Hydrothermal Growth of ZnO Nanowires on UV-Nanoimprinted Polymer Structures.

PubMed

Park, Sooyeon; Moore, Sean A; Lee, Jaejong; Song, In-Hyouk; Farshchian, Bahador; Kim, Namwon

2018-05-01

Integration of zinc oxide (ZnO) nanowires on miniaturized polymer structures can broaden its application in multi-functional polymer devices by taking advantages of unique physical properties of ZnO nanowires and recent development of polymer microstructures in analytical systems. In this paper, we demonstrate the hydrothermal growth of ZnO nanowires on polymer microstructures fabricated by UV nanoimprinting lithography (NIL) using a polyurethane acrylate (PUA). Since PUA is a siloxane-urethane-acrylate compound containing the alpha-hydroxyl ketone, UV-cured PUA include carboxyl groups, which inhibit and suppress the nucleation and growth of ZnO nanowires on polymer structures. The presence of carboxyl groups in UV-cured PUA was substantiated by Fourier transform infrared spectroscopy (FTIR), and a Ag thin film was deposited on the nanoimprinted polymer structures to limit their inhibitive influence on the growth of ZnO nanowires. Furthermore, the naturally oxidized Ag layer (Ag2O) reduced crystalline lattice mismatches at the interface between ZnO-Ag during the seed annealing process. The ZnO nanowires grown on the Ag-deposited PUA microstructures were found to have comparable morphological characteristics with ZnO nanowires grown on a Si wafer.

Permanent bending and alignment of ZnO nanowires.

PubMed

Borschel, Christian; Spindler, Susann; Lerose, Damiana; Bochmann, Arne; Christiansen, Silke H; Nietzsche, Sandor; Oertel, Michael; Ronning, Carsten

2011-05-06

Ion beams can be used to permanently bend and re-align nanowires after growth. We have irradiated ZnO nanowires with energetic ions, achieving bending and alignment in different directions. Not only the bending of single nanowires is studied in detail, but also the simultaneous alignment of large ensembles of ZnO nanowires. Computer simulations reveal how the bending is initiated by ion beam induced damage. Detailed structural characterization identifies dislocations to relax stresses and make the bending and alignment permanent, even surviving annealing procedures.

Superhydrophobicity of Hierarchical and ZNO Nanowire Coatings

DTIC Science & Technology

2014-01-01

AFRL-RX-WP-TP-2014-0141 SUPERHYDROPHOBICITY OF HIERARCHICAL ZNO NANOWIRE COATINGS (POSTPRINT) Shin Mou AFRL/RXAN JANUARY... SUPERHYDROPHOBICITY OF HIERARCHICAL ZNO NANOWIRE COATINGS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...or disclose the work. The final publication is available at www.rsc.org/MaterialsA. 14. ABSTRACT Hierarchical superhydrophobic surfaces were

Angle-dependent photodegradation over ZnO nanowire arrays on flexible paper substrates

PubMed Central

2014-01-01

In this study, we grew zinc oxide (ZnO) nanowire arrays on paper substrates using a two-step growth strategy. In the first step, we formed single-crystalline ZnO nanoparticles of uniform size distribution (ca. 4 nm) as seeds for the hydrothermal growth of the ZnO nanowire arrays. After spin-coating of these seeds onto paper, we grew ZnO nanowire arrays conformally on these substrates. The crystal structure of a ZnO nanowire revealed that the nanowires were single-crystalline and had grown along the c axis. Further visualization through annular bright field scanning transmission electron microscopy revealed that the hydrothermally grown ZnO nanowires possessed Zn polarity. From photocatalytic activity measurements of the ZnO nanowire (NW) arrays on paper substrate, we extracted rate constants of 0.415, 0.244, 0.195, and 0.08 s-1 for the degradation of methylene blue at incident angles of 0°, 30°, 60°, and 75°, respectively; that is, the photocatalytic activity of these ZnO nanowire arrays was related to the cosine of the incident angle of the UV light. Accordingly, these materials have promising applications in the design of sterilization systems and light-harvesting devices. PMID:25593556

Reconstruction of perfect ZnO nanowires facets with high optical quality

NASA Astrophysics Data System (ADS)

Zehani, E.; Hassani, S.; Lusson, A.; Vigneron, J.; Etcheberry, A.; Galtier, P.; Sallet, V.

2017-07-01

ZnO nanowires were grown on sapphire substrates using metalorganic chemical vapor deposition. The samples were subsequently annealed under zinc pressure in a vacuum-sealed ampoule, at temperature ranging from 500 to 800 °C. The originality and the main motivation to provide a zinc-rich atmosphere were to prevent the out-diffusion of zinc from the nanowires. In doing so, the perfect structural properties and the morphology of the nanowires are kept. Interestingly, photoluminescence experiments performed on nanowires annealed in a narrow window of temperature [580-620 °C] show a spectacular improvement of the optical quality, as transitions commonly observable in high quality bulk samples are found. In addition, the intensity of the so-called "surface excitons" (SX) is strongly decreased. To accurately investigate the chemical modifications of the surface, XPS experiments were carried out and show that zinc hydroxide species and/or Zn(OH)2 sublayer were partially removed from the surface. These results suggest that the annealing process in zinc vapor helps to properly reconstruct the surface of ZnO nanowires, and improves the optical quality of their core. Such a thermal treatment at moderate temperature should be beneficial to nanodevices involving surface reaction, e.g. gas sensors.

A Novel Nanowire Assembly Process for the Fabrication of CO Sensor

PubMed Central

Cheng, Biyao; Yang, Shuming; Liu, Tao; Vazinishayan, Ali

2018-01-01

Nanowires have been widely studied due to their outstanding mechanical and electrical properties; however, their practical applications are limited to the lack of an effective technique for controlled assembly. In the present work, zinc oxide (ZnO) nanowire arrays were assembled via a combing process using a makeup brush and the nanodevice was fabricated. The current–voltage (I–V) and ultraviolet (UV) characteristics of the device indicate stable and repeatable electrical properties. The carbon monoxide (CO) sensing properties were tested at operating temperatures of 200, 300 and 400 °C. It was found that ZnO based sensor exhibited the highest sensitivity to CO at 300 °C due to the change of dominant oxygen species. Comparing with others result, the sensitivity of the fabricated sensor exhibits higher sensing performance. The sensing mechanism of the CO sensor is also discussed. PMID:29673203

A Novel Nanowire Assembly Process for the Fabrication of CO Sensor.

PubMed

Cheng, Biyao; Yang, Shuming; Liu, Tao; Vazinishayan, Ali

2018-04-17

Nanowires have been widely studied due to their outstanding mechanical and electrical properties; however, their practical applications are limited to the lack of an effective technique for controlled assembly. In the present work, zinc oxide (ZnO) nanowire arrays were assembled via a combing process using a makeup brush and the nanodevice was fabricated. The current–voltage (I–V) and ultraviolet (UV) characteristics of the device indicate stable and repeatable electrical properties. The carbon monoxide (CO) sensing properties were tested at operating temperatures of 200, 300 and 400 °C. It was found that ZnO based sensor exhibited the highest sensitivity to CO at 300 °C due to the change of dominant oxygen species. Comparing with others result, the sensitivity of the fabricated sensor exhibits higher sensing performance. The sensing mechanism of the CO sensor is also discussed.

The Assessment for Sensitivity of a NO2 Gas Sensor with ZnGa2O4/ZnO Core-Shell Nanowires—a Novel Approach

PubMed Central

Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Hsu, Cheng-Liang; Hsueh, Ting Jen; Shieh, Tien-Yu

2010-01-01

The application of novel core-shell nanowires composed of ZnGa2O4/ZnO to improve the sensitivity of NO2 gas sensors is demonstrated in this study. The growth of ZnGa2O4/ZnO core-shell nanowires is performed by reactive evaporation on patterned ZnO:Ga/SiO2/Si templates at 600 °C. This is to form the homogeneous structure of the sensors investigated in this report to assess their sensitivity in terms of NO2 detection. These novel NO2 gas sensors were evaluated at working temperatures of 25 °C and at 250 °C, respectively. The result reveals the ZnGa2O4/ZnO core-shell nanowires present a good linear relationship (R2 > 0.99) between sensitivity and NO2 concentration at both working temperatures. These core-shell nanowire sensors also possess the highest response (<90 s) and recovery (<120 s) values with greater repeatability seen for NO2 sensors at room temperature, unlike traditional sensors that only work effectively at much higher temperatures. The data in this study indicates the newly-developed ZnGa2O4/ZnO core-shell nanowire based sensors are highly promising for industrial applications. PMID:22319286

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires.

PubMed

Araneo, Rodolfo; Rinaldi, Antonio; Notargiacomo, Andrea; Bini, Fabiano; Pea, Marialilia; Celozzi, Salvatore; Marinozzi, Franco; Lovat, Giampiero

2014-12-08

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews.

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires

PubMed Central

Araneo, Rodolfo; Rinaldi, Antonio; Notargiacomo, Andrea; Bini, Fabiano; Pea, Marialilia; Celozzi, Salvatore; Marinozzi, Franco; Lovat, Giampiero

2014-01-01

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews. PMID:25494351

Metal Oxide Nanowire Preparation and Their Integration into Chemical Sensing Devices at the SENSOR Lab in Brescia

PubMed Central

Bertuna, Angela; Faglia, Guido; Ferroni, Matteo; Kaur, Navpreet; Munasinghe Arachchige, Hashitha M. M.; Sberveglieri, Giorgio; Comini, Elisabetta

2017-01-01

Metal oxide 1D nanowires are probably the most promising structures to develop cheap stable and selective chemical sensors. The purpose of this contribution is to review almost two-decades of research activity at the Sensor Lab Brescia on their preparation during by vapor solid (n-type In2O3, ZnO), vapor liquid solid (n-type SnO2 and p-type NiO) and thermal evaporation and oxidation (n-type ZnO, WO3 and p-type CuO) methods. For each material we’ve assessed the chemical sensing performance in relation to the preparation conditions and established a rank in the detection of environmental and industrial pollutants: SnO2 nanowires were effective in DMMP detection, ZnO nanowires in NO2, acetone and ethanol detection, WO3 for ammonia and CuO for ozone. PMID:28468310

Growth of catalyst-free high-quality ZnO nanowires by thermal evaporation under air ambient

PubMed Central

2012-01-01

ZnO nanowires have been successfully fabricated on Si substrate by simple thermal evaporation of Zn powder under air ambient without any catalyst. Morphology and structure analyses indicated that ZnO nanowires had high purity and perfect crystallinity. The diameter of ZnO nanowires was 40 to 100 nm, and the length was about several tens of micrometers. The prepared ZnO nanowires exhibited a hexagonal wurtzite crystal structure. The growth of the ZnO nanostructure was explained by the vapor-solid mechanism. The simplicity, low cost and fewer necessary apparatuses of the process would suit the high-throughput fabrication of ZnO nanowires. The ZnO nanowires fabricated on Si substrate are compatible with state-of-the-art semiconductor industry. They are expected to have potential applications in functional nanodevices. PMID:22502639

Visible electroluminescence from a ZnO nanowires/p-GaN heterojunction light emitting diode.

PubMed

Baratto, C; Kumar, R; Comini, E; Faglia, G; Sberveglieri, G

2015-07-27

In the current paper we apply catalyst assisted vapour phase growth technique to grow ZnO nanowires (ZnO nws) on p-GaN thin film obtaining EL emission in reverse bias regime. ZnO based LED represents a promising alternative to III-nitride LEDs, as in free devices: the potential is in near-UV emission and visible emission. For ZnO, the use of nanowires ensures good crystallinity of the ZnO, and improved light extraction from the interface when the nanowires are vertically aligned. We prepared ZnO nanowires in a tubular furnace on GaN templates and characterized the p-n ZnO nws/GaN heterojunction for LED applications. SEM microscopy was used to study the growth of nanowires and device preparation. Photoluminescence (PL) and Electroluminescence (EL) spectroscopies were used to characterize the heterojunction, showing that good quality of PL emission is observed from nanowires and visible emission from the junction can be obtained from the region near ZnO contact, starting from onset bias of 6V.

Enhancement of Si solar cell efficiency using ZnO nanowires with various diameters

NASA Astrophysics Data System (ADS)

Gholizadeh, A.; Reyhani, A.; Parvin, P.; Mortazavi, S. Z.; Mehrabi, M.

2018-01-01

Here, Zinc Oxide nanowires are synthesized using thermal chemical vapor deposition of a Zn granulate source and used to enhance a significant Si-solar cell efficiency with simple and low cost method. The nanowires are grown in various O2 flow rates. Those affect the shape, yield, structure and the quality of ZnO nanowires according to scanning electron microscopy and x-ray diffraction analyses. This delineates that the ZnO nanostructure is dependent on the synthesis conditions. The photoluminescence spectroscopy of ZnO indicates optical emission at the Ultra-Violet and blue-green regions whose intensity varies as a function of diameter of ZnO nano-wires. The optical property of ZnO layer is measured by UV-visible and diffuse reflection spectroscopy that demonstrate high absorbance at 280-550 nm. Furthermore, the photovoltaic characterization of ZnO nanowires is investigated based on the drop casting on Si-solar cell. The ZnO nanowires with various diameters demonstrate different effects on the efficiency of Si-solar cells. We have shown that the reduction of the spectral reflectance and down-shifting process as well as the reduction of photon trapping are essential parameters on the efficiency of Si-solar cells. However, the latter is dominated here. In fact, the trapped photons during the electron-hole generation are dominant due to lessening the absorption rate in ZnO nano-wires. The results indicate that the mean diameters reduction of ZnO nanowires is also essential to improve the fill factor. The external and internal quantum efficiency analyses attest the efficiency improvement over the blue region which is related to the key parameters above.

CdTe quantum-dot-modified ZnO nanowire heterostructure

NASA Astrophysics Data System (ADS)

Shahi, Kanchana; Singh, R. S.; Singh, Ajaya Kumar; Aleksandrova, Mariya; Khenata, Rabah

2018-03-01

The effect of CdTe quantum-dot (QD) decoration on the photoluminescence (PL) behaviour of ZnO nanowire (NW) array is presented in the present work. Highly crystalline and vertically 40-50 nm diameter range and 1 µm in length aligned ZnO NWs are synthesized using low-cost method. The crystallinity and morphology of the NWs are studied by scanning electron microscopy and X-ray powder diffraction methods.Optical properties of the nanowires are studied using photo-response and PL spectroscopy. CdTe QDs are successfully synthesized on ZnO nanowire surface by dip-coating method. ZnO NWs are sensitized with CdTe QDs characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and PL spectroscopy. The highly quenched PL intensity indicates the charge transfer at interface between CdTe QDs and ZnO NWs and is due to the formation of type-II heterostructure between QDs and NWs. Photo-response behaviour of heterostructure of the film is also been incorporated in the present work.

Performance improvement of miniaturized ZnO nanowire accelerometer fabricated by refresh hydrothermal synthesis

PubMed Central

Song, Sangho; Kim, Hyun Chan; Kim, Jung Woong; Kim, Debora

2017-01-01

Miniaturized accelerometers are necessary for evaluating the performance of small devices, such as haptics, robotics and simulators. In this study, we fabricated miniaturized accelerometers using well-aligned ZnO nanowires. The layer of ZnO nanowires is used for active piezoelectric layer of the accelerometer, and copper was chosen as a head mass. Seedless and refresh hydrothermal synthesis methods were conducted to grow ZnO nanowires on the copper substrate and the effect of ZnO nanowire length on the accelerometer performance was investigated. The refresh hydrothermal synthesis exhibits longer ZnO nanowires, 12 µm, than the seedless hydrothermal synthesis, 6 µm. Performance of the fabricated accelerometers was verified by comparing with a commercial accelerometer. The sensitivity of the fabricated accelerometer by the refresh hydrothermal synthesis is shown to be 37.7 pA g−1, which is about 30 times larger than the previous result. PMID:28989760

Ultraviolet photodetection of flexible ZnO nanowire sheets in polydimethylsiloxane polymer.

PubMed

Liu, Jinzhang; Motta, Nunzio; Lee, Soonil

2012-01-01

ZnO nanowires are normally exposed to an oxygen atmosphere to achieve high performance in UV photodetection. In this work we present results on a UV photodetector fabricated using a flexible ZnO nanowire sheet embedded in polydimethylsiloxane (PDMS), a gas-permeable polymer, showing reproducible UV photoresponse and enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay time is prolonged by about a factor of four. We conclude that oxygen molecules diffusing in PDMS are responsible for the UV photoresponse.

Construction of 1D SnO2-coated ZnO nanowire heterojunction for their improved n-butylamine sensing performances

NASA Astrophysics Data System (ADS)

Wang, Liwei; Li, Jintao; Wang, Yinghui; Yu, Kefu; Tang, Xingying; Zhang, Yuanyuan; Wang, Shaopeng; Wei, Chaoshuai

2016-10-01

One-dimensional (1D) SnO2-coated ZnO nanowire (SnO2/ZnO NW) N-N heterojunctions were successfully constructed by an effective solvothermal treatment followed with calcination at 400 °C. The obtained samples were characterized by means of XRD, SEM, TEM, Scanning TEM coupled with EDS and XPS analysis, which confirmed that the outer layers of N-type SnO2 nanoparticles (avg. 4 nm) were uniformly distributed onto our pre-synthesized n-type ZnO nanowire supports (diameter 80~100 nm, length 12~16 μm). Comparisons of the gas sensing performances among pure SnO2, pure ZnO NW and the as-fabricated SnO2/ZnO NW heterojunctions revealed that after modification, SnO2/ZnO NW based sensor exhibited remarkably improved response, fast response and recovery speeds, good selectivity and excellent reproducibility to n-butylamine gas, indicating it can be used as promising candidates for high-performance organic amine sensors. The enhanced gas-sensing behavior should be attributed to the unique 1D wire-like morphology of ZnO support, the small size effect of SnO2 nanoparticles, and the semiconductor depletion layer model induced by the strong interfacial interaction between SnO2 and ZnO of the heterojunctions. The as-prepared SnO2/ZnO NW heterojunctions may also supply other novel applications in the fields like photocatalysis, lithium-ion batteries, waste water purification, and so on.

Luminescence dynamics of bound exciton of hydrogen doped ZnO nanowires

DOE PAGES

Yoo, Jinkyoung; Yi, Gyu -Chul; Chon, Bonghwan; ...

2016-04-11

In this study, all-optical camera, converting X-rays into visible photons, is a promising strategy for high-performance X-ray imaging detector requiring high detection efficiency and ultrafast detector response time. Zinc oxide is a suitable material for all-optical camera due to its fast radiative recombination lifetime in sub-nanosecond regime and its radiation hardness. ZnO nanostructures have been considered as proper building blocks for ultrafast detectors with spatial resolution in sub-micrometer scale. To achieve remarkable enhancement of luminescence efficiency n-type doping in ZnO has been employed. However, luminescence dynamics of doped ZnO nanostructures have not been thoroughly investigated whereas undoped ZnO nanostructures havemore » been employed to study their luminescence dynamics. Here we report a study of luminescence dynamics of hydrogen doped ZnO nanowires obtained by hydrogen plasma treatment. Hydrogen doping in ZnO nanowires gives rise to significant increase in the near-band-edge emission of ZnO and decrease in averaged photoluminescence lifetime from 300 to 140 ps at 10 K. The effects of hydrogen doping on the luminescent characteristics of ZnO nanowires were changed by hydrogen doping process variables.« less

Ultraviolet photodetection of flexible ZnO nanowire sheets in polydimethylsiloxane polymer

PubMed Central

Motta, Nunzio; Lee, Soonil

2012-01-01

Summary ZnO nanowires are normally exposed to an oxygen atmosphere to achieve high performance in UV photodetection. In this work we present results on a UV photodetector fabricated using a flexible ZnO nanowire sheet embedded in polydimethylsiloxane (PDMS), a gas-permeable polymer, showing reproducible UV photoresponse and enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay time is prolonged by about a factor of four. We conclude that oxygen molecules diffusing in PDMS are responsible for the UV photoresponse. PMID:23016139

Effects of mechanical strain on optical properties of ZnO nanowire

NASA Astrophysics Data System (ADS)

Vazinishayan, Ali; Lambada, Dasaradha Rao; Yang, Shuming; Zhang, Guofeng; Cheng, Biyao; Woldu, Yonas Tesfaye; Shafique, Shareen; Wang, Yiming; Anastase, Ndahimana

2018-02-01

The main objective of this study is to investigate the influences of mechanical strain on optical properties of ZnO nanowire (NW) before and after embedding ZnS nanowire into the ZnO nanowire, respectively. For this work, commercial finite element modeling (FEM) software package ABAQUS and three-dimensional (3D) finite-difference time-domain (FDTD) methods were utilized to analyze the nonlinear mechanical behavior and optical properties of the sample, respectively. Likewise, in this structure a single focused Gaussian beam with wavelength of 633 nm was used as source. The dimensions of ZnO nanowire were defined to be 12280 nm in length and 103.2 nm in diameter with hexagonal cross-section. In order to investigate mechanical properties, three-point bending technique was adopted so that both ends of the model were clamped with mid-span under loading condition and then the physical deformation model was imported into FDTD solutions to study optical properties of ZnO nanowire under mechanical strain. Moreover, it was found that increase in the strain due to the external load induced changes in reflectance, transmittance and absorptance, respectively.

