance must be related to half-cell redox potentials as well as polyelectrolyte and gate material properties. We further extend the analogy with semiconductor FETs through numerical simulations of elementary amplifier circuits in which we successfully substitute the semiconductor transistor by an ionic FET.

  8. Electronic Model of a Ferroelectric Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Ho, Fat Duen; Russell, Larry (Technical Monitor)

    2001-01-01

    A pair of electronic models has been developed of a Ferroelectric Field Effect transistor. These models can be used in standard electrical circuit simulation programs to simulate the main characteristics of the FFET. The models use the Schmitt trigger circuit as a basis for their design. One model uses bipolar junction transistors and one uses MOSFET's. Each model has the main characteristics of the FFET, which are the current hysterisis with different gate voltages and decay of the drain current when the gate voltage is off. The drain current from each model has similar values to an actual FFET that was measured experimentally. T'he input and o Output resistance in the models are also similar to that of the FFET. The models are valid for all frequencies below RF levels. No attempt was made to model the high frequency characteristics of the FFET. Each model can be used to design circuits using FFET's with standard electrical simulation packages. These circuits can be used in designing non-volatile memory circuits and logic circuits and is compatible with all SPICE based circuit analysis programs. The models consist of only standard electrical components, such as BJT's, MOSFET's, diodes, resistors, and capacitors. Each model is compared to the experimental data measured from an actual FFET.

  9. Silicon junctionless field effect transistors as room temperature terahertz detectors

    SciTech Connect

    Marczewski, J. Tomaszewski, D.; Zaborowski, M.; Zagrajek, P.

    2015-09-14

    Terahertz (THz) radiation detection by junctionless metal-oxide-semiconductor field-effect transistors (JL MOSFETs) was studied and compared with THz detection using conventional MOSFETs. It has been shown that in contrast to the behavior of standard transistors, the junctionless devices have a significant responsivity also in the open channel (low resistance) state. The responsivity for a photolithographically defined JL FET was 70 V/W and the noise equivalent power 460 pW/√Hz. Working in the open channel state may be advantageous for THz wireless and imaging applications because of its low thermal noise and possible high operating speed or large bandwidth. It has been proven that the junctionless MOSFETs can also operate in a zero gate bias mode, which enables simplification of the THz array circuitry. Existing models of THz detection by MOSFETs were considered and it has been demonstrated that the process of detection by these junctionless devices cannot be explained within the framework of the commonly accepted models and therefore requires a new theoretical approach.

  10. Nano-textured high sensitivity ion sensitive field effect transistors

    NASA Astrophysics Data System (ADS)

    Hajmirzaheydarali, M.; Sadeghipari, M.; Akbari, M.; Shahsafi, A.; Mohajerzadeh, S.

    2016-02-01

    Nano-textured gate engineered ion sensitive field effect transistors (ISFETs), suitable for high sensitivity pH sensors, have been realized. Utilizing a mask-less deep reactive ion etching results in ultra-fine poly-Si features on the gate of ISFET devices where spacing of the order of 10 nm and less is achieved. Incorporation of these nano-sized features on the gate is responsible for high sensitivities up to 400 mV/pH in contrast to conventional planar structures. The fabrication process for this transistor is inexpensive, and it is fully compatible with standard complementary metal oxide semiconductor fabrication procedure. A theoretical modeling has also been presented to predict the extension of the diffuse layer into the electrolyte solution for highly featured structures and to correlate this extension with the high sensitivity of the device. The observed ultra-fine features by means of scanning electron microscopy and transmission electron microscopy tools corroborate the theoretical prediction.

  11. Slowing DNA Translocation in a Nanofluidic Field-Effect Transistor.

    PubMed

    Liu, Yifan; Yobas, Levent

    2016-04-26

    Here, we present an experimental demonstration of slowing DNA translocation across a nanochannel by modulating the channel surface charge through an externally applied gate bias. The experiments were performed on a nanofluidic field-effect transistor, which is a monolithic integrated platform featuring a 50 nm-diameter in-plane alumina nanocapillary whose entire length is surrounded by a gate electrode. The field-effect transistor behavior was validated on the gating of ionic conductance and protein transport. The gating of DNA translocation was subsequently studied by measuring discrete current dips associated with single λ-DNA translocation events under a source-to-drain bias of 1 V. The translocation speeds under various gate bias conditions were extracted by fitting event histograms of the measured translocation time to the first passage time distributions obtained from a simple 1D biased diffusion model. A positive gate bias was observed to slow the translocation of single λ-DNA chains markedly; the translocation speed was reduced by an order of magnitude from 18.4 mm/s obtained under a floating gate down to 1.33 mm/s under a positive gate bias of 9 V. Therefore, a dynamic and flexible regulation of the DNA translocation speed, which is vital for single-molecule sequencing, can be achieved on this device by simply tuning the gate bias. The device is realized in a conventional semiconductor microfabrication process without the requirement of advanced lithography, and can be potentially further developed into a compact electronic single-molecule sequencer. PMID:27019102

  12. Fabrication and analysis of polymer field-effect transistors

    NASA Astrophysics Data System (ADS)

    Scheinert, S.; Paasch, G.

    2004-05-01

    Parameters of organic field-effect transistors (OFET) achieved in recent years are promising enough for R & D activities towards a commercial low-cost polymer electronics. In spite of the fast progress, preparations dominated by trial and error are concentrated essentially on higher mobility polymers and shorter channel patterning, and the analysis of measured data is based on oversimplified models. Here ways to professionalize the research on polymer field-effect transistors are discussed exploiting experience accumulated in microelectronics. First of all, designing the devices before fabricating and subsequently analyzing them requires appropriate modelling. Almost independently from the nature of the transport process, the device physics is basically described by the drift-diffusion model, combined with non-degenerate carrier statistics. Therefore, with a modified interpretation of the so-called effective density of states, existing simulation tools can be applied, except for special cases which are discussed. Analytical estimates are helpful already in designing devices, and applied to experimental data they yield input parameters for the numerical simulations. Preparations of OFET's and capacitors with poly(3-ocylthiophene) (P3OT), poly(3-dodecylthiophene) P3HT, Arylamino-poly-(phenylene-vinylene) (PPV), poly(2-methoxy, 5 ethyl (2 hexyloxy) paraphenylenevinylene) MEH-PPV, and pentacene from a soluble precursor are described, with silicon dioxide (SiO2) or poly(4-vinylphenol) (P4VP) as gate insulator, and with rather different channel length. We demonstrate the advantage of combining all steps from design/fabrication to analysis of the experimental data with analytical estimates and numerical simulation. Of special importance is the connection between mobility, transistor channel length, cut-off frequency and operation voltage, which was the starting point for the development of a low-cost fabrication of high-performance submicrometer OFET's by an underetching

  13. Gas sensors based on semiconducting nanowire field-effect transistors.

    PubMed

    Feng, Ping; Shao, Feng; Shi, Yi; Wan, Qing

    2014-01-01

    One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs) are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concentration of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concentration of the gas molecules. In addition, extra controls such as metal decoration, local heating and light irradiation can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed. PMID:25232915

  14. Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

    PubMed Central

    Feng, Ping; Shao, Feng; Shi, Yi; Wan, Qing

    2014-01-01

    One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs) are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concentration of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concentration of the gas molecules. In addition, extra controls such as metal decoration, local heating and light irradiation can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed. PMID:25232915

  15. Biologically sensitive field-effect transistors: from ISFETs to NanoFETs.

    PubMed

    Pachauri, Vivek; Ingebrandt, Sven

    2016-06-30

    Biologically sensitive field-effect transistors (BioFETs) are one of the most abundant classes of electronic sensors for biomolecular detection. Most of the time these sensors are realized as classical ion-sensitive field-effect transistors (ISFETs) having non-metallized gate dielectrics facing an electrolyte solution. In ISFETs, a semiconductor material is used as the active transducer element covered by a gate dielectric layer which is electronically sensitive to the (bio-)chemical changes that occur on its surface. This review will provide a brief overview of the history of ISFET biosensors with general operation concepts and sensing mechanisms. We also discuss silicon nanowire-based ISFETs (SiNW FETs) as the modern nanoscale version of classical ISFETs, as well as strategies to functionalize them with biologically sensitive layers. We include in our discussion other ISFET types based on nanomaterials such as carbon nanotubes, metal oxides and so on. The latest examples of highly sensitive label-free detection of deoxyribonucleic acid (DNA) molecules using SiNW FETs and single-cell recordings for drug screening and other applications of ISFETs will be highlighted. Finally, we suggest new device platforms and newly developed, miniaturized read-out tools with multichannel potentiometric and impedimetric measurement capabilities for future biomedical applications. PMID:27365038

  16. Biologically sensitive field-effect transistors: from ISFETs to NanoFETs

    PubMed Central

    Pachauri, Vivek

    2016-01-01

    Biologically sensitive field-effect transistors (BioFETs) are one of the most abundant classes of electronic sensors for biomolecular detection. Most of the time these sensors are realized as classical ion-sensitive field-effect transistors (ISFETs) having non-metallized gate dielectrics facing an electrolyte solution. In ISFETs, a semiconductor material is used as the active transducer element covered by a gate dielectric layer which is electronically sensitive to the (bio-)chemical changes that occur on its surface. This review will provide a brief overview of the history of ISFET biosensors with general operation concepts and sensing mechanisms. We also discuss silicon nanowire-based ISFETs (SiNW FETs) as the modern nanoscale version of classical ISFETs, as well as strategies to functionalize them with biologically sensitive layers. We include in our discussion other ISFET types based on nanomaterials such as carbon nanotubes, metal oxides and so on. The latest examples of highly sensitive label-free detection of deoxyribonucleic acid (DNA) molecules using SiNW FETs and single-cell recordings for drug screening and other applications of ISFETs will be highlighted. Finally, we suggest new device platforms and newly developed, miniaturized read-out tools with multichannel potentiometric and impedimetric measurement capabilities for future biomedical applications. PMID:27365038

  17. Plasma wave instability in a quantum field effect transistor with magnetic field effect

    SciTech Connect

    Zhang, Li-Ping; Xue, Ju-Kui

    2013-08-15

    The current-carrying state of a nanometer Field Effect Transistor (FET) may become unstable against the generation of high-frequency plasma waves and lead to generation of terahertz radiation. In this paper, the influences of magnetic field, quantum effects, electron exchange-correlation, and thermal motion of electrons on the instability of the plasma waves in a nanometer FET are reported. We find that, while the electron exchange-correlation suppresses the radiation power, the magnetic field, the quantum effects, and the thermal motion of electrons can enhance the radiation power. The radiation frequency increases with quantum effects and thermal motion of electrons, but decreases with electron exchange-correlation effect. Interestingly, we find that magnetic field can suppress the quantum effects and the thermal motion of electrons and the radiation frequency changes non-monotonely with the magnetic field. These properties could make the nanometer FET advantageous for realization of practical terahertz oscillations.

  18. Interfacial fields in organic field-effect transistors and sensors

    NASA Astrophysics Data System (ADS)

    Dawidczyk, Thomas J.

    Organic electronics are currently being commercialized and present a viable alternative to conventional electronics. These organic materials offer the ability to chemically manipulate the molecule, allowing for more facile mass processing techniques, which in turn reduces the cost. One application where organic semiconductors (OSCs) are being investigated is sensors. This work evaluates an assortment of n- and p-channel semiconductors as organic field-effect transistor (OFET) sensors. The sensor responses to dinitrotoluene (DNT) vapor and solid along with trinitrotoluene (TNT) solid were studied. Different semiconductor materials give different magnitude and direction of electrical current response upon exposure to DNT. Additional OFET parameters---mobility and threshold voltage---further refine the response to the DNT with each OFET sensor requiring a certain gate voltage for an optimized response to the vapor. The pattern of responses has sufficient diversity to distinguish DNT from other vapors. To effectively use these OFET sensors in a circuit, the threshold voltage needs to be tuned for each transistor to increase the efficiency of the circuit and maximize the sensor response. The threshold voltage can be altered by embedding charges into the dielectric layer of the OFET. To study the quantity and energy of charges needed to alter the threshold voltage, charge carriers were injected into polystyrene (PS) and investigated with scanning Kelvin probe microscopy (SKPM) and thermally stimulated discharge current (TSDC). Lateral heterojunctions of pentacene/PS were scanned using SKPM, effectively observing polarization along a side view of a lateral nonvolatile organic field-effect transistor dielectric interface. TSDC was used to observe charge migration out of PS films and to estimate the trap energy level inside the PS, using the initial rise method. The process was further refined to create lateral heterojunctions that were actual working OFETs, consisting of a

  19. SiC Optically Modulated Field-Effect Transistor

    NASA Technical Reports Server (NTRS)

    Tabib-Azar, Massood

    2009-01-01

    An optically modulated field-effect transistor (OFET) based on a silicon carbide junction field-effect transistor (JFET) is under study as, potentially, a prototype of devices that could be useful for detecting ultraviolet light. The SiC OFET is an experimental device that is one of several devices, including commercial and experimental photodiodes, that were initially evaluated as detectors of ultraviolet light from combustion and that could be incorporated into SiC integrated circuits to be designed to function as combustion sensors. The ultraviolet-detection sensitivity of the photodiodes was found to be less than desired, such that it would be necessary to process their outputs using high-gain amplification circuitry. On the other hand, in principle, the function of the OFET could be characterized as a combination of detection and amplification. In effect, its sensitivity could be considerably greater than that of a photodiode, such that the need for amplification external to the photodetector could be reduced or eliminated. The experimental SiC OFET was made by processes similar to JFET-fabrication processes developed at Glenn Research Center. The gate of the OFET is very long, wide, and thin, relative to the gates of typical prior SiC JFETs. Unlike in prior SiC FETs, the gate is almost completely transparent to near-ultraviolet and visible light. More specifically: The OFET includes a p+ gate layer less than 1/4 m thick, through which photons can be transported efficiently to the p+/p body interface. The gate is relatively long and wide (about 0.5 by 0.5 mm), such that holes generated at the body interface form a depletion layer that modulates the conductivity of the channel between the drain and the source. The exact physical mechanism of modulation of conductivity is a subject of continuing research. It is known that injection of minority charge carriers (in this case, holes) at the interface exerts a strong effect on the channel, resulting in amplification

  20. A silicon carbide nanowire field effect transistor for DNA detection.

    PubMed

    Fradetal, L; Bano, E; Attolini, G; Rossi, F; Stambouli, V

    2016-06-10

    This work reports on the label-free electrical detection of DNA molecules for the first time, using silicon carbide (SiC) as a novel material for the realization of nanowire field effect transistors (NWFETs). SiC is a promising semiconductor for this application due to its specific characteristics such as chemical inertness and biocompatibility. Non-intentionally n-doped SiC NWs are first grown using a bottom-up vapor-liquid-solid (VLS) mechanism, leading to the NWs exhibiting needle-shaped morphology, with a length of approximately 2 μm and a diameter ranging from 25 to 60 nm. Then, the SiC NWFETs are fabricated and functionalized with DNA molecule probes via covalent coupling using an amino-terminated organosilane. The drain current versus drain voltage (I d-V d) characteristics obtained after the DNA grafting and hybridization are reported from the comparative and simultaneous measurements carried out on the SiC NWFETs, used either as sensors or references. As a representative result, the current of the sensor is lowered by 22% after probe DNA grafting and by 7% after target DNA hybridization, while the current of the reference does not vary by more than ±0.6%. The current decrease confirms the field effect induced by the negative charges of the DNA molecules. Moreover, the selectivity, reproducibility, reversibility and stability of the studied devices are emphasized by de-hybridization, non-complementary hybridization and re-hybridization experiments. This first proof of concept opens the way for future developments using SiC-NW-based sensors. PMID:27120971

  1. A silicon carbide nanowire field effect transistor for DNA detection

    NASA Astrophysics Data System (ADS)

    Fradetal, L.; Bano, E.; Attolini, G.; Rossi, F.; Stambouli, V.

    2016-06-01

    This work reports on the label-free electrical detection of DNA molecules for the first time, using silicon carbide (SiC) as a novel material for the realization of nanowire field effect transistors (NWFETs). SiC is a promising semiconductor for this application due to its specific characteristics such as chemical inertness and biocompatibility. Non-intentionally n-doped SiC NWs are first grown using a bottom-up vapor–liquid–solid (VLS) mechanism, leading to the NWs exhibiting needle-shaped morphology, with a length of approximately 2 μm and a diameter ranging from 25 to 60 nm. Then, the SiC NWFETs are fabricated and functionalized with DNA molecule probes via covalent coupling using an amino-terminated organosilane. The drain current versus drain voltage (I d–V d) characteristics obtained after the DNA grafting and hybridization are reported from the comparative and simultaneous measurements carried out on the SiC NWFETs, used either as sensors or references. As a representative result, the current of the sensor is lowered by 22% after probe DNA grafting and by 7% after target DNA hybridization, while the current of the reference does not vary by more than ±0.6%. The current decrease confirms the field effect induced by the negative charges of the DNA molecules. Moreover, the selectivity, reproducibility, reversibility and stability of the studied devices are emphasized by de-hybridization, non-complementary hybridization and re-hybridization experiments. This first proof of concept opens the way for future developments using SiC-NW-based sensors.

  2. 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.

  3. Organic gate dielectrics for tetracene field effect transistors

    NASA Astrophysics Data System (ADS)

    Bertolazzi, Simone

    Over the last three decades, thin films of organic semiconductors (OS) have been the object of intense research. These films can be used in a wide variety of new-generation optoelectronic devices, such as Organic Light Emitting Diodes (OLED), Organic Field Effect Transistors (OFET) and photovoltaic cells. Recently, vacuum sublimed tetracene films were used to realize the first Organic Light Emitting Field Effect Transistor (OLEFET), which integrates in a single device the current modulation function of a FET with the light generation capability of a LED. The demonstration of OLEFETs is not straightforward. First of all, an efficient integration of optical and electronic functionalities requires the use of a semiconductor with both efficient electroluminescence and good charge transport properties. Secondly, an ambipolar charge transport has to be achieved to produce high performance OLEFETs. Within this context, controlling the dielectric substrate surface chemistry has proven to be an efficient strategy, since it contributes to avoid the suppression of the electron transport induced by the electronic trap states at the dielectric/semiconductor interface. At the same time, the modification of the chemical and physical nature of the dielectric substrate influences the morphology/structure of the organic thin-films, in turn influencing the final device performance. In this work, polycrystalline tetracene thin films - to be incorporated in OLEFETs - were vacuum sublimed on different organic dielectric substrates, including polymers (parylene C, polymethylmethacrylate, polystyrene) and self-assembled monolayers of hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (OTS). The scope of the work was indeed to shed light on the role of the organic dielectric surface in influencing the charge transport properties of tetracene OLEFETs. The tetracene deposition rate was 3.5 A/s, the substrates were kept at room temperature and the pressure inside the vacuum chamber was

  4. Ion-implanted GaN junction field effect transistor

    SciTech Connect

    Zolper, J.C.; Shul, R.J.; Baca, A.G.; Wilson, R.G.; Pearton, S.J.; Stall, R.A.

    1996-04-01

    Selective area ion implantation doping has been used to fabricate GaN junction field effect transistors (JFETs). {ital p}-type and {ital n}-type doping was achieved with Ca and Si implantation, respectively, followed by a 1150{degree}C rapid thermal anneal. A refractory W gate contact was employed that allows the {ital p}-gate region to be self-aligned to the gate contact. A gate turn-on voltage of 1.84 V at 1 mA/mm of gate current was achieved. For a {approximately}1.7 {mu}m{times}50 {mu}m JFET with a {minus}6 V threshold voltage, a maximum transconductance of 7 mS/mm at {ital V}{sub GS}={minus} 2V and saturation current of 33 mA/mm at {ital V}{sub GS}=0 V were measured. These results were limited by excess access resistance and can be expected to be improved with optimized {ital n}{sup +} implants in the source and drain regions. {copyright} {ital 1996 American Institute of Physics.}

  5. Tailoring Functional Interlayers in Organic Field-Effect Transistor Biosensors.

    PubMed

    Magliulo, Maria; Manoli, Kyriaki; Macchia, Eleonora; Palazzo, Gerardo; Torsi, Luisa

    2015-12-01

    This review aims to provide an update on the development involving dielectric/organic semiconductor (OSC) interfaces for the realization of biofunctional organic field-effect transistors (OFETs). Specific focus is given on biointerfaces and recent technological approaches where biological materials serve as interlayers in back-gated OFETs for biosensing applications. Initially, to better understand the effects produced by the presence of biomolecules deposited at the dielectric/OSC interfacial region, the tuning of the dielectric surface properties by means of self-assembled monolayers is discussed. Afterward, emphasis is given to the modification of solid-state dielectric surfaces, in particular inorganic dielectrics, with biological molecules such as peptides and proteins. Special attention is paid on how the presence of an interlayer of biomolecules and bioreceptors underneath the OSC impacts on the charge transport and sensing performance of the device. Moreover, naturally occurring materials, such as carbohydrates and DNA, used directly as bulk gating materials in OFETs are reviewed. The role of metal contact/OSC interface in the overall performance of OFET-based sensors is also discussed. PMID:25429859

  6. Simulation Model of A Ferroelectric Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Ho, Fat Duen; Russell, Larry W. (Technical Monitor)

    2002-01-01

    An electronic simulation model has been developed of a ferroelectric field effect transistor (FFET). This model can be used in standard electrical circuit simulation programs to simulate the main characteristics of the FFET. The model uses a previously developed algorithm that incorporates partial polarization as a basis for the design. The model has the main characteristics of the FFET, which are the current hysterisis with different gate voltages and decay of the drain current when the gate voltage is off. The drain current has values matching actual FFET's, which were measured experimentally. The input and output resistance in the model is similar to that of the FFET. The model is valid for all frequencies below RF levels. A variety of different ferroelectric material characteristics can be modeled. The model can be used to design circuits using FFET'S with standard electrical simulation packages. The circuit can be used in designing non-volatile memory circuits and logic circuits and is compatible with all SPICE based circuit analysis programs. The model is a drop in library that integrates seamlessly into a SPICE simulation. A comparison is made between the model and experimental data measured from an actual FFET.

  7. Strain Engineering for Transition Metal Dichalcogenides Based Field Effect Transistors.

    PubMed

    Shen, Tingting; Penumatcha, Ashish V; Appenzeller, Joerg

    2016-04-26

    Using electrical characteristics from three-terminal field-effect transistors (FETs), we demonstrate substantial strain induced band gap tunability in transition metal dichalcogenides (TMDs) in line with theoretical predictions and optical experiments. Devices were fabricated on flexible substrates, and a cantilever sample holder was used to apply uniaxial tensile strain to the various multilayer TMD FETs. Analyzing in particular transfer characteristics, we argue that the modified device characteristics under strain are clear evidence of a band gap reduction of 100 meV in WSe2 under 1.35% uniaxial tensile strain at room temperature. Furthermore, the obtained device characteristics imply that the band gap does not shrink uniformly under strain relative to a reference potential defined by the source/drain contacts. Instead, the band gap change is only related to a change of the conduction band edge of WSe2, resulting in a decrease in the Schottky barrier (SB) for electrons without any change for hole injection into the valence band. Simulations of SB device characteristics are employed to explain this point and to quantify our findings. Last, our experimental results are compared with DFT calculations under strain showing excellent agreement between theoretical predictions and the experimental data presented here. PMID:27043387

  8. Dynamic Charge Carrier Trapping in Quantum Dot Field Effect Transistors.

    PubMed

    Zhang, Yingjie; Chen, Qian; Alivisatos, A Paul; Salmeron, Miquel

    2015-07-01

    Noncrystalline semiconductor materials often exhibit hysteresis in charge transport measurements whose mechanism is largely unknown. Here we study the dynamics of charge injection and transport in PbS quantum dot (QD) monolayers in a field effect transistor (FET). Using Kelvin probe force microscopy, we measured the temporal response of the QDs as the channel material in a FET following step function changes of gate bias. The measurements reveal an exponential decay of mobile carrier density with time constants of 3-5 s for holes and ∼10 s for electrons. An Ohmic behavior, with uniform carrier density, was observed along the channel during the injection and transport processes. These slow, uniform carrier trapping processes are reversible, with time constants that depend critically on the gas environment. We propose that the underlying mechanism is some reversible electrochemical process involving dissociation and diffusion of water and/or oxygen related species. These trapping processes are dynamically activated by the injected charges, in contrast with static electronic traps whose presence is independent of the charge state. Understanding and controlling these processes is important for improving the performance of electronic, optoelectronic, and memory devices based on disordered semiconductors. PMID:26099508

  9. Vertical Microcavity Organic Light-emitting Field-effect Transistors

    PubMed Central

    Hu, Yongsheng; Lin, Jie; Song, Li; Lu, Qipeng; Zhu, Wanbin; Liu, Xingyuan

    2016-01-01

    Organic light-emitting field-effect transistors (OLEFETs) are regarded as a novel kind of device architecture for fulfilling electrical-pumped organic lasers. However, the realization of OLEFETs with high external quantum efficiency (EQE) and high brightness simultaneously is still a tough task. Moreover, the design of the resonator structure in LED is far from satisfactory. Here, OLEFETs with EQE of 1.5% at the brightness of 2600 cdm−2, and the corresponding ON/OFF ratio and current efficiency reaches above 104 and 3.1 cdA−1, respectively, were achieved by introducing 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN) as a charge generation layer. Moreover, a vertical microcavity based on distributed Bragg reflector (DBR) and Ag source/drain electrodes is successfully introduced into the high performance OLEFETs, which results in electroluminescent spectrum linewidth narrowing from 96 nm to 6.9 nm. The results manifest the superiority of the vertical microcavity as an optical resonator in OLEFETs, which sheds some light on achieving the electrically pumped organic lasers. PMID:26986944

  10. Ambipolar organic field-effect transistors on unconventional substrates

    NASA Astrophysics Data System (ADS)

    Cosseddu, P.; Mattana, G.; Orgiu, E.; Bonfiglio, A.

    2009-04-01

    In this paper we report on the realization of flexible all-organic ambipolar field-effect transistors (FETs) realized on unconventional substrates, such as plastic films and textile yarns. A double layer pentacene-C60 heterojunction was used as the semiconductor layer. The contacts were made with poly(ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) and patterned by means of soft lithography microcontact printing (μCP). Very interestingly growing C60 on a predeposited pentacene buffer layer leads to a clear improvement in the morphology and crystallinity of the film so it obtains n-type conduction despite the very high electron injection barrier at the interface between PEDOT:PSS and C60. As a result, it was possible to obtain all-organic ambipolar FETs and to optimize their electrical properties by tuning the thicknesses of the two employed active layers. Moreover, it will be shown that modifying the triple interface between dielectric/semiconductor/electrodes is a crucial point for optimizing and balancing injection and transport of both kinds of charge carriers. In particular, we demonstrate that using a middle contact configuration in which source and drain electrodes are sandwiched between pentacene and C60 layers allows significantly improving the electrical performance in planar ambipolar devices. These findings are very important because they pave the way for the realization of low-cost, fully flexible and stretchable organic complementary circuits for smart wearable and textile electronics applications.

  11. Mixed Carrier Conduction in Modulation-doped Field Effect Transistors

    NASA Technical Reports Server (NTRS)

    Schacham, S. E.; Haugland, E. J.; Mena, R. A.; Alterovitz, S. A.

    1995-01-01

    The contribution of more than one carrier to the conductivity in modulation-doped field effect transistors (MODFET) affects the resultant mobility and complicates the characterization of these devices. Mixed conduction arises from the population of several subbands in the two-dimensional electron gas (2DEG), as well as the presence of a parallel path outside the 2DEG. We characterized GaAs/AlGaAs MODFET structures with both delta and continuous doping in the barrier. Based on simultaneous Hall and conductivity analysis we conclude that the parallel conduction is taking place in the AlGaAs barrier, as indicated by the carrier freezeout and activation energy. Thus, simple Hall analysis of these structures may lead to erroneous conclusions, particularly for real-life device structures. The distribution of the 2D electrons between the various confined subbands depends on the doping profile. While for a continuously doped barrier the Shubnikov-de Haas analysis shows superposition of two frequencies for concentrations below 10(exp 12) cm(exp -2), for a delta doped structure the superposition is absent even at 50% larger concentrations. This result is confirmed by self-consistent analysis, which indicates that the concentration of the second subband hardly increases.

  12. Organic field-effect transistor-based gas sensors.

    PubMed

    Zhang, Congcong; Chen, Penglei; Hu, Wenping

    2015-04-21

    Organic field-effect transistors (OFETs) are one of the key components of modern organic electronics. While the past several decades have witnessed huge successes in high-performance OFETs, their sophisticated functionalization with regard to the responses towards external stimulations has also aroused increasing attention and become an important field of general concern. This is promoted by the inherent merits of organic semiconductors, including considerable variety in molecular design, low cost, light weight, mechanical flexibility, and solution processability, as well as by the intrinsic advantages of OFETs including multiparameter accessibility and ease of large-scale manufacturing, which provide OFETs with great potential as portable yet reliable sensors offering high sensitivity, selectivity, and expeditious responses. With special emphases on the works achieved since 2009, this tutorial review focuses on OFET-based gas sensors. The working principles of this type of gas sensors are discussed in detail, the state-of-the-art protocols developed for high-performance gas sensing are highlighted, and the advanced gas discrimination systems in terms of sensory arrays of OFETs are also introduced. This tutorial review intends to provide readers with a deep understanding for the future design of high-quality OFET gas sensors for potential uses. PMID:25727357

  13. Epitaxially-Grown GaN Junction Field Effect Transistors

    SciTech Connect

    Baca, A.G.; Chang, P.C.; Denbaars, S.P.; Lester, L.F.; Mishra, U.K.; Shul, R.J.; Willison, C.G.; Zhang, L.; Zolper, J.C.

    1999-05-19

    Junction field effect transistors (JFET) are fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition (MOCVD). The DC and microwave characteristics of the device are presented. A junction breakdown voltage of 56 V is obtained corresponding to the theoretical limit of the breakdown field in GaN for the doping levels used. A maximum extrinsic transconductance (gm) of 48 mS/mm and a maximum source-drain current of 270 mA/mm are achieved on a 0.8 µ m gate JFET device at VGS= 1 V and VDS=15 V. The intrinsic transconductance, calculated from the measured gm and the source series resistance, is 81 mS/mm. The fT and fmax for these devices are 6 GHz and 12 GHz, respectively. These JFETs exhibit a significant current reduction after a high drain bias is applied, which is attributed to a partially depleted channel caused by trapped hot-electrons in the semi-insulating GaN buffer layer. A theoretical model describing the current collapse is described, and an estimate for the length of the trapped electron region is given.

  14. Bioinspired peptide nanostructures for organic field-effect transistors.

    PubMed

    Cipriano, Thiago; Knotts, Grant; Laudari, Amrit; Bianchi, Roberta C; Alves, Wendel A; Guha, Suchismita

    2014-12-10

    Peptide-based nanostructures derived from natural amino acids are superior building blocks for biocompatible devices as they can be used in a bottom-up process without the need for expensive lithography. A dense nanostructured network of l,l-diphenylalanine (FF) was synthesized using the solid-vapor-phase technique. Formation of the nanostructures and structure-phase relationship were investigated by electron microscopy and Raman scattering. Thin films of l,l-diphenylalanine micro/nanostructures (FF-MNSs) were used as the dielectric layer in pentacene-based field-effect transistors (FETs) and metal-insulator-semiconductor diodes both in bottom-gate and in top-gate structures. Bias stress studies show that FF-MNS-based pentacene FETs are more resistant to degradation than pentacene FETs using FF thin film (without any nanostructures) as the dielectric layer when both are subjected to sustained electric fields. Furthermore, it is demonstrated that the FF-MNSs can be functionalized for detection of enzyme-analyte interactions. This work opens up a novel and facile route toward scalable organic electronics using peptide nanostructures as scaffolding and as a platform for biosensing. PMID:25376495

  15. Understanding charge transport in organometal halide field effect transistors

    NASA Astrophysics Data System (ADS)

    Senanayak, Satyaprasad P.; Yang, Bingyan; Sadhanala, Aditya; Friend, Richard, Prof. _., Sir; Sirrnighaus, Henning, , Prof.

    Organometal halide based perovskite are emerging materials for wide range of electronic applications. A range of optoelectronic applications like high efficiency solar cells, color pure LEDs and optical pumped lasers have been demonstrated. Here, we report the demonstration of a high performance field effect transistor fabricated from iodide perovskite material at room temperature. The devices exhibit clean saturation behavior with electron μFET >3 cm2V-1s-1 and current modulation in the range of 106 - 107 which are till date the best performance achieved with these class of materials. This high performance is attributed to a combination of novel film fabrication technique and device engineering strategies. Detailed understanding of the observed band-like transport phenomenon is developed by tuning the different sources of dynamic and static disorder prevalent in the system. These finding are expected to pave way for developing next generation electronic application from perovskite materials. Authors acknowledge EPSRC for funding and SPS acknowledges Royal Society Newton Fellowship.

  16. Silicene field-effect transistors operating at room temperature

    NASA Astrophysics Data System (ADS)

    Tao, Li; Cinquanta, Eugenio; Chiappe, Daniele; Grazianetti, Carlo; Fanciulli, Marco; Dubey, Madan; Molle, Alessandro; Akinwande, Deji

    2015-03-01

    Free-standing silicene, a silicon analogue of graphene, has a buckled honeycomb lattice and, because of its Dirac bandstructure combined with its sensitive surface, offers the potential for a widely tunable two-dimensional monolayer, where external fields and interface interactions can be exploited to influence fundamental properties such as bandgap and band character for future nanoelectronic devices. The quantum spin Hall effect, chiral superconductivity, giant magnetoresistance and various exotic field-dependent states have been predicted in monolayer silicene. Despite recent progress regarding the epitaxial synthesis of silicene and investigation of its electronic properties, to date there has been no report of experimental silicene devices because of its air stability issue. Here, we report a silicene field-effect transistor, corroborating theoretical expectations regarding its ambipolar Dirac charge transport, with a measured room-temperature mobility of ˜100 cm2 V-1 s-1 attributed to acoustic phonon-limited transport and grain boundary scattering. These results are enabled by a growth-transfer-fabrication process that we have devised—silicene encapsulated delamination with native electrodes. This approach addresses a major challenge for material preservation of silicene during transfer and device fabrication and is applicable to other air-sensitive two-dimensional materials such as germanene and phosphorene. Silicene's allotropic affinity with bulk silicon and its low-temperature synthesis compared with graphene or alternative two-dimensional semiconductors suggest a more direct integration with ubiquitous semiconductor technology.

  17. Graphene based field effect transistor for the detection of ammonia

    NASA Astrophysics Data System (ADS)

    Gautam, Madhav; Jayatissa, Ahalapitiya H.

    2012-09-01

    Graphene synthesized by chemical vapor deposition has been used to fabricate the back-gated field effect transistor to study the sensing of ammonia (NH3) in ppm levels. Graphene has been synthesized directly on a target substrate using a thin Cu film as a catalyst, which has several advantages over deposition of graphene on Cu foil followed by a transferring process to another substrate. Raman spectroscopy was used to monitor the quality of the deposited graphene films on SiO2/Si substrates. The adsorption/desorption behavior of NH3 on graphene in dry air was analyzed from the progressive shift of the Dirac peak at smaller/larger gate voltages based on different time exposures to different concentrations of NH3. The relative change in the shift of the Dirac peak was consistent with a small charge transfer (0.039 ± 0.001 electrons per molecule at room temperature). The response of the device was found to increase with increasing NH3 concentrations and operating temperatures. The dependence of device response on concentration indicated that the graphene sensors exhibited two different adsorption modes for NH3 close to room temperature, whereas only one adsorption mode was observed at higher temperatures close to100 °C. The shift rate of the Dirac peak estimated with a simple model using the Langmuir approach indicated that the rate was increasing linearly with temperature within the range of temperature studied (25 °C-100 °C) in this work.

  18. Vertical Microcavity Organic Light-emitting Field-effect Transistors.

    PubMed

    Hu, Yongsheng; Lin, Jie; Song, Li; Lu, Qipeng; Zhu, Wanbin; Liu, Xingyuan

    2016-01-01

    Organic light-emitting field-effect transistors (OLEFETs) are regarded as a novel kind of device architecture for fulfilling electrical-pumped organic lasers. However, the realization of OLEFETs with high external quantum efficiency (EQE) and high brightness simultaneously is still a tough task. Moreover, the design of the resonator structure in LED is far from satisfactory. Here, OLEFETs with EQE of 1.5% at the brightness of 2600 cdm(-2), and the corresponding ON/OFF ratio and current efficiency reaches above 10(4) and 3.1 cdA(-1), respectively, were achieved by introducing 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN) as a charge generation layer. Moreover, a vertical microcavity based on distributed Bragg reflector (DBR) and Ag source/drain electrodes is successfully introduced into the high performance OLEFETs, which results in electroluminescent spectrum linewidth narrowing from 96 nm to 6.9 nm. The results manifest the superiority of the vertical microcavity as an optical resonator in OLEFETs, which sheds some light on achieving the electrically pumped organic lasers. PMID:26986944

  19. Boron doped simulated graphene field effect transistor model

    NASA Astrophysics Data System (ADS)

    Sharma, Preetika; Kaur, Inderpreet; Gupta, Shuchi; Singh, Sukhbir

    2016-05-01

    Graphene based electronic devices due to its unique properties has transformed electronics. A Graphene Field Effect Transistor (GNRFET) model is simulated in Virtual Nano Lab (VNL) and the calculations are based on density functional theory (DFT). Simulations were performed on this pristine GNRFET model and the transmission spectrum was observed. The graph obtained showed a uniform energy gap of +1 to -1eV and the highest transmission peak at -1.75 eV. To this pristine model of GNRFET, doping was introduced and its effect was seen on the Fermi level obtained in the transmission spectrum. Boron as a dopant was used which showed variations in both the transmission peaks and the energy gap. In this model, first the single boron was substituted in place of carbon and Fermi level showed an energy gap of 1.5 to -0.5eV with the highest transmission peak at -1.3 eV. In another variation in the model, two carbon atoms were replaced by two boron atoms and Fermi level shifted from 2 to 0.25eV. In this observation, the highest transmission peak was observed at -1(approx.). The use of nanoelectronic devices have opened many areas of applications as GFET is an excellent building block for electronic circuits, and is being used in applications such as high-performance frequency doublers and mixers, digital modulators, phase detectors, optoelectronics and spintronics.

  20. Vertical Microcavity Organic Light-emitting Field-effect Transistors

    NASA Astrophysics Data System (ADS)

    Hu, Yongsheng; Lin, Jie; Song, Li; Lu, Qipeng; Zhu, Wanbin; Liu, Xingyuan

    2016-03-01

    Organic light-emitting field-effect transistors (OLEFETs) are regarded as a novel kind of device architecture for fulfilling electrical-pumped organic lasers. However, the realization of OLEFETs with high external quantum efficiency (EQE) and high brightness simultaneously is still a tough task. Moreover, the design of the resonator structure in LED is far from satisfactory. Here, OLEFETs with EQE of 1.5% at the brightness of 2600 cdm‑2, and the corresponding ON/OFF ratio and current efficiency reaches above 104 and 3.1 cdA‑1, respectively, were achieved by introducing 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN) as a charge generation layer. Moreover, a vertical microcavity based on distributed Bragg reflector (DBR) and Ag source/drain electrodes is successfully introduced into the high performance OLEFETs, which results in electroluminescent spectrum linewidth narrowing from 96 nm to 6.9 nm. The results manifest the superiority of the vertical microcavity as an optical resonator in OLEFETs, which sheds some light on achieving the electrically pumped organic lasers.

  1. Polyfluorene-based organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Hamilton, Michael C.

    The electrical performance and device stability of a patterned-gate, gate-planarized, inverted, coplanar thin-film transistor with an organic polymer F8T2 active layer semiconductor was studied. The validity of electrical performance parameter extraction methods was studied and the inclusion of a field-dependent mobility provided the most reliable results. A gate-bias dependent activation energy near 0.2eV for the field-effect mobility of holes in F8T2 was found. The source and drain contact and channel resistances were characterized and are similar with values near 109O. Additionally, these devices showed promise for use in high-voltage applications. The effects of broadband and monochromatic illumination were characterized and strongly absorbed illumination reduced the threshold voltage. Application of a photo-field effect theory provided an estimation of the density and slope of the gap states. This method also provided an estimate of the flat-band voltage of -10V. The performance of the device as a photodetector showed a responsivity of 1A/W, a photosensitivity greater than 100, an external quantum efficiency greater than 100%, a noise equivalent power of 10-14 WHz-0.5 and a specific detectivity of approximately 2x1011 cmHz0.5W-1. Hysteresis in the transfer characteristics was characterized by the dependence on the applied gate-bias, temperature and illumination. It was observed that the hysteresis is a charge trapping effect that is dependent on the charge density within the channel. The hysteresis was eliminated by incorporating an organic insulator layer between the inorganic insulator and the organic semiconductor. Bias temperature stress effects were characterized and the major effect was an increase in threshold voltage. Analysis using a stretched exponential behavior for DC bias stress effects showed that there exists a distribution of trap states centered at 0.25eV above the valence band. Negative AC BTS resulted in a dependence on the total stress time

  2. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks. Carbon nanotube transistor based high-frequency electronics.

  3. Low-frequency noise in MoSe2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Das, Suprem R.; Kwon, Jiseok; Prakash, Abhijith; Delker, Collin J.; Das, Saptarshi; Janes, David B.

    2015-02-01

    One of the important performance metrics of emerging nanoelectronic devices, including low dimensional Field Effect Transistors (FETs), is the magnitude of the low-frequency noise. Atomically thin 2D semiconductor channel materials such as MoX2 (X ≡ S, Se) have shown promising transistor characteristics such as ION/IOFF ratio exceeding 106 and low IOFF, making them attractive as channel materials for next generation nanoelectronic devices. However, MoS2 FETs demonstrated to date exhibit high noise levels under ambient conditions. In this letter, we report at least two orders of magnitude smaller values of Hooge parameter in a back-gated MoSe2 FET (10 atomic layers) with nickel S/D contacts and measured at atmospheric pressure and temperature. The channel dominated regime of noise was extracted from the total noise spectrum and is shown to follow a mobility fluctuation model with 1/f dependence. The low noise in MoSe2 FETs is comparable to other 1D nanoelectronic devices such as carbon nanotube FETs (CNT-FETs) and paves the way for use in future applications in precision sensing and communications.

  4. Low-frequency noise in MoSe{sub 2} field effect transistors

    SciTech Connect

    Das, Suprem R. E-mail: janes@purdue.edu; Kwon, Jiseok; Prakash, Abhijith; Janes, David B. E-mail: janes@purdue.edu; Delker, Collin J.; Das, Saptarshi

    2015-02-23

    One of the important performance metrics of emerging nanoelectronic devices, including low dimensional Field Effect Transistors (FETs), is the magnitude of the low-frequency noise. Atomically thin 2D semiconductor channel materials such as MoX{sub 2} (X ≡ S, Se) have shown promising transistor characteristics such as I{sub ON}/I{sub OFF} ratio exceeding 10{sup 6} and low I{sub OFF}, making them attractive as channel materials for next generation nanoelectronic devices. However, MoS{sub 2} FETs demonstrated to date exhibit high noise levels under ambient conditions. In this letter, we report at least two orders of magnitude smaller values of Hooge parameter in a back-gated MoSe{sub 2} FET (10 atomic layers) with nickel S/D contacts and measured at atmospheric pressure and temperature. The channel dominated regime of noise was extracted from the total noise spectrum and is shown to follow a mobility fluctuation model with 1/f dependence. The low noise in MoSe{sub 2} FETs is comparable to other 1D nanoelectronic devices such as carbon nanotube FETs (CNT-FETs) and paves the way for use in future applications in precision sensing and communications.

  5. Electric Characteristics of the Carbon Nanotube Network Transistor with Directly Grown ZnO Nanoparticles.

    PubMed

    Kim, Un Jeong; Bae, Gi Yoon; Suh, Dong Ik; Park, Wanjun

    2016-03-01

    We report on the electrical characteristics of field effect transistors fabricated with random networks of single-walled carbon nanotubes with surfaces modified by ZnO nanoparticles. ZnO nanoparticles are directly grown on single-walled carbon nanotubes by atomic layer deposition using diethylzinc (DEZ) and water. Electrical observations show that ZnO nanoparticles act as charge transfer sources that provide electrons to the nanotube channel. The valley position in ambipolar transport of nanotube transistors is negatively shifted for 3V due to the electronic n-typed property of ZnO nanoparticles. However, the Raman resonance remains invariant despite the charge transfer effect produced by ZnO nanoparticles. PMID:27455727

  6. Controlled deposition or organic semiconductor single crystals and its application in field-effect transistors

    NASA Astrophysics Data System (ADS)

    Liu, Shuhong

    single crystals are selectively nucleated on patterned templates of carbon nanotube (CNT) bundles. Several organic semiconductor materials are successfully patterned, including p-type pentacene, tetracene, sexiphenylene, and sexithiophene, as well as n-type tetracyanoquinodimethane. This study suggests that the selective growth of crystals onto patterned carbon nanotubes is most likely due to the coarse topography of the CNT bundles. Moreover, I observe that the crystals nucleate from CNT bundles and grow onto CNT bundles in a conformal fashion. The crystal growth can be directly applied onto transistor source-drain electrodes and arrays of organic single-crystal field effect transistors are demonstrated. To investigate the impact of CNTs on device performance, CNT bundles are incorporated into thin-film FETs and a mobility enhancement of organic semiconductors is observed. In the third approach, organic single crystals with well controlled sizes and shapes are successfully grown using patterned Au films as templates. It is observed that sexithiophene crystals nucleate from the edge or the top surface of Au films and then grow two dimensionally on SiO2 surface. The sizes and shapes of sexithiophene crystals are precisely determined by that of the Au patterns. After removing Au templates, large arrays of sexithiophene crystals with controlled sizes and various shapes such as stripes, squares, hexagons, etc. are achieved. Top-contact FETs made of sexithiophene ribbons are demonstrated. Besides organic single crystals, Au templates can also act as templates to pattern vapor- and solution-deposited organic semiconductor thin films. Patterned organic thin-film FETs exhibit superior performance compared to unpatterned devices. Finally, oriented growth of organic semiconductor single crystals on templates with various features is studied. On substrates with aligned features, such as friction-transferred poly(tetrafluoroethylene) thin films, organic semiconductor thin films

  7. Intracellular recordings of action potentials by an extracellular nanoscale field-effect transistor.

    PubMed

    Duan, Xiaojie; Gao, Ruixuan; Xie, Ping; Cohen-Karni, Tzahi; Qing, Quan; Choe, Hwan Sung; Tian, Bozhi; Jiang, Xiaocheng; Lieber, Charles M

    2012-03-01

    The ability to make electrical measurements inside cells has led to many important advances in electrophysiology. The patch clamp technique, in which a glass micropipette filled with electrolyte is inserted into a cell, offers both high signal-to-noise ratio and temporal resolution. Ideally, the micropipette should be as small as possible to increase the spatial resolution and reduce the invasiveness of the measurement, but the overall performance of the technique depends on the impedance of the interface between the micropipette and the cell interior, which limits how small the micropipette can be. Techniques that involve inserting metal or carbon microelectrodes into cells are subject to similar constraints. Field-effect transistors (FETs) can also record electric potentials inside cells, and because their performance does not depend on impedance, they can be made much smaller than micropipettes and microelectrodes. Moreover, FET arrays are better suited for multiplexed measurements. Previously, we have demonstrated FET-based intracellular recording with kinked nanowire structures, but the kink configuration and device design places limits on the probe size and the potential for multiplexing. Here, we report a new approach in which a SiO2 nanotube is synthetically integrated on top of a nanoscale FET. This nanotube penetrates the cell membrane, bringing the cell cytosol into contact with the FET, which is then able to record the intracellular transmembrane potential. Simulations show that the bandwidth of this branched intracellular nanotube FET (BIT-FET) is high enough for it to record fast action potentials even when the nanotube diameter is decreased to 3 nm, a length scale well below that accessible with other methods. Studies of cardiomyocyte cells demonstrate that when phospholipid-modified BIT-FETs are brought close to cells, the nanotubes can spontaneously penetrate the cell membrane to allow the full-amplitude intracellular action potential to be

  8. Intracellular recordings of action potentials by an extracellular nanoscale field-effect transistor

    NASA Astrophysics Data System (ADS)

    Duan, Xiaojie; Gao, Ruixuan; Xie, Ping; Cohen-Karni, Tzahi; Qing, Quan; Choe, Hwan Sung; Tian, Bozhi; Jiang, Xiaocheng; Lieber, Charles M.

    2012-03-01

    The ability to make electrical measurements inside cells has led to many important advances in electrophysiology. The patch clamp technique, in which a glass micropipette filled with electrolyte is inserted into a cell, offers both high signal-to-noise ratio and temporal resolution. Ideally, the micropipette should be as small as possible to increase the spatial resolution and reduce the invasiveness of the measurement, but the overall performance of the technique depends on the impedance of the interface between the micropipette and the cell interior, which limits how small the micropipette can be. Techniques that involve inserting metal or carbon microelectrodes into cells are subject to similar constraints. Field-effect transistors (FETs) can also record electric potentials inside cells, and because their performance does not depend on impedance, they can be made much smaller than micropipettes and microelectrodes. Moreover, FET arrays are better suited for multiplexed measurements. Previously, we have demonstrated FET-based intracellular recording with kinked nanowire structures, but the kink configuration and device design places limits on the probe size and the potential for multiplexing. Here, we report a new approach in which a SiO2 nanotube is synthetically integrated on top of a nanoscale FET. This nanotube penetrates the cell membrane, bringing the cell cytosol into contact with the FET, which is then able to record the intracellular transmembrane potential. Simulations show that the bandwidth of this branched intracellular nanotube FET (BIT-FET) is high enough for it to record fast action potentials even when the nanotube diameter is decreased to 3 nm, a length scale well below that accessible with other methods. Studies of cardiomyocyte cells demonstrate that when phospholipid-modified BIT-FETs are brought close to cells, the nanotubes can spontaneously penetrate the cell membrane to allow the full-amplitude intracellular action potential to be

  9. Wafer-level hysteresis-free resonant carbon nanotube transistors.

    PubMed

    Cao, Ji; Bartsch, Sebastian T; Ionescu, Adrian M

    2015-03-24

    We report wafer-level fabrication of resonant-body carbon nanotube (CNT) field-effect transistors (FETs) in a dual-gate configuration. An integration density of >10(6) CNTFETs/cm(2), an assembly yield of >80%, and nanoprecision have been simultaneously obtained. Through combined chemical and thermal treatments, hysteresis-free (in vacuum) suspended-body CNTFETs have been demonstrated. Electrostatic actuation by lateral gate and FET-based readout of mechanical resonance have been achieved at room temperature. Both upward and downward in situ frequency tuning has been experimentally demonstrated in the dual-gate architecture. The minuscule mass, high resonance frequency, and in situ tunability of the resonant CNTFETs offer promising features for applications in radio frequency signal processing and ultrasensitive sensing. PMID:25752991

  10. Exploration of vertical scaling limit in carbon nanotube transistors

    NASA Astrophysics Data System (ADS)

    Qiu, Chenguang; Zhang, Zhiyong; Yang, Yingjun; Xiao, Mengmeng; Ding, Li; Peng, Lian-Mao

    2016-05-01

    Top-gated carbon nanotube field-effect transistors (CNT FETs) were fabricated by using ultra-thin (4.5 nm or thinner) atomic-layer-deposition grown HfO2 as gate insulator, and shown to exhibit high gate efficiency, i.e., all examined (totally 76) devices present very low room temperature subthreshold swing with an averaged value of 64 mV/Dec, without observable carrier mobility degradation. The gate leakage of the CNT FET under fixed gate voltage is dependent not only on the thickness of HfO2 insulator, but also on the diameter of the CNT. The vertical scaling limit of CNT FETs is determined by gate leakage standard in ultra large scale integrated circuits. HfO2 film with effective oxide thickness of 1.2 nm can provide both excellent gate electrostatic controllability and small gate leakage for sub-5 nm FETs based on CNT with small diameter.

  11. Monoclonal Antibodies Attached to Carbon Nanotube Transistors for Paclitaxel Detection

    NASA Astrophysics Data System (ADS)

    Lee, Wonbae; Lau, Calvin; Richardson, Mark; Rajapakse, Arith; Weiss, Gregory; Collins, Philip; UCI, Molecular Biology; Biochemistry Collaboration; UCI, Departments of Physics; Astronomy Collaboration

    Paclitaxel is a naturally-occurring pharmaceutical used in numerous cancer treatments, despite its toxic side effects. Partial inhibition of this toxicity has been demonstrated using weakly interacting monoclonal antibodies (3C6 and 8A10), but accurate monitoring of antibody and paclitaxel concentrations remains challenging. Here, single-molecule studies of the kinetics of antibody-paclitaxel interactions have been performed using single-walled carbon nanotube field-effect transistors. The devices were sensitized with single antibody attachments to record the single-molecule binding dynamics of paclitaxel. This label-free technique recorded a range of dynamic interactions between the antibody and paclitaxel, and it provided sensitive paclitaxel detection for pM to nM concentrations. Measurements with two different antibodies suggest ways of extending this working range and uncovering the mechanistic differences among different antibodies.

  12. Electrical transport and field-effect transistors using inkjet-printed SWCNT films having different functional side groups.

    PubMed

    Gracia-Espino, Eduardo; Sala, Giovanni; Pino, Flavio; Halonen, Niina; Luomahaara, Juho; Mäklin, Jani; Tóth, Géza; Kordás, Krisztián; Jantunen, Heli; Terrones, Mauricio; Helistö, Panu; Seppä, Heikki; Ajayan, Pulickel M; Vajtai, Robert

    2010-06-22

    The electrical properties of random networks of single-wall carbon nanotubes (SWNTs) obtained by inkjet printing are studied. Water-based stable inks of functionalized SWNTs (carboxylic acid, amide, poly(ethylene glycol), and polyaminobenzene sulfonic acid) were prepared and applied to inkjet deposit microscopic patterns of nanotube films on lithographically defined silicon chips with a back-side gate arrangement. Source-drain transfer characteristics and gate-effect measurements confirm the important role of the chemical functional groups in the electrical behavior of carbon nanotube networks. Considerable nonlinear transport in conjunction with a high channel current on/off ratio of approximately 70 was observed with poly(ethylene glycol)-functionalized nanotubes. The positive temperature coefficient of channel resistance shows the nonmetallic behavior of the inkjet-printed films. Other inkjet-printed field-effect transistors using carboxyl-functionalized nanotubes as source, drain, and gate electrodes, poly(ethylene glycol)-functionalized nanotubes as the channel, and poly(ethylene glycol) as the gate dielectric were also tested and characterized. PMID:20481513

  13. Low Temperature Noise and Electrical Characterization of the Company Heterojunction Field-Effect Transistor

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas J.; Gee, Russell C.; Fossum, Eric R.; Baier, Steven M.

    1993-01-01

    This paper discusses the electrical properties of the complementary heterojunction field-effect transistor (CHFET) at 4K, including the gate leakage current, the subthreshold transconductance, and the input-referred noise voltage.

  14. Nonlinear photoresponse of field effect transistors terahertz detectors at high irradiation intensities

    SciTech Connect

    But, D. B.; Drexler, C.; Ganichev, S. D.; Sakhno, M. V.; Sizov, F. F.; Dyakonova, N.; Drachenko, O.; Gutin, A.; Knap, W.

    2014-04-28

    Terahertz power dependence of the photoresponse of field effect transistors, operating at frequencies from 0.1 to 3 THz for incident radiation power density up to 100 kW/cm{sup 2} was studied for Si metal–oxide–semiconductor field-effect transistors and InGaAs high electron mobility transistors. The photoresponse increased linearly with increasing radiation intensity up to the kW/cm{sup 2} range. Nonlinearity followed by saturation of the photoresponse was observed for all investigated field effect transistors for intensities above several kW/cm{sup 2}. The observed photoresponse nonlinearity is explained by nonlinearity and saturation of the transistor channel current. A theoretical model of terahertz field effect transistor photoresponse at high intensity was developed. The model explains quantitative experimental data both in linear and nonlinear regions. Our results show that dynamic range of field effect transistors is very high and can extend over more than six orders of magnitudes of power densities (from ∼0.5 mW/cm{sup 2} to ∼5 kW/cm{sup 2})

  15. Effect of uniaxial strain on electrical properties of CNT-based junctionless field-effect transistor: Numerical study

    NASA Astrophysics Data System (ADS)

    Pourian, Parisa; Yousefi, Reza; Ghoreishi, Seyed Saleh

    2016-05-01

    Numerical studies on junctionless carbon nanotube field-effect transistors (JL-CNTFETs) have indicated that these devices produce more ON current than silicon junctionless transistors in comparable dimensions. Nevertheless, due to the smaller bandgap and quantum confinement effects, they provide weaker results in the OFF state. Since the change of energy bandgap is one of the effects of applying uniaxial strain on CNTs, in this paper, using non-equilibrium Green's function method (NEGF), the effects of applying strain on electrical characteristics of JL-CNTFETs, such as ION and IOFF, intrinsic delay, ION/IOFF ratio, power-delay product, unity-gain frequency, gate transconductance, and output resistance are investigated. The simulation results show that uniaxial stain, significantly alters the OFF state behavior and as a result the electrical properties of the device.

  16. Advances in NO2 sensing with individual single-walled carbon nanotube transistors

    PubMed Central

    Muoth, Matthias; Roman, Cosmin; Haluska, Miroslav; Hierold, Christofer

    2014-01-01

    Summary The charge carrier transport in carbon nanotubes is highly sensitive to certain molecules attached to their surface. This property has generated interest for their application in sensing gases, chemicals and biomolecules. With over a decade of research, a clearer picture of the interactions between the carbon nanotube and its surroundings has been achieved. In this review, we intend to summarize the current knowledge on this topic, focusing not only on the effect of adsorbates but also the effect of dielectric charge traps on the electrical transport in single-walled carbon nanotube transistors that are to be used in sensing applications. Recently, contact-passivated, open-channel individual single-walled carbon nanotube field-effect transistors have been shown to be operational at room temperature with ultra-low power consumption. Sensor recovery within minutes through UV illumination or self-heating has been shown. Improvements in fabrication processes aimed at reducing the impact of charge traps have reduced the hysteresis, drift and low-frequency noise in carbon nanotube transistors. While open challenges such as large-scale fabrication, selectivity tuning and noise reduction still remain, these results demonstrate considerable progress in transforming the promise of carbon nanotube properties into functional ultra-low power, highly sensitive gas sensors. PMID:25551046

  17. Insulated-gate field-effect transistor strain sensor

    NASA Technical Reports Server (NTRS)

    Gross, C.

    1972-01-01

    Strain sensors that can be switched on and off were fabricated from p-channel IGFET on thin filament n-type silicon crystals with silicon dioxide layer sputtered over transistor for passivation. Applications include integration with microelectronic circuits for multiplexing.

  18. 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.

  19. 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

  20. Characteristics of a Field-Effect Transistor Fabricated with Electropolymerized Thin Film

    NASA Astrophysics Data System (ADS)

    Oyama, Noboru; Yoshimura, Fumihiro; Ohsaka, Takeo; Koezuka, Hiroshi; Ando, Torahiko

    1988-03-01

    The preparation and characteristics of the solid-state field-effect transistor (FET) based on poly(p,p'-biphenol)(PBP) thin film prepared by electropolymerization of p,p'-biphenol are presented. The PBP-based FET displayed excellent drain current (ID)-drain voltage (VD) characteristics for various gate voltages. The ID-VD characteristics were analyzed as in a conventional MOS transistor.

  1. From monolayer to multilayer N-channel polymeric field-effect transistors with precise conformational order.

    PubMed

    Fabiano, Simone; Musumeci, Chiara; Chen, Zhihua; Scandurra, Antonino; Wang, He; Loo, Yueh-Lin; Facchetti, Antonio; Pignataro, Bruno

    2012-02-14

    Monolayer field-effect transistors based on a high-mobility n-type polymer are demonstrated. The accurate control of the long-range order by Langmuir-Schäfer (LS) deposition yields dense polymer packing exhibiting good injection properties, relevant current on/off ratio and carrier mobility in a staggered configuration. Layer-by-layer LS film transistors of increasing thickness are fabricated and their performance compared to those of spin-coated films. PMID:22250060

  2. 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.

  3. Field-Effect Transistors: Ultrathin MXene-Micropattern-Based Field-Effect Transistor for Probing Neural Activity (Adv. Mater. 17/2016).

    PubMed

    Xu, Bingzhe; Zhu, Minshen; Zhang, Wencong; Zhen, Xu; Pei, Zengxia; Xue, Qi; Zhi, Chunyi; Shi, Peng

    2016-05-01

    A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed by C. Zhi, P. Shi, and co-workers, as described on page 3333. The FET can be utilized for label-free probing of small molecules in typical biological environments, e.g., for fast detection of action potentials in primary neurons. This device is produced with a microcontact printing technique, harnessing the unique advantages for easy fabrication. PMID:27122113

  4. Determination of optimal ionic liquid for organic single-crystal field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ono, S.; Miwa, K.; Seki, S.

    2016-02-01

    We investigate organic single-crystal field-effect transistors with various ionic liquids as gate dielectric. We find that the mobility of the field-effect transistors for both p-type and n-type organic semiconductors increases with decreasing total capacitance of the ionic liquid. However, it does not depend on the ion species at the interface between the organic semiconductor and the ionic liquid. By choosing an appropriate ionic liquid, a high carrier mobility of 12.4 cm2/V s in rubrene single crystals (p-type) and 0.13 cm2/V s in 7.7.8.8-Tetracyanoquinodimethane single crystals (n-type) are achieved. This study clarifies the influence of ionic liquids on the device performance of organic field-effect transistors and shows a way to maximize carrier mobility at the solid/liquid interface.

  5. Highly stable organic polymer field-effect transistor sensor for selective detection in the marine environment

    NASA Astrophysics Data System (ADS)

    Knopfmacher, Oren; Hammock, Mallory L.; Appleton, Anthony L.; Schwartz, Gregor; Mei, Jianguo; Lei, Ting; Pei, Jian; Bao, Zhenan

    2014-01-01

    In recent decades, the susceptibility to degradation in both ambient and aqueous environments has prevented organic electronics from gaining rapid traction for sensing applications. Here we report an organic field-effect transistor sensor that overcomes this barrier using a solution-processable isoindigo-based polymer semiconductor. More importantly, these organic field-effect transistor sensors are stable in both freshwater and seawater environments over extended periods of time. The organic field-effect transistor sensors are further capable of selectively sensing heavy-metal ions in seawater. This discovery has potential for inexpensive, ink-jet printed, and large-scale environmental monitoring devices that can be deployed in areas once thought of as beyond the scope of organic materials.

  6. Improvement of terahertz field effect transistor detectors by substrate thinning and radiation losses reduction.

    PubMed

    Coquillat, Dominique; Marczewski, Jacek; Kopyt, Pawel; Dyakonova, Nina; Giffard, Benoit; Knap, Wojciech

    2016-01-11

    Phenomena of the radiation coupling to the field effect transistors based terahertz (THz) detectors are studied. We show that in the case of planar metal antennas a significant portion of incoming radiation, instead of being coupled to the transistors, is coupled to an antenna substrate leading to responsivity losses and/or cross-talk effects in the field effect based THz detector arrays. Experimental and theoretical investigations of the responsivity versus substrate thickness are performed. They clearly show how to minimize the losses by the detector/ array substrate thinning. In conclusion simple quantitative rules of losses minimization by choosing a proper substrate thickness of field effect transistor THz detectors are presented for common materials (Si, GaAs, InP, GaN) used in semiconductor technologies. PMID:26832258

  7. Exploring graphene field effect transistor devices to improve spectral resolution of semiconductor radiation detectors

    SciTech Connect

    Harrison, Richard Karl; Howell, Stephen Wayne; Martin, Jeffrey B.; Hamilton, Allister B.

    2013-12-01

    Graphene, a planar, atomically thin form of carbon, has unique electrical and material properties that could enable new high performance semiconductor devices. Graphene could be of specific interest in the development of room-temperature, high-resolution semiconductor radiation spectrometers. Incorporating graphene into a field-effect transistor architecture could provide an extremely high sensitivity readout mechanism for sensing charge carriers in a semiconductor detector, thus enabling the fabrication of a sensitive radiation sensor. In addition, the field effect transistor architecture allows us to sense only a single charge carrier type, such as electrons. This is an advantage for room-temperature semiconductor radiation detectors, which often suffer from significant hole trapping. Here we report on initial efforts towards device fabrication and proof-of-concept testing. This work investigates the use of graphene transferred onto silicon and silicon carbide, and the response of these fabricated graphene field effect transistor devices to stimuli such as light and alpha radiation.

  8. Highly stable organic polymer field-effect transistor sensor for selective detection in the marine environment.

    PubMed

    Knopfmacher, Oren; Hammock, Mallory L; Appleton, Anthony L; Schwartz, Gregor; Mei, Jianguo; Lei, Ting; Pei, Jian; Bao, Zhenan

    2014-01-01

    In recent decades, the susceptibility to degradation in both ambient and aqueous environments has prevented organic electronics from gaining rapid traction for sensing applications. Here we report an organic field-effect transistor sensor that overcomes this barrier using a solution-processable isoindigo-based polymer semiconductor. More importantly, these organic field-effect transistor sensors are stable in both freshwater and seawater environments over extended periods of time. The organic field-effect transistor sensors are further capable of selectively sensing heavy-metal ions in seawater. This discovery has potential for inexpensive, ink-jet printed, and large-scale environmental monitoring devices that can be deployed in areas once thought of as beyond the scope of organic materials. PMID:24389531

  9. A Novel Metal-Ferroelectric-Semiconductor Field-Effect Transistor Memory Cell Design

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; Bailey, Mark; Ho, Fat Duen

    2004-01-01

    The use of a Metal-Ferroelectric-Semiconductor Field-Effect Transistor (MFSFET) in a resistive-load SRAM memory cell has been investigated A typical two-transistor resistive-load SRAM memory cell architecture is modified by replacing one of the NMOS transistors with an n-channel MFSFET. The gate of the MFSFET is connected to a polling voltage pulse instead of the other NMOS transistor drain. The polling voltage pulses are of sufficient magnitude to saturate the ferroelectric gate material and force the MFSFET into a particular logic state. The memory cell circuit is further modified by the addition of a PMOS transistor and a load resistor in order to improve the retention characteristics of the memory cell. The retention characteristics of both the "1" and "0" logic states are simulated. The simulations show that the MFSFET memory cell design can maintain both the "1" and "0" logic states for a long period of time.

  10. Plasmonic and bolometric terahertz detection by graphene field-effect transistor

    NASA Astrophysics Data System (ADS)

    Muraviev, A. V.; Rumyantsev, S. L.; Liu, G.; Balandin, A. A.; Knap, W.; Shur, M. S.

    2013-10-01

    Polarization dependence analysis of back-gated graphene field-effect transistor terahertz responsivity at frequencies ranging from 1.63 to 3.11 THz reveals two independent mechanisms of THz detection by graphene transistor: plasmonic, associated with the transistor nonlinearity, and bolometric, caused by graphene sheet temperature increase due to THz radiation absorption. In the bolometric regime, electron and hole branches demonstrate a very different response to THz radiation, which we link to the asymmetry of the current-voltage characteristics temperature dependence with respect to the Dirac point. Obtained results are important for development of high-efficiency graphene THz detectors.

  11. Vertical Field-Effect Transistor Based on Graphene-Transition Metal Dichalcogenides Heterostructures

    NASA Astrophysics Data System (ADS)

    Kumar, Jatinder; Chien, Hui-Chun; Bellus, Matthew Z.; Sicilian, David L.; Aubin, Davis St.; Chiu, Hsin-Ying; Physics and Astronomy, University of Kansas Team

    2014-03-01

    The remarkable properties of graphene has made it possible to create transistors just few atoms thick. A new development was that the other two-dimensional materials can be stacked on it with atomic layer precision, creating numerous heterostructures on demand. Here, novel vertical field-effect transistor composed of graphene- transition metal dichalcogenides (TMDs) heterostructures is fabricated and characterized at various temperatures. Due to ultrathin nature of these transistors, they present the ultimate limit for electron transport in heterostructures. Tunneling and thermionic transport characteristics are studied among different graphene-TMDs heterostructures. Their electronic properties have been investigated and can be used in vast range of devices.

  12. All-electric all-semiconductor spin field-effect transistors

    NASA Astrophysics Data System (ADS)

    Chuang, Pojen; Ho, Sheng-Chin; Smith, L. W.; Sfigakis, F.; Pepper, M.; Chen, Chin-Hung; Fan, Ju-Chun; Griffiths, J. P.; Farrer, I.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Chen, Tse-Ming

    2015-01-01

    The spin field-effect transistor envisioned by Datta and Das opens a gateway to spin information processing. Although the coherent manipulation of electron spins in semiconductors is now possible, the realization of a functional spin field-effect transistor for information processing has yet to be achieved, owing to several fundamental challenges such as the low spin-injection efficiency due to resistance mismatch, spin relaxation and the spread of spin precession angles. Alternative spin transistor designs have therefore been proposed, but these differ from the field-effect transistor concept and require the use of optical or magnetic elements, which pose difficulties for incorporation into integrated circuits. Here, we present an all-electric and all-semiconductor spin field-effect transistor in which these obstacles are overcome by using two quantum point contacts as spin injectors and detectors. Distinct engineering architectures of spin-orbit coupling are exploited for the quantum point contacts and the central semiconductor channel to achieve complete control of the electron spins (spin injection, manipulation and detection) in a purely electrical manner. Such a device is compatible with large-scale integration and holds promise for future spintronic devices for information processing.

  13. Polyfluorenes as organic semiconductors for polymeric field effect transistors

    NASA Astrophysics Data System (ADS)

    Brennan, David J.; Townsend, Paul H., III; Welsh, Dean M.; Dibbs, Mitchell G.; Shaw, Jeff M.; Miklovich, Jessica L.; Boeke, Robyn B.; Arias, Ana Claudia; Creswell, Lisa; MacKenzie, J. D.; Ramsdale, Catherine; Menon, Anoop; Sirringhaus, Henning

    2003-11-01

    Well-characterized F8T2 polyfluorene (Dow Chemical) has been prepared with weight average molecular weights (Mw) ranging from about 20,000 to 120,000. This semiconducting polymer has been used by Plastic Logic to fabricate arrays of 4,800 thin film transistors (TFTs) with 50 dpi, to be used as backplanes for active matrix displays. In this paper, the effects that molecular weight and thermal treatment have on the electrical characteristics of F8T2-based TFTs are reported. First, transistor performance improves with increasing molecular weight, with maximum values of TFT mobility approaching 1x 10-2 cm2 /V-s. Consistently higher mobilities are obtained when the F8T2 semiconductor makes contact with PEDOT/PSS versus gold electrodes. Alignment of F8T2 on a rubbed polyimide substrate is maintained after quenching, as determined by measurement of the dichroic ratios. Early-stage results on the development of inks based on F8T2 polyfluorene are also reported.

  14. Organic field-effect transistor nonvolatile memories utilizing sputtered C nanoparticles as nano-floating-gate

    SciTech Connect

    Liu, Jie; Liu, Chang-Hai; She, Xiao-Jian; Sun, Qi-Jun; Gao, Xu; Wang, Sui-Dong

    2014-10-20

    High-performance organic field-effect transistor nonvolatile memories have been achieved using sputtered C nanoparticles as the nano-floating-gate. The sputtered C nano-floating-gate is prepared with low-cost material and simple process, forming uniform and discrete charge trapping sites covered by a smooth and complete polystyrene layer. The devices show large memory window, excellent retention capability, and programming/reading/erasing/reading endurance. The sputtered C nano-floating-gate can effectively trap both holes and electrons, and it is demonstrated to be suitable for not only p-type but also n-type organic field-effect transistor nonvolatile memories.

  15. High performance hydrogen-terminated diamond field effect transistors

    NASA Astrophysics Data System (ADS)

    Russell, Stephen A. O.

    Diamond provides extreme properties which make it suitable as a new substrate material for high performance electronics. It has the potential to provide both high frequency and high power performance while operating in extreme environments such as elevated temperature or exposed to corrosive chemicals or radiation. Research to date has shown the potential of diamond for this purpose with hydrogen-terminated diamond surface channel transistors already showing promise in terms of high frequency operation. The inherent instability of using atmospheric molecules to induce a p-type doping at this hydrogen-terminated diamond surface has so far limited power performance and robustness of operation. This work reports upon the scaling of surface channel hydrogen-terminated transistors with FET gate lengths of 250 nm and 120 nm showing performance comparable to other devices published to date. The gate length was then scaled for the first time to sub-100 nm dimensions with a 50 nm gate length FET fabricated giving record high-frequency performance with a fT of 53 GHz. An adapted fabrication procedure was developed for this project with special attention paid to the volatility of the particles upon the diamond surface. Equivalent RF circuit models were extracted for each gate length and analysed in detail. Work was then undertaken to investigate a more stable alternative to the atmospheric induced doping effect with alternative electron accepting materials being deposited upon the hydrogen-terminated diamond surface. The as yet untested organic material F16CuPc was deposited on to hydrogen-terminated diamond and demonstrated its ability to encapsulate and preserve the atmospheric induced sub-surface conductivity at room temperature. For the first time an inorganic material was also investigated as a potential encapsulation for the hydrogen-terminated diamond surface, MoO3 was chosen due to its high electron affinity and like F16CuPc also showed the ability to preserve and

  16. Tuning the threshold voltage of MoS2 field-effect transistors via surface treatment.

    PubMed

    Leong, Wei Sun; Li, Yida; Luo, Xin; Nai, Chang Tai; Quek, Su Ying; Thong, John T L

    2015-06-28

    Controlling the threshold voltage (Vth) of a field-effect transistor is important for realizing robust logic circuits. Here, we report a facile approach to achieve bidirectional Vth tuning of molybdenum disulfide (MoS2) field-effect transistors. By increasing and decreasing the amount of sulfur vacancies in the MoS2 surface, the Vth of MoS2 transistors can be left- and right-shifted, respectively. Transistors fabricated on perfect MoS2 flakes are found to exhibit a two-fold enhancement in mobility and a very positive Vth (18.5 ± 7.5 V). More importantly, our elegant hydrogen treatment is able to tune the large Vth to a small value (∼0 V) without any performance degradation simply by reducing the atomic ratio of S : Mo slightly; in other words, it creates a certain amount of sulfur vacancies in the MoS2 surface, which generate defect states in the band gap of MoS2 that mediates conduction of a MoS2 transistor in the subthreshold regime. First-principles calculations further indicate that the defect band's edge and width can be tuned according to the vacancy density. This work not only demonstrates for the first time the ease of tuning the Vth of MoS2 transistors, but also offers a process technology solution that is critical for further development of MoS2 as a mainstream electronic material. PMID:26036230

  17. Analytical ballistic theory of carbon nanotube transistors: Experimental validation, device physics, parameter extraction, and performance projection

    NASA Astrophysics Data System (ADS)

    Akinwande, Deji; Liang, Jiale; Chong, Soogine; Nishi, Yoshio; Wong, H.-S. Philip

    2008-12-01

    We developed a fully analytical ballistic theory of carbon nanotube field effect transistors enabled by the development of an analytical surface potential capturing the temperature dependence and gate and quantum capacitance electrostatics. The analytical ballistic theory is compared to the experimental results of a ballistic transistor with good agreement. The validated analytical theory enables intuitive circuit design, provides techniques for parameter extraction of the bandgap and surface potential, and elucidates on the device physics of drain optical phonon scattering and its role in reducing the linear conductance and intrinsic gain of the transistor. Furthermore, a threshold voltage definition is proposed reflecting the bandgap-diameter dependence. Projections for key analog and digital performances are discussed.

  18. Benzocyclobutene (BCB) Polymer as Amphibious Buffer Layer for Graphene Field-Effect Transistor.

    PubMed

    Wu, Yun; Zou, Jianjun; Huo, Shuai; Lu, Haiyan; Kong, Yuecan; Chen, Tangshen; Wu, Wei; Xu, Jingxia

    2015-08-01

    Owing to the scattering and trapping effects, the interfaces of dielectric/graphene or substrate/graphene can tailor the performance of field-effect transistor (FET). In this letter, the polymer of benzocyclobutene (BCB) was used as an amphibious buffer layer and located at between the layers of substrate and graphene and between the layers of dielectric and graphene. Interestingly, with the help of nonpolar and hydrophobic BCB buffer layer, the large-scale top-gated, chemical vapor deposited (CVD) graphene transistors was prepared on Si/SiO2 substrate, its cutoff frequency (fT) and the maximum cutoff frequency (fmax) of the graphene field-effect transistor (GFET) can be reached at 12 GHz and 11 GHz, respectively. PMID:26369142

  19. Self-aligned, vertical-channel, polymer field-effect transistors.

    PubMed

    Stutzmann, Natalie; Friend, Richard H; Sirringhaus, Henning

    2003-03-21

    The manufacture of high-performance, conjugated polymer transistor circuits on flexible plastic substrates requires patterning techniques that are capable of defining critical features with submicrometer resolution. We used solid-state embossing to produce polymer field-effect transistors with submicrometer critical features in planar and vertical configurations. Embossing is used for the controlled microcutting of vertical sidewalls into polymer multilayer structures without smearing. Vertical-channel polymer field-effect transistors on flexible poly(ethylene terephthalate) substrates were fabricated, in which the critical channel length of 0.7 to 0.9 micrometers was defined by the thickness of a spin-coated insulator layer. Gate electrodes were self-aligned to minimize overlap capacitance by inkjet printing that used the embossed grooves to define a surface-energy pattern. PMID:12649478

  20. A hydrogel capsule as gate dielectric in flexible organic field-effect transistors

    SciTech Connect

    Dumitru, L. M.; Manoli, K.; Magliulo, M.; Torsi, L.; Ligonzo, T.; Palazzo, G.

    2015-01-01

    A jellified alginate based capsule serves as biocompatible and biodegradable electrolyte system to gate an organic field-effect transistor fabricated on a flexible substrate. Such a system allows operating thiophene based polymer transistors below 0.5 V through an electrical double layer formed across an ion-permeable polymeric electrolyte. Moreover, biological macro-molecules such as glucose-oxidase and streptavidin can enter into the gating capsules that serve also as delivery system. An enzymatic bio-reaction is shown to take place in the capsule and preliminary results on the measurement of the electronic responses promise for low-cost, low-power, flexible electronic bio-sensing applications using capsule-gated organic field-effect transistors.

  1. Hysteresis in single-layer MoS2 field effect transistors.

    PubMed

    Late, Dattatray J; Liu, Bin; Matte, H S S Ramakrishna; Dravid, Vinayak P; Rao, C N R

    2012-06-26

    Field effect transistors using ultrathin molybdenum disulfide (MoS(2)) have recently been experimentally demonstrated, which show promising potential for advanced electronics. However, large variations like hysteresis, presumably due to extrinsic/environmental effects, are often observed in MoS(2) devices measured under ambient environment. Here, we report the origin of their hysteretic and transient behaviors and suggest that hysteresis of MoS(2) field effect transistors is largely due to absorption of moisture on the surface and intensified by high photosensitivity of MoS(2). Uniform encapsulation of MoS(2) transistor structures with silicon nitride grown by plasma-enhanced chemical vapor deposition is effective in minimizing the hysteresis, while the device mobility is improved by over 1 order of magnitude. PMID:22577885

  2. An Organic Vertical Field-Effect Transistor with Underside-Doped Graphene Electrodes.

    PubMed

    Kim, Jong Su; Kim, Beom Joon; Choi, Young Jin; Lee, Moo Hyung; Kang, Moon Sung; Cho, Jeong Ho

    2016-06-01

    High-performance vertical field-effect transistors are developed, which are based on graphene electrodes doped using the underside doping method. The underside doping method enables effective tuning of the graphene work function while maintaining the surface properties of the pristine graphene. PMID:27071794

  3. 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.

  4. Terahertz 3D printed diffractive lens matrices for field-effect transistor detector focal plane arrays.

    PubMed

    Szkudlarek, Krzesimir; Sypek, Maciej; Cywiński, Grzegorz; Suszek, Jarosław; Zagrajek, Przemysław; Feduniewicz-Żmuda, Anna; Yahniuk, Ivan; Yatsunenko, Sergey; Nowakowska-Siwińska, Anna; Coquillat, Dominique; But, Dmytro B; Rachoń, Martyna; Węgrzyńska, Karolina; Skierbiszewski, Czesław; Knap, Wojciech

    2016-09-01

    We present the concept, the fabrication processes and the experimental results for materials and optics that can be used for terahertz field-effect transistor detector focal plane arrays. More specifically, we propose 3D printed arrays of a new type - diffractive multi-zone lenses of which the performance is superior to that of previously used mono-zone diffractive or refractive elements and evaluate them with GaN/AlGaN field-effect transistor terahertz detectors. Experiments performed in the 300-GHz atmospheric window show that the lens arrays offer both a good efficiency and good uniformity, and may improve the signal-to-noise ratio of the terahertz field-effect transistor detectors by more than one order of magnitude. In practice, we tested 3 × 12 lens linear arrays with printed circuit board THz detector arrays used in postal security scanners and observed significant signal-to-noise improvements. Our results clearly show that the proposed technology provides a way to produce cost-effective, reproducible, flat optics for large-size field-effect transistor THz-detector focal plane arrays. PMID:27607620

  5. An improved junction capacitance model for junction field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ding, Hao; Liou, Juin J.; Cirba, Claude R.; Green, Keith

    2006-07-01

    A new junction capacitance model for the four-terminal junction field-effect transistor (JFET) is presented. With a single expression, the model, which is valid for different temperatures and a wide range of bias conditions, describes correctly the JFET junction capacitance behavior and capacitance drop-off phenomenon. The model has been verified using experimental data measured at Texas Instruments.

  6. Following a protein kinase activity using a field-effect transistor device.

    PubMed

    Freeman, Ronit; Gill, Ron; Willner, Itamar

    2007-09-01

    The specific phosphorylation of a peptide-functionalized ion-sensitive field-effect transistor device by casein kinase II in the presence of ATP enables the electronic readout of the protein kinase activity; treatment of the phosphorylated surface with alkaline phosphatase results in the regeneration of the active sensing surface. PMID:17700878

  7. Silicon-on-insulator field effect transistor with improved body ties for rad-hard applications

    DOEpatents

    Schwank, James R.; Shaneyfelt, Marty R.; Draper, Bruce L.; Dodd, Paul E.

    2001-01-01

    A silicon-on-insulator (SOI) field-effect transistor (FET) and a method for making the same are disclosed. The SOI FET is characterized by a source which extends only partially (e.g. about half-way) through the active layer wherein the transistor is formed. Additionally, a minimal-area body tie contact is provided with a short-circuit electrical connection to the source for reducing floating body effects. The body tie contact improves the electrical characteristics of the transistor and also provides an improved single-event-upset (SEU) radiation hardness of the device for terrestrial and space applications. The SOI FET also provides an improvement in total-dose radiation hardness as compared to conventional SOI transistors fabricated without a specially prepared hardened buried oxide layer. Complementary n-channel and p-channel SOI FETs can be fabricated according to the present invention to form integrated circuits (ICs) for commercial and military applications.

  8. MoS₂ field-effect transistor for next-generation label-free biosensors.

    PubMed

    Sarkar, Deblina; Liu, Wei; Xie, Xuejun; Anselmo, Aaron C; Mitragotri, Samir; Banerjee, Kaustav

    2014-04-22

    Biosensors based on field-effect transistors (FETs) have attracted much attention, as they offer rapid, inexpensive, and label-free detection. While the low sensitivity of FET biosensors based on bulk 3D structures has been overcome by using 1D structures (nanotubes/nanowires), the latter face severe fabrication challenges, impairing their practical applications. In this paper, we introduce and demonstrate FET biosensors based on molybdenum disulfide (MoS2), which provides extremely high sensitivity and at the same time offers easy patternability and device fabrication, due to its 2D atomically layered structure. A MoS2-based pH sensor achieving sensitivity as high as 713 for a pH change by 1 unit along with efficient operation over a wide pH range (3-9) is demonstrated. Ultrasensitive and specific protein sensing is also achieved with a sensitivity of 196 even at 100 femtomolar concentration. While graphene is also a 2D material, we show here that it cannot compete with a MoS2-based FET biosensor, which surpasses the sensitivity of that based on graphene by more than 74-fold. Moreover, we establish through theoretical analysis that MoS2 is greatly advantageous for biosensor device scaling without compromising its sensitivity, which is beneficial for single molecular detection. Furthermore, MoS2, with its highly flexible and transparent nature, can offer new opportunities in advanced diagnostics and medical prostheses. This unique fusion of desirable properties makes MoS2 a highly potential candidate for next-generation low-cost biosensors. PMID:24588742

  9. Temperature Dependence of Field-Effect Mobility in Organic Thin-Film Transistors: Similarity to Inorganic Transistors.

    PubMed

    Okada, Jun; Nagase, Takashi; Kobayashi, Takashi; Naito, Hiroyoshi

    2016-04-01

    Carrier transport in solution-processed organic thin-film transistors (OTFTs) based on dioctylbenzothienobenzothiophene (C8-BTBT) has been investigated in a wide temperature range from 296 to 10 K. The field-effect mobility shows thermally activated behavior whose activation energy becomes smaller with decreasing temperature. The temperature dependence of field-effect mobility found in C8-BTBT is similar to that of others materials: organic semiconducting polymers, amorphous oxide semiconductors and hydrogenated amorphous silicon. These results indicate that hopping transport between isoenergetic localized states becomes dominated in a low temperature regime in these materials. PMID:27451607

  10. Simulation-based design of a strained graphene field effect transistor incorporating the pseudo magnetic field effect

    SciTech Connect

    Souma, Satofumi Ueyama, Masayuki; Ogawa, Matsuto

    2014-05-26

    We present a numerical study on the performance of strained graphene-based field-effect transistors. A local strain less than 10% is applied over a central channel region of the graphene to induce the shift of the Dirac point in the channel region along the transverse momentum direction. The left and the right unstrained graphene regions are doped to be either n-type or p-type. By using the atomistic tight-binding model and a Green's function method, we predict that the gate voltage applied to the central strained graphene region can switch the drain current on and off with an on/off ratio of more than six orders of magnitude at room temperature. This is in spite of the absence of a bandgap in the strained channel region. Steeper subthreshold slopes below 60 mV/decade are also predicted at room temperature because of a mechanism similar to the band-to-band tunneling field-effect transistors.

  11. A spiking neuron circuit based on a carbon nanotube transistor.

    PubMed

    Chen, C-L; Kim, K; Truong, Q; Shen, A; Li, Z; Chen, Y

    2012-07-11

    A spiking neuron circuit based on a carbon nanotube (CNT) transistor is presented in this paper. The spiking neuron circuit has a crossbar architecture in which the transistor gates are connected to its row electrodes and the transistor sources are connected to its column electrodes. An electrochemical cell is incorporated in the gate of the transistor by sandwiching a hydrogen-doped poly(ethylene glycol)methyl ether (PEG) electrolyte between the CNT channel and the top gate electrode. An input spike applied to the gate triggers a dynamic drift of the hydrogen ions in the PEG electrolyte, resulting in a post-synaptic current (PSC) through the CNT channel. Spikes input into the rows trigger PSCs through multiple CNT transistors, and PSCs cumulate in the columns and integrate into a 'soma' circuit to trigger output spikes based on an integrate-and-fire mechanism. The spiking neuron circuit can potentially emulate biological neuron networks and their intelligent functions. PMID:22710137

  12. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks.

  13. High performance transistors via aligned polyfluorene-sorted carbon nanotubes

    SciTech Connect

    Brady, Gerald J.; Joo, Yongho; Singha Roy, Susmit; Gopalan, Padma; Arnold, Michael S.