Nanostructured ZnO films for potential use in LPG gas sensors

NASA Astrophysics Data System (ADS)

Latyshev, V. M.; Berestok, T. O.; Opanasyuk, A. S.; Kornyushchenko, A. S.; Perekrestov, V. I.

2017-05-01

The aim of the work was to obtain ZnO nanostructures with heightened surface area and to study relationship between formation method and gas sensor properties towards propane-butane mixture (LPG). In order to synthesize ZnO nanostructures chemical and physical formation methods have been utilized. The first one was chemical bath deposition technology and the second one magnetron sputtering of Zn followed by oxidation. Optimal method and technological parameters corresponding to formation of material with the highest sensor response have been determined experimentally. Dynamical gas sensor response at different temperature values and dependencies of the sensor sensitivity on the temperature at different LPG concentrations in air have been investigated. It has been found, that sensor response depends on the sample morphology and has the highest value for the structure consisting of thin nanowires. The factors that lead to the decrease in the gas sensor operating temperature have been determined.

Hydrothermal growth of ZnO nanowire arrays: fine tuning by precursor supersaturation

DOE PAGES

Yan, Danhua; Cen, Jiajie; Zhang, Wenrui; ...

2016-12-20

In this paper, we develop a technique that fine tunes the hydrothermal growth of ZnO nanowires to address the difficulties in controlling their growth in a conventional one-pot hydrothermal method. In our technique, precursors are separately and slowly supplied with the assistance of a syringe pump, through the entire course of the growth. Compared to the one-pot method, the significantly lowered supersaturation of precursors helps eliminating competitive homogeneous nucleation and improves the reproducibility. The supersaturation degree can be readily tuned by the precursor quantity and injection rate, thus forming ZnO nanowire arrays of various geometries and packing densities in amore » highly controllable fashion. The precise control of ZnO nanowire growth enables systematic studies on the correlation between the material's properties and its morphology. Finally, in this work, ZnO nanowire arrays of various morphologies are studied as photoelectrochemical (PEC) water splitting photoanodes, in which we establish clear correlations between the water splitting performance and the nanowires' size, shape, and packing density.« less

Detecting Liquefied Petroleum Gas (LPG) at Room Temperature Using ZnSnO3/ZnO Nanowire Piezo-Nanogenerator as Self-Powered Gas Sensor.

PubMed

Fu, Yongming; Nie, Yuxin; Zhao, Yayu; Wang, Penglei; Xing, Lili; Zhang, Yan; Xue, Xinyu

2015-05-20

High sensitivity, selectivity, and reliability have been achieved from ZnSnO3/ZnO nanowire (NW) piezo-nanogenerator (NG) as self-powered gas sensor (SPGS) for detecting liquefied petroleum gas (LPG) at room temperature (RT). After being exposed to 8000 ppm LPG, the output piezo-voltage of ZnSnO3/ZnO NW SPGS under compressive deformation is 0.089 V, much smaller than that in air ambience (0.533 V). The sensitivity of the SPGS against 8000 ppm LPG is up to 83.23, and the low limit of detection is 600 ppm. The SPGS has lower sensitivity against H2S, H2, ethanol, methanol and saturated water vapor than LPG, indicating good selectivity for detecting LPG. After two months, the decline of the sensing performance is less than 6%. Such piezo-LPG sensing at RT can be ascribed to the new piezo-surface coupling effect of ZnSnO3/ZnO nanocomposites. The practical application of the device driven by human motion has also been simply demonstrated. This work provides a novel approach to fabricate RT-LPG sensors and promotes the development of self-powered sensing system.

Growth Mechanism Studies of ZnO Nanowires: Experimental Observations and Short-Circuit Diffusion Analysis.

PubMed

Shih, Po-Hsun; Wu, Sheng Yun

2017-07-21

Plenty of studies have been performed to probe the diverse properties of ZnO nanowires, but only a few have focused on the physical properties of a single nanowire since analyzing the growth mechanism along a single nanowire is difficult. In this study, a single ZnO nanowire was synthesized using a Ti-assisted chemical vapor deposition (CVD) method to avoid the appearance of catalytic contamination. Two-dimensional energy dispersive spectroscopy (EDS) mapping with a diffusion model was used to obtain the diffusion length and the activation energy ratio. The ratio value is close to 0.3, revealing that the growth of ZnO nanowires was attributed to the short-circuit diffusion.

Growth Mechanism Studies of ZnO Nanowires: Experimental Observations and Short-Circuit Diffusion Analysis

PubMed Central

Shih, Po-Hsun

2017-01-01

Plenty of studies have been performed to probe the diverse properties of ZnO nanowires, but only a few have focused on the physical properties of a single nanowire since analyzing the growth mechanism along a single nanowire is difficult. In this study, a single ZnO nanowire was synthesized using a Ti-assisted chemical vapor deposition (CVD) method to avoid the appearance of catalytic contamination. Two-dimensional energy dispersive spectroscopy (EDS) mapping with a diffusion model was used to obtain the diffusion length and the activation energy ratio. The ratio value is close to 0.3, revealing that the growth of ZnO nanowires was attributed to the short-circuit diffusion. PMID:28754030

A simple and transparent well-aligned ZnO nanowire array ultraviolet photodetector with high responsivity

NASA Astrophysics Data System (ADS)

Yin, Lei; Ding, Hesheng; Yuan, Zhaolin; Huang, Wendeng; Shuai, Chunjiang; Xiong, Zhaoxin; Deng, Jianping; Lv, Tengbo

2018-06-01

Well-aligned zinc oxide (ZnO) nanowire arrays were grown on an interdigital patterned fluorine tin oxide (FTO)-coated glass substrate by a facile chemical bath deposition at low temperature. Morphology, crystalline structure, and optical properties of the ZnO nanowire arrays were analyzed in detail. The results revealed that the ZnO nanowires had wurtzite structure, typically ∼40-60 nm in diameter, and ∼700-800 nm in length, a great number of highly uniform and dense nanowires grew vertically on the substrate to form the well-aligned ZnO nanowire arrays, which had very high optical transmission (>86%) in the visible light region. In addition, the performance of ZnO nanowire arrays ultraviolet (UV) photodetector was systematically examined. The photosensitivity (S), responsivity (R), response and decay time of the photodetector were 703 at +0.2 V, 113 A/W at +5 V, 23 s and 73 s respectively. Also, the photoresponse mechanism of the UV photodetector was illuminated in terms of the oxygen adsorption-photodesorption process.

ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts.

PubMed

Yang, Wenming; Zhu, Rong; Zong, Xianli

2016-12-01

Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 10(17)/m(3) orders of magnitude, which is practicable for most discharging applications.

Hydrothermal growth of ZnO nanowires on flexible fabric substrates

NASA Astrophysics Data System (ADS)

Hong, Gwang-Wook; Yun, Sang-Ho; Kim, Joo-Hyung

2016-04-01

ZnO nanowires (NWs) would provide significant enhancement in sensitivity due to high surface to volume ratio. We investigated the first methodical study on the quantitative relationship between the process parameters of solution concentration ratio, structure, and physical and properties of ZnO NWs grown on different flexible fabric surfaces. To develop a fundamental following concerning various substrates, we controlled the growth speed of ZnO NWs and nanowires on cotton surface with easy and moderate cost fabrication method. Using ammonium hydroxide as the reactant with zinc nitrate hexahydrate, ZnO NWs layer have been grown on metal layers, instead of seed layer. ZnO NWs fabrication was done on different fabric substrates such as wool, nylon and polypropylene (PP). After the ZnO NWs grown to each substrates, we coated insulating layer with polyurethane (PU) and ethyl cellulose for prevent external intervention. Detailed electrical characterization was subsequently performed to reveal the working characteristics of the hybrid fabric. For electrical verification of fabricated ZnO NWs, we implemented measurement impact test and material properties with FFT analyzer and LCR meter.

Fabrication and Performance Study on Individual Zno Nanowires Based Bioelectrode

NASA Astrophysics Data System (ADS)

Zhao, Yanguang; Yan, Xiaoqin; Kang, Zhuo; Lin, Pei

2012-08-01

One-dimensional zinc oxide nanowires (ZnO NWs) have unique advantages for use in biosensors as follows: oxide stable surface, excellent biosafety, high specific surface area, high isoelectric point (IEP = 9.5). In this work, we have prepared a kind of electrochemical bioelectrode based on individual ZnO NWs. Here, ZnO NWs with high quality were successfully synthesized by CVD method, which were characterized by scanning electron microscopy, X-ray diffraction and photoluminescence. Then the Raman spectra and electrical characterization demonstrated the adsorption of uricase on ZnO wires. At last, a series of electrochemical measurements were carried out by using an electrochemical workstation with a conventional three-electrode system to obtain the cyclic voltammetry characteristics of the bioelectrodes. The excellent performance of the fabricated bioelectrode implies the potential application for single ZnO nanowire to construct electrochemical biosensor for the detection of uric acid.

Engineered ZnO nanowire arrays using different nanopatterning techniques

NASA Astrophysics Data System (ADS)

Volk, János; Szabó, Zoltán; Erdélyi, Róbert; Khánh, Nguyen Q.

2012-02-01

The impact of various masking patterns and template layers on the wet chemically grown vertical ZnO nanowire arrays was investigated. The nanowires/nanorods were seeded at nucleation windows which were patterned in a mask layer using various techniques such as electron beam lithography, nanosphere photolithography, and atomic force microscope type nanolithography. The compared ZnO templates included single crystals, epitaxial layer, and textured polycrystalline films. Scanning electron microscopy revealed that the alignment and crystal orientation of the nanowires were dictated by the underlying seed layer, while their geometry can be tuned by the parameters of the certain nanopatterning technique and of the wet chemical process. The comparison of the alternative nanolithography techniques showed that using direct writing methods the diameter of the ordered ZnO nanowires can be as low as 30-40 nm at a density of 100- 1000 NW/μm2 in a very limited area (10 μm2-1 mm2). Nanosphere photolithography assisted growth, on the other hand, favors thicker nanopillars (~400 nm) and enables large-area, low-cost patterning (1-100 cm2). These alternative lowtemperature fabrication routes can be used for different novel optoelectronic devices, such as nanorod based ultraviolet photodiode, light emitting device, and waveguide laser.

Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

NASA Astrophysics Data System (ADS)

Demes, Thomas; Ternon, Céline; Morisot, Fanny; Riassetto, David; Legallais, Maxime; Roussel, Hervé; Langlet, Michel

2017-07-01

Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20-25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20-25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

Growth of Vertically Aligned ZnO Nanowire Arrays Using Bilayered Metal Catalysts

DTIC Science & Technology

2012-01-01

12] J. P. Liu, C. X. Guo, C. M. Li et al., “Carbon-decorated ZnO nanowire array: a novel platform for direct electrochemistry of enzymes and...cited. Vertically aligned, high-density ZnO nanowires (NWs) were grown for the first time on c-plane sapphire using binary alloys of Ni/Au or Cu/Au as...deleterious to the ZnO NW array growth. Significant improvement of the Au adhesion on the substrate was noted, opening the potential for direct

Persistent photoconductivity in ZnO nanowires: Influence of oxygen and argon ambient

NASA Astrophysics Data System (ADS)

Madel, M.; Huber, F.; Mueller, R.; Amann, B.; Dickel, M.; Xie, Y.; Thonke, K.

2017-03-01

ZnO nanowires typically show persistent photoconductivity (PPC), which depends in their temporal behaviour on the ambient. We investigate ZnO nanowires in oxygen and argon ambient and analyze the PPC both on the short and on the long time scale to sort out the underlying mechanisms. Wavelength dependent excitation shows the energy barrier for the PPC to be around 150 meV below the band gap of ZnO, independent of the ambient atmosphere. In photocurrent measurements at constant wavelength, a log-logistic dependence of the conductivity on the partial oxygen pressure is observed. The experimental results are compared to a model of Bonasewicz et al. [J. Electrochem. Soc. 133, 2270 (1986)] and can be explained by oxygen adsorption processes occurring on the surface of the ZnO nanowires. From temperature dependent measurements of the decay times in oxygen and argon ambient, the related activation energies for the fast and slow decay processes are determined. Comparing our results to theoretical calculations of energy levels of intrinsic defects [Janotti and Van de Walle, Phys. Status Solidi B 248, 799 (2011)], we find oxygen vacancies to be related to the fast decay processes, whereas adsorption and desorption processes of oxygen on the ZnO nanowire surface account for the slow part.

Nanowire sensor, sensor array, and method for making the same

NASA Technical Reports Server (NTRS)

Homer, Margie (Inventor); Fleurial, Jean-Pierre (Inventor); Bugga, Ratnakumar (Inventor); Vasquez, Richard (Inventor); Yun, Minhee (Inventor); Myung, Nosang (Inventor); Choi, Daniel (Inventor); Goddard, William (Inventor); Ryan, Margaret (Inventor); Yen, Shiao-Pin (Inventor)

2012-01-01

The present invention relates to a nanowire sensor and method for forming the same. More specifically, the nanowire sensor comprises at least one nanowire formed on a substrate, with a sensor receptor disposed on a surface of the nanowire, thereby forming a receptor-coated nanowire. The nanowire sensor can be arranged as a sensor sub-unit comprising a plurality of homogeneously receptor-coated nanowires. A plurality of sensor subunits can be formed to collectively comprise a nanowire sensor array. Each sensor subunit in the nanowire sensor array can be formed to sense a different stimulus, allowing a user to sense a plurality of stimuli. Additionally, each sensor subunit can be formed to sense the same stimuli through different aspects of the stimulus. The sensor array is fabricated through a variety of techniques, such as by creating nanopores on a substrate and electrodepositing nanowires within the nanopores.

Quantum dots coupled ZnO nanowire-array panels and their photocatalytic activities.

PubMed

Liao, Yulong; Que, Wenxiu; Zhang, Jin; Zhong, Peng; Yuan, Yuan; Qiu, Xinku; Shen, Fengyu

2013-02-01

Fabrication and characterization of a heterojunction structured by CdS quantum dots@ZnO nanowire-array panels were presented. Firstly, ZnO nanowire-array panels were prepared by using a chemical bath deposition approach where wurtzite ZnO nanowires with a diameter of about 100 nm and 3 microm in length grew perpendicularly to glass substrate. Secondly, CdS quantum dots were deposited onto the surface of the ZnO nanowire-arrays by using successive ion layer absorption and reaction method, and the CdS shell/ZnO core heterojunction were thus obtained. Field emission scanning electron microscopy and transmission electron microscope were employed to characterize the morphological properties of the as-obtained CdS quantum dots@ZnO nanowire-array panels. X-ray diffraction was adopted to characterize the crystalline properties of the as-obtained CdS quantum dots@ZnO nanowire-array panels. Methyl orange was taken as a model compound to confirm the photocatalytic activities of the CdS shell/ZnO core heterojunction. Results indicate that CdS with narrow band gap not only acts as a visible-light sensitizer but also is responsible for an effective charge separation.

Electrical tuning of spin splitting in Bi-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Aras, Mehmet; Kılıç, ćetin

2018-01-01

The effect of applying an external electric field on doping-induced spin-orbit splitting of the lowest conduction-band states in a bismuth-doped zinc oxide nanowire is studied by performing electronic structure calculations within the framework of density functional theory. It is demonstrated that spin splitting in Bi-doped ZnO nanowires could be tuned and enhanced electrically via control of the strength and direction of the applied electric field, thanks to the nonuniform and anisotropic response of the ZnO:Bi nanowire to external electric fields. The results reported here indicate that a single ZnO nanowire doped with a low concentration of Bi could function as a spintronic device, the operation of which is controlled by applied lateral electric fields.

Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules.

PubMed

Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

2016-01-08

We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (R air/R gas = 12.8) compared to that (R air/R gas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules

PubMed Central

Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

2016-01-01

We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (Rair/Rgas = 12.8) compared to that (Rair/Rgas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors. PMID:26743814

Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules

NASA Astrophysics Data System (ADS)

Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

2016-01-01

We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (Rair/Rgas = 12.8) compared to that (Rair/Rgas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

Opto-mechano-electrical tripling in ZnO nanowires probed by photocurrent spectroscopy in a high-resolution transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, C.; Golberg, D., E-mail: xuzhi@iphy.ac.cn, E-mail: golberg.dmitri@nims.go.jp; Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennodai 1, Tsukuba, Ibaraki 3058577

2015-08-31

Photocurrent spectroscopy of individual free-standing ZnO nanowires inside a high-resolution transmission electron microscope (TEM) is reported. By using specially designed optical in situ TEM system capable of scanning tunneling microscopy probing paired with light illumination, opto-mechano-electrical tripling phenomenon in ZnO nanowires is demonstrated. Splitting of photocurrent spectra at around 3.3 eV under in situ TEM bending of ZnO nanowires directly corresponds to nanowire deformation and appearance of expanded and compressed nanowire sides. Theoretical simulation of a bent ZnO nanowire has an excellent agreement with the experimental data. The splitting effect could be explained by a change in the valence band structuremore » of ZnO nanowires due to a lattice strain. The strain-induced splitting provides important clues for future flexible piezo-phototronics.« less

Effect of gamma radiation on the optical and structural properties of ZnO nanowires with various diameters

NASA Astrophysics Data System (ADS)

Reyhani, A.; Gholizadeh, A.; vahedi, V.; Khanlary, M. R.

2018-01-01

The effects of gamma-irradiation are studied on the morphology and structural properties of ZnO nanowire with various diameters. The ZnO nanowires are grown using Zn thin films at various initial thicknesses including 125, 250 and 500 nm in air ambient. The results illustrate dramatic effects of Gamma-irradiation on the deformation of ZnO nanowires. Thus, radiation induce ripple ZnO surfaces instead ZnO nanowires. Gamma-irradiation has also been effective on the optical and crystalline properties of the nanowires. X-ray diffraction attests that size of the ZnO nano-structures has changed and (l00) crystalline direction related to Zn metal has been created after irradiation. UV-Visible spectra display two areas for transmittance of irradiated ZnO nanowires, one in the Visible-light and the other in IR sub-region. In the Visible-light area, the layer gets thicker from 125 to 500 nm; the difference between the layer transmittance spectra is reduced before and after gamma irradiation. In the IR-light region, with increasing of ZnO initial thickness, the difference between the layer transmittance spectra is increased before and after gamma irradiation. The photoluminescence spectroscopy displays that intensity of green-yellow band improves in compared to near-band-edge emission due to formation of Zn metal and oxygen vacancies after gamma irradiation.

Power generation from base excitation of a Kevlar composite beam with ZnO nanowires

NASA Astrophysics Data System (ADS)

Malakooti, Mohammad H.; Hwang, Hyun-Sik; Sodano, Henry A.

2015-04-01

One-dimensional nanostructures such as nanowires, nanorods, and nanotubes with piezoelectric properties have gained interest in the fabrication of small scale power harvesting systems. However, the practical applications of the nanoscale materials in structures with true mechanical strengths have not yet been demonstrated. In this paper, piezoelectric ZnO nanowires are integrated into the fiber reinforced polymer composites serving as an active phase to convert the induced strain energy from ambient vibration into electrical energy. Arrays of ZnO nanowires are grown vertically aligned on aramid fibers through a low-cost hydrothermal process. The modified fabrics with ZnO nanowires whiskers are then placed between two carbon fabrics as the top and the bottom electrodes. Finally, vacuum resin transfer molding technique is utilized to fabricate these multiscale composites. The fabricated composites are subjected to a base excitation using a shaker to generate charge due to the direct piezoelectric effect of ZnO nanowires. Measuring the generated potential difference between the two electrodes showed the energy harvesting application of these multiscale composites in addition to their superior mechanical properties. These results propose a new generation of power harvesting systems with enhanced mechanical properties.

Digital selective growth of a ZnO nanowire array by large scale laser decomposition of zinc acetate.

PubMed

Hong, Sukjoon; Yeo, Junyeob; Manorotkul, Wanit; Kang, Hyun Wook; Lee, Jinhwan; Han, Seungyong; Rho, Yoonsoo; Suh, Young Duk; Sung, Hyung Jin; Ko, Seung Hwan

2013-05-07

We develop a digital direct writing method for ZnO NW micro-patterned growth on a large scale by selective laser decomposition of zinc acetate. For ZnO NW growth, by replacing the bulk heating with the scanning focused laser as a fully digital local heat source, zinc acetate crystallites can be selectively activated as a ZnO seed pattern to grow ZnO nanowires locally on a larger area. Together with the selective laser sintering process of metal nanoparticles, more than 10,000 UV sensors have been demonstrated on a 4 cm × 4 cm glass substrate to develop all-solution processible, all-laser mask-less digital fabrication of electronic devices including active layer and metal electrodes without any conventional vacuum deposition, photolithographic process, premade mask, high temperature and vacuum environment.