    2014-02-24

    We evaluate the performance of exceptionally electronic-type sorted, semiconducting, aligned single-walled carbon nanotubes (s-SWCNTs) in field effect transistors (FETs). High on-conductance and high on/off conductance modulation are simultaneously achieved at channel lengths which are both shorter and longer than individual s-SWCNTs. The s-SWCNTs are isolated from heterogeneous mixtures using a polyfluorene-derivative as a selective agent and aligned on substrates via dose-controlled, floating evaporative self-assembly at densities of ∼50 s-SWCNTs μm{sup −1}. At a channel length of 9 μm the s-SWCNTs percolate to span the FET channel, and the on/off ratio and charge transport mobility are 2.2 × 10{sup 7} and 46 cm{sup 2} V{sup −1} s{sup −1}, respectively. At a channel length of 400 nm, a large fraction of the s-SWCNTs directly span the channel, and the on-conductance per width is 61 μS μm{sup −1} and the on/off ratio is 4 × 10{sup 5}. These results are considerably better than previous solution-processed FETs, which have suffered from poor on/off ratio due to spurious metallic nanotubes that bridge the channel. 4071 individual and small bundles of s-SWCNTs are tested in 400 nm channel length FETs, and all show semiconducting behavior, demonstrating the high fidelity of polyfluorenes as selective agents and the promise of assembling s-SWCNTs from solution to create high performance semiconductor electronic devices.

  14. Highly stretchable carbon nanotube transistors enabled by buckled ion gel gate dielectrics

    SciTech Connect

    Wu, Meng-Yin; Chang, Tzu-Hsuan; Ma, Zhenqiang; Zhao, Juan; Xu, Feng; Jacobberger, Robert M.; Arnold, Michael S.

    2015-08-03

    Deformable field-effect transistors (FETs) are expected to facilitate new technologies like stretchable displays, conformal devices, and electronic skins. We previously demonstrated stretchable FETs based on buckled thin films of polyfluorene-wrapped semiconducting single-walled carbon nanotubes as the channel, buckled metal films as electrodes, and unbuckled flexible ion gel films as the dielectric. The FETs were stretchable up to 50% without appreciable degradation in performance before failure of the ion gel film. Here, we show that by buckling the ion gel, the integrity and performance of the nanotube FETs are extended to nearly 90% elongation, limited by the stretchability of the elastomer substrate. The FETs maintain an on/off ratio of >10{sup 4} and a field-effect mobility of 5 cm{sup 2} V{sup −1} s{sup −1} under elongation and demonstrate invariant performance over 1000 stretching cycles.

  15. Vertical Ge and GeSn heterojunction gate-all-around tunneling field effect transistors

    NASA Astrophysics Data System (ADS)

    Schulze, Jörg; Blech, Andreas; Datta, Arnab; Fischer, Inga A.; Hähnel, Daniel; Naasz, Sandra; Rolseth, Erlend; Tropper, Eva-Maria

    2015-08-01

    We present experimental results on the fabrication and characterization of vertical Ge and GeSn heterojunction Tunneling Field Effect Transistors (TFETs). A gate-all-around process with mesa diameters down to 70 nm is used to reduce leakage currents and improve electrostatic control of the gate over the transistor channel. An ION = 88.4 μA/μm at VDS = VG = -2 V is obtained for a TFET with a 10 nm Ge0.92Sn0.08 layer at the source/channel junction. We discuss further possibilities for device improvements.

  16. Light quasiparticles dominate electronic transport in molecular crystal field-effect transistors

    SciTech Connect

    Li, Z. Q.; Podzorov, V.; Sai, N.; Martin, Michael C.; Gershenson, M. E.; Di Ventra, M.; Basov, D. N.

    2007-03-01

    We report on an infrared spectroscopy study of mobile holes in the accumulation layer of organic field-effect transistors based on rubrene single crystals. Our data indicate that both transport and infrared properties of these transistors at room temperature are governed by light quasiparticles in molecular orbital bands with the effective masses m[small star, filled]comparable to free electron mass. Furthermore, the m[small star, filled]values inferred from our experiments are in agreement with those determined from band structure calculations. These findings reveal no evidence for prominent polaronic effects, which is at variance with the common beliefs of polaron formation in molecular solids.

  17. Ordered polymer nanofibers enhance output brightness in bilayer light-emitting field-effect transistors.

    PubMed

    Hsu, Ben B Y; Seifter, Jason; Takacs, Christopher J; Zhong, Chengmei; Tseng, Hsin-Rong; Samuel, Ifor D W; Namdas, Ebinazar B; Bazan, Guillermo C; Huang, Fei; Cao, Yong; Heeger, Alan J

    2013-03-26

    Polymer light emitting field effect transistors are a class of light emitting devices that reveal interesting device physics. Device performance can be directly correlated to the most fundamental polymer science. Control over surface properties of the transistor dielectric can dramatically change the polymer morphology, introducing ordered phase. Electronic properties such as carrier mobility and injection efficiency on the interface can be promoted by ordered nanofibers in the polymer. Moreover, by controlling space charge in the polymer interface, the recombination zone can be spatially extended and thereby enhance the optical output. PMID:23413831

  18. Utilization of a buffered dielectric to achieve high field-effect carrier mobility in graphene transistors.

    PubMed

    Farmer, Damon B; Chiu, Hsin-Ying; Lin, Yu-Ming; Jenkins, Keith A; Xia, Fengnian; Avouris, Phaedon

    2009-12-01

    We utilize an organic polymer buffer layer between graphene and conventional gate dielectrics in top-gated graphene transistors. Unlike other insulators, this dielectric stack does not significantly degrade carrier mobility, allowing for high field-effect mobilities to be retained in top-gate operation. This is demonstrated in both two-point and four-point analysis and in the high-frequency operation of a graphene transistor. Temperature dependence of the carrier mobility suggests that phonons are the dominant scatterers in these devices. PMID:19883119

  19. Ternary logic implemented on a single dopant atom field effect silicon transistor

    NASA Astrophysics Data System (ADS)

    Klein, M.; Mol, J. A.; Verduijn, J.; Lansbergen, G. P.; Rogge, S.; Levine, R. D.; Remacle, F.

    2010-01-01

    We provide an experimental proof of principle for a ternary multiplier realized in terms of the charge state of a single dopant atom embedded in a fin field effect transistor (Fin-FET). Robust reading of the logic output is made possible by using two channels to measure the current flowing through the device and the transconductance. A read out procedure that allows for voltage gain is proposed. Long numbers can be multiplied by addressing a sequence of Fin-FET transistors in a row.

  20. Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics.

    PubMed

    Bartolomeo, Antonio Di; Giubileo, Filippo; Romeo, Francesco; Sabatino, Paolo; Carapella, Giovanni; Iemmo, Laura; Schroeder, Thomas; Lupina, Grzegorz

    2015-11-27

    We fabricate back-gated field effect transistors using niobium electrodes on mechanically exfoliated monolayer graphene and perform electrical characterization in the pressure range from atmospheric down to 10(-4) mbar. We study the effect of room temperature vacuum degassing and report asymmetric transfer characteristics with a resistance plateau in the n-branch. We show that weakly chemisorbed Nb acts as p-dopant on graphene and explain the transistor characteristics by Nb/graphene interaction with unpinned Fermi level at the interface. PMID:26535591

  1. Electroluminescence imaging and microstructure of organic light-emitting field-effect transistors

    NASA Astrophysics Data System (ADS)

    Zaumseil, Jana; Kline, R. Joseph; Sirringhaus, Henning

    2008-02-01

    The effect of morphology and microstructure on the emission characteristics of ambipolar light-emitting field-effect transistors is studied using the polyfluorene copolymer F8BT [poly(9,9-di-n-octylfluorene-alt-benzothiadiazole)] as a model system. Different intensity distributions of the emission zones of amorphous, polycrystalline, and aligned F8BT films are demonstrated. Electroluminescence maps of the channel region are produced by overlaying a series of images recorded during gate voltage sweeps. They show a correlation to the microcrystalline structure of the F8BT and are assumed to visualize the current density distribution within the transistor channel.

  2. 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.

  3. Nitrogen-Doped Graphene Synthesized from a Single Liquid Precursor for a Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Van Nang, Lam; Van Duy, Nguyen; Hoa, Nguyen Duc; Van Hieu, Nguyen

    2016-01-01

    Opening the band gap of graphene is among the most important issues in modulating its electrical properties for electronic device applications. In this study, we report on the synthesis of nitrogen-doped graphene for field effect transistors. The graphene doped with nitrogen was synthesized by thermal chemical vapor deposition using a single liquid precursor of dimethylformamide, which contains both carbon and nitrogen sources. Material characterization by Raman spectroscopy, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy confirmed the successful synthesis of high-quality nitrogen-doped graphene with a thickness of two or three atomic layers. By simply using dimethylformamide as a liquid precursor, we could dope N into graphene with a doping level of 0.64 at.%. The synthesized graphene was used to fabricate a field effect transistor, the characteristics of which were systematically studied at different temperatures (15-105°C) in air and in a vacuum. Results showed that the synthesized graphene exhibits p-type behavior in air but n-type behavior in a vacuum with a band gap of about 0.03 eV. The field effect mobility calculated at room temperature was 359 cm2 V-1 s-1. The fabricated field effect transistor has potential applications in electronic devices.

  4. Carbon nanotube transistors, sensors, and beyond

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian

    Carbon nanotubes are tiny hollow cylinders, made from a single graphene sheet, that possess many amazing properties. Another reason why nanotubes have generated intense research activities from scientists of various disciplines is they represent a new class of materials for the study of one-dimensional physics. In this thesis we investigate the electrical transport of semiconducting single-walled carbon nanotubes and their potential applications as biological sensors. Electrons have been predicted, by theoretical physicists, to go through nanotubes without much resistance. But this has not been properly quantified experimentally, and the origin of the routinely observed large resistance in nanotubes is not clear. In this thesis we show that in moderate long high quality nanotubes the electrical transport is limited by electron-phonon scattering. Systematic studies are carried out using many devices of different diameters at various temperatures. The resistance and inverse of peak mobility are observed to decrease linearly with temperature, indicating the influence of phonons. The conductance and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion respectively. Based on electron-phonon scattering, a theory model is developed that can not only predict how the resistance changes with gate voltage but also explain the observed temperature and diameter dependence. This work clarifies the nature of electrical transport in nanotubes and sets a performance limit of nanotube devices in diffusive regime. The electrical transport in nanotubes is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility, making nanotubes ideal key elements in biological sensors. In the second part of this thesis, we integrate nanotubes with supported lipid bilayers, mimic structures of cell membranes, and use this platform as a way to introduce biomolecules into the vicinity of

  5. Ferroelectric Material Application: Modeling Ferroelectric Field Effect Transistor Characteristics from Micro to Nano

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd, C.; Ho, Fat Duen

    2006-01-01

    All present ferroelectric transistors have been made on the micrometer scale. Existing models of these devices do not take into account effects of nanoscale ferroelectric transistors. Understanding the characteristics of these nanoscale devices is important in developing a strategy for building and using future devices. This paper takes an existing microscale ferroelectric field effect transistor (FFET) model and adds effects that become important at a nanoscale level, including electron velocity saturation and direct tunneling. The new model analyzed FFETs ranging in length from 40,000 nanometers to 4 nanometers and ferroelectric thickness form 200 nanometers to 1 nanometer. The results show that FFETs can operate on the nanoscale but have some undesirable characteristics at very small dimensions.

  6. Silicon field-effect transistors as radiation detectors for the Sub-THz range

    SciTech Connect

    But, D. B. Golenkov, O. G.; Sakhno, N. V.; Sizov, F. F.; Korinets, S. V.; Gumenjuk-Sichevska, J. V.; Reva, V. P.; Bunchuk, S. G.

    2012-05-15

    The nonresonance response of silicon metal-oxide-semiconductor field-effect transistors (Si-MOSFETs) with a long channel (1-20 {mu}m) to radiation in the frequency range 43-135 GHz is studied. The transistors are fabricated by the standard CMOS technology with 1-{mu}m design rules. The volt-watt sensitivity and the noise equivalent power (NEP) for such detectors are estimated with the calculated effective area of the detecting element taken into account. It is shown that such transistors can operate at room temperature as broadband direct detectors of sub-THz radiation. In the 4-5 mm range of wavelengths, the volt-watt sensitivity can be as high as tens of kV/W and the NEP can amount to 10{sup -11} - 10{sup -12}W/{radical}Hz . The parameters of detectors under study can be improved by the optimization of planar antennas.

  7. Reducing flicker noise in chemical vapor deposition graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Arnold, Heather N.; Sangwan, Vinod K.; Schmucker, Scott W.; Cress, Cory D.; Luck, Kyle A.; Friedman, Adam L.; Robinson, Jeremy T.; Marks, Tobin J.; Hersam, Mark C.

    2016-02-01

    Single-layer graphene derived from chemical vapor deposition (CVD) holds promise for scalable radio frequency (RF) electronic applications. However, prevalent low-frequency flicker noise (1/f noise) in CVD graphene field-effect transistors is often up-converted to higher frequencies, thus limiting RF device performance. Here, we achieve an order of magnitude reduction in 1/f noise in field-effect transistors based on CVD graphene transferred onto silicon oxide substrates by utilizing a processing protocol that avoids aqueous chemistry after graphene transfer. Correspondingly, the normalized noise spectral density (10-7-10-8 μm2 Hz-1) and noise amplitude (4 × 10-8-10-7) in these devices are comparable to those of exfoliated and suspended graphene. We attribute the reduction in 1/f noise to a decrease in the contribution of fluctuations in the scattering cross-sections of carriers arising from dynamic redistribution of interfacial disorder.

  8. Vacuum-processed polyethylene as a dielectric for low operating voltage organic field effect transistors.

    PubMed

    Kanbur, Yasin; Irimia-Vladu, Mihai; Głowacki, Eric D; Voss, Gundula; Baumgartner, Melanie; Schwabegger, Günther; Leonat, Lucia; Ullah, Mujeeb; Sarica, Hizir; Erten-Ela, Sule; Schwödiauer, Reinhard; Sitter, Helmut; Küçükyavuz, Zuhal; Bauer, Siegfried; Sariciftci, Niyazi Serdar

    2012-05-01

    We report on the fabrication and performance of vacuum-processed organic field effect transistors utilizing evaporated low-density polyethylene (LD-PE) as a dielectric layer. With C60 as the organic semiconductor, we demonstrate low operating voltage transistors with field effect mobilities in excess of 4 cm(2)/Vs. Devices with pentacene showed a mobility of 0.16 cm(2)/Vs. Devices using tyrian Purple as semiconductor show low-voltage ambipolar operation with equal electron and hole mobilities of ∼0.3 cm(2)/Vs. These devices demonstrate low hysteresis and operational stability over at least several months. Grazing-angle infrared spectroscopy of evaporated thin films shows that the structure of the polyethylene is similar to solution-cast films. We report also on the morphological and dielectric properties of these films. Our experiments demonstrate that polyethylene is a stable dielectric supporting both hole and electron channels. PMID:23483783

  9. Topological Insulator Bi2Se3 Nanowire High Performance Field-Effect Transistors

    PubMed Central

    Zhu, Hao; Richter, Curt A.; Zhao, Erhai; Bonevich, John E.; Kimes, William A.; Jang, Hyuk-Jae; Yuan, Hui; Li, Haitao; Arab, Abbas; Kirillov, Oleg; Maslar, James E.; Ioannou, Dimitris E.; Li, Qiliang

    2013-01-01

    Topological insulators are unique electronic materials with insulating interiors and robust metallic surfaces. Device applications exploiting their remarkable properties have so far been hampered by the difficulty to electrically tune the Fermi levels of both bulk and thin film samples. Here we show experimentally that single-crystal nanowires of the topological insulator Bi2Se3 can be used as the conduction channel in high-performance field effect transistor (FET), a basic circuit building block. Its current-voltage characteristics are superior to many of those reported for semiconductor nanowire transistors, including sharp turn-on, nearly zero cutoff current, very large On/Off current ratio, and well-saturated output current. The metallic electron transport at the surface with good FET effective mobility can be effectively separated from the conduction of bulk Bi2Se3 and adjusted by field effect at a small gate voltage. This opens up a suite of potential applications in nanoelectronics and spintronics.

  10. Transferred large area single crystal MoS2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Lee, Choong Hee; McCulloch, William; Lee, Edwin W.; Ma, Lu; Krishnamoorthy, Sriram; Hwang, Jinwoo; Wu, Yiying; Rajan, Siddharth

    2015-11-01

    Transfer of epitaxial, two-dimensional (2D) MoS2 on sapphire grown via synthetic approaches is a prerequisite for practical device applications. We report centimeter-scale, single crystal, synthesized MoS2 field effect transistors (FETs) transferred onto SiO2/Si substrates, with a field-effect mobility of 4.5 cm2 V-1 s-1, which is among the highest mobility values reported for the transferred large-area MoS2 transistors. We demonstrate simple and clean transfer of large-area MoS2 films using deionized water, which can effectively avoid chemical contamination. The transfer method reported here allows standard i-line stepper lithography process to realize multiple devices over the entire film area.

  11. High-performance molybdenum disulfide field-effect transistors with spin tunnel contacts.

    PubMed

    Dankert, André; Langouche, Lennart; Kamalakar, Mutta Venkata; Dash, Saroj Prasad

    2014-01-28

    Molybdenum disulfide has recently emerged as a promising two-dimensional semiconducting material for nanoelectronic, optoelectronic, and spintronic applications. Here, we investigate the field-effect transistor behavior of MoS2 with ferromagnetic contacts to explore its potential for spintronics. In such devices, we elucidate that the presence of a large Schottky barrier resistance at the MoS2/ferromagnet interface is a major obstacle for the electrical spin injection and detection. We circumvent this problem by a reduction in the Schottky barrier height with the introduction of a thin TiO2 tunnel barrier between the ferromagnet and MoS2. This results in an enhancement of the transistor on-state current by 2 orders of magnitude and an increment in the field-effect mobility by a factor of 6. Our magnetoresistance calculation reveals that such integration of ferromagnetic tunnel contacts opens up the possibilities for MoS2-based spintronic devices. PMID:24377305

  12. Ultrasensitive, label-free, and real-time immunodetection using silicon field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kim, Ansoon; Ah, Chil Seong; Yu, Han Young; Yang, Jong-Heon; Baek, In-Bok; Ahn, Chang-Guen; Park, Chan Woo; Jun, Myung Sim; Lee, Sungjae

    2007-09-01

    Ultrasensitive, label-free, and real-time prostate-specific antigen (PSA) sensor was developed using n-type silicon nanowire-based structures configured as field-effect transistors using the conventional "top-down" semiconductor processes. Specific binding of PSA with antibody of PSA (anti-PSA) immobilized on the Si surface through covalent linkage leads to a conductivity change in response to variations of electric field at the surface. The conductance changes depending on PSA concentrations and pH values in solution according to isoelectric point of PSA provide the evidence of the real-time detection of 1fg /ml PSA. The authors also explored the sensitivity of PSA immunodetection depending on both Si-field-effect transistors (FET) dimensions and doping concentrations to provide strategy for fabrication of an ultrasensitive Si-FET biosensor.

  13. Controlling field-effect mobility in pentacene-based transistors by supersonic molecular-beam deposition

    SciTech Connect

    Toccoli, T.; Pallaoro, A.; Coppede, N.; Iannotta, S.; De Angelis, F.; Mariucci, L.; Fortunato, G.

    2006-03-27

    We show that pentacene field-effect transistors, fabricated by supersonic molecular beams, have a performance strongly depending on the precursor's kinetic energy (K{sub E}). The major role played by K{sub E} is in achieving highly ordered and flat films. In the range K{sub E}{approx_equal}3.5-6.5 eV, the organic field effect transistor linear mobility increases of a factor {approx}5. The highest value (1.0 cm{sup 2} V{sup -1} s{sup -1}) corresponds to very uniform and flat films (layer-by-layer type growth). The temperature dependence of mobility for films grown at K{sub E}>6 eV recalls that of single crystals (bandlike) and shows an opposite trend for films grown at K{sub E}{<=}5.5 eV.

  14. Light-emitting polymer/carbon nanotube hybrid transistors: below and above the percolation limit

    NASA Astrophysics Data System (ADS)

    Wang, Ming; Jakubka, Florian; Gannott, Florentina; Zaumseil, Jana

    2013-09-01

    Hybrids of semiconducting polymers and single-walled carbon nanotubes (SWNT) are interesting for organic electronic devices such as solar cells, light-emitting diodes and field-effect transistors (FETs). They are easily produced by selective dispersion of SWNTs in polymer solutions by ultrasonication followed by centrifugation. We demonstrate that nanotubes at concentration levels well below the percolation limit significantly improve charge injection of both holes and electrons into semiconducting polymers in top-gate FETs. This leads to lower contact resistances and reduced threshold voltages, thus the maximum ambipolar currents and visible light emission due to electron-hole recombination are considerably enhanced. The improved injection of holes and electrons allows for a much wider range of accessible polymers for ambipolar and light-emitting transistors. The same conjugated polymers can also be used to enrich specific semiconducting SWNT and to produce high-performance ambipolar nanotube network FETs. These show efficient nearinfrared electroluminescence. Mapping the emission from these networks during a gate voltage sweep allows us to visualize preferential current paths and investigate percolation models for purely semiconducting nanotube networks.

  15. Silicon Field Effect Transistors as Dual-Use Sensor-Heater Hybrids

    PubMed Central

    Reddy, Bobby; Elibol, Oguz H.; Nair, Pradeep R.; Dorvel, Brian R.; Butler, Felice; Ahsan, Zahab; Bergstrom, Donald E.; Alam, Muhammad A.; Bashir, Rashid

    2011-01-01

    We demonstrate the temperature mediated applications of a previously proposed novel localized dielectric heating method on the surface of dual purpose silicon field effect transistor (FET) sensor-heaters and perform modeling and characterization of the underlying mechanisms. The FETs are first shown to operate as electrical sensors via sensitivity to changes in pH in ionic fluids. The same devices are then demonstrated as highly localized heaters via investigation of experimental heating profiles and comparison to simulation results. These results offer further insight into the heating mechanism and help determine the spatial resolution of the technique. Two important biosensor platform applications spanning different temperature ranges are then demonstrated: a localized heat-mediated DNA exchange reaction and a method for dense selective functionalization of probe molecules via the heat catalyzed complete desorption and reattachment of chemical functionalization to the transistor surfaces. Our results show that the use of silicon transistors can be extended beyond electrical switching and field-effect sensing to performing localized temperature controlled chemical reactions on the transistor itself. PMID:21214189

  16. Gate induced superconductivity in layered material based electronic double layer field effect transistors

    NASA Astrophysics Data System (ADS)

    Ye, J. T.; Inoue, S.; Kobayashi, K.; Kasahara, Y.; Yuan, H. T.; Shimotani, H.; Iwasa, Y.

    2010-12-01

    Applying the principle of field effect transistor to layered materials provides new opportunities to manipulate their electronic properties for interesting sciences and applications. Novel gate dielectrics like electronic double layer (EDL) formed by ionic liquids are demonstrated to achieve an electrostatic surface charge accumulation on the order of 1014 cm-2. To realize electric field-induced superconductivity, we chose a layered compound: ZrNCl, which is known to be superconducting by introducing electrons through intercalation of alkali metals into the van der Waals gaps. A ZrNCl-based EDL transistor was micro fabricated on a thin ZrNCl single crystal made by mechanical micro-cleavage. Accumulating charges using EDL gate dielectrics onto the channel surface of ZrNCl shows effective field effect modulation of its electronic properties. Sheet resistance of ZrNCl EDL transistor is reduced by applying a gate voltage from 0 to 4.5 V. Temperature dependence of sheet resistance showed clear evidence of metal-insulator transition upon gating, observed at a gate voltage higher than 3.5 V. Furthermore, gate-induced superconductivity took place after metal-insulator transition when the transistor is cooled down to about 15 K.

  17. Multifunctional Self-Assembled Monolayers for Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Cernetic, Nathan

    Organic field effect transistors (OFETs) have the potential to reach commercialization for a wide variety of applications such as active matrix display circuitry, chemical and biological sensing, radio-frequency identification devices and flexible electronics. In order to be commercially competitive with already at-market amorphous silicon devices, OFETs need to approach similar performance levels. Significant progress has been made in developing high performance organic semiconductors and dielectric materials. Additionally, a common route to improve the performance metric of OFETs is via interface modification at the critical dielectric/semiconductor and electrode/semiconductor interface which often play a significant role in charge transport properties. These metal oxide interfaces are typically modified with rationally designed multifunctional self-assembled monolayers. As means toward improving the performance metrics of OFETs, rationally designed multifunctional self-assembled monolayers are used to explore the relationship between surface energy, SAM order, and SAM dipole on OFET performance. The studies presented within are (1) development of a multifunctional SAM capable of simultaneously modifying dielectric and metal surface while maintaining compatibility with solution processed techniques (2) exploration of the relationship between SAM dipole and anchor group on graphene transistors, and (3) development of self-assembled monolayer field-effect transistor in which the traditional thick organic semiconductor is replaced by a rationally designed self-assembled monolayer semiconductor. The findings presented within represent advancement in the understanding of the influence of self-assembled monolayers on OFETs as well as progress towards rationally designed monolayer transistors.

  18. Silicon field effect transistors as dual-use sensor-heater hybrids.

    PubMed

    Reddy, Bobby; Elibol, Oguz H; Nair, Pradeep R; Dorvel, Brian R; Butler, Felice; Ahsan, Zahab; Bergstrom, Donald E; Alam, Muhammad A; Bashir, Rashid

    2011-02-01

    We demonstrate the temperature mediated applications of a previously proposed novel localized dielectric heating method on the surface of dual purpose silicon field effect transistor (FET) sensor-heaters and perform modeling and characterization of the underlying mechanisms. The FETs are first shown to operate as electrical sensors via sensitivity to changes in pH in ionic fluids. The same devices are then demonstrated as highly localized heaters via investigation of experimental heating profiles and comparison to simulation results. These results offer further insight into the heating mechanism and help determine the spatial resolution of the technique. Two important biosensor platform applications spanning different temperature ranges are then demonstrated: a localized heat-mediated DNA exchange reaction and a method for dense selective functionalization of probe molecules via the heat catalyzed complete desorption and reattachment of chemical functionalization to the transistor surfaces. Our results show that the use of silicon transistors can be extended beyond electrical switching and field-effect sensing to performing localized temperature controlled chemical reactions on the transistor itself. PMID:21214189

  19. Performance Enhancement of Black Phosphorus Field-Effect Transistors by Chemical Doping

    NASA Astrophysics Data System (ADS)

    Du, Yuchen; Yang, Lingming; Zhou, Hong; Ye, Peide D.

    2016-04-01

    In this letter, a new approach to chemically dope black phosphorus (BP) is presented, which significantly enhances the device performance of BP field-effect transistors for an initial period of 18 h, before degrading to previously reported levels. By applying 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), low ON-state resistance of 3.2 ohm.mm and high field-effect mobility of 229 cm2/Vs are achieved with a record high drain current of 532 mA/mm at a moderate channel length of 1.5 {\\mu}m.

  20. Graphene-based field effect transistors for radiation-induced field sensing

    NASA Astrophysics Data System (ADS)

    Di Gaspare, Alessandra; Valletta, Antonio; Fortunato, Guglielmo; Larciprete, Rosanna; Mariucci, Luigi; Notargiacomo, Andrea; Cimino, Roberto

    2016-07-01

    We propose the implementation of graphene-based field effect transistor (FET) as radiation sensor. In the proposed detector, graphene obtained via chemical vapor deposition is integrated into a Si-based field effect device as the gate readout electrode, able to sense any change in the field distribution induced by ionization in the underneath absorber, because of the strong variation in the graphene conductivity close to the charge neutrality point. Different 2-dimensional layered materials can be envisaged in this kind of device.

  1. Hydrogen-bonded semiconducting pigments for air-stable field-effect transistors.

    PubMed

    Głowacki, Eric Daniel; Irimia-Vladu, Mihai; Kaltenbrunner, Martin; Gsiorowski, Jacek; White, Matthew S; Monkowius, Uwe; Romanazzi, Giuseppe; Suranna, Gian Paolo; Mastrorilli, Piero; Sekitani, Tsuyoshi; Bauer, Siegfried; Someya, Takao; Torsi, Luisa; Sariciftci, Niyazi Serdar

    2013-03-20

    Extensive intramolecular π-conjugation is considered to be requisite in the design of organic semiconductors. Here, two inkjet pigments, epindolidione and quinacridone, that break this design rule are explored. These molecules afford intermolecular π-stacking reinforced by hydrogen-bonding bridges. Air-stable organic field effect transistors are reported that support mobilities up to 1.5 cm(2)/Vs with T80 lifetimes comparable with the most stable reported organic semiconducting materials. PMID:23239229

  2. Ultrathin MXene-Micropattern-Based Field-Effect Transistor for Probing Neural Activity.

    PubMed

    Xu, Bingzhe; Zhu, Minshen; Zhang, Wencong; Zhen, Xu; Pei, Zengxia; Xue, Qi; Zhi, Chunyi; Shi, Peng

    2016-05-01

    A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed and utilized as a highly sensitive biosensor. The device is produced with the microcontact printing technique, making use of its unique advantages for easy fabrication. Using the MXene-FET device, label-free probing of small molecules in typical biological environments and fast detection of action potentials in primary neurons is demonstrated. PMID:26924616

  3. 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.

  4. Interdigitated gate electrode field effect transistor for the selective detection of nitrogen dioxide and diisopropyl methylphosphonate

    SciTech Connect

    Kolesar, E.S. Jr.; Wiseman, J.M. )

    1989-11-01

    An interdigitated gate electrode field effect transistor (IGE-FET) coupled to an electron beam evaporated copper phthalocyanine thin film was used to selectively detect part-per-billion concentration levels of nitrogen dioxide (NO{sub 2}) and diisopropyl methylphosphonate (DIMP). The sensor is excited with a voltage pulse, and the time- and frequency-domain responses are measured. The envelopes of the magnitude of the normalized difference frequency spectrums reveal features that unambiguously distinguish NO{sub 2} and DIMP exposures.

  5. Highly transparent and stretchable field-effect transistor sensors using graphene-nanowire hybrid nanostructures.

    PubMed

    Kim, Joohee; Lee, Mi-Sun; Jeon, Sangbin; Kim, Minji; Kim, Sungwon; Kim, Kukjoo; Bien, Franklin; Hong, Sung You; Park, Jang-Ung

    2015-06-01

    Transparent and stretchable electronics with remarkable bendability, conformability, and lightness are the key attributes for sensing or wearable devices. Transparent and stretchable field-effect transistor sensors using graphene-metal nanowire hybrid nanostructures have high mobility (≈3000 cm(2) V(-1) s(-1) ) with low contact resistance, and they are transferrable onto a variety of substrates. The integration of these sensors for RLC circuits enables wireless monitoring. PMID:25885929

  6. Mobility Measurement Based on Visualized Electric Field Migration in Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Manaka, Takaaki; Liu, Fei; Weis, Martin; Iwamoto, Mitsumasa

    2009-06-01

    Based on the transient electric field migration directly probed by the time-resolved microscopic optical second-harmonic generation (TRM-SHG) technique, we developed a “dynamic” approach to evaluate the carrier mobility in organic field-effect transistor (OFET). The accuracy of this potential- and current-independent approach was well confirmed by computational simulations and a comparison with the conventional mobility measured by OFET transfer characteristics.

  7. Strained silicon modulation field-effect transistor as a new sensor of terahertz radiation

    NASA Astrophysics Data System (ADS)

    Moubarak Meziani, Yahya; Garcia, Enrique; Velazquez, Enrique; Diez, Enrique; El Moutaouakil, Amine; Otsuji, Taiichi; Fobelets, K.

    2011-10-01

    In this paper, we report on room temperature detection of terahertz radiation from strained-Si modulation-doped field-effect transistors. A non-resonant signal was observed with a maximum around the threshold voltage. The signal was interpreted due to the plasma wave nonlinearities in the channel. The intensity of the signal increases for the higher applied drain-to-source current. We also observed a dependence of the signal on the polarization of the incoming radiations.

  8. The hysteresis-free negative capacitance field effect transistors using non-linear poly capacitance

    NASA Astrophysics Data System (ADS)

    Fan, S.-T.; Yan, J.-Y.; Lai, D.-C.; Liu, C. W.

    2016-08-01

    A gate structure design for negative capacitance field effect transistors (NCFETs) is proposed. The hysteresis loop in current-voltage performances is eliminated by the nonlinear C-V dependence of polysilicon in the gate dielectrics. Design considerations and optimizations to achieve the low SS and hysteresis-free transfer were elaborated. The effects of gate-to-source/drain overlap, channel length scaling, interface trap states and temperature impact on SS are also investigated.

  9. Explicit drain current model of junctionless double-gate field-effect transistors

    NASA Astrophysics Data System (ADS)

    Yesayan, Ashkhen; Prégaldiny, Fabien; Sallese, Jean-Michel

    2013-11-01

    This paper presents an explicit drain current model for the junctionless double-gate metal-oxide-semiconductor field-effect transistor. Analytical relationships for the channel charge densities and for the drain current are derived as explicit functions of applied terminal voltages and structural parameters. The model is validated with 2D numerical simulations for a large range of channel thicknesses and is found to be very accurate for doping densities exceeding 1018 cm-3, which are actually used for such devices.

  10. Measuring bi-directional current through a field-effect transistor by virtue of drain-to-source voltage measurement

    DOEpatents

    Turner, Steven Richard

    2006-12-26

    A method and apparatus for measuring current, and particularly bi-directional current, in a field-effect transistor (FET) using drain-to-source voltage measurements. The drain-to-source voltage of the FET is measured and amplified. This signal is then compensated for variations in the temperature of the FET, which affects the impedance of the FET when it is switched on. The output is a signal representative of the direction of the flow of current through the field-effect transistor and the level of the current through the field-effect transistor. Preferably, the measurement only occurs when the FET is switched on.

  11. Fabrication of graphene field-effect transistor on top of ferroelectric single-crystal substrate

    NASA Astrophysics Data System (ADS)

    Park, Nahee; Kang, Haeyong; Lee, Yourack; Kim, Jeong-Gyun; Kim, Joong-Gyu; Yun, Yoojoo; Park, Jeongmin; Kim, Taesoo; Kim, Jung Ho; Jin, Youngjo; Shin, Yong Seon; Lee, Young Hee; Suh, Dongseok

    2015-03-01

    In the analysis of Graphene field-effect transistor, the substrate material which has the direct contact with Graphene layer plays an important in the device performance. In this presentation, we have tested PMN-PT(i.e.(1-x)Pb(Mg1/3Nb2/3) O3-xPbTiO3) substrate as a gate dielectric of Graphene field-effect transistor. Unlike the case of previously used substrates such as silicon oxide or hexagonal Boron-Nitride(h-BN), the PMN-PT substrate can induce giant amount of surface charge that is directly injected to the attached Graphene layer due to its ferroelectric property. And the hysteresis of polarization versus electric field of PMN-PT can cause the device to show the ferroelectric nonvolatile memory operation. We had successfully fabricated Graphene field-effect transistor using the mechanically exfoliated Graphene layer transferred on the PMN-PT(001) substrate. Unlike the case of mechanical exfoliation on the surface of silicon-oxide or the Poly(methyl methacrylate) (PMMA), the weak adhesion properties between graphene and PMNPT required the pretreatment on PMMA before the exfoliation process. The device performance is analyzed in terms of the effect of ferro- and piezo-electric effect of PMNPT substrate.

  12. Hydrothermally Processed Photosensitive Field-Effect Transistor Based on ZnO Nanorod Networks

    NASA Astrophysics Data System (ADS)

    Kumar, Ashish; Bhargava, Kshitij; Dixit, Tejendra; Palani, I. A.; Singh, Vipul

    2016-07-01

    Formation of a stable, reproducible zinc oxide (ZnO) nanorod-network-based photosensitive field-effect transistor using a hydrothermal process at low temperature has been demonstrated. K2Cr2O7 additive was used to improve adhesion and facilitate growth of the ZnO nanorod network over the SiO2/Si substrate. Transistor characteristics obtained in the dark resemble those of the n-channel-mode field-effect transistor (FET). The devices showed I on/I off ratio above 8 × 102 under dark condition, field-effect mobility of 4.49 cm2 V-1 s-1, and threshold voltage of -12 V. Further, under ultraviolet (UV) illumination, the FET exhibited sensitivity of 2.7 × 102 in off-state (-10 V) versus 1.4 in on-state (+9.7 V) of operation. FETs based on such nanorod networks showed good photoresponse, which is attributed to the large surface area of the nanorod network. The growth temperature for ZnO nanorod networks was kept at 110°C, enabling a low-temperature, cost-effective, simple approach for high-performance ZnO-based FETs for large-scale production. The role of network interfaces in the FET performance is also discussed.

  13. Measurement and Analysis of a Ferroelectric Field-Effect Transistor NAND Gate

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeond, Todd C.; Sayyah, Rana; Ho, Fat Duen

    2009-01-01

    Previous research investigated expanding the use of Ferroelectric Field-Effect Transistors (FFET) to other electronic devices beyond memory circuits. Ferroelectric based transistors possess unique characteris tics that give them interesting and useful properties in digital logic circuits. The NAND gate was chosen for investigation as it is one of the fundamental building blocks of digital electronic circuits. In t his paper, NAND gate circuits were constructed utilizing individual F FETs. N-channel FFETs with positive polarization were used for the standard CMOS NAND gate n-channel transistors and n-channel FFETs with n egative polarization were used for the standard CMOS NAND gate p-chan nel transistors. The voltage transfer curves were obtained for the NA ND gate. Comparisons were made between the actual device data and the previous modeled data. These results are compared to standard MOS logic circuits. The circuits analyzed are not intended to be fully opera tional circuits that would interface with existing logic circuits, bu t as a research tool to look into the possibility of using ferroelectric transistors in future logic circuits. Possible applications for th ese devices are presented, and their potential benefits and drawbacks are discussed.

  14. Metal-Ferroelectric-Semiconductor Field-Effect Transistor NAND Gate Switching Time Analysis

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; Macleod, Todd C.; Ho, Fat D.

    2006-01-01

    Previous research investigated the modeling of a N Wga te constructed of Metal-Ferroelectric- Semiconductor Field-Effect Transistors (MFSFETs) to obtain voltage transfer curves. The NAND gate was modeled using n-channel MFSFETs with positive polarization for the standard CMOS n-channel transistors and n-channel MFSFETs with negative polarization for the standard CMOS p-channel transistors. This paper investigates the MFSFET NAND gate switching time propagation delay, which is one of the other important parameters required to characterize the performance of a logic gate. Initially, the switching time of an inverter circuit was analyzed. The low-to-high and high-to-low propagation time delays were calculated. During the low-to-high transition, the negatively polarized transistor pulls up the output voltage, and during the high-to-low transition, the positively polarized transistor pulls down the output voltage. The MFSFETs were simulated by using a previously developed model which utilized a partitioned ferroelectric layer. Then the switching time of a 2-input NAND gate was analyzed similarly to the inverter gate. Extension of this technique to more complicated logic gates using MFSFETs will be studied.

  15. Towards the textile transistor: Assembly and characterization of an organic field effect transistor with a cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Maccioni, Maurizio; Orgiu, Emanuele; Cosseddu, Piero; Locci, Simone; Bonfiglio, Annalisa

    2006-10-01

    Cylindrical organic field effect transistors have been obtained starting from a metallic fiber used in textile processes. The metal core of the yarn, covered with a thin polyimide layer, is the gate of the structure. A top-contact device can be obtained by depositing a layer of organic semiconductor followed by the deposition of source and drain top contacts, made by metals or conductive polymers, deposited by evaporation or soft lithography. Thanks to the flexibility of the structure and the low cost of technologies, this device is a meaningful step towards innovative applications of textile electronics.

  16. Field-effect transistors based on few-layered α-MoTe(2).

    PubMed

    Pradhan, Nihar R; Rhodes, Daniel; Feng, Simin; Xin, Yan; Memaran, Shahriar; Moon, Byoung-Hee; Terrones, Humberto; Terrones, Mauricio; Balicas, Luis

    2014-06-24

    Here we report the properties of field-effect transistors based on a few layers of chemical vapor transport grown α-MoTe2 crystals mechanically exfoliated onto SiO2. We performed field-effect and Hall mobility measurements, as well as Raman scattering and transmission electron microscopy. In contrast to both MoS2 and MoSe2, our MoTe2 field-effect transistors are observed to be hole-doped, displaying on/off ratios surpassing 10(6) and typical subthreshold swings of ∼140 mV per decade. Both field-effect and Hall mobilities indicate maximum values approaching or surpassing 10 cm(2)/(V s), which are comparable to figures previously reported for single or bilayered MoS2 and/or for MoSe2 exfoliated onto SiO2 at room temperature and without the use of dielectric engineering. Raman scattering reveals sharp modes in agreement with previous reports, whose frequencies are found to display little or no dependence on the number of layers. Given that MoS2 is electron-doped, the stacking of MoTe2 onto MoS2 could produce ambipolar field-effect transistors and a gap modulation. Although the overall electronic performance of MoTe2 is comparable to those of MoS2 and MoSe2, the heavier element Te leads to a stronger spin-orbit coupling and possibly to concomitantly longer decoherence times for exciton valley and spin indexes. PMID:24878323

  17. Nature of size effects in compact models of field effect transistors

    NASA Astrophysics Data System (ADS)

    Torkhov, N. A.; Babak, L. I.; Kokolov, A. A.; Salnikov, A. S.; Dobush, I. M.; Novikov, V. A.; Ivonin, I. V.

    2016-03-01

    Investigations have shown that in the local approximation (for sizes L < 100 μm), AlGaN/GaN high electron mobility transistor (HEMT) structures satisfy to all properties of chaotic systems and can be described in the language of fractal geometry of fractional dimensions. For such objects, values of their electrophysical characteristics depend on the linear sizes of the examined regions, which explain the presence of the so-called size effects—dependences of the electrophysical and instrumental characteristics on the linear sizes of the active elements of semiconductor devices. In the present work, a relationship has been established for the linear model parameters of the equivalent circuit elements of internal transistors with fractal geometry of the heteroepitaxial structure manifested through a dependence of its relative electrophysical characteristics on the linear sizes of the examined surface areas. For the HEMTs, this implies dependences of their relative static (A/mm, mA/V/mm, Ω/mm, etc.) and microwave characteristics (W/mm) on the width d of the sink-source channel and on the number of sections n that leads to a nonlinear dependence of the retrieved parameter values of equivalent circuit elements of linear internal transistor models on n and d. Thus, it has been demonstrated that the size effects in semiconductors determined by the fractal geometry must be taken into account when investigating the properties of semiconductor objects on the levels less than the local approximation limit and designing and manufacturing field effect transistors. In general, the suggested approach allows a complex of problems to be solved on designing, optimizing, and retrieving the parameters of equivalent circuits of linear and nonlinear models of not only field effect transistors but also any arbitrary semiconductor devices with nonlinear instrumental characteristics.

  18. Recent Progress in Obtaining Semiconducting Single-Walled Carbon Nanotubes for Transistor Applications.

    PubMed

    Islam, Ahmad E; Rogers, John A; Alam, Muhammad A

    2015-12-22

    High purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with a narrow diameter distribution are required for high-performance transistors. Achieving this goal is extremely challenging because the as-grown material contains mixtures of s-SWCNTs and metallic- (m-) SWCNTs with wide diameter distributions, typically inadequate for integrated circuits. Since 2000, numerous ex situ methods have been proposed to improve the purity of the s-SWCNTs. The majority of these techniques fail to maintain the quality and integrity of the s-SWCNTs with a few notable exceptions. Here, the progress in realizing high purity s-SWCNTs in as-grown and post-processed materials is highlighted. A comparison of transistor parameters (such as on/off ratio and field-effect mobility) obtained from test structures establishes the effectiveness of various methods and suggests opportunities for future improvements. PMID:26540144

  19. 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.

  20. A 0.5-V Six-Transistor Static Random Access Memory with Ferroelectric-Gate Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Tanakamaru, Shuhei; Hatanaka, Teruyoshi; Yajima, Ryoji; Miyaji, Kousuke; Takahashi, Mitsue; Sakai, Shigeki; Takeuchi, Ken

    2010-12-01

    A 0.5 V six-transistor static random access memory (6T-SRAM) with ferroelectric-gate field-effect-transistors (Fe-FETs) is proposed and experimentally demonstrated for the first time. During the read and the hold, the threshold voltage (VTH) of Fe-FETs automatically changes to increase the static noise margin (SNM) by 60%. During the stand-by, the VTH of the proposed SRAM cell increases to decrease the leakage current by 42%. In case of the read, the VTH of the read transistor decreases and increases the cell read current to achieve the fast read. During the write, the VTH of the SRAM cell dynamically changes and assist the cell data to flip, realizing a write assist function. The enlarged SNM realizes the VDD reduction by 0.11 V, which decreases the active power by 32%. The proposed SRAM layout is the same as the conventional 6T-SRAM and there is no area penalty.