Extreme Carrier Depletion and Superlinear Photoconductivity in Ultrathin Parallel-Aligned ZnO Nanowire Array Photodetectors Fabricated by Infiltration Synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nam, Chang-Yong; Stein, Aaron

Ultrathin semiconductor nanowires enable high-performance chemical sensors and photodetectors, but their synthesis and device integration by standard complementary metal-oxide-semiconductor (CMOS)-compatible processes remain persistent challenges. This work demonstrates fully CMOS-compatible synthesis and integration of parallel-aligned polycrystalline ZnO nanowire arrays into ultraviolet photodetectors via infiltration synthesis, material hybridization technique derived from atomic layer deposition. The nanowire photodetector features unique, high device performances originating from extreme charge carrier depletion, achieving photoconductive on–off ratios of >6 decades, blindness to visible light, and ultralow dark currents as low as 1 fA, the lowest reported for nanostructure-based photoconductive photodetectors. Surprisingly, the low dark current is invariantmore » with increasing number of nanowires and the photodetector shows unusual superlinear photoconductivity, observed for the first time in nanowires, leading to increasing detector responsivity and other parameters for higher incident light powers. Temperature-dependent carrier concentration and mobility reveal the photoelectrochemical-thermionic emission process at grain boundaries, responsible for the observed unique photodetector performances and superlinear photoconductivity. Here, the results elucidate fundamental processes responsible for photogain in polycrystalline nanostructures, providing useful guidelines for developing nanostructure-based detectors and sensors. Lastly, the developed fully CMOS-compatible nanowire synthesis and device fabrication methods also have potentials for scalable integration of nanowire sensor devices and circuitries.« less

Extreme Carrier Depletion and Superlinear Photoconductivity in Ultrathin Parallel-Aligned ZnO Nanowire Array Photodetectors Fabricated by Infiltration Synthesis

DOE PAGES

Nam, Chang-Yong; Stein, Aaron

2017-11-15

Ultrathin semiconductor nanowires enable high-performance chemical sensors and photodetectors, but their synthesis and device integration by standard complementary metal-oxide-semiconductor (CMOS)-compatible processes remain persistent challenges. This work demonstrates fully CMOS-compatible synthesis and integration of parallel-aligned polycrystalline ZnO nanowire arrays into ultraviolet photodetectors via infiltration synthesis, material hybridization technique derived from atomic layer deposition. The nanowire photodetector features unique, high device performances originating from extreme charge carrier depletion, achieving photoconductive on–off ratios of >6 decades, blindness to visible light, and ultralow dark currents as low as 1 fA, the lowest reported for nanostructure-based photoconductive photodetectors. Surprisingly, the low dark current is invariantmore » with increasing number of nanowires and the photodetector shows unusual superlinear photoconductivity, observed for the first time in nanowires, leading to increasing detector responsivity and other parameters for higher incident light powers. Temperature-dependent carrier concentration and mobility reveal the photoelectrochemical-thermionic emission process at grain boundaries, responsible for the observed unique photodetector performances and superlinear photoconductivity. Here, the results elucidate fundamental processes responsible for photogain in polycrystalline nanostructures, providing useful guidelines for developing nanostructure-based detectors and sensors. Lastly, the developed fully CMOS-compatible nanowire synthesis and device fabrication methods also have potentials for scalable integration of nanowire sensor devices and circuitries.« less

Fabrication of ZnO Nanowire Based Piezoelectric Generators and Related Structures

NASA Astrophysics Data System (ADS)

Opoku, Charles; Dahiya, Abhishek Singh; Oshman, Christopher; Cayrel, Frederic; Poulin-Vittrant, Guylaine; Alquier, Daniel; Camara, Nicolas

Using vertically grown hydrothermal ZnO nanowires, we demonstrate the assembly of fully functional piezoelectric energy harvesters on plastics substrates. A seedless hydrothermal process is employed for the growth of single crystalline vertically orientated ZnO NWs at around 100oC. Flexible NG are assembled using ∼7 μm thick PDMS polymer matrix on a 3x3cm substrate. A representative device with an active area of 4cm2 is characterised revealing average output voltage generation of ∼22mV (±1.2) and -32mV (±0.16) in the positive and negative cycles after 3-4mm periodic deflection at 20Hz. A power density of ∼288nW/cm3 is estimated for the device. It is envisaged that such energy scavengers may find potential applications targeting self-powered systems, sensors and on-body charging of electronics.

Rapidly synthesized ZnO nanowires by ultraviolet decomposition process in ambient air for flexible photodetector.

PubMed

Wu, Jyh Ming; Chen, Yi-Ru; Lin, Yu-Hung

2011-03-01

We are the first group to use a simple direct ultraviolet light (UV, λ=365 nm, I=76 mW cm(-2)) in a decomposition process to fabricate ZnO nanowires on a flexible substrate using a zinc acetylacetonate hydrate precursor in ambient air. ZnO nanocrystal (or nanowire) production only requires three to ten minutes. A field emission scanning electron microscopy (FESEM) image reveals a high aspect ratio of the ZnO nanowires, which are grown on a substrate with a diameter of ∼50-100 nm, and a length of up to several hundred microns. High resolution transmission electron microscopy (HRTEM) images reveal that the nanowires consist of many single crystalline ZnO nanoparticles that grow along the c axis, which suggests an oriented attachment process. A potential application for flexible UV photodetectors was investigated using a UV lamp (λ=365 nm, I=2.34 mW cm(-2)). A significant ratio of photocurrent to dark current--around 11,300%--was achieved.

Comparative study on CO2 and CO sensing performance of LaOCl-coated ZnO nanowires.

PubMed

Van Hieu, Nguyen; Khoang, Nguyen Duc; Trung, Do Dang; Toan, Le Duc; Van Duy, Nguyen; Hoa, Nguyen Duc

2013-01-15

Carbon dioxide (CO(2)) and carbon monoxide (CO) emissions from industries and combustion fuels such as coal, oil, hydrocarbon, and natural gases are increasing, thus causing environmental pollution and climate change. The selective detection of CO(2) and CO gases is important for environmental monitoring and industrial safety applications. In this work, LaOCl-coated ZnO nanowires (NWs) sensors are fabricated and characterized for the detection of CO(2) (250-4000 ppm) and CO (10-200 ppm) gases at different operating temperatures. The effects of the LaCl(3) coating concentration and calcination temperature of the sensors are studied. They are found to have a strong influence on the sensing performance to CO(2) gas, but a relatively slight influence on that to CO. The LaOCl coating enhances the response and shortens the response and recovery times to CO(2) compared with those to CO. The enhanced response of the LaOCl-coated ZnO NW sensors is attributed to the extension of the electron depletion layer due to the formation of p-LaOCl/n-ZnO junctions on the surfaces of the ZnO NWs. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of cobalt doping on the mechanical properties of ZnO nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vahtrus, Mikk; Šutka, Andris

In this work, we investigate the influence of doping on the mechanical properties of ZnO nanowires (NWs) by comparing the mechanical properties of pure and Co-doped ZnO NWs grown in similar conditions and having the same crystallographic orientation [0001]. The mechanical characterization included three-point bending tests made with atomic force microscopy and cantilever beam bending tests performed inside scanning electron microscopy. It was found that the Young's modulus of ZnO NWs containing 5% of Co was approximately a third lower than that of the pure ZnO NWs. Bending strength values were comparable for both materials and in both cases weremore » close to theoretical strength indicating high quality of NWs. Dependence of mechanical properties on NW diameter was found for both doped and undoped ZnO NWs. - Highlights: •Effect of Co doping on the mechanical properties of ZnO nanowires is studied. •Co substitutes Zn atoms in ZnO crystal lattice. •Co addition affects crystal lattice parameters. •Co addition results in significantly decreased Young's modulus of ZnO. •Bending strength for doped and undoped wires is close to the theoretical strength.« less

Direct synthesis of vertically aligned ZnO nanowires on FTO substrates using a CVD method and the improvement of photovoltaic performance

PubMed Central

2012-01-01

In this work, we report a direct synthesis of vertically aligned ZnO nanowires on fluorine-doped tin oxide-coated substrates using the chemical vapor deposition (CVD) method. ZnO nanowires with a length of more than 30 μm were synthesized, and dye-sensitized solar cells (DSSCs) based on the as-grown nanowires were fabricated, which showed improvement of the device performance compared to those fabricated using transferred ZnO nanowires. Dependence of the cell performance on nanowire length and annealing temperature was also examined. This synthesis method provided a straightforward, one-step CVD process to grow relatively long ZnO nanowires and avoided subsequent nanowire transfer process, which simplified DSSC fabrication and improved cell performance. PMID:22673046

Photosensitization of ZnO nanowires with CdSe quantum dots for photovoltaic devices.

PubMed

Leschkies, Kurtis S; Divakar, Ramachandran; Basu, Joysurya; Enache-Pommer, Emil; Boercker, Janice E; Carter, C Barry; Kortshagen, Uwe R; Norris, David J; Aydil, Eray S

2007-06-01

We combine CdSe semiconductor nanocrystals (or quantum dots) and single-crystal ZnO nanowires to demonstrate a new type of quantum-dot-sensitized solar cell. An array of ZnO nanowires was grown vertically from a fluorine-doped tin oxide conducting substrate. CdSe quantum dots, capped with mercaptopropionic acid, were attached to the surface of the nanowires. When illuminated with visible light, the excited CdSe quantum dots injected electrons across the quantum dot-nanowire interface. The morphology of the nanowires then provided the photoinjected electrons with a direct electrical pathway to the photoanode. With a liquid electrolyte as the hole transport medium, quantum-dot-sensitized nanowire solar cells exhibited short-circuit currents ranging from 1 to 2 mA/cm2 and open-circuit voltages of 0.5-0.6 V when illuminated with 100 mW/cm2 simulated AM1.5 spectrum. Internal quantum efficiencies as high as 50-60% were also obtained.

The fabrication of ZnO nanowire field-effect transistors by roll-transfer printing

NASA Astrophysics Data System (ADS)

Chang, Yi-Kuei; Hong, Franklin Chau-Nan

2009-05-01

A method with the potential to fabricate large-area nanowire field-effect transistors (NW-FETs) was demonstrated in this study. Using a high-speed roller (20-80 cm min-1), transfer printing was successfully employed to transfer vertically aligned zinc oxide (ZnO) nanowires grown on a donor substrate to a polydimethylsiloxane (PDMS) stamp and then print the ordered ZnO nanowire arrays on the received substrate for the fabrication of NW-FETs. ZnO NW-FETs fabricated by this method exhibit high performances with a threshold voltage of around 0.25 V, a current on/off ratio as high as 105, a subthreshold slope of 360 mV/dec, and a field-effect mobility of around 90 cm2 V-1 s-1. The excellent device characteristics suggest that the roll-transfer printing technique, which is compatible with the roll-to-roll (R2R) process and operated in atmosphere, has a good potential for the high-speed fabrication of large-area nanowire transistors for flexible devices and flat panel displays.

The fabrication of ZnO nanowire field-effect transistors by roll-transfer printing.

PubMed

Chang, Yi-Kuei; Hong, Franklin Chau-Nan

2009-05-13

A method with the potential to fabricate large-area nanowire field-effect transistors (NW-FETs) was demonstrated in this study. Using a high-speed roller (20-80 cm min(-1)), transfer printing was successfully employed to transfer vertically aligned zinc oxide (ZnO) nanowires grown on a donor substrate to a polydimethylsiloxane (PDMS) stamp and then print the ordered ZnO nanowire arrays on the received substrate for the fabrication of NW-FETs. ZnO NW-FETs fabricated by this method exhibit high performances with a threshold voltage of around 0.25 V, a current on/off ratio as high as 10(5), a subthreshold slope of 360 mV/dec, and a field-effect mobility of around 90 cm(2) V(-1) s(-1). The excellent device characteristics suggest that the roll-transfer printing technique, which is compatible with the roll-to-roll (R2R) process and operated in atmosphere, has a good potential for the high-speed fabrication of large-area nanowire transistors for flexible devices and flat panel displays.

Direct selective growth of ZnO nanowire arrays from inkjet-printed zinc acetate precursor on a heated substrate

PubMed Central

2013-01-01

Inkjet printing of functional materials has drawn tremendous interest as an alternative to the conventional photolithography-based microelectronics fabrication process development. We introduce direct selective nanowire array growth by inkjet printing of Zn acetate precursor ink patterning and subsequent hydrothermal ZnO local growth without nozzle clogging problem which frequently happens in nanoparticle inkjet printing. The proposed process can directly grow ZnO nanowires in any arbitrary patterned shape, and it is basically very fast, low cost, environmentally benign, and low temperature. Therefore, Zn acetate precursor inkjet printing-based direct nanowire local growth is expected to give extremely high flexibility in nanomaterial patterning for high-performance electronics fabrication especially at the development stage. As a proof of concept of the proposed method, ZnO nanowire network-based field effect transistors and ultraviolet photo-detectors were demonstrated by direct patterned grown ZnO nanowires as active layer. PMID:24252130

Hierarchically structured nanowires on and nanosticks in ZnO microtubes

PubMed Central

Rivaldo-Gómez, C. M.; Cabrera-Pasca, G. A.; Zúñiga, A.; Carbonari, A. W.; Souza, J. A.

2015-01-01

We report both coaxial core-shell structured microwires and ZnO microtubes with growth of nanosticks in the inner and nanowires on the outer surface as a novel hierarchical micro/nanoarchitecture. First, a core-shell structure is obtained—the core is formed by metallic Zn and the semiconducting shell is comprised by a thin oxide layer covered with a high density of nanowires. Such Zn/ZnO core-shell array showed magnetoresistance effect. It is suggested that magnetic moments in the nanostructured shell superimposes to the external magnetic field enhancing the MR effect. Second, microtubes decorated with nanowires on the external surface are obtained. In an intermediate stage, a hierarchical morphology comprised of discrete nanosticks in the inner surface of the microtube has been found. Hyperfine interaction measurements disclosed the presence of confined metallic Zn regions at the interface between linked ZnO grains forming a chain and a ZnO thicker layer. Surprisingly, the metallic clusters form highly textured thin flat regions oriented parallel to the surface of the microtube as revealed by the electrical field gradient direction. The driving force to grow the internal nanosticks has been ascribed to stress-induced migration of Zn ions due to compressive stress caused by the presence of these confined regions. PMID:26456527

Controlled Growth of Parallel Oriented ZnO Nanostructural Arrays on Ga2O3 Nanowires

DTIC Science & Technology

2008-11-01

Controlled Growth of Parallel Oriented ZnO Nanostructural Arrays on Ga2O3 Nanowires Lena Mazeina,* Yoosuf N. Picard, and Sharka M. Prokes Electronics...Manuscript ReceiVed NoVember 6, 2008 ABSTRACT: Novel hierarchical ZnO- Ga2O3 nanostructures were fabricated via a two stage growth process. Nanowires of Ga2O3 ...nanobrushes (NBs) with Ga2O3 as the core and ZnO as the branches self-assembling symmetrically in six equiangular directions around the core

Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate surface through self-seeding thermal evaporation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohanan, Ajay Achath; Parthiban, R.; Ramakrishnan, N., E-mail: ramakrishnan@monash.edu

Highlights: • ZnO nanowires were grown directly on LiNbO{sub 3} surface for the first time by thermal evaporation. • Self-alignment of the nanowires due to step bunching of LiNbO{sub 3} surface is observed. • Increased roughness in surface defects promoted well-aligned growth of nanowires. • Well-aligned growth was then replicated in 50 nm deep trenches on the surface. • Study opens novel pathway for patterned growth of ZnO nanowires on LiNbO{sub 3} surface. - Abstract: High aspect ratio catalyst-free ZnO nanowires were directly synthesized on lithium niobate substrate for the first time through thermal evaporation method without the use ofmore » a buffer layer or the conventional pre-deposited ZnO seed layer. As-grown ZnO nanowires exhibited a crisscross aligned growth pattern due to step bunching of the polished lithium niobate surface during the nanowire growth process. On the contrary, scratches on the surface and edges of the substrate produced well-aligned ZnO nanowires in these defect regions due to high surface roughness. Thus, the crisscross aligned nature of high aspect ratio nanowire growth on the lithium niobate surface can be changed to well-aligned growth through controlled etching of the surface, which is further verified through reactive-ion etching of lithium niobate. The investigations and discussion in the present work will provide novel pathway for self-seeded patterned growth of well-aligned ZnO nanowires on lithium niobate based micro devices.« less

UV-Assisted Alcohol Sensors using Gallium Nitride Nanowires Functionalized with Zinc Oxide and Tin Dioxide Nanoparticles

NASA Astrophysics Data System (ADS)

Bajpai, Ritu

The motivation behind this work has been to address two of the most challenging issues posed to semiconductor gas sensors--- tuning the device selectivity and sensitivity to a wide variety of gases. In a chemiresistor type nanowire sensor, the sensitivity and selectivity depend on the interaction of different chemical analytes with the nanowire surface. Constrained by the surface properties of the nanowire material, most nanowire sensors can detect only specific type of analytes. In order to make a nano-sensor array for a wide range of analytes, there is a need to tune the device sensitivity and selectivity towards different chemicals. Employing the inherent advantages of nanostructure based sensing such as large surface area, miniature size, low power consumption, and nmol/mol (ppb) sensitivity, an attempt has been made to propose a device with tunable selectivity and sensitivity. The idea proposed in this work is to functionalize GaN nanowires which have relatively inactive surface properties (i.e., with no chemiresistive sensitivity to different classes of organic vapors), with analyte dependent active metal oxides. The selectivity of the sensor devices is controlled independent of the surface properties of the nanowire itself. It is the surface properties of the functionalizing metal oxides which determine the selectivity of these sensors. Further facilitated by the proposed fabrication technique, these sensors can be easily tuned to detect different gases. The prototype developed in this work is that of a UV assisted alcohol sensor using GaN nanowires functionalized with ZnO and SnO2 nanoparticles. As opposed to the widely demonstrated metal oxide based sensors assisted by elevated temperature, the operation of photoconductive semiconductor sensor devices such as those fabricated in this work, can also be assisted by UV illumination at room temperature. Temperature assisted sensing requires an integrated on-chip heater, which could impose constraints on the

Fabrication of a P3HT-ZnO Nanowires Gas Sensor Detecting Ammonia Gas

PubMed Central

Kuo, Chin-Guo; Chen, Jung-Hsuan; Chao, Yi-Chieh; Chen, Po-Lin

2017-01-01

In this study, an organic-inorganic semiconductor gas sensor was fabricated to detect ammonia gas. An inorganic semiconductor was a zinc oxide (ZnO) nanowire array produced by atomic layer deposition (ALD) while an organic material was a p-type semiconductor, poly(3-hexylthiophene) (P3HT). P3HT was suitable for the gas sensing application due to its high hole mobility, good stability, and good electrical conductivity. In this work, P3HT was coated on the zinc oxide nanowires by the spin coating to form an organic-inorganic heterogeneous interface of the gas sensor for detecting ammonia gas. The thicknesses of the P3HT were around 462 nm, 397 nm, and 277 nm when the speeds of the spin coating were 4000 rpm, 5000 rpm, and 6000 rpm, respectively. The electrical properties and sensing characteristics of the gas sensing device at room temperature were evaluated by Hall effect measurement and the sensitivity of detecting ammonia gas. The results of Hall effect measurement for the P3HT-ZnO nanowires semiconductor with 462 nm P3HT film showed that the carrier concentration and the mobility were 2.7 × 1019 cm−3 and 24.7 cm2∙V−1∙s−1 respectively. The gas sensing device prepared by the P3HT-ZnO nanowires semiconductor had better sensitivity than the device composed of the ZnO film and P3HT film. Additionally, this gas sensing device could reach a maximum sensitivity around 11.58 per ppm. PMID:29295573

Fabrication of a P3HT-ZnO Nanowires Gas Sensor Detecting Ammonia Gas.

PubMed

Kuo, Chin-Guo; Chen, Jung-Hsuan; Chao, Yi-Chieh; Chen, Po-Lin

2017-12-25

In this study, an organic-inorganic semiconductor gas sensor was fabricated to detect ammonia gas. An inorganic semiconductor was a zinc oxide (ZnO) nanowire array produced by atomic layer deposition (ALD) while an organic material was a p-type semiconductor, poly(3-hexylthiophene) (P3HT). P3HT was suitable for the gas sensing application due to its high hole mobility, good stability, and good electrical conductivity. In this work, P3HT was coated on the zinc oxide nanowires by the spin coating to form an organic-inorganic heterogeneous interface of the gas sensor for detecting ammonia gas. The thicknesses of the P3HT were around 462 nm, 397 nm, and 277 nm when the speeds of the spin coating were 4000 rpm, 5000 rpm, and 6000 rpm, respectively. The electrical properties and sensing characteristics of the gas sensing device at room temperature were evaluated by Hall effect measurement and the sensitivity of detecting ammonia gas. The results of Hall effect measurement for the P3HT-ZnO nanowires semiconductor with 462 nm P3HT film showed that the carrier concentration and the mobility were 2.7 × 10 19 cm -3 and 24.7 cm²∙V -1 ∙s -1 respectively. The gas sensing device prepared by the P3HT-ZnO nanowires semiconductor had better sensitivity than the device composed of the ZnO film and P3HT film. Additionally, this gas sensing device could reach a maximum sensitivity around 11.58 per ppm.

Near band edge photoluminescence of ZnO nanowires: Optimization via surface engineering

NASA Astrophysics Data System (ADS)

Yan, Danhua; Zhang, Wenrui; Cen, Jiajie; Stavitski, Eli; Sadowski, Jerzy T.; Vescovo, Elio; Walter, Andrew; Attenkofer, Klaus; Stacchiola, Darío J.; Liu, Mingzhao

2017-12-01

Zinc oxide (ZnO) nanowire arrays have potential applications for various devices such as ultra-violet light emitting diodes and lasers, where photoluminescence of intense near band edge emission without defect emissions is usually desired. Here, we demonstrate, counter-intuitively, that the near band edge emission may become dominant by introducing certain surface defects to ZnO nanowires via surface engineering. Specifically, near band edge emission (NBE) is effectively enhanced after a low pressure O2 plasma treatment that sputters off surface oxygen species to produce a reduced and oxygen vacancy-rich surface. The effect is attributed to the lowered surface valence band maximum of the reduced ZnO surface that creates an accumulative band bending, which screens the photo-generated minority carriers (holes) from reaching or being trapped by the surface defects.

Electrical properties of lightly Ga-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Alagha, S.; Heedt, S.; Vakulov, D.; Mohammadbeigi, F.; Senthil Kumar, E.; Schäpers, Th; Isheim, D.; Watkins, S. P.; Kavanagh, K. L.

2017-12-01

We investigated the growth, crystal structure, elemental composition and electrical transport characteristics of ZnO nanowires, a promising candidate for optoelectronic applications in the UV-range. Nominally-undoped and Ga-doped ZnO nanowires were grown by metal-organic chemical vapor deposition. Photoluminescence measurements confirmed the incorporation of Ga via donor-bound exciton emission. With atom-probe tomography we estimated an upper limit of the Ga impurity concentration ({10}18 {{cm}}-3). We studied the electrical transport characteristics of these nanowires with a W-nanoprobe technique inside a scanning electron microscope and with lithographically-defined contacts allowing back-gated measurements. An increase in apparent resistivity by two orders of magnitude with decreasing radius was measured with both techniques with a much larger distribution width for the nanoprobe method. A drop in the effective carrier concentration and mobility was found with decreasing radius which can be attributed to carrier depletion and enhanced scattering due to surface states. Little evidence of a change in resistivity was observed with Ga doping, which indicates that the concentration of native or background dopants is higher than the Ga doping concentration.

ZnO nanowires: Synthesis and charge transfer mechanism in the detection of ammonia vapour

NASA Astrophysics Data System (ADS)

Nancy Anna Anasthasiya, A.; Ramya, S.; Rai, P. K.; Jeyaprakash, B. G.

2018-01-01

ZnO nanowires with hexagonal wurtzite structure were grown on the glass substrate using Successive Ionic Layer Adsorption and Reaction (SILAR) method. Both experimental and theoretical studies demonstrated that NH3 chemisorbed and transferred the charge to the surface of the nanowire via its nitrogen site to the zinc site of ZnO nanowires, leading to the detection of NH3 vapour. The adsorbed ammonia dissociated into NH2 and H due to steric repulsion, and then into N2 and H2 gas. The formation of the N2 gas during the desorption process confirmed by observing peak at 14 and 28 m/z in the GC-MS spectrum.

An optimal thermal evaporation synthesis of c-axis oriented ZnO nanowires with excellent UV sensing and emission characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, Tridib, E-mail: tridib.saha@monash.edu; Achath Mohanan, Ajay, E-mail: ajay.mohanan@monash.edu; Swamy, Varghese, E-mail: varghese.swamy@monash.edu

Highlights: • c-Axis alignment of ZnO nanowires was optimized using self-seeding thermal evaporation method. • Influence of purified air on the morphology and optoelectronic properties were studied. • Nanowires grown under optimal conditions exhibit strong UV emission peak in PL spectrum. • Optimized growth condition establish nanowires of excellent UV sensing characteristics - Abstract: Well-aligned (c-axis oriented) ZnO nanowire arrays were successfully synthesized on Si (1 0 0) substrates through an optimized self-seeding thermal evaporation method. An open-ended chemical vapor deposition (CVD) setup was used in the experiment, with argon and purified air as reaction gases. Epitaxial growth of c-axismore » oriented ZnO nanowires was observed for 5 sccm flow rate of purified air, whereas Zn/Zn suboxide layers and multiple polycrystalline layers of ZnO were obtained for absence and excess of purified air, respectively. Ultraviolet (UV) sensing and emission properties of the as-grown ZnO nanostructures were investigated through the current–voltage (I–V) characteristics of the nanowires under UV (λ = 365 nm) illumination of 8 mW/cm{sup 2} and using photoluminescence spectra. Nanowires grown under optimum flow of air emitted four times higher intensity of 380 nm UV light as well as exhibited 34 times higher UV radiation sensitivity compared to that of other nanostructures synthesized in this study.« less

Synthesis of ZnO nanowires for thin film network transistors

NASA Astrophysics Data System (ADS)

Dalal, S. H.; Unalan, H. E.; Zhang, Y.; Hiralal, Pritesh; Gangloff, L.; Flewitt, Andrew J.; Amaratunga, Gehan A. J.; Milne, William I.

2008-08-01

Zinc oxide nanowire networks are attractive as alternatives to organic and amorphous semiconductors due to their wide bandgap, flexibility and transparency. We demonstrate the fabrication of thin film transistors (TFT)s which utilize ZnO nanowires as the semiconducting channel. These thin film transistors can be transparent and flexible and processed at low temperatures on to a variety of substrates. The nanowire networks are created using a simple contact transfer method that is easily scalable. Apparent nanowire network mobility values can be as high as 3.8 cm2/Vs (effective thin film mobility: 0.03 cm2/Vs) in devices with 20μm channel lengths and ON/OFF ratios of up to 104.

Enhanced H2 sensitivity at room temperature of ZnO nanowires functionalized by Pd nanoparticles

NASA Astrophysics Data System (ADS)

Ren, Shoutian; Fan, Guanghua; Qu, Shiliang; Wang, Qiang

2011-10-01

For sensitive detection of H2, ZnO nanowires networks decorated with photo-decomposed Pd nanoparticles were fabricated between femtosecond laser-writing interdigitated electrodes by chemical vapor deposition method. When H2 concentration is increased from 20 to 4000 ppm at room temperature, sensitivity of the sample is increased from 3.7% to 1017.9%. The high sensitivity can be explained by considering the reaction between the adsorbed O2- and the disassociated H atoms facilitated by Pd nanoparticles. This mechanism is further supported by the H2 response results under UV light illumination, which can reduce the amount of O2- on the ZnO surface, leading to depressed sensitivity. The sensor also shows high selectivity, long-term stability, and ultra-low power consumption of nanowatt level, due to the novel fabrication process.

Electrical properties of fluorine-doped ZnO nanowires formed by biased plasma treatment

NASA Astrophysics Data System (ADS)

Wang, Ying; Chen, Yicong; Song, Xiaomeng; Zhang, Zhipeng; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

2018-05-01

Doping is an effective method for tuning electrical properties of zinc oxide nanowires, which are used in nanoelectronic devices. Here, ZnO nanowires were prepared by a thermal oxidation method. Fluorine doping was achieved by a biased plasma treatment, with bias voltages of 100, 200, and 300 V. Transmission electron microscopy indicated that the nanowires treated at bias voltages of 100 and 200 V featured low crystallinity. When the bias voltage was 300 V, the nanowires showed single crystalline structures. Photoluminescence measurements revealed that concentrations of oxygen and surface defects decreased at high bias voltage. X-ray photoelectron spectroscopy suggested that the F content increased as the bias voltage was increased. The conductivity of the as-grown nanowires was less than 103 S/m; the conductivity of the treated nanowires ranged from 1 × 104-5 × 104, 1 × 104-1 × 105, and 1 × 103-2 × 104 S/m for bias voltage treatments at 100, 200, and 300 V, respectively. The conductivity improvements of nanowires formed at bias voltages of 100 and 200 V, were attributed to F-doping, defects and surface states. The conductivity of nanowires treated at 300 V was attributed to the presence of F ions. Thus, we provide a method of improving electrical properties of ZnO nanowires without altering their crystal structure.

Near band edge photoluminescence of ZnO nanowires: Optimization via surface engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Danhua; Zhang, Wenrui; Cen, Jiajie

Zinc oxide (ZnO) nanowire arrays have potential applications for various devices including ultra-violet light emitting diodes and lasers, where photoluminescence of intense near band edge emission without defect emissions is usually desired. Here, we demonstrate, counter-intuitively, that the near band edge emission may become dominant by introducing certain surface defects to ZnO nanowires via surface engineering. Specifically, near band edge emission (NBE) is effectively enhanced after a low pressure O 2 plasma treatment that sputters off surface oxygen species to produce a reduced and oxygen vacancy-rich surface. The effect is attributed to the lowered surface valence band maximum of themore » reduced ZnO surface that creates an accumulative band bending, which screens the photo-generated minority carriers (holes) from reaching or being trapped by the surface defects.« less

Near band edge photoluminescence of ZnO nanowires: Optimization via surface engineering

DOE PAGES

Yan, Danhua; Zhang, Wenrui; Cen, Jiajie; ...

2017-12-04

Zinc oxide (ZnO) nanowire arrays have potential applications for various devices including ultra-violet light emitting diodes and lasers, where photoluminescence of intense near band edge emission without defect emissions is usually desired. Here, we demonstrate, counter-intuitively, that the near band edge emission may become dominant by introducing certain surface defects to ZnO nanowires via surface engineering. Specifically, near band edge emission (NBE) is effectively enhanced after a low pressure O 2 plasma treatment that sputters off surface oxygen species to produce a reduced and oxygen vacancy-rich surface. The effect is attributed to the lowered surface valence band maximum of themore » reduced ZnO surface that creates an accumulative band bending, which screens the photo-generated minority carriers (holes) from reaching or being trapped by the surface defects.« less

Transmission type flat-panel X-ray source using ZnO nanowire field emitters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Daokun; Song, Xiaomeng; Zhang, Zhipeng

2015-12-14

A transmission type flat-panel X-ray source in diode structure was fabricated. Large-scale patterned ZnO nanowires grown on a glass substrate by thermal oxidation were utilized as field emitters, and tungsten thin film coated on silica glass was used as the transmission anode. Uniform distribution of X-ray generation was achieved, which benefited from the uniform electron emission from ZnO nanowires. Self-ballasting effect induced by the intrinsic resistance of ZnO nanowire and decreasing of screening effect caused by patterned emitters account for the uniform emission. Characteristic X-ray peaks of W-L lines and bremsstrahlung X-rays have been observed under anode voltages at amore » range of 18–20 kV, the latter of which were the dominant X-ray signals. High-resolution X-ray images with spatial resolution less than 25 μm were obtained by the flat-panel X-ray source. The high resolution was attributed to the small divergence angle of the emitted X-rays from the transmission X-ray source.« less

Doping-induced spin-orbit splitting in Bi-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Aras, Mehmet; Güler-Kılıç, Sümeyra; Kılıç, ćetin

2017-04-01

Our predictions, based on density-functional calculations, reveal that surface doping of ZnO nanowires with Bi leads to a linear-in-k splitting of the conduction-band states, through spin-orbit interaction, due to the lowering of the symmetry in the presence of the dopant. This finding implies that spin polarization of the conduction electrons in Bi-doped ZnO nanowires could be controlled with applied electric (as opposed to magnetic) fields, making them candidate materials for spin-orbitronic applications. Our findings also show that the degree of spin splitting could be tuned by adjusting the dopant concentration. Defect calculations and ab initio molecular dynamics simulations indicate that stable doping configurations exhibiting the foregoing linear-in-k splitting could be realized under reasonable thermodynamic conditions.

On-chip surface modified nanostructured ZnO as functional pH sensors

NASA Astrophysics Data System (ADS)

Zhang, Qing; Liu, Wenpeng; Sun, Chongling; Zhang, Hao; Pang, Wei; Zhang, Daihua; Duan, Xuexin

2015-09-01

Zinc oxide (ZnO) nanostructures are promising candidates as electronic components for biological and chemical applications. In this study, ZnO ultra-fine nanowire (NW) and nanoflake (NF) hybrid structures have been prepared by Au-assisted chemical vapor deposition (CVD) under ambient pressure. Their surface morphology, lattice structures, and crystal orientation were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Two types of ZnO nanostructures were successfully integrated as gate electrodes in extended-gate field-effect transistors (EGFETs). Due to the amphoteric properties of ZnO, such devices function as pH sensors. We found that the ultra-fine NWs, which were more than 50 μm in length and less than 100 nm in diameter, performed better in the pH sensing process than NW-NF hybrid structures because of their higher surface-to-volume ratio, considering the Nernst equation and the Gouy-Chapman-Stern model. Furthermore, the surface coating of (3-Aminopropyl)triethoxysilane (APTES) protects ZnO nanostructures in both acidic and alkaline environments, thus enhancing the device stability and extending its pH sensing dynamic range.

Sensors and devices containing ultra-small nanowire arrays

DOEpatents

Xiao, Zhili

2014-09-23

A network of nanowires may be used for a sensor. The nanowires are metallic, each nanowire has a thickness of at most 20 nm, and each nanowire has a width of at most 20 nm. The sensor may include nanowires comprising Pd, and the sensor may sense a change in hydrogen concentration from 0 to 100%. A device may include the hydrogen sensor, such as a vehicle, a fuel cell, a hydrogen storage tank, a facility for manufacturing steel, or a facility for refining petroleum products.

Sensors and devices containing ultra-small nanowire arrays

DOEpatents

Xiao, Zhili

2017-04-11

A network of nanowires may be used for a sensor. The nanowires are metallic, each nanowire has a thickness of at most 20 nm, and each nanowire has a width of at most 20 nm. The sensor may include nanowires comprising Pd, and the sensor may sense a change in hydrogen concentration from 0 to 100%. A device may include the hydrogen sensor, such as a vehicle, a fuel cell, a hydrogen storage tank, a facility for manufacturing steel, or a facility for refining petroleum products.

Abnormal temperature dependence of conductance of single Cd-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Li, Q. H.; Wan, Q.; Wang, Y. G.; Wang, T. H.

2005-06-01

Positive temperature coefficient of resistance is observed on single Cd-doped ZnO nanowires. The current along the nanowire increases linearly with the bias and saturates at large biases. The conductance is greatly enhanced either by ultraviolet illumination or infrared illumination. However, the conductance decreases with increasing temperature, in contrast to the reported temperature behavior either for ZnO nanostructures or for CdO nanoneedles. The increase of the conductance under illumination is related to surface effect and the decrease with increasing temperature to bulk effect. These results show that Cd doping does not change surface effect but affects bulk effect. Such a bulk effect could be used to realize on-chip temperature-independent varistors.

Integration of ZnO and CuO nanowires into a thermoelectric module

PubMed Central

Dalola, Simone; Faglia, Guido; Comini, Elisabetta; Ferroni, Matteo; Soldano, Caterina; Ferrari, Vittorio; Sberveglieri, Giorgio

2014-01-01

Summary Zinc oxide (ZnO, n-type) and copper oxide (CuO, p-type) nanowires have been synthesized and preliminarily investigated as innovative materials for the fabrication of a proof-of-concept thermoelectric device. The Seebeck coefficients, electrical conductivity and thermoelectric power factors (TPF) of both semiconductor materials have been determined independently using a custom experimental set-up, leading to results in agreement with available literature with potential improvement. Combining bundles of ZnO and CuO nanowires in a series of five thermocouples on alumina leads to a macroscopic prototype of a planar thermoelectric generator (TEG) unit. This demonstrates the possibility of further integration of metal oxide nanostructures into efficient thermoelectric devices. PMID:24991531

Integration of ZnO and CuO nanowires into a thermoelectric module.

PubMed

Zappa, Dario; Dalola, Simone; Faglia, Guido; Comini, Elisabetta; Ferroni, Matteo; Soldano, Caterina; Ferrari, Vittorio; Sberveglieri, Giorgio

2014-01-01

Zinc oxide (ZnO, n-type) and copper oxide (CuO, p-type) nanowires have been synthesized and preliminarily investigated as innovative materials for the fabrication of a proof-of-concept thermoelectric device. The Seebeck coefficients, electrical conductivity and thermoelectric power factors (TPF) of both semiconductor materials have been determined independently using a custom experimental set-up, leading to results in agreement with available literature with potential improvement. Combining bundles of ZnO and CuO nanowires in a series of five thermocouples on alumina leads to a macroscopic prototype of a planar thermoelectric generator (TEG) unit. This demonstrates the possibility of further integration of metal oxide nanostructures into efficient thermoelectric devices.

Efficient photocatalytic performance enhancement in Co-doped ZnO nanowires coupled with CuS nanoparticles

NASA Astrophysics Data System (ADS)

Li, Wei; Wang, Guojing; Feng, Yimeng; Li, Zhengcao

2018-01-01

In this research, a kind of highly efficient semiconductor photocatalyst was fabricated by depositing CuS nanoparticles uniformly on the surface of Co-doped ZnO nanowires. ZnO nanowires were synthesized by hydrothermal method and CuS nanoparticles were modified by successive ionic layer adsorption and reaction (SILAR). By conducting methyl orange (MO) degradation experiments under the illumination of visible light, the photocatalytic activity of Co-doped ZnO nanowires modified with CuS nanoparticles was found to be nearly three times active when compared to bare ZnO nanowires. Its superior photocatalytic performance has two main reasons. The doped Co2+ ions can inhibit the recombination of photo-generated electron-hole pairs and decrease the optical bandgap, while the p-n heterostructure can enhance the visible light absorption ability and promote the separation of photo-excited charge carriers. Furthermore, the effect of the amount of deposited CuS nanoparticles on the photocatalysis was also investigated. The photocatalytic efficiency firstly raised along with the increment of SILAR cycle times and reached a maximum at 10 cycles but then decreased as the cycle times continue to increase. This originates from that an excessive amount of CuS would not only cover the active reacting sites, but also serve as recombination centers. Overall, this new nanostructure is expected to work as an efficient photocatalyst.

Ultra-fast microwave-assisted hydrothermal synthesis of long vertically aligned ZnO nanowires for dye-sensitized solar cell application.

PubMed

Mahpeykar, S M; Koohsorkhi, J; Ghafoori-Fard, H

2012-04-27

Long vertically aligned ZnO nanowire arrays were synthesized using an ultra-fast microwave-assisted hydrothermal process. Using this method, we were able to grow ZnO nanowire arrays at an average growth rate as high as 200 nm min(-1) for maximum microwave power level. This method does not suffer from the growth stoppage problem at long growth times that, according to our investigations, a normal microwave-assisted hydrothermal method suffers from. Longitudinal growth of the nanowire arrays was investigated as a function of microwave power level and growth time using cross-sectional FESEM images of the grown arrays. Effect of seed layer on the alignment of nanowires was also studied. X-ray diffraction analysis confirmed c-axis orientation and single-phase wurtzite structure of the nanowires. J-V curves of the fabricated ZnO nanowire-based mercurochrome-sensitized solar cells indicated that the short-circuit current density is increased with increasing the length of the nanowire array. According to the UV-vis spectra of the dyes detached from the cells, these increments were mainly attributed to the enlarged internal surface area and therefore dye loading enhancement in the lengthened nanowire arrays.

Lattice diffusion and vapor solid growths forming nanoarchitectures on ZnO nanowires

NASA Astrophysics Data System (ADS)

Sombrio, Guilherme; Rivaldo-Gómez, C. M.; Pomar, Cesar A. D.; Souza, Jose A.

2017-12-01

We report hierarchical nanoarchitectures formed on the tips and sidewalls of ZnO nanowires which is formed on the top of microtubes. The whole growth process of these micro/nanostructures during thermal oxidation combines lattice/grain/surface ionic diffusion along with vapor solid mechanism. All the process takes place along with the presence of an electric current, which plays an important role forming the ZnO molecules due to Zn metal evaporation and attracting them to condense into nanostructures of several morphologies. The observation of a very long needle-like nanowire reveals the stack nature of the growth. These nanoarchitectures are rarely observed experimentally. Raman scattering confirms phonon confinement in the nanostructures. Photoluminescence measurements indicate a route for engineering defects on the surface of ZnO microtubes after the complete coalescence of the nanostructures through heat treatment. This experiment would be useful for improving nanostructure organization which could provide an impact in the manufacturability of nanostructure-based systems.

Veritable electronic characteristics in ZnO nanowire circuits uncovered by the four-terminal method at a low temperature

NASA Astrophysics Data System (ADS)

Li, Xin; Zhang, Qi

2017-04-01

Understanding the natural electrical properties in semiconductor channels and the carrier transport across the metal-semiconductor contact is essential to improve the performance of nanowire devices. This work presents the true electronic characteristics of ZnO nanowire devices measured by a four-electrode method at a low-temperature environment. The temperature rise leads to the decrease in near-band-gap emission, which is attributed to two non-radiative recombination processes. For ZnO circuits, thermionic emission carrier transport mechanism plays a dominant role at Ti-Au/ZnO interface and the transport mechanism in ZnO nanowires is governed by two competitive thermal activation conduction processes: optical or acoustic phonons assisting hopping.

A ZnO nanowire bio-hybrid solar cell

NASA Astrophysics Data System (ADS)

Yaghoubi, Houman; Schaefer, Michael; Yaghoubi, Shayan; Jun, Daniel; Schlaf, Rudy; Beatty, J. Thomas; Takshi, Arash

2017-02-01

Harvesting solar energy as a carbon free source can be a promising solution to the energy crisis and environmental pollution. Biophotovoltaics seek to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. In the current study, we report on a combination of zinc oxide (ZnO) nanowires with monolayers of photosynthetic reaction centers which are self-assembled, via a cytochrome c linker, as photoactive electrode. In a three-probe biophotovoltaics cell, a photocurrent density of 5.5 μA cm-2 and photovoltage of 36 mV was achieved, using methyl viologen as a redox mediator in the electrolyte. Using ferrocene as a redox mediator a transient photocurrent density of 8.0 μA cm-2 was obtained, which stabilized at 6.4 μA cm-2 after 20 s. In-depth electronic structure characterization using photoemission spectroscopy in conjunction with electrochemical analysis suggests that the fabricated photoactive electrode can provide a proper electronic path for electron transport all the way from the conduction band of the ZnO nanowires, through the protein linker to the RC, and ultimately via redox mediator to the counter electrode.

Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition.

PubMed

Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D; Renevier, Hubert; Consonni, Vincent

2017-03-03

The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscale-engineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol-gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 10 7 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscale-engineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

NASA Astrophysics Data System (ADS)

Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

2017-03-01

The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscale-engineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol-gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscale-engineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guillemin, Sophie; Parize, Romain; Carabetta, Joseph

The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscaleengineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol–gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on themore » macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscaleengineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.« less

Fast Response and High Sensitivity of ZnO Nanowires-Cobalt Phthalocyanine Heterojunction Based H2S Sensor.

PubMed

Kumar, Ashwini; Samanta, Soumen; Singh, Ajay; Roy, Mainak; Singh, Surendra; Basu, Saibal; Chehimi, Mohmad M; Roy, Kallol; Ramgir, Niranjan; Navaneethan, M; Hayakawa, Y; Debnath, Anil K; Aswal, Dinesh K; Gupta, Shiv K

2015-08-19

The room temperature chemiresistive response of n-type ZnO nanowire (ZnO NWs) films modified with different thicknesses of p-type cobalt phthalocyanine (CoPc) has been studied. With increasing thickness of CoPc (>15 nm), heterojunction films exhibit a transition from n- to p-type conduction due to uniform coating of CoPc on ZnO. The heterojunction films prepared with a 25 nm thick CoPc layer exhibit the highest response (268% at 10 ppm of H2S) and the fastest response (26 s) among all samples. The X-ray photoelectron spectroscopy and work function measurements reveal that electron transfer takes place from ZnO to CoPc, resulting in formation of a p-n junction with a barrier height of 0.4 eV and a depletion layer width of ∼8.9 nm. The detailed XPS analysis suggests that these heterojunction films with 25 nm thick CoPc exhibit the least content of chemisorbed oxygen, enabling the direct interaction of H2S with the CoPc molecule, and therefore exhibit the fastest response. The improved response is attributed to the high susceptibility of the p-n junctions to the H2S gas, which manipulates the depletion layer width and controls the charge transport.

Earth-Abundant Oxygen Evolution Catalysts Coupled onto ZnO Nanowire Arrays for Efficient Photoelectrochemical Water Cleavage

PubMed Central

Jiang, Chaoran; Moniz, Savio J A; Khraisheh, Majeda; Tang, Junwang

2014-01-01

ZnO has long been considered as a model UV-driven photoanode for photoelectrochemical water splitting, but its performance has been limited by fast charge-carrier recombination, extremely poor stability in aqueous solution, and slow kinetics of water oxidation. These issues were addressed by applying a strategy of optimization and passivation of hydrothermally grown 1D ZnO nanowire arrays. The length and diameter of bare ZnO nanowires were optimized by varying the growth time and precursor concentration to achieve optimal photoelectrochemical performance. The addition of earth-abundant cobalt phosphate (Co-Pi) and nickel borate (Ni-B) oxygen evolution catalysts onto ZnO nanowires resulted in substantial cathodic shifts in onset potential to as low as about 0.3 V versus the reversible hydrogen electrode (RHE) for Ni-B/ZnO, for which a maximum photocurrent density of 1.1 mA cm−2 at 0.9 V (vs. RHE) with applied bias photon-to-current efficiency of 0.4 % and an unprecedented near-unity incident photon-to-current efficiency at 370 nm. In addition the potential required for saturated photocurrent was dramatically reduced from 1.6 to 0.9 V versus RHE. Furthermore, the stability of these ZnO nanowires was significantly enhanced by using Ni-B compared to Co-Pi due to its superior chemical robustness, and it thus has additional functionality as a stable protecting layer on the ZnO surface. These remarkable enhancements in both photocatalytic activity and stability directly address the current severe limitations in the use of ZnO-based photoelectrodes for water-splitting applications, and can be applied to other photoanodes for efficient solar-driven fuel synthesis. PMID:25156820

Synthesis and photonic property study of ZnO nanowires for a real time photodynamic therapy monitoring probe

NASA Astrophysics Data System (ADS)

Sridhar, D.; Xie, Jining; Abraham, Jose K.; Varadan, Vijay K.

2007-04-01

In this paper, we present how the photonic properties of zinc oxide (ZnO) nanowires can be used to potentially advance the effectiveness of Photodynamic therapy (PDT), one of the most recent and promising approaches among cancer therapies. Presently, PDT employs laser light to activate intravenously or topically administered photosensitizers to give rise to highly reactive singlet oxygen which has a very short lifetime and is capable of biochemical damage to cell membranes of the tumor. A probe that can monitor in real time the penetration depth of the laser in the tumor and also the evolution of the singlet oxygen, which is critical for tumor eradication, is capable of improving the efficacy of PDT quite significantly. Such a probe, by providing real time feedback, can help us determine whether to increase or decrease the light exposure dose and also if further local administration of photosensitizers is required or not. ZnO nanowires are known to be photoconductive and recent research also demonstrated the temperature dependence of the photocurrent in the nanowires. They are also sensitive to blue and other near UV spectra which is same range of activation wavelengths of most photosensitizers, and hence making them a good candidate for a potential PDT monitoring probe. ZnO nanowires were fabricated on silicon substrates by vapor phase deposition using e-beam evaporated gold as a catalyst. Control of the dimensions of the nanowires could be achieved by varying the dimensions of the catalyst by means of e-beam evaporation process. Photoluminescence properties of ZnO nanowires were investigated at UV and near UV wavelengths. Further, ZnO is also known for its antimicrobial properties, thereby ruling out any possibility of bacterial infection because of the implanted probe. This study was done to compliment the existing expertise of our research group in the design and fabrication of several nanowire based probes and microsensors specifically for neuroelectronic and

Synthesis, structural and optical properties of silver nanoparticles uniformly decorated ZnO nanowires

NASA Astrophysics Data System (ADS)

Zhang, Ke-Xin; Wen, Xing; Yao, Cheng-Bao; Li, Jin; Zhang, Meng; Li, Qiang-Hua; Sun, Wen-Jun; Wu, Jia-Da

2018-04-01

Silver (Ag) nanoparticles decorated Zinc oxide (A-ZnO) nanowires have been successfully synthesized by two-step chemical vapour deposition and magnetron sputtering method. The X-ray diffraction patterns revealed their hexagonal wurtzite structure. SEM images indicated the Ag nanoparticles are distributed uniformly on the surface of A-ZnO nanowires. By extending the sputtering time, the atomic percent of Ag increased gradually. Moreover, the photoluminescence results demonstrated two major emission peaks for the A-ZnO nanowires. Where, the visible emission peaks were stronger than those of unmodified ZnO nanowires. These studies promise their potential applications in multifunctional optical devices.

ZnO nanowires for tunable near-UV/blue LED

NASA Astrophysics Data System (ADS)

Pauporté, Thierry; Lupan, Oleg; Viana, Bruno

2012-02-01

Nanowires (NWs)-based light emitting diodes (LEDs) have drawn large interest due to many advantages compared to thin film based devices. Markedly improved performances are expected from nanostructured active layers for light emission. Nanowires can act as direct waveguides and favor light extraction without the use of lenses and reflectors. Moreover, the use of wires avoids the presence of grain boundaries and then the emission efficiency should be boosted by the absence of non-radiative recombinations at the joint defects. Electrochemical deposition technique was used for the preparation of ZnO-NWs based light emitters. Nanowires of high structural and optical quality have been epitaxially grown on p-GaN single crystalline films substrates. We have shown that the emission is directional with a wavelength that was tuned and red-shifted toward the visible region by doping with Cu in ZnO NWs.

Size-dependent Young’s modulus in ZnO nanowires with strong surface atomic bonds

NASA Astrophysics Data System (ADS)

Fan, Shiwen; Bi, Sheng; Li, Qikun; Guo, Qinglei; Liu, Junshan; Ouyang, Zhongliang; Jiang, Chengming; Song, Jinhui

2018-03-01

The mechanical properties of size-dependent nanowires are important in nano-electro-mechanical systems (NEMSs), and have attracted much research interest. Characterization of the size effect of nanowires in atmosphere directly to broaden their practical application instead of just in high vacuum situations, as reported previously, is desperately needed. In this study, we systematically studied the Young’s modulus of vertical ZnO nanowires in atmosphere. The diameters ranged from 48 nm to 239 nm with a resonance method using non-contact atomic force microscopy. The values of Young’s modulus in atmosphere present extremely strong increasing tendency with decreasing diameter of nanowire due to stronger surface atomic bonds compared with that in vacuum. A core-shell model for nanowires is proposed to explore the Young’s modulus enhancement in atmosphere, which is correlated with atoms of oxygen occurring near the nanowire surface. The modified model is more accurate for analyzing the mechanical behavior of nanowires in atmosphere compared with the model in vacuum. Furthermore, it is possible to use this characterization method to measure the size-related elastic properties of similar wire-sharp nanomaterials in atmosphere and estimate the corresponding mechanical behavior. The study of the size-dependent Young’s modulus in ZnO nanowires in atmosphere will improve the understanding of the mechanical properties of nanomaterials as well as providing guidance for applications in NEMSs, nanogenerators, biosensors and other related areas.

On the difficulties in characterizing ZnO nanowires.

PubMed

Schlenker, E; Bakin, A; Weimann, T; Hinze, P; Weber, D H; Gölzhäuser, A; Wehmann, H-H; Waag, A

2008-09-10

The electrical properties of single ZnO nanowires grown by vapor phase transport were investigated. While some samples were contacted by Ti/Au electrodes, another set of samples was investigated using a manipulator tip in a low energy electron point-source microscope. The deduced resistivities range from 1 to 10(3) Ωcm. Additionally, the resistivities of nanowires from multiple publications were brought together and compared to the values obtained from our measurements. The overview of all data shows enormous differences (10(-3)-10(5) Ωcm) in the measured resistivities. In order to reveal the origin of the discrepancies, the influence of growth parameters, measuring methods, contact resistances, crystal structures and ambient conditions are investigated and discussed in detail.

Fabrication of ZnO Nanowires Arrays by Anodization and High-Vacuum Die Casting Technique, and Their Piezoelectric Properties

PubMed Central

Kuo, Chin-Guo; Chang, Ho; Wang, Jian-Hao

2016-01-01

In this investigation, anodic aluminum oxide (AAO) with arrayed and regularly arranged nanopores is used as a template in the high-vacuum die casting of molten zinc metal (Zn) into the nanopores. The proposed technique yields arrayed Zn nanowires with an aspect ratio of over 600. After annealing, arrayed zinc oxide (ZnO) nanowires are obtained. Varying the anodizing time yields AAO templates with thicknesses of approximately 50 μm, 60 μm, and 70 μm that can be used in the fabrication of nanowires of three lengths with high aspect ratios. Experimental results reveal that a longer nanowire generates a greater measured piezoelectric current. The ZnO nanowires that are fabricated using an alumina template are anodized for 7 h and produce higher piezoelectric current of up to 69 pA. PMID:27023546

Fabrication of ZnO Nanowires Arrays by Anodization and High-Vacuum Die Casting Technique, and Their Piezoelectric Properties.

PubMed

Kuo, Chin-Guo; Chang, Ho; Wang, Jian-Hao

2016-03-24

In this investigation, anodic aluminum oxide (AAO) with arrayed and regularly arranged nanopores is used as a template in the high-vacuum die casting of molten zinc metal (Zn) into the nanopores. The proposed technique yields arrayed Zn nanowires with an aspect ratio of over 600. After annealing, arrayed zinc oxide (ZnO) nanowires are obtained. Varying the anodizing time yields AAO templates with thicknesses of approximately 50 μm, 60 μm, and 70 μm that can be used in the fabrication of nanowires of three lengths with high aspect ratios. Experimental results reveal that a longer nanowire generates a greater measured piezoelectric current. The ZnO nanowires that are fabricated using an alumina template are anodized for 7 h and produce higher piezoelectric current of up to 69 pA.

Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires.

PubMed

He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

2017-06-16

In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g -1 at a scan rate of 20 mV s -1 , which is almost twice that of ZnO NWs (191.5 F g -1 ). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g -1 at a current density of 1.33 A g -1 with an energy density of 25.2 W h kg -1 at the power density of 896.44 W kg -1 . In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires

NASA Astrophysics Data System (ADS)

He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

2017-06-01

In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g-1 at a scan rate of 20 mV s-1, which is almost twice that of ZnO NWs (191.5 F g-1). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g-1 at a current density of 1.33 A g-1 with an energy density of 25.2 W h kg-1 at the power density of 896.44 W kg-1. In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

Lipid nanotube or nanowire sensor

DOEpatents

Noy, Aleksandr [Belmont, CA; Bakajin, Olgica [San Leandro, CA; Letant, Sonia [Livermore, CA; Stadermann, Michael [Dublin, CA; Artyukhin, Alexander B [Menlo Park, CA

2009-06-09

A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

Lipid nanotube or nanowire sensor

DOEpatents

Noy, Aleksandr [Belmont, CA; Bakajin, Olgica [San Leandro, CA; Letant, Sonia [Livermore, CA; Stadermann, Michael [Dublin, CA; Artyukhin, Alexander B [Menlo Park, CA

2010-06-29

A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

Synthesis of high aspect ratio ZnO nanowires with an inexpensive handcrafted electrochemical setup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taheri, Ali, E-mail: at1361@aut.ac.ir, E-mail: atahery@aeoi.org.ir; Saramad, Shahyar; Setayeshi, Saeed

In this work, high aspect ratio zinc oxide nanowires are synthesized using templated one-step electrodeposition technique. Electrodeposition of the nanowires is done using a handcrafted electronic system. Nuclear track-etched polycarbonate membrane is used as a template to form the high aspect ratio nanowires. The result of X-ray diffraction and scanning electron microscopy shows that nanowires with a good crystallinity and an aspect ratio of more than 30 can be achieved in a suitable condition. The height of electrodeposited nanowires reaches to about 11 μm. Based on the obtained results, high aspect ratio ZnO nanowires can be formed using inexpensive electrodepositionmore » setup with an acceptable quality.« less

Growth of high-aspect ratio horizontally-aligned ZnO nanowire arrays.

PubMed

Soman, Pranav; Darnell, Max; Feldman, Marc D; Chen, Shaochen

2011-08-01

A method of fabricating horizontally-aligned zinc-oxide (ZnO) nanowire (NW) arrays with full control over the width and length is demonstrated. SEM images reveal the hexagonal structure typical of zinc oxide NWs. Arrays of high-aspect ratio horizontal ZnO NWs are fabricated by making use of the lateral overgrowth from dot patterns created by electron beam lithography (EBL). An array of patterned wires are lifted off and transferred to a flexible PDMS substrate with possible applications in several key nanotechnology areas.

Fabrication of a Combustion-Reacted High-Performance ZnO Electron Transport Layer with Silver Nanowire Electrodes for Organic Solar Cells.

PubMed

Park, Minkyu; Lee, Sang-Hoon; Kim, Donghyuk; Kang, Juhoon; Lee, Jung-Yong; Han, Seung Min

2018-02-28

Herein, a new methodology for solution-processed ZnO fabrication on Ag nanowire network electrode via combustion reaction is reported, where the amount of heat emitted during combustion was minimized by controlling the reaction temperature to avoid damaging the underlying Ag nanowires. The degree of participation of acetylacetones, which are volatile fuels in the combustion reaction, was found to vary with the reaction temperature, as revealed by thermogravimetric and compositional analyses. An optimized processing temperature of 180 °C was chosen to successfully fabricate a combustion-reacted ZnO and Ag nanowire hybrid electrode with a sheet resistance of 30 Ω/sq and transmittance of 87%. A combustion-reacted ZnO on Ag nanowire hybrid structure was demonstrated as an efficient transparent electrode and electron transport layer for the PTB7-Th-based polymer solar cells. The superior electrical conductivity of combustion-reacted ZnO, compared to that of conventional sol-gel ZnO, increased the external quantum efficiency over the entire absorption range, whereas a unique light scattering effect due to the presence of nanopores in the combustion-derived ZnO further enhanced the external quantum efficiency in the 450-550 nm wavelength range. A power conversion efficiency of 8.48% was demonstrated for the PTB7-Th-based polymer solar cell with the use of a combustion-reacted ZnO/Ag NW hybrid transparent electrode.

Single ZnO nanowire-PZT optothermal field effect transistors.

PubMed

Hsieh, Chun-Yi; Lu, Meng-Lin; Chen, Ju-Ying; Chen, Yung-Ting; Chen, Yang-Fang; Shih, Wan Y; Shih, Wei-Heng

2012-09-07

A new type of pyroelectric field effect transistor based on a composite consisting of single zinc oxide nanowire and lead zirconate titanate (ZnO NW-PZT) has been developed. Under infrared (IR) laser illumination, the transconductance of the ZnO NW can be modulated by optothermal gating. The drain current can be increased or decreased by IR illumination depending on the polarization orientation of the Pb(Zr(0.3)Ti(0.7))O(3) (PZT) substrate. Furthermore, by combining the photocurrent behavior in the UV range and the optothermal gating effect in the IR range, the wide spectrum of response of current by light offers a variety of opportunities for nanoscale optoelectronic devices.

Harvesting Mechanical and Thermal Energy by Combining ZnO Nanowires and NiTi Shape Memory Alloy

DOE PAGES

Radousky, Harry; Qian, Fang; An, Yonghao; ...

2017-02-19

In the expanding world of small scale energy harvesting, the ability to combine thermal and mechanical harvesting is growing ever more important. Here, we demonstrate the feasibility of using ZnO nanowires to harvest both mechanical and low-quality thermal energy in simple, scalable devices. These devices were fabricated on kapton films and used ZnO nanowires with the same growth direction to assure alignment of the piezoelectric potentials of all of the wires. Mechanical harvesting from these devices was demonstrated using a periodic application of force, modeling the motion of the human body. Tapping the device from the top of the devicemore » with a wood stick, for example yielded an Open Circuit Voltage (OCV) of 0.2 - 4 V, which is in an ideal range for device applications. In order to demonstrate thermal harvesting from low quality heat sources, a commercially available Nitinol (Ni-Ti alloy) foil was attached to the nanowire piezoelectric device to create a compound thermoelectric. When bent at room temperature and then heated to 50°C, the Nitinol foil was restored to its original flat shape, which yielded an output voltage of nearly 1 V from the ZnO nanowire device.« less

Harvesting Mechanical and Thermal Energy by Combining ZnO Nanowires and NiTi Shape Memory Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radousky, Harry; Qian, Fang; An, Yonghao

In the expanding world of small scale energy harvesting, the ability to combine thermal and mechanical harvesting is growing ever more important. Here, we demonstrate the feasibility of using ZnO nanowires to harvest both mechanical and low-quality thermal energy in simple, scalable devices. These devices were fabricated on kapton films and used ZnO nanowires with the same growth direction to assure alignment of the piezoelectric potentials of all of the wires. Mechanical harvesting from these devices was demonstrated using a periodic application of force, modeling the motion of the human body. Tapping the device from the top of the devicemore » with a wood stick, for example yielded an Open Circuit Voltage (OCV) of 0.2 - 4 V, which is in an ideal range for device applications. In order to demonstrate thermal harvesting from low quality heat sources, a commercially available Nitinol (Ni-Ti alloy) foil was attached to the nanowire piezoelectric device to create a compound thermoelectric. When bent at room temperature and then heated to 50°C, the Nitinol foil was restored to its original flat shape, which yielded an output voltage of nearly 1 V from the ZnO nanowire device.« less

Effect of atomic layer deposition temperature on the performance of top-down ZnO nanowire transistors

PubMed Central

2014-01-01

This paper studies the effect of atomic layer deposition (ALD) temperature on the performance of top-down ZnO nanowire transistors. Electrical characteristics are presented for 10-μm ZnO nanowire field-effect transistors (FETs) and for deposition temperatures in the range 120°C to 210°C. Well-behaved transistor output characteristics are obtained for all deposition temperatures. It is shown that the maximum field-effect mobility occurs for an ALD temperature of 190°C. This maximum field-effect mobility corresponds with a maximum Hall effect bulk mobility and with a ZnO film that is stoichiometric. The optimized transistors have a field-effect mobility of 10 cm2/V.s, which is approximately ten times higher than can typically be achieved in thin-film amorphous silicon transistors. Furthermore, simulations indicate that the drain current and field-effect mobility extraction are limited by the contact resistance. When the effects of contact resistance are de-embedded, a field-effect mobility of 129 cm2/V.s is obtained. This excellent result demonstrates the promise of top-down ZnO nanowire technology for a wide variety of applications such as high-performance thin-film electronics, flexible electronics, and biosensing. PMID:25276107

Impedance analysis of PbS colloidal quantum dot solar cells with different ZnO nanowire lengths

NASA Astrophysics Data System (ADS)

Fukuda, Takeshi; Takahashi, Akihiro; Wang, Haibin; Takahira, Kazuya; Kubo, Takaya; Segawa, Hiroshi

2018-03-01

The photoconversion efficiency of colloidal quantum dot (QD) solar cells has been markedly improved by optimizing the surface passivation and device structure, and details of device physics are now under investigation. In this study, we investigated the resistance and capacitance components at the ZnO/PbS-QD interface and inside a PbS-QD layer by measuring the impedance spectrum while the interface area was controlled by changing the ZnO nanowire length. By evaluating the dependence of optical intensity and DC bias voltage on the ZnO nanowire length, only the capacitance was observed to be influenced by the interface area, and this indicates that photoinduced carriers are generated at the surface of PbS-QD. In addition, since the capacitance is proportional to the surface area of the QD, the interface area can be evaluated from the capacitance. Finally, photovoltaic performance was observed to increase with increasing ZnO nanowire length owing to the large interface area, and this result is in good agreement with the capacitance measurement.