  1. Characterization of Field Effect Transistor Biosensors Fabricated Using Layer-by-Layer Nanoassembly Process.

    PubMed

    Pathak, Pushparaj; Que, Long

    2015-12-01

    In order to avoid the fabrication complexity involved with a single carbon nanotube (CNT) based immunosensor, herein we report an FET based biosensor, in which the channel is made out of Carbon Nanotube Thin Film (CNTF). The CNTF channel between the source and drain electrodes is assembled using a combination of photolithography and electrostatic layer-by-layer self-assembly (LbL). The fabricated device behaves like a p-type transistor. The bio-affinity interaction between Protein A and rabbit Immunoglobulin G (IgG) is used to model the immunosensing, and our initial results show the device is capable of detecting IgG concentrations as low as 1 pg/mL. PMID:26682397

  2. 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.

  3. Low dielectric constant-based organic field-effect transistors and metal-insulator-semiconductor capacitors

    NASA Astrophysics Data System (ADS)

    Ukah, Ndubuisi Benjamin

    This thesis describes a study of PFB and pentacene-based organic field-effect transistors (OFET) and metal-insulator-semiconductor (MIS) capacitors with low dielectric constant (k) poly(methyl methacrylate) (PMMA), poly(4-vinyl phenol) (PVP) and cross-linked PVP (c-PVP) gate dielectrics. A physical method -- matrix assisted pulsed laser evaporation (MAPLE) -- of fabricating all-polymer field-effect transistors and MIS capacitors that circumvents inherent polymer dissolution and solvent-selectivity problems, is demonstrated. Pentacene-based OFETs incorporating PMMA and PVP gate dielectrics usually have high operating voltages related to the thickness of the dielectric layer. Reduced PMMA layer thickness (≤ 70 nm) was obtained by dissolving the PMMA in propylene carbonate (PC). The resulting pentacene-based transistors exhibited very low operating voltage (below -3 V), minimal hysteresis in their transfer characteristics, and decent electrical performance. Also low voltage (within -2 V) operation using thin (≤ 80 nm) low-k and hydrophilic PVP and c-PVP dielectric layers obtained via dissolution in high dipole moment and high-k solvents -- PC and dimethyl sulfoxide (DMSO), is demonstrated to be a robust means of achieving improved electrical characteristics and high operational stability in OFETs incorporating PVP and c-PVP dielectrics.

  4. Suspended InAs nanowire gate-all-around field-effect transistors

    SciTech Connect

    Li, Qiang; Huang, Shaoyun E-mail: hqxu@pku.edu.cn; Wang, Jingyun; Pan, Dong; Zhao, Jianhua; Xu, H. Q. E-mail: hqxu@pku.edu.cn

    2014-09-15

    Gate-all-around field-effect transistors are realized with thin, single-crystalline, pure-phase InAs nanowires grown by molecular beam epitaxy. At room temperature, the transistors show a desired high on-state current I{sub on} of ∼10 μA and an on-off current ratio I{sub on}/I{sub off} of as high as 10{sup 6} at source-drain bias voltage of 50 mV and gate length of 1 μm with a gate underlap spacing of 1 μm from the source and from the drain. At low temperatures, the on-state current I{sub on} is only slightly reduced, while the ratio I{sub on}/I{sub off} is increased to 10{sup 7}. The field-effect mobility in the nanowire channels is also investigated and found to be ∼1500 cm{sup 2}/V s at room temperature and ∼2000 cm{sup 2}/V s at low temperatures. The excellent performance of the transistors is explained in terms of strong electrostatic and quantum confinements of carriers in the nanowires.

  5. Mobility overestimation due to gated contacts in organic field-effect transistors

    PubMed Central

    Bittle, Emily G.; Basham, James I.; Jackson, Thomas N.; Jurchescu, Oana D.; Gundlach, David J.

    2016-01-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current–voltage characteristics and interpreted by using the classical metal oxide–semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm2 V−1 s−1), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current–voltage characterization are overestimated by one order of magnitude or more. PMID:26961271

  6. Mobility overestimation due to gated contacts in organic field-effect transistors.

    PubMed

    Bittle, Emily G; Basham, James I; Jackson, Thomas N; Jurchescu, Oana D; Gundlach, David J

    2016-01-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current-voltage characteristics and interpreted by using the classical metal oxide-semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm(2) V(-1) s(-1)), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current-voltage characterization are overestimated by one order of magnitude or more. PMID:26961271

  7. Mobility overestimation due to gated contacts in organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Bittle, Emily G.; Basham, James I.; Jackson, Thomas N.; Jurchescu, Oana D.; Gundlach, David J.

    2016-03-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current-voltage characteristics and interpreted by using the classical metal oxide-semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm2 V-1 s-1), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current-voltage characterization are overestimated by one order of magnitude or more.

  8. Highly sensitive protein detection using a plasmonic field effect transistor (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shokri-Kojori, Hossein; Ji, Yiwen; Han, Xu; Paik, Younghun; Braunschweig, Adam; Kim, Sung Jin

    2016-03-01

    Localized surface Plasmon Resonance (LSPR) is a nanoscale phenomenon which presents strong resonance associated with noble metal nanostructures. This plasmon resonance based technology enables highly sensitive detection for chemical and biological applications. Recently, we have developed a plasmon field effect transistor (FET) that enables direct plasmonic-to-electric signal conversion with signal amplification. The plasmon FET consists of back-gated field effect transistor incorporated with gold nanoparticles on top of the FET channel. The gold nanostructures are physically separated from transistor electrodes and can be functionalized for a specific biological application. In this presentation, we report a successful demonstration of a model system to detect Con A proteins using Carbohydrate linkers as a capture molecule. The plasmon FET detected a very low concentration of Con A (0.006 mg/L) while it offers a wide dynamic range of 0.006-50 mg/L. In this demonstration, we used two-color light sources instead of a bulky spectrometer to achieve high sensitivity and wide dynamic range. The details of two-color based differential measurement method will be discussed. This novel protein-based sensor has several advantages such as extremely small size for point-of-care system, multiplexing capability, no need of complex optical geometry.

  9. Modeling of a Metal-Ferroelectric-Semiconductor Field-Effect Transistor NAND Gate

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat Duen

    2005-01-01

    Considerable research has been performed by several organizations in the use of the Metal- Ferroelectric-Semiconductor Field-Effect Transistors (MFSFET) in memory circuits. However, research has been limited in expanding the use of the MFSFET to other electronic circuits. This research project investigates the modeling of a NAND gate constructed from MFSFETs. The NAND gate is one of the fundamental building blocks of digital electronic circuits. The first step in forming a NAND gate is to develop an inverter circuit. The inverter circuit was modeled similar to a standard CMOS inverter. A n-channel MFSFET with positive polarization was used for the n-channel transistor, and a n-channel MFSFET with negative polarization was used for the p-channel transistor. The MFSFETs were simulated by using a previously developed current model which utilized a partitioned ferroelectric layer. The inverter voltage transfer curve was obtained over a standard input of zero to five volts. Then a 2-input NAND gate was modeled similar to the inverter circuit. Voltage transfer curves were obtained for the NAND gate for various configurations of input voltages. The resultant data shows that it is feasible to construct a NAND gate with MFSFET transistors.

  10. Labelfree fully electronic nucleic acid detection system based on a field-effect transistor device.

    PubMed

    Uslu, F; Ingebrandt, S; Mayer, D; Böcker-Meffert, S; Odenthal, M; Offenhäusser, A

    2004-07-15

    The labelfree detection of nucleic acid sequences is one of the modern attempts to develop quick, cheap and miniaturised hand-held devices for the future genetic testing in biotechnology and medical diagnostics. We present an approach to detect the hybridisation of DNA sequences using electrolyte-oxide-semiconductor field-effect transistors (EOSFETs) with micrometer dimensions. These semiconductor devices are sensitive to electrical charge variations that occur at the surface/electrolyte interface, i.e. upon hybridisation of oligonucleotides with complementary single-stranded (ss) oligonucleotides, which are immobilised on the oxide surface of the transistor gate. This method allows direct, time-resolved and in situ detection of specific nucleic acid binding events without any labelling. We focus on the detection mechanism of our sensors by using oppositely charged polyelectrolytes (PAH and PSS) subsequently attached to the transistor structures. Our results indicate that the sensor output is charge sensitive and distance dependent from the gate surface, which pinpoints the need for very defined surface chemistry at the device surface. The hybridisation of natural 19 base-pair sequences has been successfully detected with the sensors. In combination with nano-transistors a PCR free detection system might be feasible in future. PMID:15142607

  11. Low-voltage p- and n-type organic self-assembled monolayer field effect transistors.

    PubMed

    Novak, Michael; Ebel, Alexander; Meyer-Friedrichsen, Timo; Jedaa, Abdesselam; Vieweg, Benito F; Yang, Guang; Voitchovsky, Kislon; Stellacci, Francesco; Spiecker, Erdmann; Hirsch, Andreas; Halik, Marcus

    2011-01-12

    We report on p- and n-type organic self-assembled monolayer field effect transistors. On the base of quaterthiophene and fullerene units, multifunctional molecules were synthesized, which have the ability to self-assemble and provide multifunctional monolayers. The self-assembly approach, based on phosphonic acids, is very robust and allows the fabrication of functional devices even on larger areas. The p- and n-type transistor devices with only one molecular active layer were demonstrated for transistor channel lengths up to 10 μm. The monolayer composition is proven by electrical experiments and by high-resolution transmission electron microscopy, electron energy loss spectroscopy, XPS, and AFM experiments. Because of the molecular design and the contribution of isolating alkyl chains to the hybrid dielectric, our devices operate at low supply voltages (-4 V to +4 V), which is a key requirement for practical use and simplifies the integration in standard applications. The monolayer devices operate in ambient air and show hole and electron mobilities of 10(-5) cm(2)/(V s) and 10(-4) cm(2)/(V s) respectively. In particular the n-type operation of self-assembled monolayer transistors has not been reported before. Hereby, structure-property relations of the SAMs have been studied. Furthermore an approach to protect the sensitive C(60) from immediate degradation within the molecular design is provided. PMID:21133354

  12. N-Channel field-effect transistors with floating gates for extracellular recordings.

    PubMed

    Meyburg, Sven; Goryll, Michael; Moers, Jürgen; Ingebrandt, Sven; Böcker-Meffert, Simone; Lüth, Hans; Offenhäusser, Andreas

    2006-01-15

    A field-effect transistor (FET) for recording extracellular signals from electrogenic cells is presented. The so-called floating gate architecture combines a complementary metal oxide semiconductor (CMOS)-type n-channel transistor with an independent sensing area. This concept allows the transistor and sensing area to be optimised separately. The devices are robust and can be reused several times. The noise level of the devices was smaller than of comparable non-metallised gate FETs. In addition to the usual drift of FET devices, we observed a long-term drift that has to be controlled for future long-term measurements. The device performance for extracellular signal recording was tested using embryonic rat cardiac myocytes cultured on fibronectin-coated chips. The extracellular cell signals were recorded before and after the addition of the cardioactive isoproterenol. The signal shapes of the measured action potentials were comparable to the non-metallised gate FETs previously used in similar experiments. The fabrication of the devices involved the process steps of standard CMOS that were necessary to create n-channel transistors. The implementation of a complete CMOS process would facilitate the integration of the logical circuits necessary for signal pre-processing on a chip, which is a prerequisite for a greater number of sensor spots in future layouts. PMID:16029948

  13. Photocurrent microscopy of contact resistance and charge carrier traps in organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Liewald, C.; Reiser, D.; Westermeier, C.; Nickel, B.

    2016-08-01

    We use a pentacene transistor with asymmetric source drain contacts to test the sensitivity of scanning photocurrent microscopy (SPCM) for contact resistance and charge traps. The drain current of the device strongly depends on the choice of the drain electrode. In one case, more than 94% of the source drain voltage is lost due to contact resistance. Here, SPCM maps show an enhanced photocurrent signal at the hole-injecting contact. For the other bias condition, i.e., for ohmic contacts, the SPCM signal peaks heterogeneously along the channel. We argue from basic transport models that bright areas in SPCM maps indicate areas of large voltage gradients or high electric field strength caused by injection barriers or traps. Thus, SPCM allows us to identify and image the dominant voltage loss mechanism in organic field-effect transistors.

  14. Polymer-free graphene transfer for enhanced reliability of graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Park, Hamin; Park, Ick-Joon; Yool Jung, Dae; Lee, Khang June; Yang, Sang Yoon; Choi, Sung-Yool

    2016-06-01

    We propose a polymer-free graphene transfer technique for chemical vapor deposition-grown graphene to ensure the intrinsic electrical properties of graphene for reliable transistor applications. The use of a metal catalyst as a supporting layer avoids contamination from the polymer material and graphene films become free of polymer residue after the transfer process. Atomic force microscopy and Raman spectroscopy indicate that the polymer-free transferred graphene shows closer properties to intrinsic graphene properties. The reliability of graphene field-effect transistors (GFETs) was investigated through the analysis of the negative gate bias-stress-induced instability. This work reveals the effect of polymer residues on the reliability of GFETs, and that the developed new polymer-free transfer method enhances the reliability.

  15. High performance MoS2-based field-effect transistor enabled by hydrazine doping

    NASA Astrophysics Data System (ADS)

    Lim, Dongsuk; Kannan, E. S.; Lee, Inyeal; Rathi, Servin; Li, Lijun; Lee, Yoontae; Atif Khan, Muhammad; Kang, Moonshik; Park, Jinwoo; Kim, Gil-Ho

    2016-06-01

    We investigated the n-type doping effect of hydrazine on the electrical characteristics of a molybdenum disulphide (MoS2)-based field-effect transistor (FET). The threshold voltage of the MoS2 FET shifted towards more negative values (from ‑20 to ‑70 V) on treating with 100% hydrazine solution with the channel current increasing from 0.5 to 25 μA at zero gate bias. The inverse subthreshold slope decreased sharply on doping, while the ON/OFF ratio increased by a factor of 100. Gate–channel coupling improved with doping, which facilitates the reduction of channel length between the source and drain electrodes without compromising on the transistor performance, making the MoS2-based FET easily scalable.

  16. Self-aligned, full solution process polymer field-effect transistor on flexible substrates

    NASA Astrophysics Data System (ADS)

    Yan, Yan; Huang, Long-Biao; Zhou, Ye; Han, Su-Ting; Zhou, Li; Zhuang, Jiaqing; Xu, Zong-Xiang; Roy, V. A. L.

    2015-10-01

    Conventional techniques to form selective surface energy regions on rigid inorganic substrates are not suitable for polymer interfaces due to sensitive and soft limitation of intrinsic polymer properties. Therefore, there is a strong demand for finding a novel and compatible method for polymeric surface energy modification. Here, by employing the confined photo-catalytic oxidation method, we successfully demonstrate full polymer filed-effect transistors fabricated through four-step spin-coating process on a flexible polymer substrate. The approach shows negligible etching effect on polymeric film. Even more, the insulating property of polymeric dielectric is not affected by the method, which is vital for polymer electronics. Finally, the self-aligned full polymer field-effect transistors on the flexible polymeric substrate are fabricated, showing good electrical properties and mechanical flexibility under bending tests.

  17. Highly end-doped silicon nanowires for field-effect transistors on flexible substrates

    NASA Astrophysics Data System (ADS)

    Celle, Caroline; Carella, Alexandre; Mariolle, Denis; Chevalier, Nicolas; Rouvière, Emmanuelle; Simonato, Jean-Pierre

    2010-05-01

    We report on the VLS (vapour-liquid-solid) fabrication and characterization of in situ axially doped silicon nanowires (SiNWs) at both ends, and on their integration into a bottom gate-top contact geometry on both rigid and flexible substrates to realize field-effect transistors (FETs). To improve contact resistance between SiNWs and source/drain electrodes, we axially tuned the level of doping at both ends of the SiNWs by sequential in situ addition of PH3. Characterisation of SiNWs by scanning spreading resistance microscopy in the device configuration allowed us to determine precisely the different sections of the SiNWs. The transfer to flexible substrates still allowed for workable FET structures. Transistors with electron mobilities exceeding 120 cm2 V-1 s-1, Ion/Ioff ratios greater than 107 and ambipolar behaviour were achieved.

  18. Chemical Vapour Deposition Graphene Radio-Frequency Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Ma, Peng; Jin, Zhi; Guo, Jian-Nan; Pan, Hong-Liang; Liu, Xin-Yu; Ye, Tian-Chun; Wang, Hong; Wang, Guan-Zhong

    2012-05-01

    We report the dc and rf performance of graphene rf field-effect transistors, where the graphene films are grown on copper by using the chemical vapour deposition (CVD) method and transferred to SiO2/Si substrates. Composite materials, benzocyclobutene and atomic layer deposition Al2O3 are used as the gate dielectrics. The observation of n- and p-type transitions verifies the ambipolar characteristics in the graphene layers. While the intrinsic carrier mobility of CVD graphene is extracted to be 1200 cm2/V·s, the parasitic series resistances are demonstrated to have a serious impact on device performance. With a gate length of 1 μm and an extrinsic transconductance of 72 mS/mm, a cutoff frequency of 6.6 GHz and a maximum oscillation frequency of 8.8 GHz are measured for the transistors, illustrating the potential of the CVD graphene for rf applications.

  19. 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.

  20. Self-aligned, full solution process polymer field-effect transistor on flexible substrates

    PubMed Central

    Yan, Yan; Huang, Long-Biao; Zhou, Ye; Han, Su-Ting; Zhou, Li; Zhuang, Jiaqing; Xu, Zong-Xiang; Roy, V. A. L.

    2015-01-01

    Conventional techniques to form selective surface energy regions on rigid inorganic substrates are not suitable for polymer interfaces due to sensitive and soft limitation of intrinsic polymer properties. Therefore, there is a strong demand for finding a novel and compatible method for polymeric surface energy modification. Here, by employing the confined photo-catalytic oxidation method, we successfully demonstrate full polymer filed-effect transistors fabricated through four-step spin-coating process on a flexible polymer substrate. The approach shows negligible etching effect on polymeric film. Even more, the insulating property of polymeric dielectric is not affected by the method, which is vital for polymer electronics. Finally, the self-aligned full polymer field-effect transistors on the flexible polymeric substrate are fabricated, showing good electrical properties and mechanical flexibility under bending tests. PMID:26497412

  1. A novel Tunneling Graphene Nano Ribbon Field Effect Transistor with dual material gate: Numerical studies

    NASA Astrophysics Data System (ADS)

    Ghoreishi, Seyed Saleh; Saghafi, Kamyar; Yousefi, Reza; Moravvej-farshi, Mohammad Kazem

    2016-09-01

    In this work, we present Dual Material Gate Tunneling Graphene Nano-Ribbon Field Effect Transistors (DMG-T-GNRFET) mainly to suppress the am-bipolar current with assumption that sub-threshold swing which is one of the important characteristics of tunneling transistors must not be degraded. In the proposed structure, dual material gates with different work functions are used. Our investigations are based on numerical simulations which self-consistently solves the 2D Poisson based on an atomistic mode-space approach and Schrodinger equations, within the Non-Equilibrium Green's (NEGF). The proposed device shows lower off-current and on-off ratio becomes 5order of magnitude greater than the conventional device. Also two different short channel effects: Drain Induced Barrier Shortening (DIBS) and hot-electron effect are improved in the proposed device compare to the main structure.

  2. Exciton dissociation in polymer field-effect transistors studied using terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Lloyd-Hughes, J.; Richards, T.; Sirringhaus, H.; Johnston, M. B.; Herz, L. M.

    2008-03-01

    We have used terahertz time-domain spectroscopy to investigate photoinduced charge generation in conjugated polymer field-effect transistors. Our measurements show that excitons dissociate in the accumulation layer under the application of a gate voltage, with a quantum efficiency of ˜0.1 for an average gate field of ˜1×108Vm-1 . The transistor history is found to affect the exciton dissociation efficiency, which decreases as holes are increasingly trapped in the accumulation layer. The quantum efficiency of charge formation from excitons is compared with the two contrasting models proposed by Onsager and Arkhipov based on the assumption that field-induced exciton dissociation is assisted by the Brownian diffusive motion or an initial excess energy supplied by excited vibrational modes, respectively.

  3. Effect of Temperature on GaGdO/GaN Metal Oxide Semiconductor Field Effect Transistors

    SciTech Connect

    Abernathy, C.R.; Baca, A.; Chu, S.N.G.; Hong, M.; Lothian, J.R.; Marcus, M.A.; Pearton, S.J.; Ren, F.; Schurman, M.J.

    1998-10-14

    GaGdO was deposited on GaN for use as a gate dielectric in order to fabricate a depletion metal oxide semiconductor field effect transistor (MOSFET). This is the fmt demonstration of such a device in the III-Nitride system. Analysis of the effect of temperature on the device shows that gate leakage is significantly reduced at elevated temperature relative to a conventional metal semiconductor field effeet transistor (MESFET) fabricated on the same GaN layer. MOSFET device operation in fact improved upon heating to 400 C. Modeling of the effeet of temperature on contact resistance suggests that the improvement is due to a reduction in the parasitic resistances present in the device.

  4. High performance MoS2-based field-effect transistor enabled by hydrazine doping.

    PubMed

    Lim, Dongsuk; Kannan, E S; Lee, Inyeal; Rathi, Servin; Li, Lijun; Lee, Yoontae; Khan, Muhammad Atif; Kang, Moonshik; Park, Jinwoo; Kim, Gil-Ho

    2016-06-01

    We investigated the n-type doping effect of hydrazine on the electrical characteristics of a molybdenum disulphide (MoS2)-based field-effect transistor (FET). The threshold voltage of the MoS2 FET shifted towards more negative values (from -20 to -70 V) on treating with 100% hydrazine solution with the channel current increasing from 0.5 to 25 μA at zero gate bias. The inverse subthreshold slope decreased sharply on doping, while the ON/OFF ratio increased by a factor of 100. Gate-channel coupling improved with doping, which facilitates the reduction of channel length between the source and drain electrodes without compromising on the transistor performance, making the MoS2-based FET easily scalable. PMID:27098430

  5. Studies on different configurations of cobalt phthalocyanine based flexible organic field effect transistor

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Jha, P.; Samanta, S.; Singh, A.; Debnath, A. K.; Aswal, D. K.; Gupta, S. K.

    2016-05-01

    Organic Field Effect Transistors (OFETs) are being investigated for a number of low-cost, large area applications; particularly those that are compatible with flexible plastic substrates. Development of low temperature processes can make way for OFETs to be integrated on flexible plastic substrates. Here we have made systematic studies on OFETs in different configurations wherein we have chosen Cobalt Phthalocyanine (CoPc) as active material. We have found the best mobility (1.86 × 10-5 cm2/V-s) in Bottom Gate Top Contact configuration. However, threshold voltage (-5V) and On off ratio (62)were found to be better in Top Gate Bottom Contact configuration The electromechanical properties of the Bottom Gate Top Contact transistors were studied by measuring the transfer characteristics of the devices in bend condition and thereby calculating mobility under different radii of bending. No significant change in the mobility of the device was observed under bent conditions.

  6. 25th Anniversary Article: Organic Field-Effect Transistors: The Path Beyond Amorphous Silicon

    PubMed Central

    Sirringhaus, Henning

    2014-01-01

    Over the past 25 years, organic field-effect transistors (OFETs) have witnessed impressive improvements in materials performance by 3–4 orders of magnitude, and many of the key materials discoveries have been published in Advanced Materials. This includes some of the most recent demonstrations of organic field-effect transistors with performance that clearly exceeds that of benchmark amorphous silicon-based devices. In this article, state-of-the-art in OFETs are reviewed in light of requirements for demanding future applications, in particular active-matrix addressing for flexible organic light-emitting diode (OLED) displays. An overview is provided over both small molecule and conjugated polymer materials for which field-effect mobilities exceeding > 1 cm2 V–1 s–1 have been reported. Current understanding is also reviewed of their charge transport physics that allows reaching such unexpectedly high mobilities in these weakly van der Waals bonded and structurally comparatively disordered materials with a view towards understanding the potential for further improvement in performance in the future. PMID:24443057

  7. Imaging dissipation and hot spots in carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Estrada, David; Pop, Eric

    2011-02-01

    We use infrared thermometry of carbon nanotube network (CNN) transistors and find the formation of distinct hot spots during operation. However, the average CNN temperature at breakdown is significantly lower than expected from the breakdown of individual nanotubes, suggesting extremely high regions of power dissipation at the CNN junctions. Statistical analysis and comparison with a thermal model allow the estimate of an upper limit for the average tube-tube junction thermal resistance, ˜4.4×1011 K/W (thermal conductance of ˜2.27 pW/K). These results indicate that nanotube junctions have a much greater impact on CNN transport, dissipation, and reliability than extrinsic factors such as low substrate thermal conductivity.

  8. Operation of SOI P-Channel Field Effect Transistors, CHT-PMOS30, under Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2009-01-01

    Electronic systems are required to operate under extreme temperatures in NASA planetary exploration and deep space missions. Electronics on-board spacecraft must also tolerate thermal cycling between extreme temperatures. Thermal management means are usually included in today s spacecraft systems to provide adequate temperature for proper operation of the electronics. These measures, which may include heating elements, heat pipes, radiators, etc., however add to the complexity in the design of the system, increases its cost and weight, and affects its performance and reliability. Electronic parts and circuits capable of withstanding and operating under extreme temperatures would reflect in improvement in system s efficiency, reducing cost, and improving overall reliability. Semiconductor chips based on silicon-on-insulator (SOI) technology are designed mainly for high temperature applications and find extensive use in terrestrial well-logging fields. Their inherent design offers advantages over silicon devices in terms of reduced leakage currents, less power consumption, faster switching speeds, and good radiation tolerance. Little is known, however, about their performance at cryogenic temperatures and under wide thermal swings. Experimental investigation on the operation of SOI, N-channel field effect transistors under wide temperature range was reported earlier [1]. This work examines the performance of P-channel devices of these SOI transistors. The electronic part investigated in this work comprised of a Cissoid s CHT-PMOS30, high temperature P-channel MOSFET (metal-oxide semiconductor field-effect transistor) device [2]. This high voltage, medium-power transistor is designed for geothermal well logging applications, aerospace and avionics, and automotive industry, and is specified for operation in the temperature range of -55 C to +225 C. Table I shows some specifications of this transistor [2]. The CHT-PMOS30 device was characterized at various temperatures

  9. Combining axial and radial nanowire heterostructures: radial Esaki diodes and tunnel field-effect transistors.

    PubMed

    Dey, Anil W; Svensson, Johannes; Ek, Martin; Lind, Erik; Thelander, Claes; Wernersson, Lars-Erik

    2013-01-01

    The ever-growing demand on high-performance electronics has generated transistors with very impressive figures of merit (Radosavljevic et al., IEEE Int. Devices Meeting 2009, 1-4 and Cho et al., IEEE Int. Devices Meeting 2011, 15.1.1-15.1.4). The continued scaling of the supply voltage of field-effect transistors, such as tunnel field-effect transistors (TFETs), requires the implementation of advanced transistor architectures including FinFETs and nanowire devices. Moreover, integration of novel materials with high electron mobilities, such as III-V semiconductors and graphene, are also being considered to further enhance the device properties (del Alamo, Nature 2011, 479, 317-323, and Liao et al., Nature 2010, 467, 305-308). In nanowire devices, boosting the drive current at a fixed supply voltage or maintaining a constant drive current at a reduced supply voltage may be achieved by increasing the cross-sectional area of a device, however at the cost of deteriorated electrostatics. A gate-all-around nanowire device architecture is the most favorable electrostatic configuration to suppress short channel effects; however, the arrangement of arrays of parallel vertical nanowires to address the drive current predicament will require additional chip area. The use of a core-shell nanowire with a radial heterojunction in a transistor architecture provides an attractive means to address the drive current issue without compromising neither chip area nor device electrostatics. In addition to design advantages of a radial transistor architecture, we in this work illustrate the benefit in terms of drive current per unit chip area and compare the experimental data for axial GaSb/InAs Esaki diodes and TFETs to their radial counterparts and normalize the electrical data to the largest cross-sectional area of the nanowire, i.e. the occupied chip area, assuming a vertical device geometry. Our data on lateral devices show that radial Esaki diodes deliver almost 7 times higher peak

  10. A subthermionic tunnel field-effect transistor with an atomically thin channel

    NASA Astrophysics Data System (ADS)

    Sarkar, Deblina; Xie, Xuejun; Liu, Wei; Cao, Wei; Kang, Jiahao; Gong, Yongji; Kraemer, Stephan; Ajayan, Pulickel M.; Banerjee, Kaustav

    2015-10-01

    The fast growth of information technology has been sustained by continuous scaling down of the silicon-based metal-oxide field-effect transistor. However, such technology faces two major challenges to further scaling. First, the device electrostatics (the ability of the transistor's gate electrode to control its channel potential) are degraded when the channel length is decreased, using conventional bulk materials such as silicon as the channel. Recently, two-dimensional semiconducting materials have emerged as promising candidates to replace silicon, as they can maintain excellent device electrostatics even at much reduced channel lengths. The second, more severe, challenge is that the supply voltage can no longer be scaled down by the same factor as the transistor dimensions because of the fundamental thermionic limitation of the steepness of turn-on characteristics, or subthreshold swing. To enable scaling to continue without a power penalty, a different transistor mechanism is required to obtain subthermionic subthreshold swing, such as band-to-band tunnelling. Here we demonstrate band-to-band tunnel field-effect transistors (tunnel-FETs), based on a two-dimensional semiconductor, that exhibit steep turn-on; subthreshold swing is a minimum of 3.9 millivolts per decade and an average of 31.1 millivolts per decade for four decades of drain current at room temperature. By using highly doped germanium as the source and atomically thin molybdenum disulfide as the channel, a vertical heterostructure is built with excellent electrostatics, a strain-free heterointerface, a low tunnelling barrier, and a large tunnelling area. Our atomically thin and layered semiconducting-channel tunnel-FET (ATLAS-TFET) is the only planar architecture tunnel-FET to achieve subthermionic subthreshold swing over four decades of drain current, as recommended in ref. 17, and is also the only tunnel-FET (in any architecture) to achieve this at a low power-supply voltage of 0.1 volts. Our

  11. A subthermionic tunnel field-effect transistor with an atomically thin channel.

    PubMed

    Sarkar, Deblina; Xie, Xuejun; Liu, Wei; Cao, Wei; Kang, Jiahao; Gong, Yongji; Kraemer, Stephan; Ajayan, Pulickel M; Banerjee, Kaustav

    2015-10-01

    The fast growth of information technology has been sustained by continuous scaling down of the silicon-based metal-oxide field-effect transistor. However, such technology faces two major challenges to further scaling. First, the device electrostatics (the ability of the transistor's gate electrode to control its channel potential) are degraded when the channel length is decreased, using conventional bulk materials such as silicon as the channel. Recently, two-dimensional semiconducting materials have emerged as promising candidates to replace silicon, as they can maintain excellent device electrostatics even at much reduced channel lengths. The second, more severe, challenge is that the supply voltage can no longer be scaled down by the same factor as the transistor dimensions because of the fundamental thermionic limitation of the steepness of turn-on characteristics, or subthreshold swing. To enable scaling to continue without a power penalty, a different transistor mechanism is required to obtain subthermionic subthreshold swing, such as band-to-band tunnelling. Here we demonstrate band-to-band tunnel field-effect transistors (tunnel-FETs), based on a two-dimensional semiconductor, that exhibit steep turn-on; subthreshold swing is a minimum of 3.9 millivolts per decade and an average of 31.1 millivolts per decade for four decades of drain current at room temperature. By using highly doped germanium as the source and atomically thin molybdenum disulfide as the channel, a vertical heterostructure is built with excellent electrostatics, a strain-free heterointerface, a low tunnelling barrier, and a large tunnelling area. Our atomically thin and layered semiconducting-channel tunnel-FET (ATLAS-TFET) is the only planar architecture tunnel-FET to achieve subthermionic subthreshold swing over four decades of drain current, as recommended in ref. 17, and is also the only tunnel-FET (in any architecture) to achieve this at a low power-supply voltage of 0.1 volts. Our

  12. Silicon on ferroelectic insulator field effect transistor (SOF-FET) a new device for the next generation ultra low power circuits

    NASA Astrophysics Data System (ADS)

    Es-Sakhi, Azzedin D.

    Field effect transistors (FETs) are the foundation for all electronic circuits and processors. These devices have progressed massively to touch its final steps in sub-nanometer level. Left and right proposals are coming to rescue this progress. Emerging nano-electronic devices (resonant tunneling devices, single-atom transistors, spin devices, Heterojunction Transistors rapid flux quantum devices, carbon nanotubes, and nanowire devices) took a vast share of current scientific research. Non-Si electronic materials like III-V heterostructure, ferroelectric, carbon nanotubes (CNTs), and other nanowire based designs are in developing stage to become the core technology of non-classical CMOS structures. FinFET present the current feasible commercial nanotechnology. The scalability and low power dissipation of this device allowed for an extension of silicon based devices. High short channel effect (SCE) immunity presents its major advantage. Multi-gate structure comes to light to improve the gate electrostatic over the channel. The new structure shows a higher performance that made it the first candidate to substitute the conventional MOSFET. The device also shows a future scalability to continue Moor's Law. Furthermore, the device is compatible with silicon fabrication process. Moreover, the ultra-low-power (ULP) design required a subthreshold slope lower than the thermionic-emission limit of 60mV/ decade (KT/q). This value was unbreakable by the new structure (SOI-FinFET). On the other hand most of the previews proposals show the ability to go beyond this limit. However, those pre-mentioned schemes have publicized a very complicated physics, design difficulties, and process non-compatibility. The objective of this research is to discuss various emerging nano-devices proposed for ultra-low-power designs and their possibilities to replace the silicon devices as the core technology in the future integrated circuit. This thesis proposes a novel design that exploits the

  13. Tunable single hole regime of a silicon field effect transistor in standard CMOS technology

    NASA Astrophysics Data System (ADS)

    Turchetti, Marco; Homulle, Harald; Sebastiano, Fabio; Ferrari, Giorgio; Charbon, Edoardo; Prati, Enrico

    2016-01-01

    The electrical properties of a Single Hole Field Effect Transistor (SH-FET) based on CMOS technology are analyzed in a cryogenic environment. Few electron-hole Coulomb diamonds are observed using quantum transport spectroscopy measurements, down to the limit of single hole transport. Controlling the hole filling of the SH-FET is made possible by biasing the top gate, while the bulk contact is employed as a back gate that tunes the hole state coupling with the contacts and their distance from the interface. We compare the cryogenic Coulomb blockade regime with the room temperature regime, where the device operation is similar to that of a standard p-MOSFET.

  14. Scanning gate study of organic thin-film field-effect transistor

    NASA Astrophysics Data System (ADS)

    Aoki, N.; Sudou, K.; Matsusaki, K.; Okamoto, K.; Ochiai, Y.

    2008-03-01

    Scanning gate microscopy (SGM) has been applied for a study of organic thin-film field effect transistor (OFET). In contrast to one-dimensional nano-material such a carbon nanonube or nano-structure such a quantum point contact, visualization a transport characteristic of OFET channel is basically rather difficult since the channel width is much larger than the size of the SGM tip. Nevertheless, Schottky barriers are successfully visualized at the boundary between the metal electrodes and the OFET channel at ambient atmosphere.

  15. High-quality Graphenes via a facile quenching method for field-effect transistors.

    PubMed

    Tang, Y B; Lee, C S; Chen, Z H; Yuan, G D; Kang, Z H; Luo, L B; Song, H S; Liu, Y; He, Z B; Zhang, W J; Bello, I; Lee, S T

    2009-04-01

    Single- and few-layer graphene sheets with sizes up to 0.1 mm were fabricated by simply quenching hot graphite in an ammonium hydrogen carbonate aqueous solution. The identity and thickness of graphene sheets were characterized with transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. In addition to its simplicity and scalability, the present synthesis can produce graphene sheets with excellent qualities in terms of sizes, purity, and crystal quality. The as-produced graphene sheets can be easily transferred to solid substrates for further processing. Field-effect transistors based on individual graphenes were fabricated and shown to have high ambipolar carrier mobilities. PMID:19301858

  16. Polarization fluctuation dominated electrical transport processes of polymer-based ferroelectric field effect transistors

    NASA Astrophysics Data System (ADS)

    Senanayak, Satyaprasad P.; Guha, S.; Narayan, K. S.

    2012-03-01

    Ferroelectric field effect transistors (FE-FETs) consisting of tunable dielectric layers are utilized to investigate interfacial transport processes. Large changes in the dielectric constant as a function of temperature are observed in FE-FETs in conjunction with the ferroelectric to paraelectric transition. The devices offer a test bed to evaluate specific effects of polarization on the electrical processes. FE-FETs have dominant contributions from polarization fluctuation rather than static dipolar disorder prevalent in high k paraelectric dielectric-based FETs. Additionally, photo-excitation measurements in the depletion mode reveal clear features in the FET response at different temperatures, indicative of different transport regimes.

  17. Impact of graphene polycrystallinity on the performance of graphene field-effect transistors

    SciTech Connect

    Jiménez, David; Chaves, Ferney; Cummings, Aron W.; Van Tuan, Dinh; Kotakoski, Jani; Roche, Stephan

    2014-01-27

    We have used a multi-scale physics-based model to predict how the grain size and different grain boundary morphologies of polycrystalline graphene will impact the performance metrics of graphene field-effect transistors. We show that polycrystallinity has a negative impact on the transconductance, which translates to a severe degradation of the maximum and cutoff frequencies. On the other hand, polycrystallinity has a positive impact on current saturation, and a negligible effect on the intrinsic gain. These results reveal the complex role played by graphene grain boundaries and can be used to guide the further development and optimization of graphene-based electronic devices.

  18. Investigation of defect-induced abnormal body current in fin field-effect-transistors

    SciTech Connect

    Liu, Kuan-Ju; Tsai, Jyun-Yu; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Yang, Ren-Ya; Cheng, Osbert; Huang, Cheng-Tung

    2015-08-24

    This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal.

  19. Multi-finger flexible graphene field effect transistors with high bendability

    NASA Astrophysics Data System (ADS)

    Lee, Jongho; Tao, Li; Parrish, Kristen N.; Hao, Yufeng; Ruoff, Rodney S.; Akinwande, Deji

    2012-12-01

    Highly bendable graphene field-effect transistors are fabricated on polyimide films. The device offers robust performance against various conditions including immersion in liquids, and dynamic loading tests, which are hazardous to conventional electronics. Bendability of the sample is tested with the bending radius of down to 1.3 mm; the devices remain fully functional with less than 8.7% reduction and no reduction in the electron and hole mobility after repeated bending tests, respectively. Multi-finger electrodes are implemented on flexible substrates to enhance its current drive. Silicon-nitride passivation offers efficient chemical protection over diverse liquids and robust mechanical protection against impacts.

  20. Metal-oxide-semiconductor field effect transistor humidity sensor using surface conductance

    NASA Astrophysics Data System (ADS)

    Song, Seok-Ho; Yang, Hyun-Ho; Han, Chang-Hoon; Ko, Seung-Deok; Lee, Seok-Hee; Yoon, Jun-Bo

    2012-03-01

    This letter presents a metal-oxide-semiconductor field effect transistor based humidity sensor which does not use any specific materials to sense the relative humidity. We simply make use of the low pressure chemical vapor deposited (LPCVD) silicon dioxide's surface conductance change. When the gate is biased and then floated, the electrical charge in the gate is dissipated through the LPCVD silicon dioxide's surface to the surrounding ground with a time constant depending on the surface conductance which, in turn, varies with humidity. With this method, extremely high sensitivity was achieved—the charge dissipation speed increased thousand times as the relative humidity increased.

  1. Numerical study of quantum transport in the double-gate graphene nanoribbon field effect transistors

    NASA Astrophysics Data System (ADS)

    Mohammadpour, Hakimeh; Asgari, Asghar

    2011-07-01

    The ballistic performance of armchair graphene nanoribbon (GNR) field effect transistors (FET) with doped source and drain at different lengths of the channel are studied by self-consistently solving the non-equilibrium Green's Function (NEGF) transport equation in an atomistic basis set with a 3-D Poisson equation. The I- V characteristics of the simulated model manifests the ballistic top of the barrier and tunneling under the barrier currents in different lengths of the intrinsic channel for two different doping of the source and drain extensions of the device. The length-dependent maximum cut-off frequency is derived.

  2. Analysis of ballistic monolayer and bilayer graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ouyang, Yijian; Campbell, Paul; Guo, Jing

    2008-02-01

    We examine and compare ballistic performance limits of metal-oxide-semiconductor field-effect transistors with monolayer and bilayer graphene channels. Under low source-drain biases and cryogenic temperatures, the leakage current of the bilayer device is orders of magnitude smaller than that of the monolayer device. The advantage lowers at raised temperatures and source-drain biases. The bilayer device, however, still has qualitatively different and more favorable I-V characteristics. We find the ballistic on-state channel conductance and the minimum channel conductance have distinctly different dependences on the channel length.

  3. Density functional theory based simulations of silicon nanowire field effect transistors

    NASA Astrophysics Data System (ADS)

    Shin, Mincheol; Jeong, Woo Jin; Lee, Jaehyun

    2016-04-01

    First-principles density functional theory (DFT) based, atomistic, self-consistent device simulations are performed for realistically sized Si nanowire field effect transistors (NW FETs) having tens of thousands of atoms. Through mode space transformation, DFT Hamiltonian and overlap matrices are reduced in size from a few thousands to around one hundred. Ultra-efficient quantum-mechanical transport calculations in the non-equilibrium Green's function formalism in a non-orthogonal basis are therefore made possible. The n-type and p-type Si NW FETs are simulated and found to exhibit similar device performance in the nanoscale regime.

  4. Ballistic electron transport calculation of strained germanium-tin fin field-effect transistors

    SciTech Connect

    Lan, H.-S.; Liu, C. W.

    2014-05-12

    The dependence of ballistic electron current on Sn content, sidewall orientations, fin width, and uniaxial stress is theoretically studied for the GeSn fin field-effect transistors. Alloying Sn increases the direct Γ valley occupancy and enhances the injection velocity at virtual source node. (112{sup ¯}) sidewall gives the highest current enhancement due to the rapidly increasing Γ valley occupancy. The non-parabolicity of the Γ valley affects the occupancy significantly. However, uniaxial tensile stress and the shrinkage of fin width reduce the Γ valley occupancy, and the currents are enhanced by increasing occupancy of specific indirect L valleys with high injection velocity.

  5. Molecular Analysis of Blood with Micro/Nano Scale Field Effect Transistor Biosensors

    PubMed Central

    Makowski, Matthew S.

    2012-01-01

    Rapid and accurate molecular blood analysis is essential for disease diagnosis and management. Field Effect Transistor (FET) biosensors are a type of device that promise to advance blood point-of-care testing by offering desirable characteristics such as portability, high sensitivity, brief detection time, low manufacturing cost, multiplexing, and label-free detection. By controlling device parameters, desired FET biosensor performance is obtained. This review focuses on the effects of sensing environment, micro/nanoscale device structure, operation mode, and surface functionalization on device performance and long-term stability. PMID:21638783

  6. Simulation of electrical characteristics in negative capacitance surrounding-gate ferroelectric field-effect transistors

    NASA Astrophysics Data System (ADS)

    Xiao, Y. G.; Chen, Z. J.; Tang, M. H.; Tang, Z. H.; Yan, S. A.; Li, J. C.; Gu, X. C.; Zhou, Y. C.; Ouyang, X. P.

    2012-12-01

    The electrical characteristics of surrounding-gate (SG) metal-ferroelectric-semiconductor (MFS) field-effect transistors (FETs) were theoretically investigated by considering the ferroelectric negative capacitance (NC) effect. The derived results demonstrated that the NC-SG-MFS-FET displays superior electrical properties compared with that of the traditional SG-MIS-FET, in terms of better electrostatic control of the gate electrode over the channel, smaller subthreshold swing (S < 60 mV/dec), and bigger value of ION. It is expected that this investigation may provide some insight into the design and performance improvement for the fast switching and low power dissipation applications of ferroelectric FETs.

  7. Microwave Characterization of a Field Effect Transistor with Dielectrophoretically-Aligned Single Silicon Nanowire

    NASA Astrophysics Data System (ADS)

    Kang, Myung-Gil; Ahn, Jae-Hyun; Lee, Jongwoon; Hwang, Dong-Hoon; Kim, Hee-Tae; Rieh, Jae-Seong; Whang, Dongmok; Son, Maeng-Ho; Ahn, Doyeol; Yu, Yun-Seop; Hwang, Sung-Woo

    2010-06-01

    Microwave (MW) characteristics of a field effect transistor (FET) incorporating a single silicon nanowire (SiNW) were obtained from S-parameter measurements in the frequency range of 0.05 to 20 GHz. The single SiNW was aligned, using the alternating current (ac) dielectrophoresis alignment method, between the drain and source electrode forming a coplanar waveguide (CPW) structure. Analysis of the FET was performed using equivalent circuit modeling by advanced device system (ADS) simulation. By fitting the measured data with the simulation results, the parameters of the single SiNW FET were obtained and the cutoff frequency was derived.

  8. 25th anniversary article: key points for high-mobility organic field-effect transistors.

    PubMed

    Dong, Huanli; Fu, Xiaolong; Liu, Jie; Wang, Zongrui; Hu, Wenping

    2013-11-20

    Remarkable progress has been made in developing high performance organic field-effect transistors (OFETs) and the mobility of OFETs has been approaching the values of polycrystalline silicon, meeting the requirements of various electronic applications from electronic papers to integrated circuits. In this review, the key points for development of high mobility OFETs are highlighted from aspects of molecular engineering, process engineering and interface engineering. The importance of other factors, such as impurities and testing conditions is also addressed. Finally, the current challenges in this field for practical applications of OFETs are further discussed. PMID:24105677

  9. Drain current modulation in a nanoscale field-effect-transistor channel by single dopant implantation

    NASA Astrophysics Data System (ADS)

    Johnson, B. C.; Tettamanzi, G. C.; Alves, A. D. C.; Thompson, S.; Yang, C.; Verduijn, J.; Mol, J. A.; Wacquez, R.; Vinet, M.; Sanquer, M.; Rogge, S.; Jamieson, D. N.

    2010-06-01

    We demonstrate single dopant implantation into the channel of a silicon nanoscale metal-oxide-semiconductor field-effect-transistor. This is achieved by monitoring the drain current modulation during ion irradiation. Deterministic doping is crucial for overcoming dopant number variability in present nanoscale devices and for exploiting single atom degrees of freedom. The two main ion stopping processes that induce drain current modulation are examined. We employ 500 keV He ions, in which electronic stopping is dominant, leading to discrete increases in drain current and 14 keV P dopants for which nuclear stopping is dominant leading to discrete decreases in drain current.

  10. High intensity induced photocurrent polarity switching in lead sulfide nanowire field effect transistors.

    PubMed

    Yang, Yiming; Peng, Xingyue; Yu, Dong

    2014-05-16

    We report an optoelectronic investigation of lead sulfide nanowires (NWs) by scanning photocurrent microscopy. The photocurrent in p-type lead sulfide NW field effect transistors has demonstrated unusually nonlinear dependence on the intensity of local excitation. Surprisingly, the photocurrent polarity can be reversed under high illumination intensity on the order of 100 W cm(-2). The origin of this photocurrent polarity switching is that the photo-injected carriers flip the direction of the electric field near the contact. These observations shed light on the nonlinear optoelectronic characteristics in semiconductor nanostructures and may provide an innovative method for optically tailoring local band structures. PMID:24763392

  11. Flexible MoS2 Field-Effect Transistors for Gate-Tunable Piezoresistive Strain Sensors.

    PubMed

    Tsai, Meng-Yen; Tarasov, Alexey; Hesabi, Zohreh R; Taghinejad, Hossein; Campbell, Philip M; Joiner, Corey A; Adibi, Ali; Vogel, Eric M

    2015-06-17

    Atomically thin molybdenum disulfide (MoS2) is a promising two-dimensional semiconductor for high-performance flexible electronics, sensors, transducers, and energy conversion. Here, piezoresistive strain sensing with flexible MoS2 field-effect transistors (FETs) made from highly uniform large-area films is demonstrated. The origin of the piezoresistivity in MoS2 is the strain-induced band gap change, which is confirmed by optical reflection spectroscopy. In addition, the sensitivity to strain can be tuned by more than 1 order of magnitude by adjusting the Fermi level via gate biasing. PMID:26010011

  12. A new model for four-terminal junction field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ding, Hao; Liou, Juin J.; Green, Keith; Cirba, Claude R.

    2006-03-01

    This paper presents a compact and semi-empirical model for a four-terminal (independent top and bottom gates) junction field-effect transistor (JFET). The model describes the steady-state characteristics for all bias conditions with a unified equation. Moreover, the model provides a high degree of accuracy and continuity for the different operation regions, a critical factor for robust analog circuit simulations. Capacitance modeling is also included to describe the JFET small-signal behavior. The model has been implemented in Cadence framework via Verilog-A and compared with data measured from JFETs used at Texas Instruments.

  13. Highly Oriented Polymer Field-Effect Transistors with High Electrical Stability

    NASA Astrophysics Data System (ADS)

    Endo, Toshiyuki; Nagase, Takashi; Kobayashi, Takashi; Naito, Hiroyoshi

    2013-12-01

    Oriented polymer field-effect transistors (FETs) with a top-gate configuration have been fabricated using amorphous fluoropolymers as gate insulators. The oriented poly(9,9-dioctylfluorene-co-bithiophene) (F8T2) FETs exhibit a high mobility anisotropy of 13 and a high mobility of 0.043 cm2.V-1.s-1 for charge transport parallel to the alignment direction. The temperature dependence of the mobility reveals small disorder in the oriented F8T2 microstructure at the interface with the fluoropolymer gate insulator. The transfer characteristics show no hysteresis or threshold voltage shift after applying a gate bias stress.

  14. Ferroelectric gate tunnel field-effect transistors with low-power steep turn-on

    NASA Astrophysics Data System (ADS)

    Lee, M. H.; Wei, Y.-T.; Lin, J.-C.; Chen, C.-W.; Tu, W.-H.; Tang, M.

    2014-10-01

    Using a ferroelectric PbZrTiO3 gate stack, the range of the steep subthreshold swing in tunnel field-effect transistors was extended by 3.5 orders of magnitude demonstrating an improvement in the swing (by approximately double the slope). The drain conductance (gd) shows only 16% enhancement with large V DS (˜-1.5V) indicates internal voltage amplification with ferroelectric negative capacitance effect beneficial to small lateral drain-source bias voltages (-0.1 V). The concept of coupling the ferroelectric polarization is proposed. The power consumption is also discussed in low-power applications of steep subthreshold slope devices.

  15. Extended-gate organic field-effect transistor for the detection of histamine in water

    NASA Astrophysics Data System (ADS)

    Minamiki, Tsukuru; Minami, Tsuyoshi; Yokoyama, Daisuke; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2015-04-01

    As part of our ongoing research program to develop health care sensors based on organic field-effect transistor (OFET) devices, we have attempted to detect histamine using an extended-gate OFET. Histamine is found in spoiled or decayed fish, and causes foodborne illness known as scombroid food poisoning. The new OFET device possesses an extended gate functionalized by carboxyalkanethiol that can interact with histamine. As a result, we have succeeded in detecting histamine in water through a shift in OFET threshold voltage. This result indicates the potential utility of the designed OFET devices in food freshness sensing.

  16. Water electrolysis and energy harvesting with zero-dimensional ion-sensitive field-effect transistors.

    PubMed

    Clément, N; Nishiguchi, K; Dufreche, J F; Guerin, D; Fujiwara, A; Vuillaume, D

    2013-08-14

    The relationship of the gas bubble size to the size distribution critically influences the effectiveness of electrochemical processes. Several optical and acoustical techniques have been used to characterize the size and emission frequency of bubbles. Here, we used zero-dimensional (0D) ion-sensitive field-effect transistors (ISFETs) buried under a microbath to detect the emission of individual bubbles electrically and to generate statistics on the bubble emission time. The bubble size was evaluated via a simple model of the electrolytic current. We suggest that energy lost during water electrolysis could be used to generate electric pulses at an optimal efficiency with an array of 0D ISFETs. PMID:23879333

  17. Organic field-effect transistor nonvolatile memories based on hybrid nano-floating-gate

    NASA Astrophysics Data System (ADS)

    Gao, Xu; She, Xiao-Jian; Liu, Chang-Hai; Sun, Qi-Jun; Liu, Jie; Wang, Sui-Dong

    2013-01-01

    High performance organic field-effect transistor nonvolatile memory is achieved by integrating gold nanoparticles and graphene oxide sheets as the hybrid nano-floating-gate. The device shows a large memory window of about 40 V, high ON/OFF ratio of reading current over 104, excellent programming/erasing endurance, and retention ability. The hybrid nano-floating-gate can increase the density of charge trapping sites, which are electrically separate from each other and thus suppress the stored charge leakage. The memory window is increased under illumination, and the results indicate that the photon-generated carriers facilitate the electron trapping but have almost no effect on the hole trapping.

  18. High mobility, low voltage operating C(60) based n-type organic field effect transistors.

    PubMed

    Schwabegger, G; Ullah, Mujeeb; Irimia-Vladu, M; Baumgartner, M; Kanbur, Y; Ahmed, R; Stadler, P; Bauer, S; Sariciftci, N S; Sitter, H

    2011-10-01

    We report on C(60) based organic field effect transistors (OFETs) that are well optimized for low voltage operation. By replacing commonly used dielectric layers by thin parylene films or by utilizing different organic materials like divinyltetramethyldisiloxane-bis(benzocyclo-butene) (BCB), low density polyethylene (PE) or adenine in combination with aluminum oxide (AlOx) to form a bilayer gate dielectric, it was possible to significantly increase the capacitance per unit area (up to two orders of magnitude). The assembly of metal-oxide and organic passivation layer combines the properties of the high dielectric constant of the metal oxide and the good organic-organic interface between semiconductor and insulator provided by a thin capping layer on top of the AlOx film. This results in OFETs that operate with voltages lower than 500 mV, while exhibiting field effect mobilities exceeding 3 cm(2) V(-1) s(-1). PMID:22049252

  19. Producing smart sensing films by means of organic field effect transistors.

    PubMed

    Manunza, Ileana; Orgiu, Emanuele; Caboni, Alessandra; Barbaro, Massimo; Bonfiglio, Annalisa

    2006-01-01

    We have fabricated the first example of totally flexible field effect device for chemical detection based on an organic field effect transistor (OFET) made by pentacene films grown on flexible plastic structures. The ion sensitivity is achieved by employing a thin Mylar foil as gate dielectric. A sensitivity of the device to the pH of the electrolyte solution has been observed A similar structure can be used also for detecting mechanical deformations on flexible surfaces. Thanks to the flexibility of the substrate and the low cost of the employed technology, these devices open the way for the production of flexible chemical and strain gauge sensors that can be employed in a variety of innovative applications such as wearable electronics, e-textiles, new man-machine interfaces. PMID:17945836

  20. SnSe2 field-effect transistors with high drive current

    NASA Astrophysics Data System (ADS)

    Su, Yang; Ebrish, Mona A.; Olson, Eric J.; Koester, Steven J.

    2013-12-01

    SnSe2 field-effect transistors fabricated using mechanical exfoliation are reported. Substrate-gated devices with source-to-drain spacing of 0.5 μm have been fabricated with drive current of 160 μA/μm at T = 300 K. The transconductance at a drain-to-source voltage of Vds = 2 V increases from 0.94 μS/μm at 300 K to 4.0 μS/μm at 4.4 K, while the field-effect mobility increases from 8.6 cm2/Vs at 300 K to 28 cm2/Vs at 77 K. The conductance at Vds = 50 mV shows an activation energy of only 5.5 meV, indicating the absence of a significant Schottky barrier at the source and drain contacts.

  1. 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.

  2. Solution-processed trilayer inorganic dielectric for high performance flexible organic field effect transistors

    NASA Astrophysics Data System (ADS)

    Tan, H. S.; Kulkarni, S. R.; Cahyadi, T.; Lee, P. S.; Mhaisalkar, S. G.; Kasim, J.; Shen, Z. X.; Zhu, F. R.

    2008-11-01

    High performance organic field effect transistors using a solution-processable processed trilayer sol-gel silica gate dielectric architecture fabricated on plastic substrates exhibited low driving voltages of -3.0V, high saturation mobilities of ˜3.5cm2/Vs, and on-off current ratio of 105. The enhancement in field effect mobility is attributed to improved dielectric-semiconductor interfacial morphology and increased capacitance of the tristratal dielectric. The pentacene devices displayed no signs of electrical degradation upon bending through a bending radius of 24mm, 2.27% strain. The slight increase in the drain currents upon bending strain was investigated using Raman spectroscopy, which revealed enhanced in-phase intermolecular coupling.

  3. Comparison of electrical characteristics of back- and top-gate Si nanowire field-effect transistors

    NASA Astrophysics Data System (ADS)

    Yoon, Changjoon; Kang, Jeongmin; Yeom, Donghyuk; Jeong, Dong-Young; Kim, Sangsig

    2008-11-01

    Back- and top-gate field-effect transistors (FETs) with channels composed of p-type Si nanowires were fabricated by a conventional photolithographic process and their electrical properties were characterized by conventional current-voltage (I-V) measurements. For a representative top-gate FET, the peak transconductance was enhanced from 2.24 to 72.2 nS, the field-effect mobility from 1.7 to 3.1 cm 2/V s, and the I/I ratio from 2.21 to 2.49×10 6, compared with those of a representative back-gate FET. The observed improvement of the electrical characteristics is mostly attributed to both the top-gate geometry and the relatively thin gate layer.

  4. Magnetoluminescence of light-emitting field-effect transistors based on alpha sexithiophene

    NASA Astrophysics Data System (ADS)

    Pham, Song-Toan; Tada, Hirokazu

    2014-03-01

    We demonstrated the effect of a magnetic field on the luminous intensity and electric current of light-emitting field-effect transistors (LEFETs) based on alpha sexithiophene (α-6T). Sublimate-grade α-6T was thermally deposited on an n+-Si/300 nm-SiO2 substrate with patterned asymmetric gold-aluminum electrodes to fabricate a bottom-contact LEFET. We observed an increase in luminous intensity of approximately 1.3% under a magnetic field of 100 mT. A possible explanation for this is that the magnetic field increased the probability of singlet formation at the α-6T/Al interface. While the magneto-electroluminescence (MEL) was reported to be derived from the magneto-conductance (MC) in ordinary light emitting diodes, the MEL in LEFET was independent with MC. This indicates that the luminous efficiency can be improved by optimizing the magnetic field effect.

  5. Parameter modeling for nanopore lonic field effect transistors in 3-D device simulation.

    PubMed

    Park, Jun-Mo; Chun, Honggu; Park, Y Eugene; Park, Byung-Gook; Lee, Jong-Ho

    2014-11-01

    An Ion Field Effect Transistor (IFET) with nanopore structure was modeled in a conventional 3-dimensional (3-D) device simulator to understand current-voltage (I-V) characteristics and underlying physics of the device. Since the nanopore was filled with positive ions (K+) ions due to the negative interface charge on the insulator surface and negative gate bias condition, we could successfully simulate the IFET structure using modified p-type silicon to mimic KCl solution. We used p-type silicon with a doping concentration of 6.022 x 10(16) cm(-3) which has the same concentration of positive carriers (hole) as in 10(-4) M KCl. By controlling gate electric field effect on the mobility, the I-V curves obtained by the parameter modeling matched very well with the measured data. In addition, the decrease of [V(th)] with increasing V(DS) was physically analyzed. PMID:25958494

  6. Thienoacene-fused pentalenes: syntheses, structures, physical properties and applications for organic field-effect transistors.

    PubMed

    Dai, Gaole; Chang, Jingjing; Shi, Xueliang; Zhang, Wenhua; Zheng, Bin; Huang, Kuo-Wei; Chi, Chunyan

    2015-01-26

    Three soluble and stable thienoacene-fused pentalene derivatives (1-3) with different π-conjugation lengths were synthesized. X-ray crystallographic analysis and density functional theory (DFT) calculations revealed their unique geometric and electronic structures due to the interaction between the aromatic thienoacene units and antiaromatic pentalene moiety. As a result, they all possess a small energy gap and show amphoteric redox behaviour. Time dependent (TD) DFT calculations were used to explain their unique electronic absorption spectra. These new compounds exhibited good thermal stability and ordered packing in solid state and thus their applications in organic field-effect transistors (OFETs) were also investigated. The highest field-effect hole mobility of 0.016, 0.036 and 0.001 cm(2)  V(-1)  s(-1) was achieved for solution-processed thin films of 1-3, respectively. PMID:25430620

  7. Dianthraceno[a,e]pentalenes: synthesis, crystallographic structures and applications in organic field-effect transistors.

    PubMed

    Dai, Gaole; Chang, Jingjing; Zhang, Wenhua; Bai, Shiqiang; Huang, Kuo-Wei; Xu, Jianwei; Chi, Chunyan

    2015-01-11

    Two soluble and stable dianthraceno[a,e]pentalenes with two (DAP1) and six (DAP2) phenyl substituents were synthesized. Both compounds possess a small energy band gap and show amphoteric redox behaviour due to intramolecular donor-accepter interactions. X-ray crystallographic analysis revealed that DAP2 has a closely packed structure with multi-dimensional [C-H···π] interactions although there are no π-π interactions between the dianthraceno[a,e]pentalene cores. As a result, solution-processed field effect transistors based on DAP2 exhibited an average hole mobility of 0.65 cm(2) V(-1) s(-1). Under similar conditions, DAP1 showed an average field effect hole mobility of 0.001 cm(2) V(-1) s(-1). PMID:25406768

  8. Regulating charge injection in ambipolar organic field-effect transistors by mixed self-assembled monolayers.

    PubMed

    Xu, Yong; Baeg, Kang-Jun; Park, Won-Tae; Cho, Ara; Choi, Eun-Young; Noh, Yong-Young

    2014-08-27

    We report on a technique using mixed self-assembled monolayers (SAMs) to finely regulate ambipolar charge injection in polymer organic field-effect transistors. Differing from the other works that employ single SAM specifically for efficient charge injection in p-type and n-type transistors, we blend two different SAMs of alkyl- and perfluoroalkyl thiols at different ratios and apply them to ambipolar OFETs and inverter. Thanks to the utilization of ambipolar semiconductor and one SAM mixture, the device and circuit fabrications are facile with only one step for semiconductor deposition and another for SAM treatment. This is much simpler with respect to the conventional scheme for the unipolar-device-based complementary circuitry that demands separate deposition and processing for individual p-channel and n-channel transistors. Our results show that the mixed-SAM treatments not only improve ambipolar charge injection manifesting as higher hole- and electron-mobility and smaller threshold voltage but also gradually tune the device characteristics to reach a desired condition for circuit application. Therefore, this simple but useful approach is promising for ambipolar electronics. PMID:25093699

  9. Interface effects on the characteristics of metal-ferroelectric-insulator-semiconductor field-effect transistor

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Zheng, Xue Jun; Cao, Juan; Li, Wen

    2011-09-01

    The interface effects on the electrical characteristics of metal-ferroelectric-insulator- semiconductor field-effect transistor (MFIS-FET) are studied using an improved model in which the expressions for interface and the mobility model are incorporated into Lue model. The interface layer between the ferroelectric and the electrode and the SiO2 layer between the insulator and the semiconductor have been investigated. Capacitance-gate voltage (C-VG) and drain current-gate voltage (ID-VGS) characteristics are modeled with fixed interface layer and SiO2 layer thicknesses and show good agreement with the experiments, verifying the validity of the improved model and the existence of the interface in the transistor. The characteristics, such as C-VG, ID-VGS and drain current-drain voltage (ID-VDS), are modeled respectively with various interface layer and SiO2 layer thicknesses. The thicker the interface layer and SiO2 layer are, the worse the transistor characteristics become. Similar characteristics can be observed at the specific thickness of the two layers, indicating that both interface layer and SiO2 layer should be considered when the characteristics of MFIS-FETs degrade. In addition, the type of the interfaces can be distinguished by comparing the capacitance in the accumulation region. It is expected that this work can offer some useful guidance to the design and performance improvement of MFIS structure devices.

  10. Local Maps of the Polarization and Depolarization in Organic Ferroelectric Field-Effect Transistors

    PubMed Central

    Cai, Ronggang; Jonas, Alain M.

    2016-01-01

    We study the local ferroelectric polarization and depolarization of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) in p-type ferroelectric field-effect transistors (FeFETs). Piezoresponse force microscopy (PFM) is used to obtain local maps of the polarization on model metal-semiconductor-ferroelectric stacks, and on FeFETs stripped from their top-gate electrode; transfer curves are measured on complete FeFETs. The influence of the semiconductor layer thickness and of the polarity and amplitude of the poling voltage are investigated. In accumulation, the stable “on” state consists of a uniform upward-polarized ferroelectric layer, with compensation holes accumulating at the ferroelectric/semiconducting interface. In depletion, the stable “off” state consists of a depolarized region in the center of the transistor channel, surrounded by partially downward-polarized regions over the source and drain electrodes and neighboring regions. The partial depolarization of these regions is due to the incomplete screening of polarization charges by the charges of the remote electrodes. Therefore, thinner semiconducting layers provide higher downward polarizations, which result in a more depleted transistor channel and a higher charge injection barrier between the electrodes and the semiconductor, leading to lower threshold voltages and higher on/off current values at zero gate bias. Clues for optimization of the devices are finally provided. PMID:26905962

  11. SnTe field effect transistors and the anomalous electrical response of structural phase transition

    SciTech Connect

    Li, Haitao Zhu, Hao; Yuan, Hui; Li, Qiliang; You, Lin; Kopanski, Joseph J.; Richter, Curt A.; Zhao, Erhai

    2014-07-07

    SnTe is a conventional thermoelectric material and has been newly found to be a topological crystalline insulator. In this work, back-gate SnTe field-effect transistors have been fabricated and fully characterized. The devices exhibit n-type transistor behaviors with excellent current-voltage characteristics and large on/off ratio (>10{sup 6}). The device threshold voltage, conductance, mobility, and subthreshold swing have been studied and compared at different temperatures. It is found that the subthreshold swings as a function of temperature have an apparent response to the SnTe phase transition between cubic and rhombohedral structures at 110 K. The abnormal and rapid increase in subthreshold swing around the phase transition temperature may be due to the soft phonon/structure change which causes the large increase in SnTe dielectric constant. Such an interesting and remarkable electrical response to phase transition at different temperatures makes the small SnTe transistor attractive for various electronic devices.

  12. Modeling of Field Effect Transistor Channel as a Nonlinear Transmission Line for Terahertz Detection

    NASA Astrophysics Data System (ADS)

    Ibrahim, Nihal Y.; Rafat, Nadia H.; Elnahwy, Salah E. A.

    2013-10-01

    This paper revisits the theory of operation of field effect transistor in the extremely high frequency scale, where the analysis has gone beyond the conventional cutoff frequency of the transistor. In this range, which is typically the terahertz (THz) and sub-terahertz range, the transistor blocks the high frequency signal and generates a rectified signal related to the input high frequency signal. An analytical model is derived for the channel of the FET in the linear mode of operation in non-resonant THz detection conditions. A transmission line distributed circuit model is applied. This is, from the authors' point of view, the suitable model for high frequency non-quasi static operation and the characteristic parameters of this model are derived from the differential equation governing the electron gas in the channel. A comparison is presented for the calculated photoresponse with previously published experimental one showing good agreement away from the threshold potential. Finally, the effects of coupling between the present model and the external input circuit have been taken into account including the loading effects of the antenna and a discussion is given for the effect on frequency selectivity of the FET.

  13. Gate-Sensing Coherent Charge Oscillations in a Silicon Field-Effect Transistor.

    PubMed

    Gonzalez-Zalba, M Fernando; Shevchenko, Sergey N; Barraud, Sylvain; Johansson, J Robert; Ferguson, Andrew J; Nori, Franco; Betz, Andreas C

    2016-03-01

    Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong-driving regime where we observe the emergence of Landau-Zener-Stückelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 ≈ 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology. PMID:26866446

  14. Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

    SciTech Connect

    Held, Martin; Schießl, Stefan P.; Gannott, Florentina; Miehler, Dominik; Zaumseil, Jana

    2015-08-24

    Transistors for future flexible organic light-emitting diode (OLED) display backplanes should operate at low voltages and be able to sustain high currents over long times without degradation. Hence, high capacitance dielectrics with low surface trap densities are required that are compatible with solution-processable high-mobility semiconductors. Here, we combine poly(methyl methacrylate) (PMMA) and atomic layer deposition hafnium oxide (HfO{sub x}) into a bilayer hybrid dielectric for field-effect transistors with a donor-acceptor polymer (DPPT-TT) or single-walled carbon nanotubes (SWNTs) as the semiconductor and demonstrate substantially improved device performances for both. The ultra-thin PMMA layer ensures a low density of trap states at the semiconductor-dielectric interface while the metal oxide layer provides high capacitance, low gate leakage and superior barrier properties. Transistors with these thin (≤70 nm), high capacitance (100–300 nF/cm{sup 2}) hybrid dielectrics enable low operating voltages (<5 V), balanced charge carrier mobilities and low threshold voltages. Moreover, the hybrid layers substantially improve the bias stress stability of the transistors compared to those with pure PMMA and HfO{sub x} dielectrics.

  15. Multibit ferroelectric field-effect transistor with epitaxial-like Pb(Zr,Ti)O3

    NASA Astrophysics Data System (ADS)

    Park, Jae Hyo; Kim, Hyung Yoon; Seok, Ki Hwan; Kiaee, Zohreh; Lee, Sol Kyu; Joo, Seung Ki

    2016-03-01

    Being able to control grain boundaries during the phase transformation when processing a ferroelectric thin-film is crucial for the successful development of practical multibit ferroelectric memory. A novel development of ferroelectric thin-film crystallization processing for realizing epitaxial-like single crystals via artificial nucleation by Pt-seeding is reported here. Dividing the nucleation and growth mechanism by Pt-seeding, it is possible to obtain large and uniform rectangular-shaped ferroelectric grains, large enough to fabricate a field-effect transistor (FET) in the inside of the crystal grain. The fabricated ferroelectric FET, Pt/Pb(Zr,Ti)O3/ZrTiO4/Si, showed a large memory window (˜2.2 V), a low operation voltage (˜6 V), and an ultra-fast program/erase speed (˜10-6 s). Moreover, there was no degradation after 1015 cycles of bipolar fatigue testing and the sample even showed a long retention time after 1 yr. All of these characteristics correspond to the best performance among all types of ferroelectric field-effect transistors reported thus far.

  16. Selenium-Containing Fused Bicyclic Heterocycle Diselenolodiselenole: Field Effect Transistor Study and Structure-Property Relationship.

    PubMed

    Debnath, Sashi; Chithiravel, Sundaresan; Sharma, Sagar; Bedi, Anjan; Krishnamoorthy, Kothandam; Zade, Sanjio S

    2016-07-20

    The first application of the diselenolodiselenole (C4Se4) heterocycle as an active organic field effect transistor materials is demonstrated here. C4Se4 derivatives (2a-2d) were obtained by using a newly developed straightforward diselenocyclization protocol, which includes the reaction of diynes with selenium powder at elevated temperature. C4Se4 derivatives exhibit strong donor characteristics and planar structure (except 2d). The atomic force microscopic analysis and thin-film X-ray diffraction pattern of compounds 2a-2d indicated the formation of distinct crystalline films that contain large domains. A scanning electron microscopy study of compound 2b showed development of symmetrical grains with an average diameter of 150 nm. Interestingly, 2b exhibited superior hole mobility, approaching 0.027 cm(2) V(-1) s(-1) with a transconductance of 9.2 μS. This study correlate the effect of π-stacking, Se···Se intermolecular interaction, and planarity with the charge transport properties and performance in the field effect transistor devices. We have shown that the planarity in C4Se4 derivatives was achieved by varying the end groups attached to the C4Se4 core. In turn, optoelectronic properties can also be tuned for all these derivatives by end-group variation. PMID:27353123

  17. A Micro-Machined Microphone Based on a Combination of Electret and Field-Effect Transistor

    PubMed Central

    Shin, Kumjae; Jeon, Junsik; West, James Edward; Moon, Wonkyu

    2015-01-01

    Capacitive-type transduction is now widely used in MEMS microphones. However, its sensitivity decreases with reducing size, due to decreasing air gap capacitance. In the present study, we proposed and developed the Electret Gate of Field Effect Transistor (ElGoFET) transduction based on an electret and FET (field-effect-transistor) as a novel mechanism of MEMS microphone transduction. The ElGoFET transduction has the advantage that the sensitivity is dependent on the ratio of capacitance components in the transduction structure. Hence, ElGoFET transduction has high sensitivity even with a smaller air gap capacitance, due to a miniaturization of the transducer. A FET with a floating-gate electrode embedded on a membrane was designed and fabricated and an electret was fabricated by ion implantation with Ga+ ions. During the assembly process between the FET and the electret, the operating point of the FET was characterized using the static response of the FET induced by the electric field due to the trapped positive charge at the electret. Additionally, we evaluated the microphone performance of the ElGoFET by measuring the acoustic response in air using a semi-anechoic room. The results confirmed that the proposed transduction mechanism has potential for microphone applications. PMID:26295231

  18. Band gap engineered nano perforated graphene microstructures for field effect transistor

    NASA Astrophysics Data System (ADS)

    Palla, Penchalaiah; Tiwari, Durgesh Laxman; Ansari, Hasan Raza; Babu, Taraprasanna Saha; Ethiraj, Anita Sagadevan; Raina, J. P.

    2016-05-01

    To make use of exceptional properties of graphene in Field effect Transistor (FETs) for switching devices a band gap must be introduced in order to switch -off the device. Through periodic nano perforations a semi-metallic graphene is converted into semiconducting graphene. To understand the device physics behind the reported experiments theoretical simulations has been carried out. The present paper illustrates nano perforated semiconducting graphene Field effect Transistor (FETs) with micron scale dimensions. The simulation has been performed using drift-diffusion semi-classical and tight-binding based non-equilibrium green's function (NEGF) methods. The obtained simulation results are compared with previously reported experimental work. The device dimensions considered for simulations and the experiment are similar with neck width, hole periodicity and channel length of 6.3 nm, 16.3 nm and 1 µm respectively. The interesting and new finding in this work is the p-type I-V characteristics for small band gap devices and n-type behavior for large band gap devices.

  19. Instability in an amorphous In-Ga-Zn-O field effect transistor upon water exposure

    NASA Astrophysics Data System (ADS)

    Sharma, Bhupendra K.; Ahn, Jong-Hyun

    2016-02-01

    The instability of an amorphous indium-gallium-zinc oxide (IGZO) field effect transistor is investigated upon water treatment. Electrical characteristics are measured before, immediately after and a few days after water treatment in ambient as well as in vacuum conditions. It is observed that after a few days of water exposure an IGZO field effect transistor (FET) shows relatively more stable behaviour as compared to before exposure. Transfer characteristics are found to shift negatively after immediate water exposure and in vacuum. More interestingly, after water exposure the off current is found to decrease by 1-2 orders of magnitude and remains stable even after 15 d of water exposure in ambient as well as in vacuum, whereas the on current more or less remains the same. An x-ray photoelectron spectroscopic study is carried out to investigate the qualitative and quantitative analysis of IGZO upon water exposure. The changes in the FET parameters are evaluated and attributed to the formation of excess oxygen vacancies and changes in the electronic structure of the IGZO bulk channel and at the IGZO/SiO2 interface, which can further lead to the formation of subgap states. An attempt is made to distinguish which parameters of the FET are affected by the changes in the electronic structure of the IGZO bulk channel and at the IGZO/SiO2 interface separately.

  20. Temperature sensitivity analysis of polarity controlled electrostatically doped tunnel field-effect transistor

    NASA Astrophysics Data System (ADS)

    Nigam, Kaushal; Pandey, Sunil; Kondekar, P. N.; Sharma, Dheeraj

    2016-09-01

    The conventional tunnel field-effect transistors (TFETs) have shown potential to scale down in sub-22 nm regime due to its lower sub-threshold slope and robustness against short-channel effects (SCEs), however, sensitivity towards temperature variation is a major concern. Therefore, for the first time, we investigate temperature sensitivity analysis of a polarity controlled electrostatically doped tunnel field-effect transistor (ED-TFET). Different performance metrics and analog/RF figure-of-merits were considered and compared for both devices, and simulations were performed using Silvaco ATLAS device tool. We found that the variation in ON-state current in ED-TFET is almost temperature independent due to electrostatically doped mechanism, while, it increases in conventional TFET at higher temperature. Above room temperature, the variation in ION, IOFF, and SS sensitivity in ED-TFET are only 0.11%/K, 2.21%/K, and 0.63%/K, while, in conventional TFET the variations are 0.43%/K, 2.99%/K, and 0.71%/K, respectively. However, below room temperature, the variation in ED-TFET ION is 0.195%/K compared to 0.27%/K of conventional TFET. Moreover, it is analysed that the incomplete ionization effect in conventional TFET severely affects the drive current and the threshold voltage, while, ED-TFET remains unaffected. Hence, the proposed ED-TFET is less sensitive towards temperature variation and can be used for cryogenics as well as for high temperature applications.

  1. Transport studies of quantum dots sensitized single Mn-ZnO nanowire field effect transistors

    NASA Astrophysics Data System (ADS)

    Sapkota, Keshab R.; Maloney, Francis Scott; Rimal, Gaurab; Poudyal, Uma; Tang, Jinke; Wang, Wenyong

    We present opto-electrical transport properties of Mn-CdSe quantum dots (QDs) sensitized single Mn-ZnO nanowire (NW) field effect transistors (FET). The ZnO NWs with 2 atomic % of Mn doping are grown by chemical vapor deposition. The NWs are ferromagnetic at low temperature. The as grown nanowires are transferred to clean SiO2/Si substrate and single nanowire field effect transistors (FET) are fabricated by standard e-beam lithography. Mobility and carrier concentration of Mn-ZnO NWs are estimated from FET device measurement which shows NWs are n-type semiconductors. Pulse laser deposition of Mn-CdSe QDs on the single NW FET significantly increases carrier concentration of the QD-NW system in dark where the QD monolayer conduction is negligibly small. The photoconductivity study of QD sensitized NW FET enlightens the conduction spectrum of QD-NW system and QD to NW carrier transfer mechanism. This work has been supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-10ER46728.

  2. Nanoscale BaTiO3 MOSCAP formation for ferroelectric field effect transistor application

    NASA Astrophysics Data System (ADS)

    Ponath, Patrick; Posadas, Agham; Schmidt, Michael; Hurley, Paul; Duffy, Ray; Demkov, Alex

    Titanates are an important class of materials with many interesting functional properties and applications for non-volatile memory, i.e. BaTiO3, which is a promising candidate for the realization of a ferroelectric field-effect transistor. However, the difficulty of chemically etching titanates has hindered their commercial use in device manufacturing so far. Here, we report a technique to circumvent this problem. Using molecular beam epitaxy, we grew compressively strained ferroelectric BaTiO3, within photolithographically defined openings of a sacrificial SiO2 layer on germanium (001) with Pt as a top electrode. Etching away the sacrificial SiO2 can reveal isolated nanoscale gate stacks circumventing the need to etch the titanate thin film. Using X-ray diffraction we find that the BaTiO3 film is tetragonal with the longer c-axis being out of plane, which is a requirement for the ferroelectric field effect transistor. The crystal quality of the BaTiO3 films grown in the openings is confirmed using RHEED and cross-sectional transmission electron microscopy. Focused ion beam etching of the Pt layer is then used to electrically isolate a Pt/BaTiO3/SrTiO3/Ge stack to perform electrical measurements.

  3. Evaluation of doped phthalocyanines and a chemically-sensitive field effect transistor for detecting nitrogen dioxide

    NASA Astrophysics Data System (ADS)

    Jenkins, Thomas J.

    1989-12-01

    The design and fabrication of an integrated circuit microsensor for the detection of nitrogen dioxide is examined. Metal-doped phthalocyanine compounds were evaluated as a candidate chemically sensitive membrane, and their performance was compared with respect to sensitivity, reversibility, and specificity. The microsensor consisted of the integration of an array of 9 sensing elements with amplifiers, a reference amplifier, and an analog multiplexer. The 9 individual sensing elements used an interdigitated gate electrode field effect transistor (IGEFET) coupled to a serially connected pair of inverting amplifiers using metal oxide semiconductor field effect transistors(MOSFETs). The interdigitated gate electrodes were coated with thin films of cobalt (II) phthalocyanine (CoPc), copper phthalocyanine (CuPc), lead phthalocyanine (PbPc), nickel (II) phthalocyanine (NiPc), and (undoped) phthalocyanine (Pc). An excitation signal was applied to the integrated circuit, and the multiplexed electrical response was measured in the time-domain and the frequency-domain. The electrical response was evaluated upon exposure to 20-, 80-, and 320-ppb of nitrogen dioxide (NO2) and diisopropyl methylphosphonate (DIMP) using filtered room air (less than 5 percent relative humidity) as the diluent. The electrical response was evaluated for film thickness of approximately 1500 A and 500 A. The rank ordering of the sensitivity of the materials to nitrogen dioxide from the most to least sensitive was: CoPc, NiPc, CuPc, PbPc, and then (undoped) Pc.

  4. Fabrication and characterization on reduced graphene oxide field effect transistor (RGOFET) based biosensor

    NASA Astrophysics Data System (ADS)

    Rashid, A. Diyana; Ruslinda, A. Rahim; Fatin, M. F.; Hashim, U.; Arshad, M. K.

    2016-07-01

    The fabrication and characterization on reduced graphene oxide field effect transistor (RGO-FET) were demonstrated using a spray deposition method for biological sensing device purpose. A spray method is a fast, low-cost and simple technique to deposit graphene and the most promising technology due to ideal coating on variety of substrates and high production speed. The fabrication method was demonstrated for developing a label free aptamer reduced graphene oxide field effect transistor biosensor. Reduced graphene oxide (RGO) was obtained by heating on hot plate fixed at various temperatures of 100, 200 and 300°C, respectively. The surface morphology of RGO were examined via atomic force microscopy to observed the temperature effect of produced RGO. The electrical measurement verify the performance of electrical conducting RGO-FET at temperature 300°C is better as compared to other temperature due to the removal of oxygen groups in GO. Thus, reduced graphene oxide was a promising material for biosensor application.

  5. Solution-Processed Ambipolar Field-Effect Transistor Based on Diketopyrrolopyrrole Functionalized with Benzothiadiazole

    SciTech Connect

    Zhang, Yuan; Kim, Chunki; Lin, Jason; Nguyen, Thuc-Quyen

    2012-01-01

    Ambipolar charge transport in a solution-processed small molecule 4,7-bis{2-[2,5-bis(2-ethylhexyl)-3-(5-hexyl-2,2':5',2"-terthiophene-5"-yl)-pyrrolo[3,4-c]pyrrolo-1,4-dione-6-yl]-thiophene-5-yl}-2,1,3-benzothiadiazole (BTDPP2) transistor has been investigated and shows a balanced field-effect mobility of electrons and holes of up to ~10-2 cm² V-1 s-1. Using low-work-function top electrodes such as Ba, the electron injection barrier is largely reduced. The observed ambipolar transport can be enhanced over one order of magnitude compared to devices using Al or Au electrodes. The field-effect mobility increases upon thermal annealing at 150 °C due to the formation of large crystalline domains, as shown by atomic force microscopy and X-ray diffraction. Organic inverter circuits based on BTDPP2 ambipolar transistors display a gain of over 25.

  6. Deep-ultraviolet-light-driven reversible doping of WS2 field-effect transistors.

    PubMed

    Iqbal, Muhammad Waqas; Iqbal, Muhammad Zahir; Khan, Muhammad Farooq; Shehzad, Muhammad Arslan; Seo, Yongho; Eom, Jonghwa

    2015-01-14

    Improvement of the electrical and photoelectric characteristics is essential to achieve an advanced performance of field-effect transistors and optoelectronic devices. Here we have developed a doping technique to drastically improve electrical and photoelectric characteristics of single-layered, bi-layered and multi-layered WS2 field-effect transistors (FET). After illuminating with deep ultraviolet (DUV) light in a nitrogen environment, WS2 FET shows an enhanced charge carrier density, mobility and photocurrent response. The threshold voltage of WS2 FET shifted toward the negative gate voltage, and the positions of E and A1g peaks in Raman spectra shifted toward lower wavenumbers, indicating the n-type doping effect of the WS2 FET. The doping effect is reversible. The pristine characteristics of WS2 FET can be restored by DUV light illumination in an oxygen environment. The DUV-driven doping technique in a gas environment provides a very stable, effective, easily applicable way to enhance the performance of WS2 FET. PMID:25429443

  7. Biosensors based on enzyme field-effect transistors for determination of some substrates and inhibitors.

    PubMed

    Dzyadevych, Sergei V; Soldatkin, Alexey P; Korpan, Yaroslav I; Arkhypova, Valentyna N; El'skaya, Anna V; Chovelon, Jean-Marc; Martelet, Claude; Jaffrezic-Renault, Nicole

    2003-10-01

    This paper is a review of the authors' publications concerning the development of biosensors based on enzyme field-effect transistors (ENFETs) for direct substrates or inhibitors analysis. Such biosensors were designed by using immobilised enzymes and ion-selective field-effect transistors (ISFETs). Highly specific, sensitive, simple, fast and cheap determination of different substances renders them as promising tools in medicine, biotechnology, environmental control, agriculture and the food industry. The biosensors based on ENFETs and direct enzyme analysis for determination of concentrations of different substrates (glucose, urea, penicillin, formaldehyde, creatinine, etc.) have been developed and their laboratory prototypes were fabricated. Improvement of the analytical characteristics of such biosensors may be achieved by using a differential mode of measurement, working solutions with different buffer concentrations and specific agents, negatively or positively charged additional membranes, or genetically modified enzymes. These approaches allow one to decrease the effect of the buffer capacity influence on the sensor response in an aim to increase the sensitivity of the biosensors and to extend their dynamic ranges. Biosensors for the determination of concentrations of different toxic substances (organophosphorous pesticides, heavy metal ions, hypochlorite, glycoalkaloids, etc.) were designed on the basis of reversible and/or irreversible enzyme inhibition effect(s). The conception of an enzymatic multibiosensor for the determination of different toxic substances based on the enzyme inhibition effect is also described. We will discuss the respective advantages and disadvantages of biosensors based on the ENFETs developed and also demonstrate their practical application. PMID:12904953

  8. Environmental Effects on Hysteresis of Transfer Characteristics in Molybdenum Disulfide Field-Effect Transistors.

    PubMed

    Shimazu, Yoshihiro; Tashiro, Mitsuki; Sonobe, Satoshi; Takahashi, Masaki

    2016-01-01

    Molybdenum disulfide (MoS2) has recently received much attention for nanoscale electronic and photonic applications. To explore the intrinsic properties and enhance the performance of MoS2-based field-effect transistors, thorough understanding of extrinsic effects such as environmental gas and contact resistance of the electrodes is required. Here, we report the effects of environmental gases on the transport properties of back-gated multilayered MoS2 field-effect transistors. Comparisons between different gases (oxygen, nitrogen, and air and nitrogen with varying relative humidities) revealed that water molecules acting as charge-trapping centers are the main cause of hysteresis in the transfer characteristics. While the hysteresis persisted even after pumping out the environmental gas for longer than 10 h at room temperature, it disappeared when the device was cooled to 240 K, suggesting a considerable increase in the time constant of the charge trapping/detrapping at these modestly low temperatures. The suppression of the hysteresis or instability in the easily attainable temperature range without surface passivation is highly advantageous for the device application of this system. The humidity dependence of the threshold voltages in the transfer curves indicates that the water molecules dominantly act as hole-trapping centers. A strong dependence of the on-state current on oxygen pressure was also observed. PMID:27435309

  9. The interface between ferroelectric and 2D material for a Ferroelectric Field-Effect Transistor

    NASA Astrophysics Data System (ADS)

    Park, Nahee; Kang, Haeyong; Lee, Sang-Goo; Lee, Young Hee; Suh, Dongseok

    We have studied electrical property of ferroelectric field-effect transistor which consists of graphene on hexagonal Boron-Nitride (h-BN) gated by a ferroelectric, PMN-PT (i.e. (1-x)Pb(Mg1/3Nb2/3) O3-xPbTiO3) single-crystal substrate. The PMN-PT was expected to have an effect on polarization field into the graphene channel and to induce a giant amount of surface charge. The hexagonal Boron-Nitride (h-BN) flake was directly exfoliated on the PMN-PT substrate for preventing graphene from directly contacting on the PMN-PT substrate. It can make us to observe the effect of the interface between ferroelectric and 2D material on the device operation. Monolayer graphene as 2D channel material, which was confirmed by Raman spectroscopy, was transferred on top of the hexagonal Boron-Nitride (h-BN) by using the conventional dry-transfer method. Here, we can demonstrate that the structure of graphene/hexagonal-BN/ferroelectric field-effect transistor makes us to clearly understand the device operation as well as the interface between ferroelectric and 2D materials by inserting h-BN between them. The phenomena such as anti-hysteresis, current saturation behavior, and hump-like increase of channel current, will be discussed by in terms of ferroelectric switching, polarization-assisted charge trapping.