Electronic Transport Properties of One Dimensional Zno Nanowires Studied Using Maximally-Localized Wannier Functions

NASA Astrophysics Data System (ADS)

Sun, Xu; Gu, Yousong; Wang, Xueqiang

2012-08-01

One dimensional ZnO NWs with different diameters and lengths have been investigated using density functional theory (DFT) and Maximally Localized Wannier Functions (MLWFs). It is found that ZnO NWs are direct band gap semiconductors and there exist a turn on voltage for observable current. ZnO nanowires with different diameters and lengths show distinctive turn-on voltage thresholds in I-V characteristics curves. The diameters of ZnO NWs are greatly influent the transport properties of ZnO NWs. For the ZnO NW with large diameter that has more states and higher transmission coefficients leads to narrow band gap and low turn on voltage. In the case of thinner diameters, the length of ZnO NW can effects the electron tunneling and longer supercell lead to higher turn on voltage.

Growth of ZnO nanowires on polypropylene membrane surface-Characterization and reactivity

NASA Astrophysics Data System (ADS)

Bojarska, Marta; Nowak, Bartosz; Skowroński, Jarosław; Piątkiewicz, Wojciech; Gradoń, Leon

2017-01-01

Need for a new membrane is clearly visible in recent studies, mostly due to the fouling phenomenon. Authors, focused on problem of biofouling caused by microorganisms that are present in water environment. An attempt to form a new membrane with zinc oxide (ZnO) nanowires was made; where plasma treatment was used as a first step of modification followed by chemical bath deposition. Such membrane will exhibit additional reactive properties. ZnO, because of its antibacterial and photocatalytic properties, is more and more often used in commercial applications. The authors used SEM imaging, measurement of the contact angle, XRD and the FT-IR analysis for membrane characterization. Amount of ZnO deposited on membrane surface was also investigated by dithizone method. Photocatalytic properties of such membranes were examined through methylene blue and humic acid degradation in laboratory scale modules with LEDs as either: wide range white or UV light source. Antibacterial and antifouling properties of polypropylene membranes modified with ZnO nanowires were examined through a series of tests involving microorganisms: model gram-positive and -negative bacteria. The obtained results showed that it is possible to modify the membrane surface in such a way, that additional reactive properties will be given. Thus, not only did the membrane become a physical barrier, but also turned out to be a reactive one.

Characterizations of low-temperature electroluminescence from ZnO nanowire light-emitting arrays on the p-GaN layer.

PubMed

Lu, Tzu-Chun; Ke, Min-Yung; Yang, Sheng-Chieh; Cheng, Yun-Wei; Chen, Liang-Yi; Lin, Guan-Jhong; Lu, Yu-Hsin; He, Jr-Hau; Kuo, Hao-Chung; Huang, JianJang

2010-12-15

Low-temperature electroluminescence from ZnO nanowire light-emitting arrays is reported. By inserting a thin MgO current blocking layer in between ZnO nanowire and p-GaN, high-purity UV light emission at wavelength 398 nm was obtained. As the temperature is decreased, contrary to the typical GaN-based light emitting diodes, our device shows a decrease of optical output intensity. The results are associated with various carrier tunneling processes and frozen MgO defects.

Silicon Nanowire Field Effect Transistor Sensors with Minimal Sensor to Sensor Variations and Enhanced Sensing Characteristics.

PubMed

Zafar, Sufi; D'Emic, Christopher; Jagtiani, Ashish; Kratschmer, Ernst; Miao, Xin; Zhu, Yu; Mo, Renee; Sosa, Norma; Hamann, Hendrik F; Shahidi, Ghavam; Riel, Heike

2018-06-22

Silicon nanowire field effect transistor (FET) sensors have demonstrated their ability for rapid and label free detection of proteins, nucleotide sequences, and viruses at ultralow concentrations with the potential to be a transformative diagnostic technology. Their nanoscale size gives them their unique ultralow detection ability but also makes their fabrication challenging with large sensor to sensor variations, thus limiting their commercial applications. In this work, a combined approach of nanofabrication, device simulation, materials and electrical characterization is applied towards identifying and improving fabrication steps that induce sensor to sensor variations. An enhanced complementary metal-oxide-semiconductor (CMOS) compatible process for fabricating silicon nanowire FET sensors is demonstrated. Nanowire (30 nm width) FETs with aqueous solution as gates are shown to have the Nernst limit sub-threshold swing SS = 60 mV/decade with ~1.7% variations, whereas literature values for SS are ≥ 80 mV/decade with larger (>10 times) variations. Also, their threshold voltage variations are significantly (~3 times) reduced, compared to literature values. Furthermore, these improved FETs have significantly reduced drain current hysteresis (~0.6 mV) and enhanced on-current to off-current ratios (~10 6 ). These improvements resulted in nanowire FET sensors with lowest (~3%) reported sensor to sensor variations, compared to literature studies. Also, these improved nanowire sensors have the highest reported sensitivity and enhanced signal to noise ratio with the lowest reported defect density of 1x10 18 eV -1 cm -3 in comparison to literature data. In summary, this work brings the nanowire sensor technology a step closer to commercial products for early diagnosis and monitoring of diseases.

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

Structural, optical and electrical properties of well-ordered ZnO nanowires grown on (1 1 1) oriented Si, GaAs and InP substrates by electrochemical deposition method

NASA Astrophysics Data System (ADS)

Pham, Huyen T.; Nguyen, Tam D.; Tran, Dat Q.; Akabori, Masashi

2017-05-01

ZnO semiconductors, especially in form of nanomaterials, possess many excellent properties and have been employed in many applications. In this article, we reported the selective area growth of ZnO nanowires on different (1 1 1) oriented Si, GaAs, and first time on InP substrates by electrochemical deposition method without any seed layers, using zinc nitrate hexahydrate precursor in the presence of hexamethylenetetramine. The position, density and orientation of such ZnO nanowires were controlled by the substrate patterning technique using electron-beam lithography. As-synthesized ZnO nanowires grown on patterned substrates show smaller diameter, higher density and better orientation, compared to the one grown on unpatterned substrates. In particular, the ZnO nanowires grown on GaAs patterned substrate indicate the best morphological property, with the average diameter, length and density of about 100 nm, 2.4 µm and 35 µm-2, respectively. The x-ray diffraction and Raman scattering also demonstrate high crystalline quality of our ZnO nanowires. Moreover, as-reported ZnO nanowires are also conductive, which would allow their use in field-effect transistor and other potential nanoscale device applications.

A ZnO nanowire-based photo-inverter with pulse-induced fast recovery.

PubMed

Raza, Syed Raza Ali; Lee, Young Tack; Hosseini Shokouh, Seyed Hossein; Ha, Ryong; Choi, Heon-Jin; Im, Seongil

2013-11-21

We demonstrate a fast response photo-inverter comprised of one transparent gated ZnO nanowire field-effect transistor (FET) and one opaque FET respectively as the driver and load. Under ultraviolet (UV) light the transfer curve of the transparent gate FET shifts to the negative side and so does the voltage transfer curve (VTC) of the inverter. After termination of UV exposure the recovery of photo-induced current takes a long time in general. This persistent photoconductivity (PPC) is due to hole trapping on the surface of ZnO NWs. Here, we used a positive voltage short pulse after UV exposure, for the first time resolving the PPC issue in nanowire-based photo-detectors by accumulating electrons at the ZnO/dielectric interface. We found that a pulse duration as small as 200 ns was sufficient to reach a full recovery to the dark state from the UV induced state, realizing a fast UV detector with a voltage output.

Conductive polymer nanowire gas sensor fabricated by nanoscale soft lithography.

PubMed

Tang, Ning; Jiang, Yang; Qu, Hemi; Duan, Xuexin

2017-12-01

Resistive devices composed of one-dimensional nanostructures are promising candidates for the next generation of gas sensors. However, the large-scale fabrication of nanowires is still challenging, which restricts the commercialization of such devices. Here, we report a highly efficient and facile approach to fabricating poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) nanowire chemiresistive gas sensors by nanoscale soft lithography. Well-defined sub-100 nm nanowires are fabricated on silicon substrate, which facilitates device integration. The nanowire chemiresistive gas sensor is demonstrated for NH 3 and NO 2 detection at room temperature and shows a limit of detection at ppb level, which is compatible with nanoscale PEDOT:PSS gas sensors fabricated with the conventional lithography technique. In comparison with PEDOT:PSS thin-film gas sensors, the nanowire gas sensor exhibits higher sensitivity and a much faster response to gas molecules.

Conductive polymer nanowire gas sensor fabricated by nanoscale soft lithography

NASA Astrophysics Data System (ADS)

Tang, Ning; Jiang, Yang; Qu, Hemi; Duan, Xuexin

2017-12-01

Resistive devices composed of one-dimensional nanostructures are promising candidates for the next generation of gas sensors. However, the large-scale fabrication of nanowires is still challenging, which restricts the commercialization of such devices. Here, we report a highly efficient and facile approach to fabricating poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) nanowire chemiresistive gas sensors by nanoscale soft lithography. Well-defined sub-100 nm nanowires are fabricated on silicon substrate, which facilitates device integration. The nanowire chemiresistive gas sensor is demonstrated for NH3 and NO2 detection at room temperature and shows a limit of detection at ppb level, which is compatible with nanoscale PEDOT:PSS gas sensors fabricated with the conventional lithography technique. In comparison with PEDOT:PSS thin-film gas sensors, the nanowire gas sensor exhibits higher sensitivity and a much faster response to gas molecules.

A metal-semiconductor-metal detector based on ZnO nanowires grown on a graphene layer.

PubMed

Xu, Qiang; Cheng, Qijin; Zhong, Jinxiang; Cai, Weiwei; Zhang, Zifeng; Wu, Zhengyun; Zhang, Fengyan

2014-02-07

High quality ZnO nanowires (NWs) were grown on a graphene layer by a hydrothermal method. The ZnO NWs revealed higher uniform surface morphology and better structural properties than ZnO NWs grown on SiO2/Si substrate. A low dark current metal-semiconductor-metal photodetector based on ZnO NWs with Au Schottky contact has also been fabricated. The photodetector displays a low dark current of 1.53 nA at 1 V bias and a large UV-to-visible rejection ratio (up to four orders), which are significantly improved compared to conventional ZnO NW photodetectors. The improvement in UV detection performance is attributed to the existence of a surface plasmon at the interface of the ZnO and the graphene.

Highly stable field emission from ZnO nanowire field emitters controlled by an amorphous indium–gallium–zinc-oxide thin film transistor

NASA Astrophysics Data System (ADS)

Li, Xiaojie; Wang, Ying; Zhang, Zhipeng; Ou, Hai; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

2018-04-01

Lowering the driving voltage and improving the stability of nanowire field emitters are essential for them to be applied in devices. In this study the characteristics of zinc oxide (ZnO) nanowire field emitter arrays (FEAs) controlled by an amorphous indium–gallium–zinc-oxide thin film transistor (a-IGZO TFT) were studied. A low driving voltage along with stabilization of the field emission current were achieved. Modulation of field emission currents up to three orders of magnitude was achieved at a gate voltage of 0–32 V for a constant anode voltage. Additionally, a-IGZO TFT control can dramatically reduce the emission current fluctuation (i.e., from 46.11 to 1.79% at an emission current of ∼3.7 µA). Both the a-IGZO TFT and ZnO nanowire FEAs were prepared on glass substrates in our research, demonstrating the feasibility of realizing large area a-IGZO TFT-controlled ZnO nanowire FEAs.

Low-Cost and High-Productivity Three-Dimensional Nanocapacitors Based on Stand-Up ZnO Nanowires for Energy Storage.

PubMed

Wei, Lei; Liu, Qi-Xuan; Zhu, Bao; Liu, Wen-Jun; Ding, Shi-Jin; Lu, Hong-Liang; Jiang, Anquan; Zhang, David Wei

2016-12-01

Highly powered electrostatic capacitors based on nanostructures with a high aspect ratio are becoming critical for advanced energy storage technology because of their high burst power and energy storage capability. We report the fabrication process and the electrical characteristics of high capacitance density capacitors with three-dimensional solid-state nanocapacitors based on a ZnO nanowire template. Stand-up ZnO nanowires are grown face down on p-type Si substrates coated with a ZnO seed layer using a hydrothermal method. Stacks of AlZnO/Al2O3/AlZnO are then deposited sequentially on the ZnO nanowires using atomic layer deposition. The fabricated capacitor has a high capacitance density up to 92 fF/μm(2) at 1 kHz (around ten times that of the planar capacitor without nanowires) and an extremely low leakage current density of 3.4 × 10(-8) A/cm(2) at 2 V for a 5-nm Al2O3 dielectric. Additionally, the charge-discharge characteristics of the capacitor were investigated, indicating that the resistance-capacitance time constants were 550 ns for both the charging and discharging processes and the time constant was not dependent on the voltage. This reflects good power characteristics of the fabricated capacitors. Therefore, the current work provides an exciting strategy to fabricate low-cost and easily processable, high capacitance density capacitors for energy storage.

The kinetic friction of ZnO nanowires on amorphous SiO2 and SiN substrates

NASA Astrophysics Data System (ADS)

Roy, Aditi; Xie, Hongtao; Wang, Shiliang; Huang, Han

2016-12-01

ZnO nanowires were bent on amorphous SiO2 and SiN substrates in an ambient atmosphere using optical nanomanipulation. The kinetic friction between the nanowires and substrate was determined from the bent shape of the nanowires. The kinetic friction force per unit area, i.e. frictional shear stress, for the ZnO/SiO2 and ZnO/SiN nanowire/substrate systems being measured were 1.05 ± 0.28 and 2.08 ± 0.33 MPa, respectively. The surface roughness and the Hamaker constant of SiO2 and SiN substrates had significant effect on the frictional stresses.

Adsorbed Molecules and Surface Treatment Effect on Optical Properties of ZnO Nanowires Grown by MOCVD

NASA Astrophysics Data System (ADS)

Jabri, S.; Souissi, H.; Sallet, V.; Lusson, A.; Meftah, A.; Galtier, P.; Oueslati, M.

2017-07-01

We have investigated the optical properties of ZnO nanowires grown by metalorganic chemical vapor deposition (MOCVD) with nitrous oxide (N2O) as oxygen precursor. Photoluminescence (PL) and Raman measurements showed the influence of adsorbed molecules on the optical properties. Low-temperature (4 K) PL studies on the surface exciton (SX) at 3.3660 eV elucidated the nature and origin of this emission. In particular, surface treatment by annealing at high temperature under inert gas reduced the emission intensity of SX. Raman vibrational spectra proved that presence of a considerable amount of adsorbed molecules on the surface of ZnO nanowires plays a key role in the occurrence of surface excitons.

Penetration length-dependent hot electrons in the field emission from ZnO nanowires

NASA Astrophysics Data System (ADS)

Chen, Yicong; Song, Xiaomeng; Li, Zhibing; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

2018-01-01

In the framework of field emission, whether or not hot electrons can form in the semiconductor emitters under a surface penetration field is of great concern, which will provide not only a comprehensive physical picture of field emission from semiconductor but also guidance on how to improve device performance. However, apart from some theoretical work, its experimental evidence has not been reported yet. In this article, the field penetration length-dependent hot electrons were observed in the field emission of ZnO nanowires through the in-situ study of its electrical and field emission characteristic before and after NH3 plasma treatment in an ultrahigh vacuum system. After the treatment, most of the nanowires have an increased carrier density but reduced field emission current. The raised carrier density was caused by the increased content of oxygen vacancies, while the degraded field emission current was attributed to the lower kinetic energy of hot electrons caused by the shorter penetration length. All of these results suggest that the field emission properties of ZnO nanowires can be optimized by modifying their carrier density to balance both the kinetic energy of field induced hot electrons and the limitation of saturated current under a given field.

2D XANES-XEOL mapping: observation of enhanced band gap emission from ZnO nanowire arrays

NASA Astrophysics Data System (ADS)

Wang, Zhiqiang; Guo, Xiaoxuan; Sham, Tsun-Kong

2014-05-01

Using 2D XANES-XEOL spectroscopy, it is found that the band gap emission of ZnO nanowire arrays is substantially enhanced i.e. that the intensity ratio between the band gap and defect emissions increases by more than an order of magnitude when the excitation energy is scanned across the O K-edge. Possible mechanisms are discussed.Using 2D XANES-XEOL spectroscopy, it is found that the band gap emission of ZnO nanowire arrays is substantially enhanced i.e. that the intensity ratio between the band gap and defect emissions increases by more than an order of magnitude when the excitation energy is scanned across the O K-edge. Possible mechanisms are discussed. Electronic supplementary information (ESI) available: XEOL spectra with different excitation energies. X-ray attenuation length vs. photon energy. Details of surface defects in ZnO NWs. The second O K-edge and Zn L-edge 2D XANES-XEOL maps. Comparison of the first and second TEY at O K-edge and Zn L-edge scans, respectively. Raman spectra of the ZnO NWs with different IBGE/IDE ratios. See DOI: 10.1039/c4nr01049c

Investigation of the temperature dependent field emission from individual ZnO nanowires for evidence of field-induced hot electrons emission.

PubMed

Chen, Yicong; Zhang, Zhipeng; Li, Zhi-Bing; She, Juncong; Deng, Shaozhi; Xu, Ning-Sheng; Chen, Jun

2018-06-27

ZnO nanowires as field emitters have important applications in flat panel display and X-ray source. Understanding the intrinsic field emission mechanism is crucial for further improving the performance of ZnO nanowire field emitters. In this article, the temperature dependent field emission from individual ZnO nanowires was investigated by an in-situ measurement in ultra-high vacuum. The divergent temperature-dependent Fowler-Nordheim plots is found in the low field region. A field-induced hot electrons emission model that takes into account penetration length is proposed to explain the results. The carrier density and temperature dependence of the field-induced hot electrons emission current are derived theoretically. The obtained results are consistent with the experimental results, which could be attributed to the variation of effective electron temperature. All of these are important for a better understanding on the field emission process of semiconductor nanostructures. © 2018 IOP Publishing Ltd.

Nanowire sensors and arrays for chemical/biomolecule detection

NASA Technical Reports Server (NTRS)

Yun, Minhee; Lee, Choonsup; Vasquez, Richard P.; Ramanathan, K.; Bangar, M. A.; Chen, W.; Mulchandan, A.; Myung, N. V.

2005-01-01

We report electrochemical growth of single nanowire based sensors using e-beam patterned electrolyte channels, potentially enabling the controlled fabrication of individually addressable high density arrays. The electrodeposition technique results in nanowires with controlled dimensions, positions, alignments, and chemical compositions. Using this technique, we have fabricated single palladium nanowires with diameters ranging between 75 nm and 300 nm and conducting polymer nanowires (polypyrrole and polyaniline) with diameters between 100 nm and 200 nm. Using these single nanowires, we have successfully demonstrated gas sensing with Pd nanowires and pH sensing with polypirrole nanowires.

In Situ X-ray Absorption Near-Edge Structure Spectroscopy of ZnO Nanowire Growth During Chemical Bath Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

McPeak, Kevin M.; Becker, Matthew A.; Britton, Nathan G.

2010-12-03

Chemical bath deposition (CBD) offers a simple and inexpensive route to deposit semiconductor nanostructures, but lack of fundamental understanding and control of the underlying chemistry has limited its versatility. Here we report the first use of in situ X-ray absorption spectroscopy during CBD, enabling detailed investigation of both reaction mechanisms and kinetics of ZnO nanowire growth from zinc nitrate and hexamethylenetetramine (HMTA) precursors. Time-resolved X-ray absorption near-edge structure (XANES) spectra were used to quantify Zn(II) speciation in both solution and solid phases. ZnO crystallizes directly from [Zn(H{sub 2}O){sub 6}]{sup 2+} without long-lived intermediates. Using ZnO nanowire deposition as an example,more » this study establishes in situ XANES spectroscopy as an excellent quantitative tool to understand CBD of nanomaterials.« less

Effect of indium on photovoltaic property of n-ZnO/p-Si heterojunction device prepared using solution-synthesized ZnO nanowire film

NASA Astrophysics Data System (ADS)

Kathalingam, Adaikalam; Kim, Hyun-Seok; Park, Hyung-Moo; Valanarasu, Santiyagu; Mahalingam, Thaiyan

2015-01-01

Preparation of n-ZnO/p-Si heterostructures using solution-synthesized ZnO nanowire films and their photovoltaic characterization is reported. The solution-grown ZnO nanowire film is characterized using scanning electron microscope, electron dispersive x-ray, and optical absorption studies. Electrical and photovoltaic properties of the fabricated heterostructures are studied using e-beam-evaporated aluminum as metal contacts. In order to use transparent contact and to simultaneously collect the photogenerated carriers, sandwich-type solar cells were fabricated using ZnO nanorod films grown on p-silicon and indium tin oxide (ITO) coated glass as ITO/n-ZnO NR/p-Si. The electrical properties of these structures are analyzed from current-voltage (I-V) characteristics. ZnO nanowire film thickness-dependent photovoltaic properties are also studied. Indium metal was also deposited over the ZnO nanowires and its effects on the photovoltaic response of the devices were studied. The results demonstrated that all the samples exhibit a strong rectifying behavior indicating the diode nature of the devices. The sandwich-type ITO/n-ZnO NR/p-Si solar cells exhibit improved photovoltaic performance over the Al-metal-coated n-ZnO/p-Si structures. The indium deposition is found to show enhancement in photovoltaic behavior with a maximum open-circuit voltage (Voc) of 0.3 V and short-circuit current (Isc) of 70×10-6 A under ultraviolet light excitation.