  10. Compound semiconductor field-effect transistors with improved dc and high frequency performance

    SciTech Connect

    Zolper, J.C.; Sherwin, M.E.; Baca, A.G.

    1995-12-31

    A method for making compound semiconductor devices including the use of a p-type dopant is disclosed wherein the dopant is co-implanted with an n-type donor species at the time the n-channel is deposited. Also disclosed are devices manufactured using the method. In the preferred embodiment n-MESFETs and other similar field effect transistor devices are manufactured using C ions implanted with Si atoms in GaAs to form an n-channel. C exhibits a unique characteristic in the context of the invention in that it exhibits a low activation efficiency (typically, 50% or less) as a p-type dopant, and consequently, it acts to sharpen the Si n-channel by compensating Si donors in the region the Si-channel tail, but does not contribute substantially to the acceptor concentration in the region of the buried p-implant. As a result, the invention provides for improved field effect transistor devices with enhancement of both DC and high-frequency performance.

  11. Inversion channel diamond metal-oxide-semiconductor field-effect transistor with normally off characteristics.

    PubMed

    Matsumoto, Tsubasa; Kato, Hiromitsu; Oyama, Kazuhiro; Makino, Toshiharu; Ogura, Masahiko; Takeuchi, Daisuke; Inokuma, Takao; Tokuda, Norio; Yamasaki, Satoshi

    2016-01-01

    We fabricated inversion channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with normally off characteristics. At present, Si MOSFETs and insulated gate bipolar transistors (IGBTs) with inversion channels are widely used because of their high controllability of electric power and high tolerance. Although a diamond semiconductor is considered to be a material with a strong potential for application in next-generation power devices, diamond MOSFETs with an inversion channel have not yet been reported. We precisely controlled the MOS interface for diamond by wet annealing and fabricated p-channel and planar-type MOSFETs with phosphorus-doped n-type body on diamond (111) substrate. The gate oxide of Al2O3 was deposited onto the n-type diamond body by atomic layer deposition at 300 °C. The drain current was controlled by the negative gate voltage, indicating that an inversion channel with a p-type character was formed at a high-quality n-type diamond body/Al2O3 interface. The maximum drain current density and the field-effect mobility of a diamond MOSFET with a gate electrode length of 5 μm were 1.6 mA/mm and 8.0 cm(2)/Vs, respectively, at room temperature. PMID:27545201

  12. Position sensitivity of graphene field effect transistors to X-rays

    SciTech Connect

    Cazalas, Edward Moore, Michael E.; Jovanovic, Igor; Sarker, Biddut K.; Childres, Isaac; Chen, Yong P.

    2015-06-01

    Device architectures that incorporate graphene to realize detection of electromagnetic radiation typically utilize the direct absorbance of radiation by graphene. This limits their effective area to the size of the graphene and their applicability to lower-energy, less penetrating forms of radiation. In contrast, graphene-based transistor architectures that utilize the field effect as the detection mechanism can be sensitive to interactions of radiation not only with graphene but also with the surrounding substrate. Here, we report the study of the position sensitivity and response of a graphene-based field effect transistor (GFET) to penetrating, well-collimated radiation (micro-beam X-rays), producing ionization in the substrate primarily away from graphene. It is found that responsivity and response speed are strongly dependent on the X-ray beam distance from graphene and the gate voltage applied to the GFET. To develop an understanding of the spatially dependent response, a model is developed that incorporates the volumetric charge generation, transport, and recombination. The model is in good agreement with the observed spatial response characteristics of the GFET and predicts a greater response potential of the GFET to radiation interacting near its surface. The study undertaken provides the necessary insight into the volumetric nature of the GFET response, essential for development of GFET-based detectors for more penetrating forms of ionizing radiation.

  13. Environmental Effects on Hysteresis of Transfer Characteristics in Molybdenum Disulfide Field-Effect Transistors

    PubMed Central

    Shimazu, Yoshihiro; Tashiro, Mitsuki; Sonobe, Satoshi; Takahashi, Masaki

    2016-01-01

    Molybdenum disulfide (MoS2) has recently received much attention for nanoscale electronic and photonic applications. To explore the intrinsic properties and enhance the performance of MoS2-based field-effect transistors, thorough understanding of extrinsic effects such as environmental gas and contact resistance of the electrodes is required. Here, we report the effects of environmental gases on the transport properties of back-gated multilayered MoS2 field-effect transistors. Comparisons between different gases (oxygen, nitrogen, and air and nitrogen with varying relative humidities) revealed that water molecules acting as charge-trapping centers are the main cause of hysteresis in the transfer characteristics. While the hysteresis persisted even after pumping out the environmental gas for longer than 10 h at room temperature, it disappeared when the device was cooled to 240 K, suggesting a considerable increase in the time constant of the charge trapping/detrapping at these modestly low temperatures. The suppression of the hysteresis or instability in the easily attainable temperature range without surface passivation is highly advantageous for the device application of this system. The humidity dependence of the threshold voltages in the transfer curves indicates that the water molecules dominantly act as hole-trapping centers. A strong dependence of the on-state current on oxygen pressure was also observed. PMID:27435309

  14. A Water-Soluble Polythiophene for Organic Field-Effect Transistors

    SciTech Connect

    Shao, Ming; He, Youjun; Hong, Kunlun; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2013-01-01

    Synthesis of a non-ionic, water-soluble poly(thiophene) (PT) derivative, poly(3-(2-(2-methoxyethoxy) ethoxy)ethoxy) methylthiophene) (P3TEGT) with a hydrophilic tri-ethylene glycol side group, is reported and thin films of the polymer suitable for organic field-effect transistors (OFETs) are characterized by combining analysis techniques that include UV-Vis absorption and fluorescence spectroscopy, x-ray diffraction, and atomic force microscopy. After thermal annealing, P3TEGT films exhibit a well-organized nanofibrillar lamellar nanostructure that originates from the strong - stacking of the thiophene backbones. P-type organic field-effect transistors (OFETs) with hole mobilities of 10-5 cm2V-1s-1 were fabricated from this water-soluble poly(thiophene) derivative, demonstrating the possibility that environmentally-friendly solvents may be promising alternatives for the low-cost, green solution-based organic electronic device manufacturing of OFETs, organic photovoltaics (OPVs), and biosensors.

  15. Environmental Effects on Hysteresis of Transfer Characteristics in Molybdenum Disulfide Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Shimazu, Yoshihiro; Tashiro, Mitsuki; Sonobe, Satoshi; Takahashi, Masaki

    2016-07-01

    Molybdenum disulfide (MoS2) has recently received much attention for nanoscale electronic and photonic applications. To explore the intrinsic properties and enhance the performance of MoS2-based field-effect transistors, thorough understanding of extrinsic effects such as environmental gas and contact resistance of the electrodes is required. Here, we report the effects of environmental gases on the transport properties of back-gated multilayered MoS2 field-effect transistors. Comparisons between different gases (oxygen, nitrogen, and air and nitrogen with varying relative humidities) revealed that water molecules acting as charge-trapping centers are the main cause of hysteresis in the transfer characteristics. While the hysteresis persisted even after pumping out the environmental gas for longer than 10 h at room temperature, it disappeared when the device was cooled to 240 K, suggesting a considerable increase in the time constant of the charge trapping/detrapping at these modestly low temperatures. The suppression of the hysteresis or instability in the easily attainable temperature range without surface passivation is highly advantageous for the device application of this system. The humidity dependence of the threshold voltages in the transfer curves indicates that the water molecules dominantly act as hole-trapping centers. A strong dependence of the on-state current on oxygen pressure was also observed.

  16. Inversion channel diamond metal-oxide-semiconductor field-effect transistor with normally off characteristics

    PubMed Central

    Matsumoto, Tsubasa; Kato, Hiromitsu; Oyama, Kazuhiro; Makino, Toshiharu; Ogura, Masahiko; Takeuchi, Daisuke; Inokuma, Takao; Tokuda, Norio; Yamasaki, Satoshi

    2016-01-01

    We fabricated inversion channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with normally off characteristics. At present, Si MOSFETs and insulated gate bipolar transistors (IGBTs) with inversion channels are widely used because of their high controllability of electric power and high tolerance. Although a diamond semiconductor is considered to be a material with a strong potential for application in next-generation power devices, diamond MOSFETs with an inversion channel have not yet been reported. We precisely controlled the MOS interface for diamond by wet annealing and fabricated p-channel and planar-type MOSFETs with phosphorus-doped n-type body on diamond (111) substrate. The gate oxide of Al2O3 was deposited onto the n-type diamond body by atomic layer deposition at 300 °C. The drain current was controlled by the negative gate voltage, indicating that an inversion channel with a p-type character was formed at a high-quality n-type diamond body/Al2O3 interface. The maximum drain current density and the field-effect mobility of a diamond MOSFET with a gate electrode length of 5 μm were 1.6 mA/mm and 8.0 cm2/Vs, respectively, at room temperature. PMID:27545201

  17. Integrated digital inverters based on two-dimensional anisotropic ReS₂ field-effect transistors

    SciTech Connect

    Liu, Erfu; Fu, Yajun; Wang, Yaojia; Feng, Yanqing; Liu, Huimei; Wan, Xiangang; Zhou, Wei; Wang, Baigeng; Shao, Lubin; Ho, Ching -Hwa; Huang, Ying -Sheng; Cao, Zhengyi; Wang, Laiguo; Li, Aidong; Zeng, Junwen; Song, Fengqi; Wang, Xinran; Shi, Yi; Yuan, Hongtao; Hwang, Harold Y.; Cui, Yi; Miao, Feng; Xing, Dingyu

    2015-05-07

    Semiconducting two-dimensional transition metal dichalcogenides are emerging as top candidates for post-silicon electronics. While most of them exhibit isotropic behaviour, lowering the lattice symmetry could induce anisotropic properties, which are both scientifically interesting and potentially useful. Here we present atomically thin rhenium disulfide (ReS₂) flakes with unique distorted 1T structure, which exhibit in-plane anisotropic properties. We fabricated monolayer and few-layer ReS₂ field-effect transistors, which exhibit competitive performance with large current on/off ratios (~10⁷) and low subthreshold swings (100 mV per decade). The observed anisotropic ratio along two principle axes reaches 3.1, which is the highest among all known two-dimensional semiconducting materials. Furthermore, we successfully demonstrated an integrated digital inverter with good performance by utilizing two ReS₂ anisotropic field-effect transistors, suggesting the promising implementation of large-scale two-dimensional logic circuits. Our results underscore the unique properties of two-dimensional semiconducting materials with low crystal symmetry for future electronic applications.

  18. Integrated digital inverters based on two-dimensional anisotropic ReS₂ field-effect transistors

    DOE PAGESBeta

    Liu, Erfu; Fu, Yajun; Wang, Yaojia; Feng, Yanqing; Liu, Huimei; Wan, Xiangang; Zhou, Wei; Wang, Baigeng; Shao, Lubin; Ho, Ching -Hwa; et al

    2015-05-07

    Semiconducting two-dimensional transition metal dichalcogenides are emerging as top candidates for post-silicon electronics. While most of them exhibit isotropic behaviour, lowering the lattice symmetry could induce anisotropic properties, which are both scientifically interesting and potentially useful. Here we present atomically thin rhenium disulfide (ReS₂) flakes with unique distorted 1T structure, which exhibit in-plane anisotropic properties. We fabricated monolayer and few-layer ReS₂ field-effect transistors, which exhibit competitive performance with large current on/off ratios (~10⁷) and low subthreshold swings (100 mV per decade). The observed anisotropic ratio along two principle axes reaches 3.1, which is the highest among all known two-dimensional semiconductingmore » materials. Furthermore, we successfully demonstrated an integrated digital inverter with good performance by utilizing two ReS₂ anisotropic field-effect transistors, suggesting the promising implementation of large-scale two-dimensional logic circuits. Our results underscore the unique properties of two-dimensional semiconducting materials with low crystal symmetry for future electronic applications.« less

  19. Demonstration of hetero-gate-dielectric tunneling field-effect transistors (HG TFETs)

    NASA Astrophysics Data System (ADS)

    Choi, Woo Young; Lee, Hyun Kook

    2016-06-01

    The steady scaling-down of semiconductor device for improving performance has been the most important issue among researchers. Recently, as low-power consumption becomes one of the most important requirements, there have been many researches about novel devices for low-power consumption. Though scaling supply voltage is the most effective way for low-power consumption, performance degradation is occurred for metal-oxide-semiconductor field-effect transistors (MOSFETs) when supply voltage is reduced because subthreshold swing (SS) of MOSFETs cannot be lower than 60 mV/dec. Thus, in this thesis, hetero-gate-dielectric tunneling field-effect transistors (HG TFETs) are investigated as one of the most promising alternatives to MOSFETs. By replacing source-side gate insulator with a high- k material, HG TFETs show higher on-current, suppressed ambipolar current and lower SS than conventional TFETs. Device design optimization through simulation was performed and fabrication based on simulation demonstrated that performance of HG TFETs were better than that of conventional TFETs. Especially, enlargement of gate insulator thickness while etching gate insulator at the source side was improved by introducing HF vapor etch process. In addition, the proposed HG TFETs showed higher performance than our previous results by changing structure of sidewall spacer by high- k etching process.

  20. Utilizing self-assembled-monolayer-based gate dielectrics to fabricate molybdenum disulfide field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kawanago, Takamasa; Oda, Shunri

    2016-01-01

    In this study, we apply self-assembled-monolayer (SAM)-based gate dielectrics to the fabrication of molybdenum disulfide (MoS2) field-effect transistors. A simple fabrication process involving the selective formation of a SAM on metal oxides in conjunction with the dry transfer of MoS2 flakes was established. A subthreshold slope (SS) of 69 mV/dec and no hysteresis were demonstrated with the ultrathin SAM-based gate dielectrics accompanied by a low gate leakage current. The small SS and no hysteresis indicate the superior interfacial properties of the MoS2/SAM structure. Cross-sectional transmission electron microscopy revealed a sharp and abrupt interface of the MoS2/SAM structure. The SAM-based gate dielectrics are found to be applicable to the fabrication of low-voltage MoS2 field-effect transistors and can also be extended to various layered semiconductor materials. This study opens up intriguing possibilities of SAM-based gate dielectrics in functional electronic devices.

  1. MoS2 Field-effect Transistors with Graphene/Metal Hetero-contacts

    NASA Astrophysics Data System (ADS)

    Du, Yuchen; Yang, Lingming; Zhang, Jingyun; Conrad, Nathan; Liu, Han; Ye, Peide

    2014-03-01

    MoS2, as one of the mostly studied transition-metal dichalcogenides, has already revealed a series of new physics and potential device applications. However, the performance of the MoS2 field-effect transistors is limited by the large contact resistance at metal/MoS2 interface due to the non-negligible Schottky barrier. In this study, n-type few-layer MoS2 field-effect transistors with graphene/Ti as the metal contacts have been fabricated showing more than 160 mA/mm drain current at 1 μm gate length and on-off current ratio of 107. Different metal contacts (Ti, Ni, Au, and Pd) from low work function to high work function metals on MoS2/graphene hetero contacts have been performed and studied. Moreover, for the first time, 2D Fermi-level pinning concept is introduced to understand the band alignment of hetero-structured metal/graphene/MoS2 or other 2D semiconductor interfaces. Temperature dependent, noise, and stress measurement results will also be presented.

  2. Photoresponsive and Gas Sensing Field-Effect Transistors based on Multilayer WS2 Nanoflakes

    PubMed Central

    Huo, Nengjie; Yang, Shengxue; Wei, Zhongming; Li, Shu-Shen; Xia, Jian-Bai; Li, Jingbo

    2014-01-01

    The photoelectrical properties of multilayer WS2 nanoflakes including field-effect, photosensitive and gas sensing are comprehensively and systematically studied. The transistors perform an n-type behavior with electron mobility of 12 cm2/Vs and exhibit high photosensitive characteristics with response time (τ) of <20 ms, photo-responsivity (Rλ) of 5.7 A/W and external quantum efficiency (EQE) of 1118%. In addition, charge transfer can appear between the multilayer WS2 nanoflakes and the physical-adsorbed gas molecules, greatly influencing the photoelectrical properties of our devices. The ethanol and NH3 molecules can serve as electron donors to enhance the Rλ and EQE significantly. Under the NH3 atmosphere, the maximum Rλ and EQE can even reach 884 A/W and 1.7 × 105%, respectively. This work demonstrates that multilayer WS2 nanoflakes possess important potential for applications in field-effect transistors, highly sensitive photodetectors, and gas sensors, and it will open new way to develop two-dimensional (2D) WS2-based optoelectronics. PMID:24909387

  3. High-Resolution ac Measurements of the Hall Effect in Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Yi, H. T.; Podzorov, V.

    2016-03-01

    We describe a high resolving power technique for Hall-effect measurements, efficient in determining Hall mobility and carrier density in organic field-effect transistors and other low-mobility systems. We utilize a small low-frequency ac magnetic field (Brms<0.25 T ) and a phase-sensitive (lock-in) detection of Hall voltage, with the necessary corrections for Faraday induction. This method significantly enhances the signal-to-noise ratio and eliminates the necessity of using high magnetic fields in Hall-effect studies. With the help of this method, we are able to obtain the Hall mobility and carrier density in organic transistors with a mobility as low as μ ˜0.3 cm2 V-1 s-1 by using a compact desktop apparatus and low magnetic fields. We find a good agreement between Hall-effect and electric-field-effect measurements, indicating that, contrary to the common belief, certain organic semiconductors with mobilities below 1 cm2 V-1 s-1 can still exhibit a fully developed, band-semiconductor-like Hall effect, with the Hall mobility and carrier density matching those obtained in longitudinal transistor measurements. This suggests that, even when μ <1 cm2 V-1 s-1 , charges in organic semiconductors can still behave as delocalized coherent carriers. This technique paves the way to ubiquitous Hall-effect studies in a wide range of low-mobility materials and devices, where it is typically very difficult to resolve the Hall effect even in very high dc magnetic fields.

  4. Focused Ion Beam Fabrication of Silicon-On Field-Effect Transistors.

    NASA Astrophysics Data System (ADS)

    Mattiussi, Greg Andrew

    N-channel metal-oxide-semiconductor field-effect transistors (MOSFET's) have been fabricated on silicon -on-insulator (SOI) substrates using a Focused Ion Beam (FIB) to pattern the gate and to dope the source and drains. Lightly -doped source (LDS) structures were implemented with the FIB to increase the drain-to-source voltage at which single transistor latch-up occurred. FIB exposure of two electron-beam resists was investigated for lithography of the transistor gate and the device mesas. Vertical resist profiles were achieved for linewidths down to 0.2 μm in width in the case of the negative-tone SAL-601 resist from Shipley Co. Openings in resist as narrow as 0.35 μm were made using the positive-tone P28 resist from OCG Microelectronic Materials. Optimal doses, pre- and post-exposure processing conditions were determined for both resists. Transistors with LDS structures showed higher latching voltages than those without. The magnitude of the increase in latching voltage due to the LDS was a function of body doping level, SOI thickness, and coded gate length. The largest increase was 5.1 V for a 0.8 μm MOSFET fabricated in a 125 nm thick SOI film with a body implant dose of 5.6times10^ {12} B cm^{-2}. Devices fabricated in SOI films of thickness 250 nm showed smaller increases in latching voltage with the LDS than those in 125 nm SOI films.

  5. Carbon Nanostructure-Based Field-Effect Transistors for Label-Free Chemical/Biological Sensors

    PubMed Central

    Hu, PingAn; Zhang, Jia; Li, Le; Wang, Zhenlong; O’Neill, William; Estrela, Pedro

    2010-01-01

    Over the past decade, electrical detection of chemical and biological species using novel nanostructure-based devices has attracted significant attention for chemical, genomics, biomedical diagnostics, and drug discovery applications. The use of nanostructured devices in chemical/biological sensors in place of conventional sensing technologies has advantages of high sensitivity, low decreased energy consumption and potentially highly miniaturized integration. Owing to their particular structure, excellent electrical properties and high chemical stability, carbon nanotube and graphene based electrical devices have been widely developed for high performance label-free chemical/biological sensors. Here, we review the latest developments of carbon nanostructure-based transistor sensors in ultrasensitive detection of chemical/biological entities, such as poisonous gases, nucleic acids, proteins and cells. PMID:22399927

  6. Carbon Nanotube Synaptic Transistor Network for Pattern Recognition.

    PubMed

    Kim, Sungho; Yoon, Jinsu; Kim, Hee-Dong; Choi, Sung-Jin

    2015-11-18

    Inspired by the human brain, a neuromorphic system combining complementary metal-oxide semiconductor (CMOS) and adjustable synaptic devices may offer new computing paradigms by enabling massive neural-network parallelism. In particular, synaptic devices, which are capable of emulating the functions of biological synapses, are used as the essential building blocks for an information storage and processing system. However, previous synaptic devices based on two-terminal resistive devices remain challenging because of their variability and specific physical mechanisms of resistance change, which lead to a bottleneck in the implementation of a high-density synaptic device network. Here we report that a three-terminal synaptic transistor based on carbon nanotubes can provide reliable synaptic functions that encode relative timing and regulate weight change. In addition, using system-level simulations, the developed synaptic transistor network associated with CMOS circuits can perform unsupervised learning for pattern recognition using a simplified spike-timing-dependent plasticity scheme. PMID:26512729

  7. Radio frequency analog electronics based on carbon nanotube transistors.

    PubMed

    Kocabas, Coskun; Kim, Hoon-Sik; Banks, Tony; Rogers, John A; Pesetski, Aaron A; Baumgardner, James E; Krishnaswamy, S V; Zhang, Hong

    2008-02-01

    The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies. PMID:18227509

  8. Radio frequency analog electronics based on carbon nanotube transistors

    PubMed Central

    Kocabas, Coskun; Kim, Hoon-sik; Banks, Tony; Rogers, John A.; Pesetski, Aaron A.; Baumgardner, James E.; Krishnaswamy, S. V.; Zhang, Hong

    2008-01-01

    The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies. PMID:18227509

  9. Defect Screening Effects of Fluoropolymer Capping in Single Walled Carbon Nanotube Transistors

    NASA Astrophysics Data System (ADS)

    Jang, Seonpil; Kim, Bongjun; Geier, Michael; Hersam, Mark; Dodabalapur, Ananth

    2015-03-01

    One of the most promising uses of single walled carbon nanotubes (SWCNTs) is as active channel semiconductor materials in field-effect transistors (FETs). Recent advances in the availability of highly sorted semiconducting SWCNT source material and in printing such nanotubes to realize high-performance thin-film transistors make them very promising candidates for printed electronics. In this presentation, we report on the substantial improvements in the characteristics of SWCNT FET devices and circuits comprised of these devices by the use of coatings of the fluoropolymer containing copolymer, PVDF-TrFE. The origins of these improvements may be attributed to the polar nature of C-F bonds and the local organization of the fluoropolymer at the interfaces with the SWCNTs so as to partially neutralize charged defects. This hypothesis was tested by the experiments using a number of vapor phase polar molecules which produce similar effects on the FET characteristics. The polar vapor experiments show that dipoles can partially neutralize residual charges arising from defects/impurities. The dipole present in polar molecules adopts an orientation that tends to cancel the effects of the charged defect/impurity from the perspective of mobile charges in the SWCNTs.

  10. 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. PMID:27121370

  11. Water soluble poly(1-vinyl-1,2,4-triazole) as novel dielectric layer for organic field effect transistors

    PubMed Central

    Abbas, Mamatimin; Cakmak, Gulbeden; Tekin, Nalan; Kara, Ali; Guney, Hasan Yuksel; Arici, Elif; Sariciftci, Niyazi Serdar

    2011-01-01

    Water soluble poly(1-vinyl-1,2,4-triazole) (PVT) as a novel dielectric layer for organic field effect transistor is studied. Dielectric spectroscopy characterization reveals it has low leakage current and rather high breakdown voltage. Both n-channel and p-channel organic field effect transistors are fabricated using pentacene and fullerene as active layers. Both devices show device performances with lack of hysteresis, very low threshold voltages and high on/off ratios. Excellent film formation property is utilized to make AlOx and thin PVT bilayer in order to decrease the operating voltage of the devices. All solution processed ambipolar device is fabricated with simple spin coating steps using poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH–PPV) end capped with polyhedral oligomeric silsesquioxanes (POSS) as active layer. Our investigations show that PVT can be a very promising dielectric for organic field effect transistors. PMID:23794963

  12. Position-dependent performance of copper phthalocyanine based field-effect transistors by gold nanoparticles modification.

    PubMed

    Luo, Xiao; Li, Yao; Lv, Wenli; Zhao, Feiyu; Sun, Lei; Peng, Yingquan; Wen, Zhanwei; Zhong, Junkang; Zhang, Jianping

    2015-01-21

    A facile fabrication and characteristics of copper phthalocyanine (CuPc)-based organic field-effect transistor (OFET) using the gold nanoparticles (Au NPs) modification is reported, thereby achieving highly improved performance. The effect of Au NPs located at three different positions, that is, at the SiO2/CuPc interface (device B), embedding in the middle of CuPc layer (device C), and on the top of CuPc layer (device D), is investigated, and the results show that device D has the best performance. Compared with the device without Au NPs (reference device A), device D displays an improvement of field-effect mobility (μ(sat)) from 1.65 × 10(-3) to 5.51 × 10(-3) cm(2) V(-1) s(-1), and threshold voltage decreases from -23.24 to -16.12 V. Therefore, a strategy for the performance improvement of the CuPc-based OFET with large field-effect mobility and saturation drain current is developed, on the basis of the concept of nanoscale Au modification. The model of an additional electron transport channel formation by FET operation at the Au NPs/CuPc interface is therefore proposed to explain the observed performance improvement. Optimum CuPc thickness is confirmed to be about 50 nm in the present study. The device-to-device uniformity and time stability are discussed for future application. PMID:25548878

  13. Material properties and field-effect transistor characteristics of hybrid organic/graphene active layers

    NASA Astrophysics Data System (ADS)

    Ha, Tae-Jun; Lee, Jongho; Chowdhury, Sk. Fahad; Akinwande, Deji; Dodabalapur, Ananth

    2012-10-01

    We report on the material properties and device characteristics of field-effect transistors (FETs) consisting of hybrid mono-layer graphene/organic semiconductor active layers. By capping with selected organic and polymeric layers, transformation of the electronic characteristics of mono-layer graphene FETs was observed. The off-state current is reduced while the on-state current and field-effect mobility are either unaffected or increased after depositing π-conjugated organic semiconductors. Significantly, capping mono-layer graphene FETs with fluoropolymer improved the on-off current ratio from 5 to 10 as well as increased the field-effect mobility by factor of two compared to plain graphene FETs. Removal of π-conjugated organic semiconductors or fluoropolymer from graphene FETs results in a return to the original electronic properties of mono-layer graphene FETs. This suggests that weak reversible electronic interactions between graphene and π-conjugated organic semiconductors/fluoropolymer favorably tune the material and electrical characteristics of mono-layer graphene.

  14. Terahertz signal detection in a short gate length field-effect transistor with a two-dimensional electron gas

    SciTech Connect

    Vostokov, N. V. Shashkin, V. I.

    2015-11-28

    We consider the problem of non-resonant detection of terahertz signals in a short gate length field-effect transistor having a two-dimensional electron channel with zero external bias between the source and the drain. The channel resistance, gate-channel capacitance, and quadratic nonlinearity parameter of the transistor during detection as a function of the gate bias voltage are studied. Characteristics of detection of the transistor connected in an antenna with real impedance are analyzed. The consideration is based on both a simple one-dimensional model of the transistor and allowance for the two-dimensional distribution of the electric field in the transistor structure. The results given by the different models are discussed.

  15. Phonon populations and electrical power dissipation in carbon nanotube transistors.

    PubMed

    Steiner, Mathias; Freitag, Marcus; Perebeinos, Vasili; Tsang, James C; Small, Joshua P; Kinoshita, Megumi; Yuan, Dongning; Liu, Jie; Avouris, Phaedon

    2009-05-01

    Carbon nanotubes and graphene are candidate materials for nanoscale electronic devices. Both materials show weak acoustic phonon scattering and long mean free paths for low-energy charge carriers. However, high-energy carriers couple strongly to optical phonons, which leads to current saturation and the generation of hot phonons. A non-equilibrium phonon distribution has been invoked to explain the negative differential conductance observed in suspended metallic nanotubes, while Raman studies have shown the electrical generation of hot G-phonons in metallic nanotubes. Here, we present a complete picture of the phonon distribution in a functioning nanotube transistor including the G and the radial breathing modes, the Raman-inactive zone boundary K mode and the intermediate-frequency mode populated by anharmonic decay. The effective temperatures of the high- and intermediate-frequency phonons are considerably higher than those of acoustic phonons, indicating a phonon-decay bottleneck. Most importantly, inclusion of scattering by substrate polar phonons is needed to fully account for the observed electronic transport behaviour. PMID:19421219

  16. Detection of terahertz radiation by tightly concatenated InGaAs field-effect transistors integrated on a single chip

    SciTech Connect

    Popov, V. V.; Yermolaev, D. M.; Shapoval, S. Yu.; Maremyanin, K. V.; Gavrilenko, V. I.; Zemlyakov, V. E.; Bespalov, V. A.; Yegorkin, V. I.; Maleev, N. A.; Ustinov, V. M.

    2014-04-21

    A tightly concatenated chain of InGaAs field-effect transistors with an asymmetric T-gate in each transistor demonstrates strong terahertz photovoltaic response without using supplementary antenna elements. We obtain the responsivity above 1000 V/W and up to 2000 V/W for unbiased and drain-biased transistors in the chain, respectively, with the noise equivalent power below 10{sup −11} W/Hz{sup 0.5} in the unbiased mode of the detector operation.

  17. Low-power bacteriorhodopsin-silicon n-channel metal-oxide field-effect transistor photoreceiver.

    PubMed

    Shin, Jonghyun; Bhattacharya, Pallab; Yuan, Hao-Chih; Ma, Zhenqiang; Váró, György

    2007-03-01

    A bacteriorhodopsin (bR)-silicon n-channel metal-oxide field-effect transistor (NMOSFET) monolithically integrated photoreceiver is demonstrated. The bR film is selectively formed on an external gate electrode of the transistor by electrophoretic deposition. A modified biasing circuit is incorporated, which helps to match the resistance of the bR film to the input impedance of the NMOSFET and to shift the operating point of the transistor to coincide with the maximum gain. The photoreceiver exhibits a responsivity of 4.7 mA/W. PMID:17392901

  18. High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Che, Yuchi; Seo, Jung-Woo T.; Gui, Hui; Hersam, Mark C.; Zhou, Chongwu

    2016-06-01

    In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ˜1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ˜100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

  19. Micropatterned single-walled carbon nanotube electrodes for use in high-performance transistors and inverters.

    PubMed

    Kang, Woonggi; Kim, Nam Hee; Lee, Dong Yun; Chang, Suk Tai; Cho, Jeong Ho

    2014-06-25

    We demonstrated the solution-processed single-walled carbon nanotube (SWNT) source-drain electrodes patterned using a plasma-enhanced detachment patterning method for high-performance organic transistors and inverters. The high-resolution SWNT electrode patterning began with the formation of highly uniform SWNT thin films on a hydrophobic silanized substrate. The SWNT source-drain patterns were then formed by modulating the interfacial energies of the prepatterned elastomeric mold and the SWNT thin film using oxygen plasma. The SWNT films were subsequently selectively delaminated using a rubber mold. The patterned SWNTs could be used as the source-drain electrodes for both n-type PTCDI-C8 and p-type pentacene field-effect transistors (FETs). The n- and p-type devices exhibited good and exactly matched electrical performances, with a field-effect mobility of around 0.15 cm(2) V(-1) s(-1) and an ON/OFF current ratio exceeding 10(6). The single electrode material was used for both the n and p channels, permitting the successful fabrication of a high-performance complementary inverter by connecting a p-type pentacene FET to an n-type PTCDI-C8 FET. This patterning technique was simple, inexpensive, and easily scaled for the preparation of large-area electrode micropatterns for flexible microelectronic device fabrication. PMID:24915751

  20. Field Effect Transistor Behavior in Electrospun Polyaniline/Polyethylene Oxide Demonstrated

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; Theofylaktos, Onoufrios; Robinson, Daryl C.; Miranda, Felix A.

    2004-01-01

    Novel transistors and logic devices based on nanotechnology concepts are under intense development. The potential for ultra-low-power circuitry makes nanotechnology attractive for applications such as digital electronics and sensors. For NASA applications, nanotechnology offers tremendous opportunities for increased onboard data processing, and thus autonomous decisionmaking ability, and novel sensors that detect and respond to environmental stimuli with little oversight requirements. Polyaniline/polyethylene oxide (PANi/PEO) nanofibers are of interest because they have electrical conductivities that can be changed from insulating to metallic by varying the doping levels and conformations of the polymer chain. At the NASA Glenn Research Center, we have observed field effect transistor (FET) behavior in electrospun PANi/PEO nanofibers doped with camphorsulfonic acid. The nanofibers were deposited onto Au electrodes, which had been prepatterned onto oxidized silicon substrates. The preceding scanning electron image shows the device used in the transistor measurements. Saturation channel currents are observed at surprisingly low source/drain voltages (see the following graph). The hole mobility in the depletion regime is 1.4x10(exp -4)sq cm/V sec, whereas the one-dimensional charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx.10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating one-dimensional polymer FET's.

  1. A graphene field-effect transistor as a molecule-specific probe of DNA nucleobases.

    PubMed

    Dontschuk, Nikolai; Stacey, Alastair; Tadich, Anton; Rietwyk, Kevin J; Schenk, Alex; Edmonds, Mark T; Shimoni, Olga; Pakes, Chris I; Prawer, Steven; Cervenka, Jiri

    2015-01-01

    Fast and reliable DNA sequencing is a long-standing target in biomedical research. Recent advances in graphene-based electrical sensors have demonstrated their unprecedented sensitivity to adsorbed molecules, which holds great promise for label-free DNA sequencing technology. To date, the proposed sequencing approaches rely on the ability of graphene electric devices to probe molecular-specific interactions with a graphene surface. Here we experimentally demonstrate the use of graphene field-effect transistors (GFETs) as probes of the presence of a layer of individual DNA nucleobases adsorbed on the graphene surface. We show that GFETs are able to measure distinct coverage-dependent conductance signatures upon adsorption of the four different DNA nucleobases; a result that can be attributed to the formation of an interface dipole field. Comparison between experimental GFET results and synchrotron-based material analysis allowed prediction of the ultimate device sensitivity, and assessment of the feasibility of single nucleobase sensing with graphene. PMID:25800494

  2. Design Architecture of field-effect transistor with back gate electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

    2016-07-01

    This paper presents the preparation method of photolithography chrome mask design used in fabrication process of field-effect transistor with back gate biasing based biosensor. Initially, the chrome masks are designed by studying the process flow of the biosensor fabrication, followed by drawing of the actual chrome mask using the AutoCAD software. The overall width and length of the device is optimized at 16 mm and 16 mm, respectively. Fabrication processes of the biosensor required five chrome masks, which included source and drain formation mask, the back gate area formation mask, electrode formation mask, front gate area formation mask, and passivation area formation mask. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

  3. An underlap field-effect transistor for electrical detection of influenza

    NASA Astrophysics Data System (ADS)

    Lee, Kwang-Won; Choi, Sung-Jin; Ahn, Jae-Hyuk; Moon, Dong-Il; Park, Tae Jung; Lee, Sang Yup; Choi, Yang-Kyu

    2010-01-01

    An underlap channel-embedded field-effect transistor (FET) is proposed for label-free biomolecule detection. Specifically, silica binding protein fused with avian influenza (AI) surface antigen and avian influenza antibody (anti-AI) were designed as a receptor molecule and a target material, respectively. The drain current was significantly decreased after the binding of negatively charged anti-AI on the underlap channel. A set of control experiments supports that only the biomolecules on the underlap channel effectively modulate the drain current. With the merits of a simple fabrication process, complementary metal-oxide-semiconductor compatibility, and enhanced sensitivity, the underlap FET could be a promising candidate for a chip-based biosensor.

  4. Low frequency noise characteristics in multilayer WSe2 field effect transistor

    NASA Astrophysics Data System (ADS)

    Cho, In-Tak; Kim, Jong In; Hong, Yoonki; Roh, Jeongkyun; Shin, Hyeonwoo; Baek, Geun Woo; Lee, Changhee; Hong, Byung Hee; Jin, Sung Hun; Lee, Jong-Ho

    2015-01-01

    This paper investigates the low-frequency noise properties of multilayer WSe2 field effect transistors (FETs) in subthreshold, linear, and saturation regime. The measured noise power spectral density of drain current (SID) shows that the low-frequency noise in multilayer WSe2 FET fits well to a 1/fγ power law with γ ˜ 1 in the frequency range of 10 Hz-200 Hz. From the dependence of SID on the drain current, carrier mobility fluctuation is considered as a dominant low frequency noise mechanism from all operation regimes in multilayer WSe2 FET. Extracted Hooge's parameter in this study is within the value of 0.12, comparable to those of the transition metal dichalcogenide FETs in recent reports.

  5. High-gain inverters based on WSe2 complementary field-effect transistors.

    PubMed

    Tosun, Mahmut; Chuang, Steven; Fang, Hui; Sachid, Angada B; Hettick, Mark; Lin, Yongjing; Zeng, Yuping; Javey, Ali

    2014-05-27

    In this work, the operation of n- and p-type field-effect transistors (FETs) on the same WSe2 flake is realized,and a complementary logic inverter is demonstrated. The p-FET is fabricated by contacting WSe2 with a high work function metal, Pt, which facilities hole injection at the source contact. The n-FET is realized by utilizing selective surface charge transfer doping with potassium to form degenerately doped n+ contacts for electron injection. An ON/OFF current ratio of >10(4) is achieved for both n- and p-FETs with similar ON current densities. A dc voltage gain of >12 is measured for the complementary WSe2 inverter. This work presents an important advance toward realization of complementary logic devices based on layered chalcogenide semiconductors for electronic applications. PMID:24684575

  6. Electrically configurable graphene field-effect transistors with a graded-potential gate.

    PubMed

    Wang, Xiaowei; Jiang, Xingbin; Wang, Ting; Shi, Jia; Liu, Mingju; Zeng, Qibin; Cheng, Zhihai; Qiu, Xiaohui

    2015-05-13

    A device architecture for electrically configurable graphene field-effect transistor (GFET) using a graded-potential gate is present. The gating scheme enables a linearly varying electric field that modulates the electronic structure of graphene and causes a continuous shift of the Dirac points along the channel of GFET. This spatially varying electrostatic modulation produces a pseudobandgap observed as a suppressed conductance of graphene within a controllable energy range. By tuning the electrical gradient of the gate, a GFET device is reversibly transformed between ambipolar and n- and p-type unipolar characteristics. We further demonstrate an electrically programmable complementary inverter, showing the extensibility of the proposed architecture in constructing logic devices based on graphene and other Dirac materials. The electrical configurable GFET might be explored for novel functionalities in smart electronics. PMID:25897889

  7. 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.

  8. Effect of ferroelectric substrate on carrier mobility in graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Bidmeshkipour, S.; Vorobiev, A.; Andersson, M. A.; Kompany, A.; Stake, J.

    2015-10-01

    Effect of LiNbO3 ferroelectric substrate on the carrier mobility in top gated graphene field-effect transistors (G-FETs) is demonstrated. It is shown that, at the same residual concentration of the charge carriers, the mobility in the G-FETs on the LiNbO3 substrate is higher than that on the SiO2/Si substrate. The effect is associated with reduction of Coulomb scattering via screening the charged impurity field by the field induced in the ferroelectric substrate, but significant only for mobilities below 1000 cm2/V s. Raman spectra analysis and correlations established between mobility and microwave loss tangent of the Al2O3 gate dielectric indicate that the charged impurities are located predominantly at the gate dielectric and/or at the gate dielectric/graphene interface and are likely associated with oxygen vacancies.

  9. Investigation of drift effect on silicon nanowire field effect transistor based pH sensor

    NASA Astrophysics Data System (ADS)

    Kim, Sihyun; Kwon, Dae Woong; Lee, Ryoongbin; Kim, Dae Hwan; Park, Byung-Gook

    2016-06-01

    It is widely accepted that the operation mechanism of pH-sensitive ion sensitive field effect transistor (ISFET) can be divided into three categories; reaction of surface sites, chemical modification of insulator surface, and ionic diffusion into the bulk of insulator. The first mechanism is considered as the main operation mechanism of pH sensors due to fast response, while the others with relatively slow responses disturb accurate pH detection. In this study, the slow responses (often called drift effects) are investigated in silicon nanowire (SiNW) pH-sensitive ISFETs. Based on the dependence on the channel type of SiNW, liquid gate bias, and pH, it is clearly revealed that the drift of n-type SiNW results from H+ diffusion into the insulator whereas that of p-type SiNW is caused by chemical modification (hydration) of the insulator.

  10. Tuning the electronic properties of ZnO nanowire field effect transistors via surface functionalization.

    PubMed

    Han, Cheng; Xiang, Du; Zheng, Minrui; Lin, Jiadan; Zhong, Jianqiang; Sow, Chorng Haur; Chen, Wei

    2015-03-01

    Using in situ field effect transistor (FET) characterization combined with the molecular beam epitaxy technique, we demonstrate a significant depletion of electron charge carriers in single zinc oxide (ZnO) nanowire through the surface modification with molybdenum trioxide (MoO3) and 1, 4, 5, 8, 9, 11-hexaazatriphenylene hexacarbonitrile (HATCN) layers. The electron mobility of ZnO nanowire was found to sharply decrease after the surface modification with MoO3; in contrast, the electron mobility significantly increased after functionalization with HATCN layers. Such depletion of n-type conduction originates from the interfacial charge transfer, corroborated by in situ photoelectron spectroscopy studies. The air exposure effect on MoO(3-) and HATCN-coated ZnO nanowire devices was also investigated. PMID:25676393

  11. Tuning the electronic properties of ZnO nanowire field effect transistors via surface functionalization

    NASA Astrophysics Data System (ADS)

    Han, Cheng; Xiang, Du; Zheng, Minrui; Lin, Jiadan; Zhong, Jianqiang; Haur Sow, Chorng; Chen, Wei

    2015-03-01

    Using in situ field effect transistor (FET) characterization combined with the molecular beam epitaxy technique, we demonstrate a significant depletion of electron charge carriers in single zinc oxide (ZnO) nanowire through the surface modification with molybdenum trioxide (MoO3) and 1, 4, 5, 8, 9, 11-hexaazatriphenylene hexacarbonitrile (HATCN) layers. The electron mobility of ZnO nanowire was found to sharply decrease after the surface modification with MoO3; in contrast, the electron mobility significantly increased after functionalization with HATCN layers. Such depletion of n-type conduction originates from the interfacial charge transfer, corroborated by in situ photoelectron spectroscopy studies. The air exposure effect on MoO3- and HATCN-coated ZnO nanowire devices was also investigated.

  12. Organic nanofibers integrated by transfer technique in field-effect transistor devices

    PubMed Central

    2011-01-01

    The electrical properties of self-assembled organic crystalline nanofibers are studied by integrating these on field-effect transistor platforms using both top and bottom contact configurations. In the staggered geometries, where the nanofibers are sandwiched between the gate and the source-drain electrodes, a better electrical conduction is observed when compared to the coplanar geometry where the nanofibers are placed over the gate and the source-drain electrodes. Qualitatively different output characteristics were observed for top and bottom contact devices reflecting the significantly different contact resistances. Bottom contact devices are dominated by contact effects, while the top contact device characteristics are determined by the nanofiber bulk properties. It is found that the contact resistance is lower for crystalline nanofibers when compared to amorphous thin films. These results shed light on the charge injection and transport properties for such organic nanostructures and thus constitute a significant step forward toward a nanofiber-based light-emitting device. PMID:21711821

  13. Controlling the on/off current ratio of ferroelectric field-effect transistors

    PubMed Central

    Katsouras, Ilias; Zhao, Dong; Spijkman, Mark-Jan; Li, Mengyuan; Blom, Paul W. M.; Leeuw, Dago M. de; Asadi, Kamal

    2015-01-01

    The on/off current ratio in organic ferroelectric field-effect transistors (FeFETs) is largely determined by the position of the threshold voltage, the value of which can show large device-to-device variations. Here we show that by employing a dual-gate layout for the FeFET, we can gain full control over the on/off ratio. In the resulting dual-gate FeFET the ferroelectric gate provides the memory functionality and the second, non-ferroelectric, control gate is advantageously used to set the threshold voltage. The on/off ratio can thus be maximized at the readout bias. The operation is explained by the quantitative analysis of charge transport in a dual-gate FeFET. PMID:26160465

  14. Electrical properties of high density arrays of silicon nanowire field effect transistors

    NASA Astrophysics Data System (ADS)

    Kim, Hye-Young; Lee, Kangho; Lee, Jae Woo; Kim, Sangwook; Kim, Gyu-Tae; Duesberg, Georg S.

    2013-10-01

    Proximity effect corrected e-beam lithography of hydrogen silsesquioxane on silicon on insulator was used to fabricate multi-channel silicon nanowire field-effect transistors (SiNW FETs). Arrays of 15-channels with a line width of 18 nm and pitch as small as 50 nm, the smallest reported for electrically functional devices, were fabricated. These high density arrays were back-gated by the substrate and allowed for investigation of the effects of scaling on the electrical performance of this multi-channel SiNW FET. It was revealed that the drain current and the transconductance (gm) are both reduced with decreasing pitch size. The drain induced barrier lowering and the threshold voltage (Vth) are also decreased, whereas the subthreshold swing (S) is increased. The results are in agreement with our simulations of the electric potential profile of the devices. The study contains valuable information on SiNW FET integration and scaling for future devices.

  15. Low Temperature Solution-Processed Gate Dielectrics for Low-Voltage Organic Field-Effect Transistors.

    PubMed

    Ha, Young-Geun

    2015-09-01

    We report on the design, preparation, and electrical properties of novel solution-processed organic-inorganic hybrid dielectric films for the low-voltage operation of organic field-effect transistors (OFETs). Hybrid dielectric thin films (-20 nm thick) are easily fabricated by spin-coating a zirconium chloride precursor/organic additive reagent mixture, followed by annealing at low temperatures (-150 degrees C). The smooth and transparent hybrid dielectrics exhibit great insulating properties (leakage current densities -10(-7) A/cm2 at 2 MV/cm), high capacitance (170 nF/cm2). OFETs fabricated with hybrid dielectric and pentacene semiconductor function great at relatively low voltage (mobility: 1 cm2/V x s, on/off current ratio: 10(5)). PMID:26716219

  16. Disturbance characteristics of charge trap flash memory with tunneling field-effect transistor

    NASA Astrophysics Data System (ADS)

    Xi, Ning; Cho, Eou-Sik; Choi, Woo Young; Cho, Il Hwan

    2014-11-01

    In this study, the disturbance characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) memory based on the tunneling field-effect transistor (TFET) are investigated in terms of the Fowler-Nordheim (FN) program. Since the TFET SONOS memory uses a depletion channel region for program inhibition, the tunneling of an inhibited cell considers both the electron concentration and the vertical electric field. The effects of both parameters on tunneling current are analyzed using device simulation and the tunneling current equation. The tunneling current of the source-side region depends on the electric field and that of the drain-side region depends on the electron concentration. These results can be applied to the performance optimization of the TFET SONOS memory.

  17. Self-aligned multi-channel silicon nanowire field-effect transistors

    NASA Astrophysics Data System (ADS)

    Zhu, Hao; Li, Qiliang; Yuan, Hui; Baumgart, Helmut; Ioannou, Dimitris E.; Richter, Curt A.

    2012-12-01

    Si nanowire field effect transistors (SiNW FETs) with multiple nanowire channels and different gate lengths have been fabricated by using a directed assembly approach combined with a standard photolithographic process. The electrical characteristics of SiNW FETs containing different numbers of nanowire channels were measured and compared. The multi-channel SiNW FETs show excellent performance: small subthreshold slope (≈75 mV/dec), large ON/OFF ratio (≈108), good break-down voltage (>30 V) and good carrier mobility (μp ≈ 100 cm2 V-1s-1). These excellent device properties were achieved by using a clean self-alignment process and an improved device structure with Schottky barriers at the source and drain contacts. Such high-performance multi-nanowire FETs are attractive for logic, memory, and sensor applications.

  18. High-Mobility Holes in Dual-Gated WSe2 Field-Effect Transistors.

    PubMed

    Movva, Hema C P; Rai, Amritesh; Kang, Sangwoo; Kim, Kyounghwan; Fallahazad, Babak; Taniguchi, Takashi; Watanabe, Kenji; Tutuc, Emanuel; Banerjee, Sanjay K

    2015-10-27

    We demonstrate dual-gated p-type field-effect transistors (FETs) based on few-layer tungsten diselenide (WSe2) using high work-function platinum source/drain contacts and a hexagonal boron nitride top-gate dielectric. A device topology with contacts underneath the WSe2 results in p-FETs with ION/IOFF ratios exceeding 10(7) and contacts that remain ohmic down to cryogenic temperatures. The output characteristics show current saturation and gate tunable negative differential resistance. The devices show intrinsic hole mobilities around 140 cm(2)/(V s) at room temperature and approaching 4000 cm(2)/(V s) at 2 K. Temperature-dependent transport measurements show a metal-insulator transition, with an insulating phase at low densities and a metallic phase at high densities. The mobility shows a strong temperature dependence consistent with phonon scattering, and saturates at low temperatures, possibly limited by Coulomb scattering or defects. PMID:26343531

  19. Microscopic origin of low frequency noise in MoS{sub 2} field-effect transistors

    SciTech Connect

    Ghatak, Subhamoy; Jain, Manish; Ghosh, Arindam; Mukherjee, Sumanta; Sarma, D. D.

    2014-09-01

    We report measurement of low frequency 1/f noise in molybdenum di-sulphide (MoS{sub 2}) field-effect transistors in multiple device configurations including MoS{sub 2} on silicon dioxide as well as MoS{sub 2}-hexagonal boron nitride (hBN) heterostructures. All as-fabricated devices show similar magnitude of noise with number fluctuation as the dominant mechanism at high temperatures and density, although the calculated density of traps is two orders of magnitude higher than that at the SiO{sub 2} interface. Measurements on the heterostructure devices with vacuum annealing and dual gated configuration reveals that along with the channel, metal-MoS{sub 2} contacts also play a significant role in determining noise magnitude in these devices.

  20. A theoretical design of graphene-based spin field-effect transistors

    NASA Astrophysics Data System (ADS)

    Liu, Lixue; Liu, Shudun; Zhu, Wenguang

    The search for a feasible design of graphene-based materials for spintronics applications has been intensified in recent years. Encouraged by recent experimental achievements, here we propose a new scheme to realize graphene-based spin field-effect transistors. The new design is constituted of a half-hydrogenated graphene nanoroad embedded in a fully-hydrogenated graphene. Using first-principles density function theory calculations, we demonstrate that such a design can convert non-magnetic pristine graphene into a bipolar ferromagnetic semiconductor. More importantly, the magnetism of such a nanoroad is very robust: independent of its width and orientation. We also discuss the stability of such nanoroads, as well as a simple design of an all-electric controlled device for generation and detection of a fully spin-polarized electric current.

  1. Optical and electrical properties of electrochemically doped organic field effect transistors.

    PubMed

    Yumusak, Cigdem; Abbas, Mamatimin; Sariciftci, Niyazi Serdar

    2013-02-01

    Mixed ionic/electronic conduction in conducting polymers introduces new physics/chemistry and an additional functionality in organic optoelectronic devices. The incorporation of an ionic species in a conjugated polymer matrix results in the increase in electrical conductivity associated with the electrochemical doping of the material. In recent years polymer light emitting electrochemical cells (LECs) have been demonstrated. In such electrochemical optoelectronic devices, mobile ions facilitate the efficient injection of electronic charge carriers creating "in situ" doping regions near the electrodes and lead to efficient electroluminescence light emission. Here, we introduce the same concept of an LEC in the organic field effect transistors (OFETs). The presence of both electronic and ionic charge carriers in the active layers of OFETs brings high charge carrier mobility and light emission even using symmetric source and drain metal electrodes. PMID:23482672

  2. Recovery Based Nanowire Field-Effect Transistor Detection of Pathogenic Avian Influenza DNA

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Heng; Chu, Chia-Jung; Teng, Kang-Ning; Su, Yi-Jr; Chen, Chii-Dong; Tsai, Li-Chu; Yang, Yuh-Shyong

    2012-02-01

    Fast and accurate diagnosis is critical in infectious disease surveillance and management. We proposed a DNA recovery system that can easily be adapted to DNA chip or DNA biosensor for fast identification and confirmation of target DNA. This method was based on the re-hybridization of DNA target with a recovery DNA to free the DNA probe. Functionalized silicon nanowire field-effect transistor (SiNW FET) was demonstrated to monitor such specific DNA-DNA interaction using high pathogenic strain virus hemagglutinin 1 (H1) DNA of avian influenza (AI) as target. Specific electric changes were observed in real-time for AI virus DNA sensing and device recovery when nanowire surface of SiNW FET was modified with complementary captured DNA probe. The recovery based SiNW FET biosensor can be further developed for fast identification and further confirmation of a variety of influenza virus strains and other infectious diseases.

  3. Leakage and field emission in side-gate graphene field effect transistors

    NASA Astrophysics Data System (ADS)

    Di Bartolomeo, A.; Giubileo, F.; Iemmo, L.; Romeo, F.; Russo, S.; Unal, S.; Passacantando, M.; Grossi, V.; Cucolo, A. M.

    2016-07-01

    We fabricate planar graphene field-effect transistors with self-aligned side-gate at 100 nm from the 500 nm wide graphene conductive channel, using a single lithographic step. We demonstrate side-gating below 1 V with conductance modulation of 35% and transconductance up to 0.5 mS/mm at 10 mV drain bias. We measure the planar leakage along the SiO2/vacuum gate dielectric over a wide voltage range, reporting rapidly growing current above 15 V. We unveil the microscopic mechanisms driving the leakage, as Frenkel-Poole transport through SiO2 up to the activation of Fowler-Nordheim tunneling in vacuum, which becomes dominant at higher voltages. We report a field-emission current density as high as 1 μA/μm between graphene flakes. These findings are important for the miniaturization of atomically thin devices.

  4. TCAD Simulations of graphene field-effect transistors based on the quantum capacitance effect

    NASA Astrophysics Data System (ADS)

    Hafsi, Bilel; Boubaker, Aïmen; Ismaïl, Naoufel; Kalboussi, Adel; Lmimouni, Kamal

    2015-10-01

    In this paper, the results of a comparative study between experimental measurements and technology computer-aided design (TCAD) simulations of graphene field-effect transistors (GFET) are presented. Our simulations were performed to study the electrical properties of few-layer graphene, and the physical approach to the simulation tools is described by using the basics of band theory, Poisson's equation, the continuity equation and the drift diffusion equations that are suitable for devices with small active regions. A correct formulation of the carrier density was performed to take into account the quantum capacitance. The modeled current was compared to the measured results for a prototype and was shown to be accurate and to have a predictive behavior.

  5. Enhanced CAD model for gate leakage current in heterostructure field effect transistors

    SciTech Connect

    Lee, K.Y. |; Lund, B.; Ytterdal, T.; Robertson, J.; Shur, M.S.; Robertson, P.; Martinez, E.J.

    1996-06-01

    A simple and accurate circuit model for Heterostructure Field Effect Transistors (HFET`s) is proposed to simulate both the gate and the drain current characteristics accounting for hot-electron effects on gate current and the effect of the gate current on the channel current. An analytical equation that describes the effective electron temperature is developed in a simple form. This equation is suitable for implementation in circuit simulators. The model describes both the drain and gate currents at high gate bias voltages. It has been implemented in the circuit simulator AIM-Spice, and good agreement between simulated and measured results is achieved for enhancement-mode HFET`s fabricated in different laboratories. The proposed equivalent circuit and model equations are applicable to other compound semiconductor FET`s, i.e., GaAs MESFET`s.

  6. MoS2 Field Effect Transistors with different polarity: study of electrode work functions

    NASA Astrophysics Data System (ADS)

    Dube, Isha; Boyd, Anthony K.; Fontana, Marcio; Gayduchenko, Igor; Fedorov, Georgy; Liu, Amy; Paranjape, Makarand; Barbara, Paola

    2013-03-01

    The transfer characteristics of Molybdenum disulfide (MoS2) field effect transistors (FETs) depend on the Schottky barrier formed between the metal electrode and the semiconducting MoS2. We obtained p-type behavior for Pd-contacted MoS2 FETs and n-type with both Au and Nb contacts. We study the work function of these electrode metals to understand their effect on the Schottky barrier and therefore the polarity of the MoS2 FETs. The work function of the above metals is measured using a non-contact Kelvin Probe technique under different ambient conditions. We will discuss the observed n-type and p-type behavior of MoS2 FETs in relation to the measured metal work functions. Work Funded by NSF, DMR 1008242

  7. The Effect of Gas Absorption on Multilayer Black Phosphorus Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Liu, Xue; Hu, Jin; Yue, Chunlei; Della Fera, Nicholas; Mao, Zhiqiang; Wei, Jiang

    2015-03-01

    Multilayer black phosphorus (BP) is drawing much attention recently due to its reported high mobility (up to 1000 cm2V-1s-1) and on/off ratio (up to 105) as the channel material for field effect transistor (FET). We investigated the interplay between the electrical response of high performing BPFET and gas adsorbate introduced to its surrounding environment. Different type of gas including CO2, H2O, Ethanol, CO, NO, NH3, etc. has been tested. We observed that the absorption of gas molecules generally reduces the overall on-state conductance of the device with an order of 10 ~ 100. And such reduction can be fully recovered by purging with inert gas or baking at mild temperature (about 100°C). The absorption dynamics and detailed mechanism are also been investigated. We conclude that multilayer black phosphorus is an excellent material for chemical sensing.

  8. Characterisation of Organic Field-Effect Transistor by Scanning Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Leung, Shee-Ann; Tojo, Takayuki; Murata, Hideyuki

    2005-06-01

    Organic molecular semiconductors, such as pentacene (C22H14), is of great interest for potential application in thin-film organic field-effect transistors (OFETs). Novel scanning Raman microscopy was applied to the analysis of OFETs. Effective channel sizes in top-contact and bottom-contact OFETs were determined from scanning Raman spectra. The bottom-contact OFET showed a sharp change in Raman intensity at the gold/pentacene interface over a short distance while the top-contact OFET showed a gradual change in Raman intensity over a wide region. In the case of a gold electrode deposited on pentacene, the real channel size could be as small as half of the intended size. This resulted in the decrease in effective channel size and thus in the overestimation of the calculated mobility. The small channel length could be attributed to the presence of gold (composite) inside the channel in the top-contact OFET.

  9. Method for extracting relevant electrical parameters from graphene field-effect transistors using a physical model

    SciTech Connect

    Boscá, A.; Pedrós, J.; Martínez, J.; Calle, F.

    2015-01-28

    Due to its intrinsic high mobility, graphene has proved to be a suitable material for high-speed electronics, where graphene field-effect transistor (GFET) has shown excellent properties. In this work, we present a method for extracting relevant electrical parameters from GFET devices using a simple electrical characterization and a model fitting. With experimental data from the device output characteristics, the method allows to calculate parameters such as the mobility, the contact resistance, and the fixed charge. Differentiated electron and hole mobilities and direct connection with intrinsic material properties are some of the key aspects of this method. Moreover, the method output values can be correlated with several issues during key fabrication steps such as the graphene growth and transfer, the lithographic steps, or the metalization processes, providing a flexible tool for quality control in GFET fabrication, as well as a valuable feedback for improving the material-growth process.

  10. Optimal design of an electret microphone metal-oxide-semiconductor field-effect transistor preamplifier.

    PubMed

    van der Donk, A G; Bergveld, P

    1992-04-01

    A theoretical noise analysis of the combination of a capacitive microphone and a preamplifier containing a metal-oxide-semiconductor field-effect transistor (MOSFET) and a high-value resistive bias element is given. It is found that the output signal-to-noise ratio for a source follower and for a common-source circuit is almost the same. It is also shown that the output noise can be reduced by making the microphone capacitance as well as the bias resistor as large as possible, and furthermore by keeping the parasitic gate capacitances as low as possible and finally by using an optimum value for the gate area of the MOSFET. The main noise source is the thermal noise of the gate leakage resistance of the MOSFET. It is also shown that short-channel MOSFETs produce more thermal channel noise than longer channel devices. PMID:1597614

  11. ON current enhancement of nanowire Schottky barrier tunnel field effect transistors

    NASA Astrophysics Data System (ADS)

    Takei, Kohei; Hashimoto, Shuichiro; Sun, Jing; Zhang, Xu; Asada, Shuhei; Xu, Taiyu; Matsukawa, Takashi; Masahara, Meishoku; Watanabe, Takanobu

    2016-04-01

    Silicon nanowire Schottky barrier tunnel field effect transistors (NW-SBTFETs) are promising structures for high performance devices. In this study, we fabricated NW-SBTFETs to investigate the effect of nanowire structure on the device characteristics. The NW-SBTFETs were operated with a backgate bias, and the experimental results demonstrate that the ON current density is enhanced by narrowing the width of the nanowire. We confirmed using the Fowler-Nordheim plot that the drain current in the ON state mainly comprises the quantum tunneling component through the Schottky barrier. Comparison with a technology computer aided design (TCAD) simulation revealed that the enhancement is attributed to the electric field concentration at the corners of cross-section of the NW. The study findings suggest an effective approach to securing the ON current by Schottky barrier width modulation.

  12. Hysteresis mechanism and control in pentacene organic field-effect transistors with polymer dielectric

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Shi, Wei; Han, Shijiao; Yu, Junsheng

    2013-05-01

    Hysteresis mechanism of pentacene organic field-effect transistors (OFETs) with polyvinyl alcohol (PVA) and/or polymethyl methacrylate (PMMA) dielectrics is studied. Through analyzing the electrical characteristics of OFETs with various PVA/PMMA arrangements, it shows that charge, which is trapped in PVA bulk and at the interface of pentacene/PVA, is one of the origins of hysteresis. The results also show that memory window is proportional to both trap amount in PVA and charge density at the gate/PVA or PVA/pentacene interfaces. Hence, the controllable memory window of around 0 ˜ 10 V can be realized by controlling the thickness and combination of triple-layer polymer dielectrics.

  13. Selective vapor phase sensing of small molecules using biofunctionalized field effect transistors

    NASA Astrophysics Data System (ADS)

    Hagen, Joshua A.; Kim, Sang Nyon; Kelley-Loughnane, Nancy; Naik, Rajesh R.; Stone, Morley O.

    2011-05-01

    This work details a proof of concept study for vapor phase selective sensing using a strategy of biorecognition elements (BRE) integrated into a zinc oxide field effect transistor (ZnO FET). ZnO FETs are highly sensitive to changes to the environment with little to no selectivity. Addition of a biorecognition element retains the sensitivity of the device while adding selectivity. The DNA aptamer designed to bind the small molecule riboflavin was covalently integrated into the ZnO FET and detects the presence of 116 ppb of riboflavin in a nitrogen atmosphere by a change in current. The unfunctionalized ZnO FET shows no response to this same concentrations of riboflavin, showing that the aptamerbinding strategy may be a promising strategy for vapor phase sensing.

  14. Plasma treatment introduced memory properties in MoS2 field-effect transistors

    NASA Astrophysics Data System (ADS)

    Zhang, Miaomiao; Tong, Yanhong; Tang, Qingxin; Liu, Yichun

    2016-01-01

    We present a facile method to obtain MoS2-based nonvolatile memory field-effect transistors by oxygen plasma treatment on the MoS2 surface that is in contact with a dielectric. The oxygen plasma treatment provides a way of introducing deep defects into the MoS2 surface. Only those deep defects located at the semiconductor/dielectric interface can behave as charge trapping sites to develop the memory capability. No memory properties can be observed when the MoS2 surface far from the conductive channel was treated with oxygen plasma. This method brings promising advantages to MoS2-based memory devices obtained using a simple fabrication method and small device dimensions.

  15. Enhanced memory characteristics in organic ferroelectric field-effect transistors through thermal annealing

    SciTech Connect

    Sugano, Ryo; Tashiro, Tomoya; Sekine, Tomohito; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2015-11-15

    We report on the memory characteristics of organic ferroelectric field-effect transistors (FeFETs) using spin-coated poly(vinylidene difluoride/trifluoroethylene) (P(VDF/TrFE)) as a gate insulating layer. By thermal annealing the P(VDF/TrFE) layer at temperatures above its melting point, we could significantly improve the on/off current ratio to over 10{sup 4}. Considerable changes in the surface morphology and x-ray diffraction patterns were also observed in the P(VDF/TrFE) layer as a result of the annealing process. The enhanced memory effect is attributed to large polarization effects caused by rearranged ferroelectric polymer chains and improved crystallinity in the organic semiconductor layer of the FeFET devices.

  16. Theoretical Investigation of Graphene Nanoribbon Field-Effect Transistors Designed for Digital Applications

    NASA Astrophysics Data System (ADS)

    Harada, Naoki; Sato, Shintaro; Yokoyama, Naoki

    2013-09-01

    Nanometer-scale, single-gate graphene nanoribbon Schottky barrier field-effect transistors (FETs) were theoretically investigated using self-consistent atomistic simulation. The device geometry was determined by referring to the International Technology Roadmap for Semiconductors. The target performance levels were the requirements specified in the roadmap for 2024, particularly a maximum leakage current of 0.1 A/m, an on-current of 2017 A/m, and a delay time of 0.13 ps. The device conditions needed to meet these requirements were found to be a bandgap larger than 1.1 eV, a supply voltage of 0.6 V, and a gate length of 7 nm.

  17. Drift-diffusion equation for ballistic transport in nanoscale metal-oxide-semiconductor field effect transistors

    NASA Astrophysics Data System (ADS)

    Rhew, Jung-Hoon; Lundstrom, Mark S.

    2002-11-01

    We develop a drift-diffusion equation that describes ballistic transport in a nanoscale metal-oxide-semiconductor field effect transistor (MOSFET). We treat injection from different contacts separately, and describe each injection with a set of extended McKelvey one-flux equations [Phys. Rev. 123, 51 (1961); 125, 1570 (1962)] that include hierarchy closure approximations appropriate for high-field ballistic transport and degenerate carrier statistics. We then reexpress the extended one-flux equations in a drift-diffusion form with a properly defined Einstein relationship. The results obtained for a nanoscale MOSFET show excellent agreement with the solution of the ballistic Boltzmann transport equation with no fitting parameters. These results show that a macroscopic transport model based on the moments of the Boltzmann transport equation can describe ballistic transport.

  18. A graphene field-effect transistor as a molecule-specific probe of DNA nucleobases

    NASA Astrophysics Data System (ADS)

    Dontschuk, Nikolai; Stacey, Alastair; Tadich, Anton; Rietwyk, Kevin J.; Schenk, Alex; Edmonds, Mark T.; Shimoni, Olga; Pakes, Chris I.; Prawer, Steven; Cervenka, Jiri

    2015-03-01

    Fast and reliable DNA sequencing is a long-standing target in biomedical research. Recent advances in graphene-based electrical sensors have demonstrated their unprecedented sensitivity to adsorbed molecules, which holds great promise for label-free DNA sequencing technology. To date, the proposed sequencing approaches rely on the ability of graphene electric devices to probe molecular-specific interactions with a graphene surface. Here we experimentally demonstrate the use of graphene field-effect transistors (GFETs) as probes of the presence of a layer of individual DNA nucleobases adsorbed on the graphene surface. We show that GFETs are able to measure distinct coverage-dependent conductance signatures upon adsorption of the four different DNA nucleobases; a result that can be attributed to the formation of an interface dipole field. Comparison between experimental GFET results and synchrotron-based material analysis allowed prediction of the ultimate device sensitivity, and assessment of the feasibility of single nucleobase sensing with graphene.

  19. Manipulation of transport hysteresis on graphene field effect transistors with Ga ion irradiation

    SciTech Connect

    Wang, Quan; Liu, Shuai; Ren, Naifei

    2014-09-29

    We have studied the effect of Ga ion irradiation on the controllable hysteretic behavior of graphene field effect transistors fabricated on Si/SO{sub 2} substrates. The various densities of defects in graphene were monitored by Raman spectrum. It was found that the Dirac point shifted to the positive gate voltage constantly, while the hysteretic behavior was enhanced first and then weakened, with the dose of ion irradiation increasing. By contrasting the trap charges density induced by dopant and the total density of effective trap charges, it demonstrated that adsorbate doping was not the decisive factor that induced the hysteretic behavior. The tunneling between the defect sites induced by ion irradiation was also an important cause for the hysteresis.

  20. Contact-dependent performance variability of monolayer MoS{sub 2} field-effect transistors

    SciTech Connect

    Han, Gyuchull; Yoon, Youngki

    2014-11-24

    Using self-consistent quantum transport simulations, we investigate the performance variability of monolayer molybdenum disulfide (MoS{sub 2}) field-effect transistors (FETs) with various contact properties. Varying the Schottky barrier in MoS{sub 2} FETs affects the output characteristics more significantly than the transfer characteristics. If doped contacts are realized, the performance variation due to non-ideal contacts becomes negligible; otherwise, channel doping can effectively suppress the performance variability in metal-contact devices. Our scaling study also reveals that for sub-10-nm channels, doped-contact devices can be more robust in terms of switching, while metal-contact MoS{sub 2} FETs can undergo the smaller penalty in output conductance.

  1. High-performance integrated field-effect transistor-based sensors.

    PubMed

    Adzhri, R; Md Arshad, M K; Gopinath, Subash C B; Ruslinda, A R; Fathil, M F M; Ayub, R M; Nor, M Nuzaihan Mohd; Voon, C H

    2016-04-21

    Field-effect transistors (FETs) have succeeded in modern electronics in an era of computers and hand-held applications. Currently, considerable attention has been paid to direct electrical measurements, which work by monitoring changes in intrinsic electrical properties. Further, FET-based sensing systems drastically reduce cost, are compatible with CMOS technology, and ease down-stream applications. Current technologies for sensing applications rely on time-consuming strategies and processes and can only be performed under recommended conditions. To overcome these obstacles, an overview is presented here in which we specifically focus on high-performance FET-based sensor integration with nano-sized materials, which requires understanding the interaction of surface materials with the surrounding environment. Therefore, we present strategies, material depositions, device structures and other characteristics involved in FET-based devices. Special attention was given to silicon and polyaniline nanowires and graphene, which have attracted much interest due to their remarkable properties in sensing applications. PMID:27026595

  2. Current crowding in two-dimensional black-phosphorus field-effect transistors

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Tao, X.; Yang, L.; Gu, Y.

    2016-03-01

    By combining electrical measurements, scanning Kelvin probe microscopy, and numerical electrical simulations, we find significant current crowding in two-dimensional (2D) black phosphorus field-effect transistors. This current crowding can lead to localized Joule heating close to the metal contacts, and it is consistent with the features of the device failure observed in this study. Importantly, by considering both Schottky and resistive Ohmic contact models, we find that the commonly used transmission-line model, in general, significantly underestimates the extent of the current crowding. These findings, which are likely to be relevant in other 2D materials, suggest the need to take into account the current crowding effect in designing 2D devices.

  3. Field-effect memory transistors based on arrays of nanowires of a ferroelectric polymer

    NASA Astrophysics Data System (ADS)

    Cai, Ronggang; Kassa, Hailu G.; Marrani, Alessio; van Breemen, Albert J. J. M.; Gelinck, Gerwin H.; Nysten, Bernard; Hu, Zhijun; Jonas, Alain M.

    2015-09-01

    Ferroelectric poly(vinylidene fluoride-co-trifluoroethylene), P(VDF-TrFE), is increasingly used in organic non-volatile memory devices, e.g., in ferroelectric field effect transistors (FeFETs). Here, we report on FeFETs integrating nanoimprinted arrays of P(VDF-TrFE) nanowires. Two previously-unreported architectures are tested, the first one consisting of stacked P(VDF-TrFE) nanowires placed over a continuous semiconducting polymer film; the second one consisting of a nanostriped blend layer wherein the semiconducting and ferroelectric components alternate regularly. The devices exhibit significant reversible memory effects, with operating voltages reduced compared to their continuous film equivalent, and with different possible geometries of the channels of free charge carriers accumulating in the semiconductor.

  4. An analytical model for bio-electronic organic field-effect transistor sensors

    NASA Astrophysics Data System (ADS)

    Macchia, Eleonora; Giordano, Francesco; Magliulo, Maria; Palazzo, Gerardo; Torsi, Luisa

    2013-09-01

    A model for the electrical characteristics of Functional-Bio-Interlayer Organic Field-Effect Transistors (FBI-OFETs) electronic sensors is here proposed. Specifically, the output current-voltage characteristics of a streptavidin (SA) embedding FBI-OFET are modeled by means of the analytical equations of an enhancement mode p-channel OFET modified according to an ad hoc designed equivalent circuit that is also independently simulated with pspice. An excellent agreement between the model and the experimental current-voltage output characteristics has been found upon exposure to 5 nM of biotin. A good agreement is also found with the SA OFET parameters graphically extracted from the device transfer I-V curves.

  5. A facile process to achieve hysteresis-free and fully stabilized graphene field-effect transistors.

    PubMed

    Kim, Yun Ji; Lee, Young Gon; Jung, Ukjin; Lee, Sangchul; Lee, Sang Kyung; Lee, Byoung Hun

    2015-03-01

    The operation of chemical vapor-deposited (CVD) graphene field-effect transistors (GFETs) is highly sensitive to environmental factors such as the substrate, polymer residues, ambient condition, and other species adsorbed on the graphene surface due to their high defect density. As a result, CVD GFETs often exhibit a large hysteresis and time-dependent instability. These problems become a major roadblock in the systematic study of graphene devices. We report a facile process to alleviate these problems, which can be used to fabricate stable high performance CVD GFETs with symmetrical current-voltage (I-V) characteristics and an effective carrier mobility over 6000 cm(2) V(-1) s(-1). This process combined a few steps of processes in sequence including pre-annealing in a vacuum, depositing a passivation layer, and the final annealing in a vacuum, and eliminated ∼50% of charging sources primarily originating from water reduction reactions. PMID:25672592

  6. Light emitting field effect transistor with two self-aligned Si nanocrystal layers

    SciTech Connect

    Beyer, V.; Schmidt, B.; Heinig, K.-H.; Stegemann, K.-H.

    2009-11-09

    Light emitting field effect transistors based on narrow layers of silicon nanocrystals (NCs) in the gate oxide were fabricated. Direct quantum mechanical electron and hole tunneling into NCs was achieved by self-alignment of NCs-interface-distances to {approx}2 nm. The direct tunneling reduces oxide degradation, prolongs device lifetime and increases operation speed. Self-alignment occurs during thermal treatment of ion irradiated stacks of 50 nm polycrystalline silicon/15 nm SiO{sub 2}/(001)Si substrate. An alternating voltage (ac) was applied to the gate to inject charges into the NCs. Due to injection by direct tunneling, electroluminescence extends to higher ac frequencies than reported so far.

  7. Selective detection of heavy metal ions by self assembled chemical field effect transistors

    NASA Astrophysics Data System (ADS)

    Ruan, Hang; Kang, Yuhong; Gladwin, Elizabeth; Claus, Richard O.

    2015-04-01

    Multiple layer-by-layer sensor material modifications were designed and implemented to achieve selectivity of semiconductor based chemical field effect transistors (ChemFETs) to particular heavy metal ions. The ChemFET sensors were fabricated and modified in three ways, with the intent to initially target first mercury and lead ions and then chromium ions, respectively. Sensor characterization was performed with the gate regions of the sensor elements exposed to different concentrations of target heavy metal ion solutions. A minimum detection level in the range of 0.1 ppm and a 10%-90% response time of less than 10 s were demonstrated. By combining layer-by-layer gold nanoparticles and lead ionophores, a sensor is produced that is sensitive and selective not only to chromium but also to Cr3+ and Cr6+. This result supports the claim that high selectivity can be achieved by designing self-assembled bonding for lead, arsenic, chromium, cesium, mercury, and cadmium.

  8. Enhanced stability of black phosphorus field-effect transistors with SiO2 passivation

    NASA Astrophysics Data System (ADS)

    Wan, Bensong; Yang, Bingchao; Wang, Yue; Zhang, Junying; Zeng, Zhongming; Liu, Zhongyuan; Wang, Wenhong

    2015-10-01

    Few-layer black phosphorus (BP) has attracted much attention due to its high mobility and suitable band gap for potential applic5ations in optoelectronics and flexible devices. However, its instability under ambient conditions limits its practical applications. Our investigations indicate that by passivation of the mechanically exfoliated BP flakes with a SiO2 layer, the fabricated BP field-effect transistors (FETs) exhibit greatly enhanced environmental stability. Compared to the unpassivated BP devices, which show a fast drop of on/off current ratio by a factor of 10 after one week of ambient exposure, the SiO2-passivated BP devices display a high retained on/off current ratio of over 600 after one week of exposure, just a little lower than the initial value of 810. Our investigations provide an effective route to passivate the few-layer BPs for enhancement of their environmental stability.

  9. Enhanced stability of black phosphorus field-effect transistors with SiO₂ passivation.

    PubMed

    Wan, Bensong; Yang, Bingchao; Wang, Yue; Zhang, Junying; Zeng, Zhongming; Liu, Zhongyuan; Wang, Wenhong

    2015-10-30

    Few-layer black phosphorus (BP) has attracted much attention due to its high mobility and suitable band gap for potential applic5ations in optoelectronics and flexible devices. However, its instability under ambient conditions limits its practical applications. Our investigations indicate that by passivation of the mechanically exfoliated BP flakes with a SiO2 layer, the fabricated BP field-effect transistors (FETs) exhibit greatly enhanced environmental stability. Compared to the unpassivated BP devices, which show a fast drop of on/off current ratio by a factor of 10 after one week of ambient exposure, the SiO2-passivated BP devices display a high retained on/off current ratio of over 600 after one week of exposure, just a little lower than the initial value of 810. Our investigations provide an effective route to passivate the few-layer BPs for enhancement of their environmental stability. PMID:26436439

  10. Organic-inorganic proximity effect in the magneto-conductance of vertical organic field effect transistors

    NASA Astrophysics Data System (ADS)

    Khachatryan, B.; Greenman, M.; Devir-Wolfman, A. H.; Tessler, N.; Ehrenfreund, E.

    2016-07-01

    Vertical organic field effect transistors having a patterned source electrode and an a-SiO2 insulation layer show high performance as a switching element with high transfer characteristics. By measuring the low field magneto-conductance under ambient conditions at room temperature, we show here that the proximity of the inorganic a-SiO2 insulation to the organic conducting channel affects considerably the magnetic response. We propose that in n-type devices, electrons in the organic conducting channel and spin bearing charged defects in the inorganic a-SiO2 insulation layer (e.g., O2 = Si+.) form oppositely charged spin pairs whose singlet-triplet spin configurations are mixed through the relatively strong hyperfine field of 29Si. By increasing the contact area between the insulation layer and the conducting channel, the ˜2% magneto-conductance response may be considerably enhanced.

  11. Single particle transport in two-dimensional heterojunction interlayer tunneling field effect transistor

    SciTech Connect

    Li, Mingda Snider, Gregory; Jena, Debdeep; Grace Xing, Huili; Esseni, David

    2014-02-21

    The single particle tunneling in a vertical stack consisting of monolayers of two-dimensional semiconductors is studied theoretically, and its application to a novel Two-dimensional Heterojunction Interlayer Tunneling Field Effect Transistor (Thin-TFET) is proposed and described. The tunneling current is calculated by using a formalism based on the Bardeen's transfer Hamiltonian, and including a semi-classical treatment of scattering and energy broadening effects. The misalignment between the two 2D materials is also studied and found to influence the magnitude of the tunneling current but have a modest impact on its gate voltage dependence. Our simulation results suggest that the Thin-TFETs can achieve very steep subthreshold swing, whose lower limit is ultimately set by the band tails in the energy gaps of the 2D materials produced by energy broadening. The Thin-TFET is thus very promising as a low voltage, low energy solid state electronic switch.

  12. Examination of hot-carrier stress induced degradation on fin field-effect transistor

    SciTech Connect

    Yang, Yi-Lin Yen, Tzu-Sung; Ku, Chao-Chen; Wu, Tai-Hsuan; Wang, Tzuo-Li; Li, Chien-Yi; Wu, Bing-Tze; Zhang, Wenqi; Hong, Jia-Jian; Wong, Jie-Chen; Yeh, Wen-Kuan; Lin, Shih-Hung

    2014-02-24

    Degradation in fin field-effect transistor devices was investigated in detail under various hot-carrier stress conditions. The threshold voltage (V{sub TH}) shift, substrate current (I{sub B}), and subthreshold swing were extracted to determine the degradation of a device. The power-law time exponent of the V{sub TH} shift was largest at V{sub G} = 0.3 V{sub D}, indicating that the V{sub TH} shift was dominated by interface state generation. Although the strongest impact ionization occurred at V{sub G} = V{sub D}, the V{sub TH} shift was mainly caused by electron trapping resulting from a large gate leakage current.

  13. Simulation of GeSn/Ge tunneling field-effect transistors for complementary logic applications

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Liang, Renrong; Wang, Jing; Xiao, Lei; Xu, Jun

    2016-09-01

    GeSn/Ge tunneling field-effect transistors (TFETs) with different device configurations are comprehensively investigated by numerical simulation. The lateral PIN- and PNPN-type point-tunneling and vertical line-tunneling device structures are analyzed and compared. Both n- and p-type TFETs are optimized to construct GeSn complementary logic applications. Simulation results indicate that GeSn/Ge heterochannel and heterosource structures significantly improve the device characteristics of point- and line-TFETs, respectively. Device performance and subthreshold swing can be further improved by increasing the Sn composition. GeSn/Ge heterosource line-TFETs exhibit excellent device performance and superior inverter voltage-transfer characteristic, which make them promising candidates for GeSn complementary TFET applications.

  14. Field-effect transistor having a superlattice channel and high carrier velocities at high applied fields

    DOEpatents

    Chaffin, R.J.; Dawson, L.R.; Fritz, I.J.; Osbourn, G.C.; Zipperian, T.E.

    1987-06-08

    A field effect transistor comprises a semiconductor having a source, a drain, a channel and a gate in operational relationship. The semiconductor is a strained layer superlattice comprising alternating quantum well and barrier layers, the quantum well layers and barrier layers being selected from the group of layer pairs consisting of InGaAs/AlGaAs, InAs/InAlGaAs, and InAs/InAlAsP. The layer thicknesses of the quantum well and barrier layers are sufficiently thin that the alternating layers constitute a superlattice which has a superlattice conduction band energy level structure in k-vector space. The layer thicknesses of the quantum well layers are selected to provide a superlattice L/sub 2D/-valley which has a shape which is substantially more two-dimensional than that of said bulk L-valley. 2 figs.

  15. Direct Growth of Vertically-oriented Graphene for Field-Effect Transistor Biosensor

    PubMed Central

    Mao, Shun; Yu, Kehan; Chang, Jingbo; Steeber, Douglas A.; Ocola, Leonidas E.; Chen, Junhong

    2013-01-01

    A sensitive and selective field-effect transistor (FET) biosensor is demonstrated using vertically-oriented graphene (VG) sheets labeled with gold nanoparticle (NP)-antibody conjugates. VG sheets are directly grown on the sensor electrode using a plasma-enhanced chemical vapor deposition (PECVD) method and function as the sensing channel. The protein detection is accomplished through measuring changes in the electrical signal from the FET sensor upon the antibody-antigen binding. The novel biosensor with unique graphene morphology shows high sensitivity (down to ~2 ng/ml or 13 pM) and selectivity towards specific proteins. The PECVD growth of VG presents a one-step and reliable approach to prepare graphene-based electronic biosensors. PMID:23603871

  16. Giant plasmon instability in a dual-grating-gate graphene field-effect transistor

    NASA Astrophysics Data System (ADS)

    Koseki, Y.; Ryzhii, V.; Otsuji, T.; Popov, V. V.; Satou, A.

    2016-06-01

    We study the instability of plasmons in a dual-grating-gate graphene field-effect transistor induced by dc current injection using self-consistent simulations with the Boltzmann equation. With only acoustic-phonon-limited electron scattering, it is demonstrated that a total growth rate of the plasmon instability, with a terahertz/midinfrared range of the frequency, can exceed 4 ×1012s-1 at room temperature, which is an order of magnitude larger than in two-dimensional electron gases based on the usual semiconductors. By comparing the simulation results with existing theory, it is revealed that the giant total growth rate originates from a simultaneous occurrence of the so-called Dyakonov-Shur and Ryzhii-Satou-Shur instabilities.

  17. High-mobility bio-organic field effect transistors with photoreactive DNAs as gate insulators

    NASA Astrophysics Data System (ADS)

    Kim, Youn Sun; Jung, Ki Hwa; Lee, U. Ra; Kim, Kyung Hwan; Hoang, Mai Ha; Jin, Jung-Il; Choi, Dong Hoon

    2010-03-01

    Organic-soluble DNAs bearing chalcone moieties were synthesized by using purified natural sodium DNA. In addition to the chalcone-containing DNA homopolymer (CcDNA), a copolymer (CTMADNA-co-CcDNA) was synthesized. They were employed as gate insulators for fabricating organic thin-film transistors. An organic semiconductor (5,5'-(9,10-bis((4-hexylphenyl)ethynyl)anthracene-2,6-yl-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene; HB-ant-THT) was deposited on the photocrosslinked DNA-based gate insulators via a solution process. Interestingly, the resulting TFT devices had extremely high field-effect mobilities, and their corresponding transfer curves indicated low hysteresis. The carrier mobility of the device with HB-ant-THT deposited on the CTMADNA-co-CcDNA gate insulator was the best, i.e., 0.31 cm2 V-1 s-1 (Ion/Ioff=1.0×104).

  18. Self-assembled metallic nanowire-based vertical organic field-effect transistor.

    PubMed

    Ben-Sasson, Ariel J; Azulai, Daniel; Gilon, Hagit; Facchetti, Antonio; Markovich, Gil; Tessler, Nir

    2015-02-01

    We report on in situ, self-assembly, solution-processing of metallic (Au/Ag) nanowire-based transparent electrodes integrated to vertical organic field-effect transistors (VOFETs). In the VOFET architecture, the nanowires' microstructure facilitates current modulation by the gate across the otherwise shielding sandwiched source electrode. We show N-type VOFETs operation with on/off ratio ∼1 × 10(5) and high current density (>1 mA cm(-2) at VDS = 5 V). The integration of the device design and the transparent electrode deposition methods offers a potential route for all-solution processing-based, large-area, high-efficiency organic electronics. PMID:25602371

  19. High temperature study of flexible silicon-on-insulator fin field-effect transistors

    SciTech Connect

    Diab, Amer; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Hussain, Muhammad M.