High carrier concentration ZnO nanowire arrays for binder-free conductive support of supercapacitors electrodes by Al doping.

PubMed

Zheng, Xin; Sun, Yihui; Yan, Xiaoqin; Sun, Xu; Zhang, Guangjie; Zhang, Qian; Jiang, Yaru; Gao, Wenchao; Zhang, Yue

2016-12-15

Doping semiconductor nanowires (NWs) for altering their electrical and optical properties is a critical strategy for tailoring the performance of nanodevices. Here, we prepared in situ Al-doped ZnO nanowire arrays by using continuous flow injection (CFI) hydrothermal method to promote the conductivity. This reasonable method offers highly stable precursor concentration for doping that effectively avoid the appearance of the low conductivity ZnO nanosheets. Benefit from this, three orders of magnitude rise of the carrier concentration from 10 16 cm -3 to 10 19 cm -3 can be achieved compared with the common hydrothermal (CH) mothed in Mott-Schottky measurement. Possible effect of Al-doping was discussed by first-principle theory. On this basis, Al-doped ZnO nanowire arrays was developed as a binder-free conductive support for supercapacitor electrodes and high capacitance was triggered. It is owing to the dramatically decreased transfer resistance induced by the growing free-moving electrons and holes. Our results have a profound significance not merely in the controlled synthesis of other doping nanomaterials by co-precipitation method but also in the application of binder-free energy materials or other materials. Copyright © 2016 Elsevier Inc. All rights reserved.

Single conducting polymer nanowire based conductometric sensors

NASA Astrophysics Data System (ADS)

Bangar, Mangesh Ashok

The detection of toxic chemicals, gases or biological agents at very low concentrations with high sensitivity and selectivity has been subject of immense interest. Sensors employing electrical signal readout as transduction mechanism offer easy, label-free detection of target analyte in real-time. Traditional thin film sensors inherently suffered through loss of sensitivity due to current shunting across the charge depleted/added region upon analyte binding to the sensor surface, due to their large cross sectional area. This limitation was overcome by use of nanostructure such as nanowire/tube as transducer where current shunting during sensing was almost eliminated. Due to their benign chemical/electrochemical fabrication route along with excellent electrical properties and biocompatibility, conducting polymers offer cost-effective alternative over other nanostructures. Biggest obstacle in using these nanostructures is lack of easy, scalable and cost-effective way of assembling these nanostructures on prefabricated micropatterns for device fabrication. In this dissertation, three different approaches have been taken to fabricate individual or array of single conducting polymer (and metal) nanowire based devices and using polymer by itself or after functionalization with appropriate recognition molecule they have been applied for gas and biochemical detection. In the first approach electrochemical fabrication of multisegmented nanowires with middle functional Ppy segment along with ferromagnetic nickel (Ni) and end gold segments for better electrical contact was studied. This multi-layered nanowires were used along with ferromagnetic contact electrode for controlled magnetic assembly of nanowires into devices and were used for ammonia gas sensing. The second approach uses conducting polymer, polypyrrole (Ppy) nanowires using simple electrophoretic alignment and maskless electrodeposition to anchor nanowire which were further functionalized with antibodies against

Effects of annealing on the ferromagnetism and photoluminescence of Cu-doped ZnO nanowires.

PubMed

Xu, H J; Zhu, H C; Shan, X D; Liu, Y X; Gao, J Y; Zhang, X Z; Zhang, J M; Wang, P W; Hou, Y M; Yu, D P

2010-01-13

Room temperature ferromagnetic Cu-doped ZnO nanowires have been synthesized using the chemical vapor deposition method. By combining structural characterizations and comparative annealing experiments, it has been found that both extrinsic (CuO nanoparticles) and intrinsic (Zn(1-x)Cu(x)O nanowires) sources are responsible for the observed ferromagnetic ordering of the as-grown samples. As regards the former, annealing in Zn vapor led to a dramatic decrease of the ferromagnetism. For the latter, a reversible switching of the ferromagnetism was observed with sequential annealings in Zn vapor and oxygen ambience respectively, which agreed well with previous reports for Cu-doped ZnO films. In addition, we have for the first time observed low temperature photoluminescence changed with magnetic properties upon annealing in different conditions, which revealed the crucial role played by interstitial zinc in directly mediating high T(c) ferromagnetism and indirectly modulating the Cu-related structured green emission via different charge transfer transitions.

Fabrication of a Miniaturized ZnO Nanowire Accelerometer and Its Performance Tests

PubMed Central

Kim, Hyun Chan; Song, Sangho; Kim, Jaehwan

2016-01-01

This paper reports a miniaturized piezoelectric accelerometer suitable for a small haptic actuator array. The accelerometer is made with zinc oxide (ZnO) nanowire (NW) grown on a copper wafer by a hydrothermal process. The size of the accelerometer is 1.5 × 1.5 mm2, thus fitting the 1.8 × 1.8 mm2 haptic actuator array cell. The detailed fabrication process of the miniaturized accelerometer is illustrated. Performance evaluation of the fabricated accelerometer is conducted by comparing it with a commercial piezoelectric accelerometer. The output current of the fabricated accelerometer increases linearly with the acceleration. The miniaturized ZnO NW accelerometer is feasible for acceleration measurement of small and lightweight devices. PMID:27649184

Flexible Dye-Sensitized Solar Cell Based on Vertical ZnO Nanowire Arrays

PubMed Central

2011-01-01

Flexible dye-sensitized solar cells are fabricated using vertically aligned ZnO nanowire arrays that are transferred onto ITO-coated poly(ethylene terephthalate) substrates using a simple peel-off process. The solar cells demonstrate an energy conversion efficiency of 0.44% with good bending tolerance. This technique paves a new route for building large-scale cost-effective flexible photovoltaic and optoelectronic devices. PMID:27502660

A fast and effective approach for reversible wetting-dewetting transitions on ZnO nanowires

PubMed Central

Yadav, Kavita; Mehta, B. R.; Bhattacharya, Saswata; Singh, J. P.

2016-01-01

Here, we demonstrate a facile approach for the preparation of ZnO nanowires (NWs) with tunable surface wettability that can be manipulated reversibly in a controlled manner from a superhydrophilic state to a superhydrophobic state. The as-synthesized ZnO NWs obtained by a chemical vapor deposition method are superhydrophilic with a contact angle (CA) value of ~0°. After H2 gas annealing at 300 °C for 90 minutes, ZnO NWs display superhydrophobic behavior with a roll-off angle less than 5°. However, O2 gas annealing converts these superhydrophobic ZnO NWs into a superhydrophilic state. For switching from superhydrophobic to superhydrophilic state and vice versa in cyclic manner, H2 and O2 gas annealing treatment was used, respectively. A model based on density functional theory indicates that the oxygen-related defects are responsible for CA switching. The water resistant properties of the ZnO NWs coating is found to be durable and can be applied to a variety of substrates including glass, metals, semiconductors, paper and even flexible polymers. PMID:27713536

A photonic crystal fiber glucose sensor filled with silver nanowires

NASA Astrophysics Data System (ADS)

Yang, X. C.; Lu, Y.; Wang, M. T.; Yao, J. Q.

2016-01-01

We report a photonic crystal fiber glucose sensor filled with silver nanowires in this paper. The proposed sensor is both analyzed by COMSOL multiphysics software and demonstrated by experiments. The extremely high average spectral sensitivity 19009.17 nm/RIU for experimental measurement is obtained, equivalent to 44.25 mg/dL of glucose in water, which is lower than 70 mg/dL for efficient detection of hypoglycemia episodes. The silver nanowires diameter which may affect the sensor's spectral sensitivity is also discussed and an optimal range of silver nanowires diameter 90-120 nm is obtained. We expect that the sensor can provide an effective platform for glucose sensing and potentially leading to a further development towards minimal-invasive glucose measurement.

Zinc oxide nanowire networks for macroelectronic devices

NASA Astrophysics Data System (ADS)

Unalan, Husnu Emrah; Zhang, Yan; Hiralal, Pritesh; Dalal, Sharvari; Chu, Daping; Eda, Goki; Teo, K. B. K.; Chhowalla, Manish; Milne, William I.; Amaratunga, Gehan A. J.

2009-04-01

Highly transparent zinc oxide (ZnO) nanowire networks have been used as the active material in thin film transistors (TFTs) and complementary inverter devices. A systematic study on a range of networks of variable density and TFT channel length was performed. ZnO nanowire networks provide a less lithographically intense alternative to individual nanowire devices, are always semiconducting, and yield significantly higher mobilites than those achieved from currently used amorphous Si and organic TFTs. These results suggest that ZnO nanowire networks could be ideal for inexpensive large area electronics.

Investigations into the impact of various substrates and ZnO ultra thin seed layers prepared by atomic layer deposition on growth of ZnO nanowire array

PubMed Central

2012-01-01

The impact of various substrates and zinc oxide (ZnO) ultra thin seed layers prepared by atomic layer deposition on the geometric morphology of subsequent ZnO nanowire arrays (NWs) fabricated by the hydrothermal method was investigated. The investigated substrates included B-doped ZnO films, indium tin oxide films, single crystal silicon (111), and glass sheets. Scanning electron microscopy and X-ray diffraction measurements revealed that the geometry and aligment of the NWs were controlled by surface topography of the substrates and thickness of the ZnO seed layers, respectively. According to atomic force microscopy data, we suggest that the substrate, fluctuate amplitude and fluctuate frequency of roughness on ZnO seed layers have a great impact on the alignment of the resulting NWs, whereas the influence of the seed layers' texture was negligible. PMID:22759838

Flexible cellulose and ZnO hybrid nanocomposite and its UV sensing characteristics

PubMed Central

Mun, Seongcheol; Kim, Hyun Chan; Ko, Hyun-U; Zhai, Lindong; Kim, Jung Woong; Kim, Jaehwan

2017-01-01

Abstract This paper reports the synthesis and UV sensing characteristics of a cellulose and ZnO hybrid nanocomposite (CEZOHN) prepared by exploiting the synergetic effects of ZnO functionality and the renewability of cellulose. Vertically aligned ZnO nanorods were grown well on a flexible cellulose film by direct ZnO seeding and hydrothermal growing processes. The ZnO nanorods have the wurtzite structure and an aspect ratio of 9 ~ 11. Photoresponse of the prepared CEZOHN was evaluated by measuring photocurrent under UV illumination. CEZOHN shows bi-directional, linear and fast photoresponse as a function of UV intensity. Electrode materials, light sources, repeatability, durability and flexibility of the prepared CEZOHN were tested and the photocurrent generation mechanism is discussed. The silver nanowire coating used for electrodes on CEZOHN is compatible with a transparent UV sensor. The prepared CEZOHN is flexible, transparent and biocompatible, and hence can be used for flexible and wearable UV sensors. PMID:28740560

Flexible cellulose and ZnO hybrid nanocomposite and its UV sensing characteristics

NASA Astrophysics Data System (ADS)

Mun, Seongcheol; Kim, Hyun Chan; Ko, Hyun-U.; Zhai, Lindong; Kim, Jung Woong; Kim, Jaehwan

2017-12-01

This paper reports the synthesis and UV sensing characteristics of a cellulose and ZnO hybrid nanocomposite (CEZOHN) prepared by exploiting the synergetic effects of ZnO functionality and the renewability of cellulose. Vertically aligned ZnO nanorods were grown well on a flexible cellulose film by direct ZnO seeding and hydrothermal growing processes. The ZnO nanorods have the wurtzite structure and an aspect ratio of 9 11. Photoresponse of the prepared CEZOHN was evaluated by measuring photocurrent under UV illumination. CEZOHN shows bi-directional, linear and fast photoresponse as a function of UV intensity. Electrode materials, light sources, repeatability, durability and flexibility of the prepared CEZOHN were tested and the photocurrent generation mechanism is discussed. The silver nanowire coating used for electrodes on CEZOHN is compatible with a transparent UV sensor. The prepared CEZOHN is flexible, transparent and biocompatible, and hence can be used for flexible and wearable UV sensors.

ZnO nanowire Schottky barrier ultraviolet photodetector with high sensitivity and fast recovery speed

NASA Astrophysics Data System (ADS)

Cheng, Gang; Wu, Xinghui; Liu, Bing; Li, Bing; Zhang, Xingtang; Du, Zuliang

2011-11-01

ZnO nanowire (NW) ultraviolet (UV) photodetectors have high sensitivity, while the long recovery time is an important limitation for its applications. In this paper, we demonstrate the promising applications of ZnO NW Schottky barrier as high performance UV photodetector with high sensitivity and fast recovery speed. The on/off ratio, sensitivity, and photocurrent gain are 4 × 105, 2.6 × 103 A/W, and 8.5 × 103, respectively. The recovery time is 0.28 s when photocurrent decreases by 3 orders of magnitude, and the corresponding time constant is as short as 46 ms. The physical mechanisms of the fast recovery properties have also been discussed.

An Enhanced UV-Vis-NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure.

PubMed

Zheng, Zhi; Gan, Lin; Zhang, Jianbing; Zhuge, Fuwei; Zhai, Tianyou

2017-03-01

ZnO nanostructure-based photodetectors have a wide applications in many aspects, however, the response range of which are mainly restricted in the UV region dictated by its bandgap. Herein, UV-vis-NIR sensitive ZnO photodetectors consisting of ZnO nanowires (NW) array/PbS quantum dots (QDs) heterostructures are fabricated through modified electrospining method and an exchanging process. Besides wider response region compared to pure ZnO NWs based photodetectors, the heterostructures based photodetectors have faster response and recovery speed in UV range. Moreover, such photodetectors demonstrate good flexibility as well, which maintain almost constant performances under extreme (up to 180°) and repeat (up to 200 cycles) bending conditions in UV-vis-NIR range. Finally, this strategy is further verified on other kinds of 1D nanowires and 0D QDs, and similar enhancement on the performance of corresponding photodetecetors can be acquired, evidencing the universality of this strategy.

Structural and optical characterization of ZnO nanowires grown on alumina by thermal evaporation method.

PubMed

Mute, A; Peres, M; Peiris, T C; Lourenço, A C; Jensen, Lars R; Monteiro, T

2010-04-01

Zinc oxide nanowires have been grown on alumina substrate by thermal evaporation of zinc nanopowder in the presence of oxygen flow. The growth was performed under ambient pressure and without the use of foreign catalyst. Scanning electron microscopy (SEM) observation showed that the as-grown sample consists of bulk ZnO crystal on the substrate surface with nanowires growing from this base. Growth mechanism of the observed morphology is suggested to be governed by the change of zinc vapour supersaturation during the growth process. X-ray diffraction (XRD) measurement was used to identify the crystalline phase of the nanowires. Optical properties of the nanowires were investigated using Raman scattering and photoluminescence (PL). The appearance of dominant, Raman active E2 (high) phonon mode in the Raman spectrum has confirmed the wurtzite hexagonal phase of the nanowires. With above bandgap excitation the low temperature PL recombination is dominated by donor bound exciton luminescence at -3.37 eV with a narrow full width at half maximum. Free exciton emission is also seen at low temperature and can be observed up to room temperature. The optical data indicates that the grown nanowires have high optical quality.

Low-Temperature Preparation of Ag-Doped ZnO Nanowire Arrays, DFT Study, and Application to Light-Emitting Diode.

PubMed

Pauporté, Thierry; Lupan, Oleg; Zhang, Jie; Tugsuz, Tugba; Ciofini, Ilaria; Labat, Frédéric; Viana, Bruno

2015-06-10

Doping ZnO nanowires (NWs) by group IB elements is an important challenge for integrating nanostructures into functional devices with better and tuned performances. The growth of Ag-doped ZnO NWs by electrodeposition at 90 °C using a chloride bath and molecular oxygen precursor is reported. Ag acts as an electrocatalyst for the deposition and influences the nucleation and growth of the structures. The silver atomic concentration in the wires is controlled by the additive concentration in the deposition bath and a content up to 3.7 atomic % is reported. XRD analysis shows that the integration of silver enlarges the lattice parameters of ZnO. The optical measurements also show that the direct optical bandgap of ZnO is reduced by silver doping. The bandgap shift and lattice expansion are explained by first principle calculations using the density functional theory (DFT) on the silver impurity integration as an interstitial (Ag(i)) and as a substitute of zinc atom (Ag(Zn)) in the crystal lattice. They notably indicate that Ag(Zn) doping forms an impurity band because of Ag 4d and O 2p orbital interactions, shifting the Fermi level toward the valence band. At least, Ag-doped ZnO vertically aligned nanowire arrays have been epitaxially grown on GaN(001) substrate. The heterostructure has been inserted in a light emitting device. UV-blue light emission has been achieved with a low emission threshold of 5 V and a tunable red-shifted emission spectrum related to the bandgap reduction induced by silver doping of the ZnO emitter material.

Diameter and location control of ZnO nanowires using electrodeposition and sodium citrate

NASA Astrophysics Data System (ADS)

Lifson, Max L.; Levey, Christopher G.; Gibson, Ursula J.

2013-10-01

We report single-step growth of spatially localized ZnO nanowires of controlled diameter to enable improved performance of piezoelectric devices such as nanogenerators. This study is the first to demonstrate the combination of electrodeposition with zinc nitrate and sodium citrate in the growth solution. Electrodeposition through a thermally-grown silicon oxide mask results in localization, while the growth voltage and solution chemistry are tuned to control the nanowire geometry. We observe a competition between lateral (relative to the (0001) axis) citrate-related morphology and voltage-driven vertical growth which enables this control. High aspect ratios result with either pure nitrate or nitrate-citrate mixtures if large voltages are used, but low growth voltages permit the growth of large diameter nanowires in solution with citrate. Measurements of the current density suggest a two-step growth process. An oxide mask blocks the electrodeposition, and suppresses nucleation of thermally driven growth, permitting single-step lithography on low cost p-type silicon substrates.

Investigation of nanoscale voids in Sb-doped p-type ZnO nanowires.

PubMed

Pradel, Ken C; Uzuhashi, Jun; Takei, Toshiaki; Ohkubo, Tadakatsu; Hono, Kazuhiro; Fukata, Naoki

2018-08-17

While it has multiple advantageous optoelectronic and piezoelectric properties, the application of zinc oxide has been limited by the lack of a stable p-type dopant. Recently, it was discovered that antimony doping can lead to stable p-type doping in ZnO, but one curious side effect of the doping process is the formation of voids inside the nanowire. While previously used as a signifier of successful doping, up until now, little research has been performed on these structures themselves. In this work, the effect of annealing on the size and microstructure of the voids was investigated using TEM and XRD, finding that the voids form around a region of Zn 7 Sb 2 O 12 . Furthermore, using Raman spectroscopy, a new peak associated with successful doping was identified. The most surprising finding, however, was the presence of water trapped inside the nanowire, showing that this is actually a composite structure. Water was initially discovered in the nanowires using atom probe tomography, and verified using Raman spectroscopy.

Passivation of surface states in the ZnO nanowire with thermally evaporated copper phthalocyanine for hybrid photodetectors.

PubMed

Chen, Qi; Ding, Huaiyi; Wu, Yukun; Sui, Mengqiao; Lu, Wei; Wang, Bing; Su, Wenming; Cui, Zheng; Chen, Liwei

2013-05-21

The adsorption of O2/H2O molecules on the ZnO nanowire (NW) surface results in the long lifetime of photo-generated carriers and thus benefits ZnO NW-based ultraviolet photodetectors by suppressing the dark current and improving the photocurrent gain, but the slow adsorption process also leads to slow detector response time. Here we show that a thermally evaporated copper phthalocyanine film is effective in passivating surface trap states of ZnO NWs. As a result, the organic/inorganic hybrid photodetector devices exhibit simultaneously improved photosensitivity and response time. This work suggests that it could be an effective way in interfacial passivation using organic/inorganic hybrid structures.

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

NASA Astrophysics Data System (ADS)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

Effect of in situ Al doping on structure and optical properties of ZnO nanowires grown by MOCVD

NASA Astrophysics Data System (ADS)

Souissi, H.; Jabri, S.; Souissi, A.; Lusson, A.; Galtier, P.; Meftah, A.; Sallet, V.; Oueslati, M.

2018-01-01

Al-doped ZnO nanowires (NWs) were grown on C-axis oriented sapphire by metal organic chemical vapor deposition using dimethylzinc-triethylamine (DMZn-TEN), nitrogen dioxide (NO2) and TMAl as zinc, oxygen and aluminum doping sources respectively. The NWs morphology has been characterized by scanning electron microscopy and transmission electron microscopy. The photoluminescence (PL) spectra exhibit a strong excitonic transition bond that confirms the Al incorporation in the ZnO NWs. Raman results support PL conclusion by showing additional modes in Al-doped ZnO NWs at nearly 270, 510, 579 and 641 cm-1. The micro-Raman scattering analysis along a single Al-doped ZnO needle-like NW shows an increase of the Al concentration from the basis to the tip of the wire.