    2014-09-29

    We report high temperature electrical transport characteristics of a flexible version of the semiconductor industry's most advanced architecture: fin field-effect transistor on silicon-on-insulator with sub-20 nm fins and high-κ/metal gate stacks. Characterization from room to high temperature (150 °C) was completed to determine temperature dependence of drain current (I{sub ds}), gate leakage current (I{sub gs}), transconductance (g{sub m}), and extracted low-field mobility (μ{sub 0}). Mobility degradation with temperature is mainly caused by phonon scattering. The other device characteristics show insignificant difference at high temperature which proves the suitability of inorganic flexible electronics with advanced device architecture.

  20. Gold-coated graphene field-effect transistors for quantitative analysis of protein-antibody interactions

    NASA Astrophysics Data System (ADS)

    Tarasov, Alexey; Tsai, Meng-Yen; Flynn, Erin M.; Joiner, Corey A.; Taylor, Robert C.; Vogel, Eric M.

    2015-12-01

    Field-effect transistors (FETs) based on large-area graphene and other 2D materials can potentially be used as low-cost and flexible potentiometric biological sensors. However, there have been few attempts to use these devices for quantifying molecular interactions and to compare their performance to established sensor technology. Here, gold-coated graphene FETs are used to measure the binding affinity of a specific protein-antibody interaction. Having a gold surface gives access to well-known thiol chemistry for the self-assembly of linker molecules. The results are compared with potentiometric silicon-based extended-gate sensors and a surface plasmon resonance system. The estimated dissociation constants are in excellent agreement for all sensor types as long as the active surfaces are the same (gold). The role of the graphene transducer is to simply amplify surface potential changes caused by adsorption of molecules on the gold surface.

  1. Polarity control in MoS2 and MoSe2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Fragapane, A.; Bobek, S.; Barroso, D.; Nguyen, A.; Bonilla, E.; Naghibi, S.; von Son Palacio, G.; Klee, V.; Preciado, E.; Martinez, J.; Pleskot, D.; Mann, J.; Shidpoor, R.; Bartels, L.; Sorger, V.; Liu, A.; Paranjape, M.; Barbara, P.

    2014-03-01

    Ambipolar operation is essential for a variety of optoelectronic applications, where both electron and hole transport are required simultaneously. However, hole transport and p-type Schottky barriers have been difficult to achieve in all-solid state field effect transistors based on MoS2 charge channels. In prior work we demonstrated that Schottky barriers of either polarity (p-type or n-type) can be obtained with multilayer MoS2 flakes exfoliated from geological crystals. Here we study Schottky barrier polarity in thinner flakes of MoS2 and MoSe2 (down to single-layer thicknesses) that are grown by CVD, towards understanding how both variations in the bandgap and material work functions affect band alignment at the interface between the flakes and the metal contacts. Supported by the NSF, DMR-1008242, 1106210 and C-SPIN.

  2. First-principles simulations of a graphene-based field-effect transistor

    NASA Astrophysics Data System (ADS)

    Wang, Yun-Peng; Cheng, Hai-Ping

    2015-06-01

    We improvise an approach to carry out first-principles simulations of graphene-based vertical field-effect tunneling transistors that consist of a graphene|h -BN |graphene multilayer structure. Within the density functional theory framework, we exploit the effective screening medium (ESM) method to properly treat boundary conditions for electrostatic potentials and investigate the effect of gate voltage. The distribution of free carriers and the band structure of both top and bottom graphene layers are calculated self-consistently. The dielectric properties of h -BN thin films sandwiched between graphene layers are computed layer-by-layer following the theory of microscopic permittivity. We find that the permittivities of BN layers are very close to that of crystalline h -BN . The effect of interface with graphene on the dielectric properties of h -BN is weak according to an analysis on the interface charge redistribution.

  3. Focused Laser Induced Spatially Controllable p-n junction in Graphene Field-Effect Transistor

    NASA Astrophysics Data System (ADS)

    Kim, Young; Bae, Myung-Ho; Shu, Jung-Tak; Kim, Young; Ahn, Joung; Chun, Seung-Hyun; Park, Yun

    2013-03-01

    Tunable local doping on graphene is an important issue for future graphene-based electronics. Here we investigate a local doping effect by a focused laser irradiation and demonstrate a spatially controllable p-n junction in graphene field-effect transistor. Scanning photocurrent microscopy with varying back-gate voltages reveals the local charge trap in gate oxide near the laser-irradiated region. This is manifested by itself as double peaks in resistance as a function of gate voltage in graphene device, where the region between the double peaks corresponds to the p-n junction. Irradiation of a focused laser on graphene device suggests a new pave to spatially control the doping level, position and size of doped segment on graphene channel in a nondestructive way without high electrical bias, local gate electrode and chemical process. Korea Research Institute of Standards and Science

  4. Modeling of quasi-ballistic transport in nanowire metal-oxide-semiconductor field-effect transistors

    NASA Astrophysics Data System (ADS)

    Lee, Yeonghun; Kakushima, Kuniyuki; Natori, Kenji; Iwai, Hiroshi

    2015-10-01

    We developed a semi-analytical quasi-ballistic transport model for the nanowire metal-oxide-semiconductor field-effect transistors, dealing with finite lengths of source, channel, and drain. For the modeling, we used a combination of one-flux scattering matrices and analytical solutions of Boltzmann transport equations. The developed model was in quantitatively good agreement with numerical results, and well represented intermediate-scaled devices. In addition, we illustrated that the finite source seriously affect the distribution function of the carriers injected from the source, and the finite drain does for the backscattering into the channel from the drain. Finally, our model and results would help to understand physical aspects regarding quasi-ballistic transport in nanoscale devices.

  5. Enhanced memory characteristics in organic ferroelectric field-effect transistors through thermal annealing

    NASA Astrophysics Data System (ADS)

    Sugano, Ryo; Tashiro, Tomoya; Sekine, Tomohito; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2015-11-01

    We report on the memory characteristics of organic ferroelectric field-effect transistors (FeFETs) using spin-coated poly(vinylidene difluoride/trifluoroethylene) (P(VDF/TrFE)) as a gate insulating layer. By thermal annealing the P(VDF/TrFE) layer at temperatures above its melting point, we could significantly improve the on/off current ratio to over 104. Considerable changes in the surface morphology and x-ray diffraction patterns were also observed in the P(VDF/TrFE) layer as a result of the annealing process. The enhanced memory effect is attributed to large polarization effects caused by rearranged ferroelectric polymer chains and improved crystallinity in the organic semiconductor layer of the FeFET devices.

  6. Attofarad resolution capacitance-voltage measurement of nanometer scale field effect transistors utilizing ambient noise.

    PubMed

    Gokirmak, Ali; Inaltekin, Hazer; Tiwari, Sandip

    2009-08-19

    A high resolution capacitance-voltage (C-V) characterization technique, enabling direct measurement of electronic properties at the nanoscale in devices such as nanowire field effect transistors (FETs) through the use of random fluctuations, is described. The minimum noise level required for achieving sub-aF (10(-18) F) resolution, the leveraging of stochastic resonance, and the effect of higher levels of noise are illustrated through simulations. The non-linear DeltaC(gate-source/drain)-V(gate) response of FETs is utilized to determine the inversion layer capacitance (C(inv)) and carrier mobility. The technique is demonstrated by extracting the carrier concentration and effective electron mobility in a nanoscale Si FET with C(inv) = 60 aF. PMID:19636094

  7. Linearly Fused Azaacenes: Novel Approaches and New Applications Beyond Field-Effect Transistors (FETs).

    PubMed

    Li, Junbo; Zhang, Qichun

    2015-12-30

    Replacing the CH groups in the backbones of acenes with heteroatoms offers scientists greater opportunities to tune their properties, as the type, position, number, and the valence of the introduced heteroatoms have strong effects on the frontier orbital energy levels. When the heteroatoms are nitrogen atoms, all of the resulting materials are called azaacenes. Recently, the synthesis, structure, physical properties, and applications of azaacene derivatives have been intensively investigated. This review focuses on recent synthetic efforts (since 2013) toward making novel azaacenes as well as their potential applications beyond field-effect transistors (FETs) including organic light-emitting diodes (OLEDs), memory devices, phototransistors, solar cells, photoelectrical chemical cells, sensors, and conductors. PMID:25992713

  8. Understanding the electrolyte background for biochemical sensing with ion-sensitive field-effect transistors.

    PubMed

    Tarasov, Alexey; Wipf, Mathias; Stoop, Ralph L; Bedner, Kristine; Fu, Wangyang; Guzenko, Vitaliy A; Knopfmacher, Oren; Calame, Michel; Schönenberger, Christian

    2012-10-23

    Silicon nanowire field-effect transistors have attracted substantial interest for various biochemical sensing applications, yet there remains uncertainty concerning their response to changes in the supporting electrolyte concentration. In this study, we use silicon nanowires coated with highly pH-sensitive hafnium oxide (HfO(2)) and aluminum oxide (Al(2)O(3)) to determine their response to variations in KCl concentration at several constant pH values. We observe a nonlinear sensor response as a function of ionic strength, which is independent of the pH value. Our results suggest that the signal is caused by the adsorption of anions (Cl(-)) rather than cations (K(+)) on both oxide surfaces. By comparing the data to three well-established models, we have found that none of those can explain the present data set. Finally, we propose a new model which gives excellent quantitative agreement with the data. PMID:23016890

  9. Oxygen Implant Isolation of n-GaN Field-Effect Transistor Structures

    SciTech Connect

    Dang, G.; Cao, X.A.; Ren, F.; Pearton, S.J.; Han, J.; Baca, A.G.; Shul, R.J.

    1999-07-20

    Multiple-energy (30-325 keV) O{sup +} implantation into GaN field-effect transistor structures (n {approximately} 10{sup 18} cm{sup {minus}3}, 3000 {angstrom} thick) can produce as-implanted sheet resistances of 4 x 10{sup 12} {Omega}/{open_square}, provided care is taken to ensure compensation of the region up to the projected range of the lowest energy implant. The sheet resistance remains above 10{sup 7} {Omega}/{open_square} to annealing temperatures of {approximately} 650 C and displays an activation energy of 0.29 eV. No diffusion of the implanted oxygen was observed for anneals up to 800 C.

  10. Gallium nitride junction field effect transistors for high-temperature operation

    SciTech Connect

    Zolper, J.C.; Shul, R.J.; Baca, A.G.; Hietala, V.M.; Pearton, S.J.; Stall, R.A.; Wilson, R.G.

    1996-06-01

    GaN is an attractive material for use in high-temperature or high-power electronic devices due to its high bandgap (3.39 eV), high breakdown field ({approximately}5 {times} 10{sup 6} V/cm), high saturation drift velocity (2.7 {times} 10{sup 7} cm/s), and chemical inertness. To this end, Metal Semiconductor FETs (MESFETs), High Electron Mobility Transistors (HEMTs), Heterostructure FETs (HFETs), and Metal Insulator Semiconductor FETs (MISFETs) have all been reported based on epitaxial AlN/GaN structures (Khan 1993a,b; Binari 1994 and 1995). GaN Junction Field Effect Transistors (JFETs), however, had not been reported until recently (Zolper 1996b). JFETs are attractive for high-temperature operation due to the inherently higher thermal stability of the p/n junction gate of a JFET as compared to the Schottky barrier gate of a MESFET or HFET. In this paper the authors present the first results for elevated temperature performance of a GaN JFET. Although the forward gate properties are well behaved at higher temperatures, the reverse characteristics show increased leakage at elevated temperature. However, the increased date leakage alone does not explain the observed increase in drain current with temperature. Therefore, they believe this first device is limited by temperature activated substrate conduction.

  11. 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.

  12. Improved Drain Current Saturation and Voltage Gain in Graphene-on-Silicon Field Effect Transistors.

    PubMed

    Song, Seung Min; Bong, Jae Hoon; Hwang, Wan Sik; Cho, Byung Jin

    2016-01-01

    Graphene devices for radio frequency (RF) applications are of great interest due to their excellent carrier mobility and saturation velocity. However, the insufficient current saturation in graphene field effect transistors (FETs) is a barrier preventing enhancements of the maximum oscillation frequency and voltage gain, both of which should be improved for RF transistors. Achieving a high output resistance is therefore a crucial step for graphene to be utilized in RF applications. In the present study, we report high output resistances and voltage gains in graphene-on-silicon (GoS) FETs. This is achieved by utilizing bare silicon as a supporting substrate without an insulating layer under the graphene. The GoSFETs exhibit a maximum output resistance of 2.5 MΩ∙μm, maximum intrinsic voltage gain of 28 dB, and maximum voltage gain of 9 dB. This method opens a new route to overcome the limitations of conventional graphene-on-insulator (GoI) FETs and subsequently brings graphene electronics closer to practical usage. PMID:27142861

  13. Metrology solutions for high performance germanium multi-gate field-effect transistors using optical scatterometry

    NASA Astrophysics Data System (ADS)

    Chin, Hock-Chun; Ling, Moh-Lung; Liu, Bin; Zhang, Xingui; Li, Jie; Liu, Yongdong; Hu, Jiangtao; Yeo, Yee-Chia

    2013-04-01

    In this work, we report the first demonstration of scatterometry Optical Critical Dimension (OCD) characterization on advanced Ge Multi-Gate Field-Effect Transistor (MuGFET) or FinFET formed on a Germanium-on-Insulator (GeOI) substrate. Two critical process steps in the Ge MuGFET process flow were investigated, i.e. after Ge Fin formation, and after TaN gate stack etching process. All key process variations in the test structures were successfully monitored by the floating or fitting parameters in the OCD models. In addition, excellent static repeatability, with 3σ lower than 0.12 nm, was also achieved. The measurement results from OCD were also compared with both Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) measurements. Excellent correlation with both SEM and TEM was achieved by employing OCD characterization, confirming scatterometry OCD as a promising metrology technique for next generation multi-gate transistor with an advanced channel material.

  14. Improved Drain Current Saturation and Voltage Gain in Graphene–on–Silicon Field Effect Transistors

    PubMed Central

    Song, Seung Min; Bong, Jae Hoon; Hwang, Wan Sik; Cho, Byung Jin

    2016-01-01

    Graphene devices for radio frequency (RF) applications are of great interest due to their excellent carrier mobility and saturation velocity. However, the insufficient current saturation in graphene field effect transistors (FETs) is a barrier preventing enhancements of the maximum oscillation frequency and voltage gain, both of which should be improved for RF transistors. Achieving a high output resistance is therefore a crucial step for graphene to be utilized in RF applications. In the present study, we report high output resistances and voltage gains in graphene-on-silicon (GoS) FETs. This is achieved by utilizing bare silicon as a supporting substrate without an insulating layer under the graphene. The GoSFETs exhibit a maximum output resistance of 2.5 MΩ∙μm, maximum intrinsic voltage gain of 28 dB, and maximum voltage gain of 9 dB. This method opens a new route to overcome the limitations of conventional graphene-on-insulator (GoI) FETs and subsequently brings graphene electronics closer to practical usage. PMID:27142861

  15. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis

    PubMed Central

    Córdoba, Ainara López; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R. Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V.; Korchev, Yuri

    2016-01-01

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

  16. Electron and hole photoemission detection for band offset determination of tunnel field-effect transistor heterojunctions

    SciTech Connect

    Li, Wei; Zhang, Qin; Kirillov, Oleg A.; Levin, Igor; Richter, Curt A.; Gundlach, David J.; Nguyen, N. V. E-mail: liangxl@pku.edu.cn; Bijesh, R.; Datta, S.; Liang, Yiran; Peng, Lian-Mao; Liang, Xuelei E-mail: liangxl@pku.edu.cn

    2014-11-24

    We report experimental methods to ascertain a complete energy band alignment of a broken-gap tunnel field-effect transistor based on an InAs/GaSb hetero-junction. By using graphene as an optically transparent electrode, both the electron and hole barrier heights at the InAs/GaSb interface can be quantified. For a Al{sub 2}O{sub 3}/InAs/GaSb layer structure, the barrier height from the top of the InAs and GaSb valence bands to the bottom of the Al{sub 2}O{sub 3} conduction band is inferred from electron emission whereas hole emissions reveal the barrier height from the top of the Al{sub 2}O{sub 3} valence band to the bottom of the InAs and GaSb conduction bands. Subsequently, the offset parameter at the broken gap InAs/GaSb interface is extracted and thus can be used to facilitate the development of predicted models of electron quantum tunneling efficiency and transistor performance.

  17. Room-temperature amorphous alloy field-effect transistor exhibiting particle and wave electronic transport

    SciTech Connect

    Fukuhara, M.; Kawarada, H.

    2015-02-28

    The realization of room-temperature macroscopic field effect transistors (FETs) will lead to new epoch-making possibilities for electronic applications. The I{sub d}-V{sub g} characteristics of the millimeter-sized aluminum-oxide amorphous alloy (Ni{sub 0.36}Nb{sub 0.24}Zr{sub 0.40}){sub 90}H{sub 10} FETs were measured at a gate-drain bias voltage of 0–60 μV in nonmagnetic conditions and under a magnetic fields at room temperature. Application of dc voltages to the gate electrode resulted in the transistor exhibiting one-electron Coulomb oscillation with a period of 0.28 mV, Fabry-Perot interference with a period of 2.35 μV under nonmagnetic conditions, and a Fano effect with a period of 0.26 mV for Vg and 0.2 T under a magnetic field. The realization of a low-energy controllable device made from millimeter-sized Ni-Nb-Zr-H amorphous alloy throws new light on cluster electronics.

  18. Nb-doped single crystalline MoS{sub 2} field effect transistor

    SciTech Connect

    Das, Saptarshi E-mail: das@anl.gov; Demarteau, Marcellinus; Roelofs, Andreas

    2015-04-27

    We report on the demonstration of a p-type, single crystalline, few layer MoS{sub 2} field effect transistor (FET) using Niobium (Nb) as the dopant. The doping concentration was extracted and determined to be ∼3 × 10{sup 19}/cm{sup 3}. We also report on bilayer Nb-doped MoS{sub 2} FETs with ambipolar conduction. We found that the current ON-OFF ratio of the Nb-doped MoS{sub 2} FETs changes significantly as a function of the flake thickness. We attribute this experimental observation to bulk-type electrostatic effect in ultra-thin MoS{sub 2} crystals. We provide detailed analytical modeling in support of our claims. Finally, we show that in the presence of heavy doping, even ultra-thin 2D-semiconductors cannot be fully depleted and may behave as a 3D material when used in transistor geometry. Our findings provide important insights into the doping constraints of 2D materials, in general.

  19. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis.

    PubMed

    Zhang, Yanjun; Clausmeyer, Jan; Babakinejad, Babak; López Córdoba, Ainara; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V; Korchev, Yuri

    2016-03-22

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

  20. High performance field-effect transistor based on multilayer tungsten disulfide.

    PubMed

    Liu, Xue; Hu, Jin; Yue, Chunlei; Della Fera, Nicholas; Ling, Yun; Mao, Zhiqiang; Wei, Jiang

    2014-10-28

    Semiconducting two-dimensional transition metal chalcogenide crystals have been regarded as the promising candidate for the future generation of transistor in modern electronics. However, how to fabricate those crystals into practical devices with acceptable performance still remains as a challenge. Employing tungsten disulfide multilayer thin crystals, we demonstrate that using gold as the only contact metal and choosing appropriate thickness of the crystal, high performance transistor with on/off ratio of 10(8) and mobility up to 234 cm(2) V(-1) s(-1) at room temperature can be realized in a simple device structure. Furthermore, low temperature study revealed that the high performance of our device is caused by the minimized Schottky barrier at the contact and the existence of a shallow impurity level around 80 meV right below the conduction band edge. From the analysis on temperature dependence of field-effect mobility, we conclude that strongly suppressed phonon scattering and relatively low charge impurity density are the key factors leading to the high mobility of our tungsten disulfide devices. PMID:25266248

  1. Ways and peculiarities of submillimeter wavelength detection with short-channel field-effect transistors

    SciTech Connect

    Orlov, M. L. Panin, A. N.; Orlov, L. K.

    2009-06-15

    The detection properties of some short-channel field-effect transistors (FETs) have been analyzed using the steady-state output characteristics of these devices. The calculated dependences of voltage-power sensitivity on applied voltage are compared with the corresponding curves obtained from high-frequency measurements. It is shown that the nonmonotonic dependence of the FET photosensitivity on gate voltage that is observed in the frequency range of 400-750 GHz is not related to resonant excitation of 2D plasmons in the subgate plasma but is due to the change in the distribution of stationary fields in the structure and, as a result, to the change in the efficiency of nonresonant nonlinearity procedures in the transistor's electron subsystem with an increase in the gate-channel voltage. This conclusion is confirmed by analysis of the frequency dependences of photoresponse in the range under consideration, which do not exhibit resonant behavior at the frequencies corresponding to the peaks in the curves measured at a fixed frequency and different gate voltages.

  2. Improved Drain Current Saturation and Voltage Gain in Graphene–on–Silicon Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Song, Seung Min; Bong, Jae Hoon; Hwang, Wan Sik; Cho, Byung Jin

    2016-05-01

    Graphene devices for radio frequency (RF) applications are of great interest due to their excellent carrier mobility and saturation velocity. However, the insufficient current saturation in graphene field effect transistors (FETs) is a barrier preventing enhancements of the maximum oscillation frequency and voltage gain, both of which should be improved for RF transistors. Achieving a high output resistance is therefore a crucial step for graphene to be utilized in RF applications. In the present study, we report high output resistances and voltage gains in graphene-on-silicon (GoS) FETs. This is achieved by utilizing bare silicon as a supporting substrate without an insulating layer under the graphene. The GoSFETs exhibit a maximum output resistance of 2.5 MΩ•μm, maximum intrinsic voltage gain of 28 dB, and maximum voltage gain of 9 dB. This method opens a new route to overcome the limitations of conventional graphene-on-insulator (GoI) FETs and subsequently brings graphene electronics closer to practical usage.

  3. Graphene field-effect transistor array with integrated electrolytic gates scaled to 200 mm

    NASA Astrophysics Data System (ADS)

    Vieira, N. C. S.; Borme, J.; Machado, G., Jr.; Cerqueira, F.; Freitas, P. P.; Zucolotto, V.; Peres, N. M. R.; Alpuim, P.

    2016-03-01

    Ten years have passed since the beginning of graphene research. In this period we have witnessed breakthroughs both in fundamental and applied research. However, the development of graphene devices for mass production has not yet reached the same level of progress. The architecture of graphene field-effect transistors (FET) has not significantly changed, and the integration of devices at the wafer scale has generally not been sought. Currently, whenever an electrolyte-gated FET (EGFET) is used, an external, cumbersome, out-of-plane gate electrode is required. Here, an alternative architecture for graphene EGFET is presented. In this architecture, source, drain, and gate are in the same plane, eliminating the need for an external gate electrode and the use of an additional reservoir to confine the electrolyte inside the transistor active zone. This planar structure with an integrated gate allows for wafer-scale fabrication of high-performance graphene EGFETs, with carrier mobility up to 1800 cm2 V-1 s-1. As a proof-of principle, a chemical sensor was achieved. It is shown that the sensor can discriminate between saline solutions of different concentrations. The proposed architecture will facilitate the mass production of graphene sensors, materializing the potential of previous achievements in fundamental and applied graphene research.

  4. Uncovering edge states and electrical inhomogeneity in MoS2 field-effect transistors.

    PubMed

    Wu, Di; Li, Xiao; Luan, Lan; Wu, Xiaoyu; Li, Wei; Yogeesh, Maruthi N; Ghosh, Rudresh; Chu, Zhaodong; Akinwande, Deji; Niu, Qian; Lai, Keji

    2016-08-01

    The understanding of various types of disorders in atomically thin transition metal dichalcogenides (TMDs), including dangling bonds at the edges, chalcogen deficiencies in the bulk, and charges in the substrate, is of fundamental importance for TMD applications in electronics and photonics. Because of the imperfections, electrons moving on these 2D crystals experience a spatially nonuniform Coulomb environment, whose effect on the charge transport has not been microscopically studied. Here, we report the mesoscopic conductance mapping in monolayer and few-layer MoS2 field-effect transistors by microwave impedance microscopy (MIM). The spatial evolution of the insulator-to-metal transition is clearly resolved. Interestingly, as the transistors are gradually turned on, electrical conduction emerges initially at the edges before appearing in the bulk of MoS2 flakes, which can be explained by our first-principles calculations. The results unambiguously confirm that the contribution of edge states to the channel conductance is significant under the threshold voltage but negligible once the bulk of the TMD device becomes conductive. Strong conductance inhomogeneity, which is associated with the fluctuations of disorder potential in the 2D sheets, is also observed in the MIM images, providing a guideline for future improvement of the device performance. PMID:27444021

  5. Group IV nanotube transistors for next generation ubiquitous computing

    NASA Astrophysics Data System (ADS)

    Fahad, Hossain M.; Hussain, Aftab M.; Sevilla Torres, Galo A.; Banerjee, Sanjay K.; Hussain, Muhammad M.

    2014-06-01

    Evolution in transistor technology from increasingly large power consuming single gate planar devices to energy efficient multiple gate non-planar ultra-narrow (< 20 nm) fins has enhanced the scaling trend to facilitate doubling performance. However, this performance gain happens at the expense of arraying multiple devices (fins) per operation bit, due to their ultra-narrow dimensions (width) originated limited number of charges to induce appreciable amount of drive current. Additionally arraying degrades device off-state leakage and increases short channel characteristics, resulting in reduced chip level energy-efficiency. In this paper, a novel nanotube device (NTFET) topology based on conventional group IV (Si, SiGe) channel materials is discussed. This device utilizes a core/shell dual gate strategy to capitalize on the volume-inversion properties of an ultra-thin (< 10 nm) group IV nanotube channel to minimize leakage and short channel effects while maximizing performance in an area-efficient manner. It is also shown that the NTFET is capable of providing a higher output drive performance per unit chip area than an array of gate-all-around nanowires, while maintaining the leakage and short channel characteristics similar to that of a single gate-all-around nanowire, the latter being the most superior in terms of electrostatic gate control. In the age of big data and the multitude of devices contributing to the internet of things, the NTFET offers a new transistor topology alternative with maximum benefits from performance-energy efficiency-functionality perspective.

  6. Detection of α-fetoprotein in human serum using carbon nanotube transistor

    NASA Astrophysics Data System (ADS)

    So, Hye-Mi; Park, Dong-Won; Lee, Seong-Kyu; Kim, Beom Soo; Chang, Hyunju; Lee, Jeong-O.

    2009-03-01

    We have fabricated antibody-coated carbon nanotube field effect transistor (CNT-FET) sensor for the detection of α-fetoprotein (AFP), single chain glycoprotein of 70 kDa that is normally expressed in the fetal liver, in human serum. The AFP-specific antibodies were immobilized on CNT with linker molecule such as pyrenebutyric acid N-hydroxysuccinimide ester. To prevent nonspecific adsorption of antigen, we performed blocking procedure using bovine serum albumin (BSA). Antibody-antigen binding was determined by measuring electrical conductance change of FET and took an average of thereshold voltage change before and after binding. Also we checked concentration-dependent conductance change in human serum using both p-type SWNT-FETs and n-type SWNT-FETs.

  7. Inkjet printed ambipolar transistors and inverters based on carbon nanotube/zinc tin oxide heterostructures

    SciTech Connect

    Kim, Bongjun; Jang, Seonpil; Dodabalapur, Ananth; Geier, Michael L.; Prabhumirashi, Pradyumna L.; Hersam, Mark C.

    2014-02-10

    We report ambipolar field-effect transistors (FETs) consisting of inkjet printed semiconductor bilayer heterostructures utilizing semiconducting single-walled carbon nanotubes (SWCNTs) and amorphous zinc tin oxide (ZTO). The bilayer structure allows for electron transport to occur principally in the amorphous oxide layer and hole transport to occur exclusively in the SWCNT layer. This results in balanced electron and hole mobilities exceeding 2 cm{sup 2} V{sup −1} s{sup −1} at low operating voltages (<5 V) in air. We further show that the SWCNT-ZTO hybrid ambipolar FETs can be integrated into functional inverter circuits that display high peak gain (>10). This work provides a pathway for realizing solution processable, inkjet printable, large area electronic devices, and systems based on SWCNT-amorphous oxide heterostructures.

  8. Field effect transistor with HfO2/Parylene-C bilayer hybrid gate insulator

    NASA Astrophysics Data System (ADS)

    Kumar, Neeraj; Kito, Ai; Inoue, Isao

    2015-03-01

    We have investigated the electric field control of the carrier density and the mobility at the surface of SrTiO3, a well known transition-metal oxide, in a field effect transistor (FET) geometry. We have used a Parylene-C (8 nm)/HfO2 (20 nm) double-layer gate insulator (GI), which can be a potential candidate for a solid state GI for the future Mott FETs. So far, only examples of the Mott FET used liquid electrolyte or ferroelectric oxides for the GI. However, possible electrochemical reaction at the interface causes damage to the surface of the Mott insulator. Thus, an alternative GI has been highly desired. We observed that even an ultra thin Parylene-C layer is effective for keeping the channel surface clean and free from oxygen vacancies. The 8 nm Parylene-C film has a relatively low resistance and consequentially its capacitance does not dominate the total capacitance of the Parylene-C/HfO2 GI. The breakdown gate voltage at 300 K is usually more than 10 V (~ 3.4 MV/cm). At gate voltage of 3 V the carrier density measured by the Hall effect is about 3 ×1013 cm-2, competent to cause the Mott transition. Moreover, the field effect mobility reaches in the range of 10 cm2/Vs indicating the Parylene-C passivated surface is actually very clean.

  9. Scaling behavior of hysteresis in multilayer MoS{sub 2} field effect transistors

    SciTech Connect

    Li, Tao; Du, Gang; Zhang, Baoshun; Zeng, Zhongming

    2014-09-01

    Extrinsic hysteresis effects are often observed in MoS{sub 2} field effect devices due to adsorption of gas molecules on the surface of MoS{sub 2} channel. Scaling is a common method used in ferroics to quantitatively study the hysteresis. Here, the scaling behavior of hysteresis in multilayer MoS{sub 2} field effect transistors with a back-gated configuration was investigated. The power-law scaling relations were obtained for hysteresis area (〈A〉) and memory window (ΔV) with varying the region of back-gate voltage (V{sub bg,max}). It is interesting to find that the transition voltage in the forward sweep (V{sub FW}) and in the backward sweep (V{sub BW}) shifted to the opposite directions of back-gate voltage (V{sub bg}) with increasing V{sub bg,max}. However, when decreasing V{sub bg,max}, V{sub FW} shifted to positive and reversibly recovered, but V{sub BW} almost kept unchanged. The evolution of 〈A〉, ΔV, V{sub FW,} and V{sub BW} with V{sub bg,max} were discussed by the electrons transferring process between the adsorbate and MoS{sub 2} channel.

  10. Improvement of graphene field-effect transistors by hexamethyldisilazane surface treatment

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sk. Fahad; Sonde, Sushant; Rahimi, Somayyeh; Tao, Li; Banerjee, Sanjay; Akinwande, Deji

    2014-07-01

    We report the improvement of the electrical characteristics of graphene field-effect transistors (FETs) by hexamethyldisilazane (HMDS) treatment. Both electron and hole field-effect mobilities are increased by 1.5 × -2×, accompanied by effective residual carrier concentration reduction. Dirac point also moves closer to zero Volt. Time evolution of mobility data shows that mobility improvement saturates after a few hours of HMDS treatment. Temperature-dependent transport measurements show small mobility variation between 77 K and room temperature (295 K) before HMDS application. But mobility at 77 K is almost 2 times higher than mobility at 295 K after HMDS application, indicating reduced carrier scattering. Performance improvement is also observed for FETs made on hydrophobic substrate—an HMDS-graphene-HMDS sandwich structure. Raman spectroscopic analysis shows that G peak width is increased, G peak position is down shifted, and intensity ratio between 2D and G peaks is increased after HMDS application. We attribute the improvements in electronic transport mainly to enhanced screening and mitigation of adsorbed impurities from graphene surface upon HMDS treatment.

  11. A sub kBT/q semimetal nanowire field effect transistor

    NASA Astrophysics Data System (ADS)

    Ansari, L.; Fagas, G.; Gity, F.; Greer, J. C.

    2016-08-01

    The key challenge for nanoelectronics technologies is to identify the designs that work on molecular length scales, provide reduced power consumption relative to classical field effect transistors (FETs), and that can be readily integrated at low cost. To this end, a FET is introduced that relies on the quantum effects arising for semimetals patterned with critical dimensions below 5 nm, that intrinsically has lower power requirements due to its better than a "Boltzmann tyranny" limited subthreshold swing (SS) relative to classical field effect devices, eliminates the need to form heterojunctions, and mitigates against the requirement for abrupt doping profiles in the formation of nanowire tunnel FETs. This is achieved through using a nanowire comprised of a single semimetal material while providing the equivalent of a heterojunction structure based on shape engineering to avail of the quantum confinement induced semimetal-to-semiconductor transition. Ab initio calculations combined with a non-equilibrium Green's function formalism for charge transport reveals tunneling behavior in the OFF state and a resonant conduction mechanism for the ON state. A common limitation to tunnel FET (TFET) designs is related to a low current in the ON state. A discussion relating to the semimetal FET design to overcome this limitation while providing less than 60 meV/dec SS at room temperature is provided.

  12. Sub-10 nm transparent all-around-gated ambipolar ionic field effect transistor.

    PubMed

    Lee, Seung-Hyun; Lee, Hyomin; Jin, Tianguang; Park, Sungmin; Yoon, Byung Jun; Sung, Gun Yong; Kim, Ki-Bum; Kim, Sung Jae

    2015-01-21

    In this paper, we developed a versatile ionic field effect transistor (IFET) which has an ambipolar function for manipulating molecules regardless of their polarity and can be operated at a wide range of electrolytic concentrations (10(-5) M-1 M). The IFET has circular nanochannels radially covered by gate electrodes, called "all-around-gate", with an aluminum oxide (Al2O3) oxide layer of a near-zero surface charge. Experimental and numerical validations were conducted for characterizing the IFET. We found that the versatility originated from the zero-charge density of the oxide layer and all-around-gate structure which increased the efficiency of the gate effect 5 times higher than a previously developed planar-gate by capacitance calculations. Our numerical model adapted Poisson-Nernst-Planck-Stokes (PNPS) formulations with additional nonlinear constraints of a fringing field effect and a counter-ion condensation and the experimental and numerical results were well matched. The device can control the transportation of ions at concentrations up to 1 M electrolyte which resembles a backflow of a shale gas extraction process. Furthermore, while traditional IFETs can manipulate either positively or negatively charged species depending on the inherently large surface charge of oxide layer, the presenting device and mechanism provide effective means to control the motion of both negatively and positively charged molecules which is important in biomolecule transport through nanochannels, medical diagnosis system and point-of-care system, etc. PMID:25363392

  13. Method for manufacturing compound semiconductor field-effect transistors with improved DC and high frequency performance

    DOEpatents

    Zolper, John C.; Sherwin, Marc E.; Baca, Albert G.

    2000-01-01

    A method for making compound semiconductor devices including the use of a p-type dopant is disclosed wherein the dopant is co-implanted with an n-type donor species at the time the n-channel is formed and a single anneal at moderate temperature is then performed. Also disclosed are devices manufactured using the method. In the preferred embodiment n-MESFETs and other similar field effect transistor devices are manufactured using C ions co-implanted with Si atoms in GaAs to form an n-channel. C exhibits a unique characteristic in the context of the invention in that it exhibits a low activation efficiency (typically, 50% or less) as a p-type dopant, and consequently, it acts to sharpen the Si n-channel by compensating Si donors in the region of the Si-channel tail, but does not contribute substantially to the acceptor concentration in the buried p region. As a result, the invention provides for improved field effect semiconductor and related devices with enhancement of both DC and high-frequency performance.

  14. The Hall coefficient: a tool for characterizing graphene field effect transistors

    NASA Astrophysics Data System (ADS)

    Wehrfritz, Peter; Seyller, Thomas

    2014-12-01

    Graphene field effect transistors are considered as a candidate for future high-frequency applications. For their realization, the optimal combination of substrate, graphene preparation, and insulator deposition and composition is required. This optimization must be based on an in-depth characterization of the obtained graphene insulator metal (GIM) stack. Hall effect measurements are frequently employed to study such systems, thereby focussing primarily on the charge carrier mobility. In this work we show how an analysis of the sheet Hall coefficient can reveal further important properties of the GIM stack, like, e.g., the interface trap density and the spacial charge inhomogeneity. To that end, we provide an extensive description of the GIM diode, which leads to an accurate calculation of the sheet Hall coefficient dependent on temperature and gate voltage. The gate dependent inverse sheet Hall coefficient is discussed in detail before we introduce the concept of an equivalent temperature, which is a measure of the spacial charge inhomogeneity. In order to test the concept, we apply it to evaluate already measured Hall data taken from the literature. This evaluation allows us to determine the Drude mobility, even at the charge neutrality point, which is inaccessible with a simple one band Hall mobility analysis, and to shed light on the spacial charge inhomogeneity. The formalism is easily adaptable and provides experimentalists a powerful tool for the characterization of their graphene field effect devices.

  15. Improvement of graphene field-effect transistors by hexamethyldisilazane surface treatment

    SciTech Connect

    Chowdhury, Sk. Fahad; Sonde, Sushant; Rahimi, Somayyeh; Tao, Li; Banerjee, Sanjay; Akinwande, Deji

    2014-07-21

    We report the improvement of the electrical characteristics of graphene field-effect transistors (FETs) by hexamethyldisilazane (HMDS) treatment. Both electron and hole field-effect mobilities are increased by 1.5 × –2×, accompanied by effective residual carrier concentration reduction. Dirac point also moves closer to zero Volt. Time evolution of mobility data shows that mobility improvement saturates after a few hours of HMDS treatment. Temperature-dependent transport measurements show small mobility variation between 77 K and room temperature (295 K) before HMDS application. But mobility at 77 K is almost 2 times higher than mobility at 295 K after HMDS application, indicating reduced carrier scattering. Performance improvement is also observed for FETs made on hydrophobic substrate–an HMDS-graphene-HMDS sandwich structure. Raman spectroscopic analysis shows that G peak width is increased, G peak position is down shifted, and intensity ratio between 2D and G peaks is increased after HMDS application. We attribute the improvements in electronic transport mainly to enhanced screening and mitigation of adsorbed impurities from graphene surface upon HMDS treatment.

  16. Three-Dimensional Percolation and Performance of Nanocrystal Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Aigner, Willi; Wiesinger, Markus; Wiggers, Hartmut; Stutzmann, Martin; Pereira, Rui N.

    2016-05-01

    The understanding of charge transport through films of semiconductor nanocrystals (NCs) is fundamental for most applications envisaged for these materials, e.g., light-emitting diodes, solar cells, and thin-film field-effect transistors (FETs). In this work, we show that three-dimensional film-thickness-dependent percolation effects taking place above the percolation threshold strongly affect the charge transport in NC films and greatly determine the performance of NC devices such as NC FETs. We use thin films of Si NCs with a wide range of thicknesses controllable by spray coating of NC inks to thoroughly investigate the electronic properties and charge transport in thin NC films. We find a steep (superlinear) increase of the electrical conductivity with increasing film thickness, which is not observed in bulk semiconductor thin films with bandlike charge transport. We explain this increase by an exponentially increasing number of charge percolation paths in a system dominated by hopping charge transport. Thin-film NC FETs reveal thickness-independent field-effect mobilities and threshold voltages, whereas on:off current ratios decrease quickly with increasing film thickness. We show that the steep enhancement of electrical conductivity with increasing film thickness provided by three-dimensional percolation effects is, in fact, responsible for the dramatic degradation of NC FET performance observed with increasing film thickness. Our work demonstrates that the performance of NC FETs is much more critically sensitive to film thickness than in conventional FET-based bulk semiconductor materials.

  17. Modeling interface trapping effect in organic field-effect transistor under illumination

    NASA Astrophysics Data System (ADS)

    Kwok, H. L.

    2009-02-01

    Organic field-effect transistors (OFETs) have received significant attention recently because of the potential application in low-cost flexible electronics. The physics behind their operation are relatively complex and require careful consideration particularly with respect to the effect of charge trapping at the insulator-semiconductor interface and field effect in a region with a thickness of a few molecular layers. Recent studies have shown that the so-called “onset” voltage ( V onset) in the rubrene OFET can vary significantly depending on past illumination and bias history. It is therefore important to define the role of the interface trap states in more concrete terms and show how they may affect device performance. In this work, we propose an equivalent-circuit model for the OFET to include mechanism(s) linked to trapping. This includes the existence of a light-sensitive “resistor” controlling charge flow into/out of the interface trap states. Based on the proposed equivalent-circuit model, an analytical expression of V onset is derived showing how it can depend on gate bias and illumination. Using data from the literature, we analyzed the I- V characteristics of a rubrene OFET after pulsed illumination and a tetracene OFET during steady-state illumination.

  18. Organic/inorganic interfaced field-effect transistor properties with a novel organic semiconducting material

    NASA Astrophysics Data System (ADS)

    Demir, Ahmet; Atahan, Alparslan; Bağcı, Sadık; Aslan, Metin; Saif Islam, M.

    2016-01-01

    A novel 1,3,4-oxadiazole-substituted benzo[b]triphenylene was synthesized by three-step synthetic procedure and OFET device design was successfully designed after theoretical calculations made using Gaussian software. For investigating the field-effect properties of designed organic electronic device, a SiO2 (300 nm) was thermally grown on p-Si wafer at 1000 °C as a dielectric layer and gate, source and drain contacts have been deposited using Au metal with physical vapour deposition. 1,3,4-Oxadiazole-substituted benzo[b]triphenylene was spin coated on the source and drain electrodes of our device, forming organic/inorganic interfaced field-effect transistors. Surface morphology and thin film properties were investigated using AFM. All electrical measurements were done in air ambient. The device showed a typical p-type channel behaviour with increasing negative gate bias voltage values. Our results have surprisingly shown that the saturation regime of this device has high mobility (μFET), excellent on/off ratio (Ion/Ioff), high transconductance (gm) and a small threshold voltage (VTh). The values of μFET, Ion/Ioff, gm and VTh were found as 5.02 cm2/Vs, 0.7 × 103, 5.64 μS/mm and 1.37 V, respectively. These values show that our novel organic material could be a potential candidate for organic electronic device applications in the future.

  19. Chemical vapor deposition grown monolayer graphene field-effect transistors with reduced impurity concentration

    NASA Astrophysics Data System (ADS)

    Ha, Tae-Jun; Lee, Alvin

    2015-07-01

    We report on the restoration of the electronic characteristics of waferscale chemical vapor deposition (CVD) monolayer graphene field-effect transistors (GFETs) by reducing the impurity concentration. An optimized electropolishing process on copper foils combined with carbon-fluorine encapsulation using a suitable amorphous fluoropolymer enables reducing the surface roughness of graphene and screening out interfacial impurity scattering, which leads to an improvement in all key device metrics. The conductivity at the Dirac point is substantially reduced, resulting in an increase in the on-off current ratio. In addition, the field-effect mobility increased from 1817 to 3918 cm2/V-s, the impurity concentration decreased from 1.1 × 1012 to 2.1 × 1011 cm-2 and the electron and hole transport became more symmetric. Significantly, favorable shifts toward zero voltage were observed in the Dirac point. We postulate that the smoother surface due to electropolishing and a pool of strong dipole-dipole moments in the flouropolymer coating provide a charge buffer that relaxes the fluctuation in the electron-hole puddles. We also investigate the long-term stability in GFETs encapsulated with fluoropolymer, which exhibit a high hydrophobicity that suppresses the chemical interaction with water molecules. [Figure not available: see fulltext.

  20. Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric

    NASA Astrophysics Data System (ADS)

    Jia, Li; Cui, Yu; Li, Wang; Qingbin, Liu; Zezhao, He; Shujun, Cai; Zhihong, Feng

    2014-07-01

    A scalable self-aligned approach is employed to fabricate monolayer graphene field-effect transistors on semi-insulated 4H-SiC (0001) substrates. The self-aligned process minimized access resistance and parasitic capacitance. Self-oxidized Al2O3, formed by deposition of 2 nm Al followed by exposure in air to be oxidized, is used as gate dielectric and shows excellent insulation. An intrinsic cutoff frequency of 34 GHz and maximum oscillation frequency of 36.4 GHz are realized for the monolayer graphene field-effect transistor with a gate length of 0.2 μm. These studies show a pathway to fabricate graphene transistors for future applications in ultra-high frequency circuits.