Efficient room temperature hydrogen sensor based on UV-activated ZnO nano-network

NASA Astrophysics Data System (ADS)

Kumar, Mohit; Kumar, Rahul; Rajamani, Saravanan; Ranwa, Sapana; Fanetti, Mattia; Valant, Matjaz; Kumar, Mahesh

2017-09-01

Room temperature hydrogen sensors were fabricated from Au embedded ZnO nano-networks using a 30 mW GaN ultraviolet LED. The Au-decorated ZnO nano-networks were deposited on a SiO2/Si substrate by a chemical vapour deposition process. X-ray diffraction (XRD) spectrum analysis revealed a hexagonal wurtzite structure of ZnO and presence of Au. The ZnO nanoparticles were interconnected, forming nano-network structures. Au nanoparticles were uniformly distributed on ZnO surfaces, as confirmed by FESEM imaging. Interdigitated electrodes (IDEs) were fabricated on the ZnO nano-networks using optical lithography. Sensor performances were measured with and without UV illumination, at room temperate, with concentrations of hydrogen varying from 5 ppm to 1%. The sensor response was found to be ˜21.5% under UV illumination and 0% without UV at room temperature for low hydrogen concentration of 5 ppm. The UV-photoactivated mode enhanced the adsorption of photo-induced O- and O2- ions, and the d-band electron transition from the Au nanoparticles to ZnO—which increased the chemisorbed reaction between hydrogen and oxygen. The sensor response was also measured at 150 °C (without UV illumination) and found to be ˜18% at 5 ppm. Energy efficient low cost hydrogen sensors can be designed and fabricated with the combination of GaN UV LEDs and ZnO nanostructures.

Effect of morphology evolution on the thermoelectric properties of oxidized ZnO thin films

NASA Astrophysics Data System (ADS)

Liu, Shiying; Li, Guojian; Xiao, Lin; Jia, Baohai; Gao, Yang; Wang, Qiang

2018-04-01

The effects of nanowire content on the thermoelectric properties of ZnO films were investigated. The nanowire content of ZnO films was tuned by thermal oxidation of evaporated Zn films. The results showed that hexagonal and polyhedral morphologies on the surface of Zn films can be used to tune the nanowire content of ZnO films. Hexagonal nanoplates with a diameter of 100-350 nm readily grew ZnO nanowires with c-axis preferential orientation. Conversely, it was difficult to grow nanowires on polyhedral nanoparticles with diameters of 500-750 nm because the meeting of ZnO (101) and (001) facets suppressed nanowire growth. Thermoelectric parameters were strongly affected by nanowire content. In particular, carrier concentration increased with nanowire content. Carrier mobility also increased with nanowire content because the nanowires behaved as channels for electronic migration. The band gap of the films narrowed with increasing nanowire content because the binding energy of O 1s electrons with oxygen vacancies decreased. The maximum power factor of the film with high nanowire content (8.80 μW/m K2 at 530 K) was approximately 300% higher than that of the film with low nanowire content.

Nanostructure based EO/IR sensor development for homeland security applications

NASA Astrophysics Data System (ADS)

Sood, Ashok K.; Welser, Roger E.; Sood, Adam W.; Puri, Yash R.; Manzur, Tariq; Dhar, Nibir K.; Polla, Dennis L.; Wang, Zhong L.; Wijewarnasuriya, Priyalal S.; Anwar, A. F. M.

2011-06-01

Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense and Homeland Security Sensor Applications. Several different nanomaterials are being evaluated for these applications. These include ZnO nanowires, GaN Nanowires and II-VI nanowires, which have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under way using Carbon Nanotubes (CNT) for a high speed detector and focal plane array as two-dimensional array as bolometer for IR bands of interest, which can be implemented for the sensors for homeland security applications. In this paper, we will discuss the sensor design and model predicting performance of an EO/IR focal plane array and Sensor that can cover the UV to IR bands of interest. The model can provide a robust means for comparing performance of the EO/IR FPA's and Sensors that can operate in the UV, Visible-NIR (0.4- 1.8μ), SWIR (2.0-2.5μ), MWIR (3-5μ), and LWIR bands (8-14μ). This model can be used as a tool for predicting performance of nanostructure arrays under development. We will also discuss our results on growth and characterization of ZnO nanowires and CNT's for the next generation sensor applications. We also present several approaches for integrated energy harvesting using nanostructure based solar cells and Nanogenerators that can be used to supplement the energy required for nanostructure based sensors.

Atomistic Interface Dynamics in Sn-Catalyzed Growth of Wurtzite and Zinc-Blende ZnO Nanowires.

PubMed

Jia, Shuangfeng; Hu, Shuaishuai; Zheng, He; Wei, Yanjie; Meng, Shuang; Sheng, Huaping; Liu, Huihui; Zhou, Siyuan; Zhao, Dongshan; Wang, Jianbo

2018-06-11

Unraveling the phase selection mechanisms of semiconductor nanowires (NWs) is critical for the applications in future advanced nanodevices. In this study, the atomistic vapor-solid-liquid growth processes of Sn-catalyzed wurtzite (WZ) and zinc blende (ZB) ZnO are directly revealed based on the in situ transmission electron microscopy. The growth kinetics of WZ and ZB crystal phases in ZnO appear markedly different in terms of the NW-droplet interface, whereas the nucleation site as determined by the contact angle ϕ between the seed particle and the NW is found to be crucial for tuning the NW structure through combined experimental and theoretical investigations. These results offer an atomic-scale view into the dynamic growth process of ZnO NW, which has implications for the phase-controllable synthesis of II-VI compounds and heterostructures with tunable band structures.

Facile preparation of branched hierarchical ZnO nanowire arrays with enhanced photocatalytic activity: A photodegradation kinetic model

NASA Astrophysics Data System (ADS)

Ebrahimi, M.; Yousefzadeh, S.; Samadi, M.; Dong, Chunyang; Zhang, Jinlong; Moshfegh, A. Z.

2018-03-01

Branched hierarchical zinc oxide nanowires (BH-ZnO NWs) were fabricated successfully by a facile and rapid synthesis using two-step growth process. Initially, ZnO NWs have been prepared by anodizing zinc foil at room temperature and followed by annealing treatment. Then, the BH- ZnO NWs were grown on the ZnO NWs by a solution based method at very low temperature (31 oC). The BH- ZnO NWs with different aspect ratio were obtained by varying reaction time (0.5, 2, 5, 10 h). Photocatalytic activity of the samples was studied under both UV and visible light. The results indicated that the optimized BH-ZnO NWs (5 h) as a photocatalyst exhibited the highest photoactivity with about 3 times higher than the ZnO NWs under UV light. In addition, it was also determined that photodegradation rate constant (k) for the BH- ZnO NWs surface obeys a linear function with the branch length (l) and their correlation was described by using a proposed kinetic model.

Plasmonic Properties of Vertically Aligned Nanowire Arrays

DTIC Science & Technology

2012-01-01

scattering (SERS) applications. In this investigation, two types of vertical NW arrays were studied; those of ZnO NWs grown on nanosphere lithography...plasmonic nanowires to investigate this SERS effect. Here we used two types of vertical NWs, ZnO NWs, and Si NWs, respectively, to investigate SERS...successfully grow vertically aligned ZnO nanowires by the well-known VLS process. In this way, the ZnO NWs can be arranged in a repeatable hexagonal pattern

Exciton diffusion coefficient measurement in ZnO nanowires under electron beam irradiation.

PubMed

Donatini, Fabrice; Pernot, Julien

2018-03-09

In semiconductor nanowires (NWs) the exciton diffusion coefficient can be determined using a scanning electron microscope fitted with a cathodoluminescence system. High spatial and temporal resolution cathodoluminescence experiments are needed to measure independently the exciton diffusion length and lifetime in single NWs. However, both diffusion length and lifetime can be affected by the electron beam bombardment during observation and measurement. Thus, in this work the exciton lifetime in a ZnO NW is measured versus the electron beam dose (EBD) via a time-resolved cathodoluminescence experiment with a temporal resolution of 50 ps. The behavior of the measured exciton lifetime is consistent with our recent work on the EBD dependence of the exciton diffusion length in similar NWs investigated under comparable SEM conditions. Combining the two results, the exciton diffusion coefficient in ZnO is determined at room temperature and is found constant over the full span of EBD.

Near-Field Imaging of Free Carriers in ZnO Nanowires with a Scanning Probe Tip Made of Heavily Doped Germanium

NASA Astrophysics Data System (ADS)

Sakat, Emilie; Giliberti, Valeria; Bollani, Monica; Notargiacomo, Andrea; Pea, Marialilia; Finazzi, Marco; Pellegrini, Giovanni; Hugonin, Jean-Paul; Weber-Bargioni, Alexander; Melli, Mauro; Sassolini, Simone; Cabrini, Stefano; Biagioni, Paolo; Ortolani, Michele; Baldassarre, Leonetta

2017-11-01

A novel scanning probe tip made of heavily doped semiconductor is fabricated and used instead of standard gold-coated tips in infrared scattering-type near-field microscopy. Midinfrared near-field microscopy experiments are conducted on ZnO nanowires with a lateral resolution better than 100 nm, using tips made of heavily electron-doped germanium with a plasma frequency in the midinfrared (plasma wavelength of 9.5 μ m ). Nanowires embedded in a dielectric matrix are imaged at two wavelengths, 11.3 and 8.0 μ m , above and below the plasma wavelength of the tips. An opposite sign of the imaging contrasts between the nanowire and the dielectric matrix is observed at the two infrared wavelengths, indicating a clear role of the free-electron plasma in the heavily doped germanium tip in building the imaging contrast. Electromagnetic simulations with a multispherical dipole model accounting for the finite size of the tip are well consistent with the experiments. By comparison of the simulated and measured imaging contrasts, an estimate for the local free-carrier density in the investigated ZnO nanowires in the low 1019 cm-3 range is retrieved. The results are benchmarked against the scattering intensity and phase maps obtained on the same sample with a gold-coated probe tip in pseudoheterodyne detection mode.

The impact of nanocontact on nanowire based nanoelectronics.

PubMed

Lin, Yen-Fu; Jian, Wen-Bin

2008-10-01

Nanowire-based nanoelectronic devices will be innovative electronic building blocks from bottom up. The reduced nanocontact area of nanowire devices magnifies the contribution of contact electrical properties. Although a lot of two-contact-based ZnO nanoelectronics have been demonstrated, the electrical properties bringing either from the nanocontacts or from the nanowires have not been considered yet. High quality ZnO nanowires with a small deviation and an average diameter of 38 nm were synthesized to fabricate more than thirty nanowire devices. According to temperature behaviors of current-voltage curves and resistances, the devices could be grouped into three types. Type I devices expose thermally activated transport in ZnO nanowires and they could be considered as two Ohmic nanocontacts of the Ti electrode contacting directly on the nanowire. For those nanowire devices having a high resistance at room temperatures, they can be fitted accurately with the thermionic-emission theory and classified into type II and III devices according to their rectifying and symmetrical current-voltage behaviors. The type II device has only one deteriorated nanocontact and the other one Ohmic contact on single ZnO nanowire. An insulating oxide layer with thickness less than 20 nm should be introduced to describe electron hopping in the nanocontacts, so as to signalize one- and high-dimensional hopping conduction in type II and III devices.

Template-Assisted Hydrothermal Growth of One-Dimensional Zinc Oxide Nanowires for Photocatalytic Application.

PubMed

Ma, Shuai-Shuai; Xu, Peng; Cai, Zhi-Lan; Li, Qing; Ye, Zhao-Lian; Zhou, Yu-Ming

2018-07-01

One-dimensional (1D) semiconductor ZnO nanowires have been successfully synthesized by a novel soft-chemical hydrothermal method with allylpolyethoxy amino carboxylate (AA-APEA) at low temperature. Their structure and properties have been characterized by a series of techniques, including X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). It was found that ZnO nanowires with diameters around 50 nm and lengths up to about several micrometers are well-distributed. The photocatalytic activity toward degradation of methylene blue (MB) aqueous solution under ultraviolet (UV) was investigated and the results showed that the ZnO nanowires exhibit a markedly higher photoactivity compared to the ZnO nanoparticles which were obtained without AA-APEA polymer assistant, and it can be ascribed to the special 1D morphology of the ZnO nanowires. In particular, the rate of degradation of the ZnO nanowires was 11 times faster than that of ZnO nanoparticles. In addition, the ZnO nanowires could be easily recycled in UV photocatalytic activity. These observations could promote new applications of photocatalyst for wastewater treatment utilizing oxide semiconductor nanostructures.

Gravimetric humidity sensor based on ZnO nanorods covered piezoresistive Si microcantilever

NASA Astrophysics Data System (ADS)

Xu, Jiushuai; Bertke, Maik; Li, Xiaojing; Gad, Alaaeldin; Zhou, Hao; Wasisto, Hutomo Suryo; Peiner, Erwin

2017-06-01

A ZnO nanorods film covered silicon resonant cantilever sensor is developed for atmosphere humidity detection by monitoring the resonant frequency shifts induced by the additional weight of adsorbed water molecules. Two different crystalline seed-layer deposition methods were applied to grow different nanorods films. The morphology of the ZnO films were characterized and the sensor sensitivities were measured under different relative humidity (RH) levels. The experiments results showed that this novel humidity sensor with ZnO nanorods has a sensitivity of 101.5 +/- 12.0 ppm/RH% (amount of adsorbed water of 36.9 +/- 4.4 ng/RH%), indicating its potential for portable sensing applications.

Chip-to-chip SnO2 nanowire network sensors for room temperature H2 detection

NASA Astrophysics Data System (ADS)

Köck, A.; Brunet, E.; Mutinati, G. C.; Maier, T.; Steinhauer, S.

2012-06-01

The employment of nanowires is a very powerful strategy to improve gas sensor performance. We demonstrate a gas sensor device, which is based on silicon chip-to-chip synthesis of ultralong tin oxide (SnO2) nanowires. The sensor device employs an interconnected SnO2 nanowire network configuration, which exhibits a huge surface-to-volume ratio and provides full access of the target gas to the nanowires. The chip-to-chip SnO2 nanowire device is able to detect a H2 concentration of only 20 ppm in synthetic air with ~ 60% relative humidity at room temperature. At an operating temperature of 300°C a concentration of 50 ppm H2 results in a sensitivity of 5%. At this elevated temperature the sensor shows a linear response in a concentration range between 10 ppm and 100 ppm H2. The SnO2-nanowire fabrication procedure based on spray pyrolysis and subsequent annealing is performed at atmospheric pressure, requires no vacuum and allows upscale of the substrate to a wafer size. 3D-integration with CMOS chips is proposed as viable way for practical realization of smart nanowire based gas sensor devices for the consumer market.

Production of zinc oxide nanowires power with precisely defined morphology

NASA Astrophysics Data System (ADS)

Mičová, Júlia; Remeš, Zdeněk; Chan, Yu-Ying

2017-12-01

The interest about zinc oxide is increasing thanks to its unique chemical and physical properties. Our attention has focused on preparation powder of 1D nanostructures of ZnO nanowires with precisely defined morphology include characterization size (length and diameter) and shape controlled in the scanning electron microscopy (SEM). We have compared results of SEM with dynamic light scattering (DLS) technique. We have found out that SEM method gives more accurate results. We have proposed transformation process from ZnO nanowires on substrates to ZnO nanowires powder by ultrasound peeling to colloid followed by lyophilization. This method of the mass production of the ZnO nanowires powder has some advantages: simplicity, cost effective, large-scale and environment friendly.

Long-Term Stability of Oxide Nanowire Sensors via Heavily Doped Oxide Contact.

PubMed

Zeng, Hao; Takahashi, Tsunaki; Kanai, Masaki; Zhang, Guozhu; He, Yong; Nagashima, Kazuki; Yanagida, Takeshi

2017-12-22

Long-term stability of a chemical sensor is an essential quality for long-term collection of data related to exhaled breath, environmental air, and other sources in the Internet of things (IoT) era. Although an oxide nanowire sensor has shown great potential as a chemical sensor, the long-term stability of sensitivity has not been realized yet due to electrical degradation under harsh sensing conditions. Here, we report a rational concept to accomplish long-term electrical stability of metal oxide nanowire sensors via introduction of a heavily doped metal oxide contact layer. Antimony-doped SnO 2 (ATO) contacts on SnO 2 nanowires show much more stable and lower electrical contact resistance than conventional Ti contacts for high temperature (200 °C) conditions, which are required to operate chemical sensors. The stable and low contact resistance of ATO was confirmed for at least 1960 h under 200 °C in open air. This heavily doped oxide contact enables us to realize the long-term stability of SnO 2 nanowire sensors while maintaining the sensitivity for both NO 2 gas and light (photo) detections. The applicability of our method is confirmed for sensors on a flexible polyethylene naphthalate (PEN) substrate. Since the proposed fundamental concept can be applied to various oxide nanostructures, it will give a foundation for designing long-term stable oxide nanomaterial-based IoT sensors.

Cr2O3-modified ZnO thick film resistors as LPG sensors.

PubMed

Patil, D R; Patil, L A

2009-02-15

Thick films of pure ZnO were obtained by screen-printing technique. Surface functionalized ZnO thick films by Cr(2)O(3) were obtained by dipping pure ZnO thick films into 0.01M aqueous solution of chromium trioxide (CrO(3)). The dipped films were fired at 500 degrees C for 30 min. Upon firing, the CrO(3) would reduce to Cr(2)O(3). Cr(2)O(3)-activated (0.47 mass%) ZnO thick films resulted in LPG sensor. Upon exposure to 100 ppm LPG, the barrier height between Cr(2)O(3) and ZnO grains decreases markedly, leading to a drastic decrease in resistance. The sensor was found to sense LPG at 350 degrees C and no cross sensitivity was observed to other hazardous, polluting and inflammable gases. The quick response ( approximately 18s) and fast recovery ( approximately 42s) are the main features of this sensor. The effects of microstructures and dopant concentrations on the gas sensing performance of the sensor were studied and discussed.

High-efficiency second harmonic generation from a single hybrid ZnO nanowire/Au plasmonic nano-oligomer.

PubMed

Grinblat, Gustavo; Rahmani, Mohsen; Cortés, Emiliano; Caldarola, Martín; Comedi, David; Maier, Stefan A; Bragas, Andrea V

2014-11-12

We introduce a plasmonic-semiconductor hybrid nanosystem, consisting of a ZnO nanowire coupled to a gold pentamer oligomer by crossing the hot-spot. It is demonstrated that the hybrid system exhibits a second harmonic (SH) conversion efficiency of ∼3 × 10(-5)%, which is among the highest values for a nanoscale object at optical frequencies reported so far. The SH intensity was found to be ∼1700 times larger than that from the same nanowire excited outside the hot-spot. Placing high nonlinear susceptibility materials precisely in plasmonic confined-field regions to enhance SH generation opens new perspectives for highly efficient light frequency up-conversion on the nanoscale.

Flexible Piezoelectric-Induced Pressure Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures.

PubMed

Chen, Zefeng; Wang, Zhao; Li, Xinming; Lin, Yuxuan; Luo, Ningqi; Long, Mingzhu; Zhao, Ni; Xu, Jian-Bin

2017-05-23

The piezoelectric effect is widely applied in pressure sensors for the detection of dynamic signals. However, these piezoelectric-induced pressure sensors have challenges in measuring static signals that are based on the transient flow of electrons in an external load as driven by the piezopotential arisen from dynamic stress. Here, we present a pressure sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-induced polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene pressure sensors, this sensor is capable of measuring static pressures with a sensitivity of up to 9.4 × 10 -3 kPa -1 and a fast response time down to 5-7 ms. This demonstration of pressure sensors shows great potential in the applications of electronic skin and wearable devices.

Wearable multifunctional sensors using printed stretchable conductors made of silver nanowires

NASA Astrophysics Data System (ADS)

Yao, Shanshan; Zhu, Yong

2014-01-01

Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ~1.2 MPa) and finger touch with high sensitivity, fast response time (~40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels.Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ~1.2 MPa) and finger touch with high sensitivity, fast response time (~40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels. Electronic

Silver nanowires network encapsulated by low temperature sol-gel ZnO for transparent flexible electrodes with ambient stability

NASA Astrophysics Data System (ADS)

Shin, Wonjung; Cho, Wonki; Baik, Seung Jae

2018-01-01

As a geometrically engineered realization of transparent electrode, Ag nanowires network is promising for its superior characteristics both on electrical conductivity and optical transmittance. However, for a potential commercialization of Ag nanowires network, further investigations on encapsulation materials are necessary to prevent degradation caused by ambient aging. In addition, the temperature range of the coating process for the encapsulation material needs to be low enough to prevent degradation of polymer substrates during the film coating processes, when considering emerging flexible device application of transparent electrodes. We present experimental results showing that low temperature sol-gel ZnO processed under 130 °C is an effective encapsulation material preventing ambient oxidation of Ag nanowires network without degrading electrical, optical, and mechanical properties.

Toward blue emission in ZnO based LED

NASA Astrophysics Data System (ADS)

Viana, Bruno; Pauporté, Thierry; Lupan, Oleg; Le Bahers, Tangui; Ciofini, Ilaria

2012-03-01

The bandgap engineering of ZnO nanowires by doping is of great importance for tunable light emitting diode (LED) applications. We present a combined experimental and computational study of ZnO doping with Cd or Cu atoms in the nanomaterial. Zn1-xTMxO (TM=Cu, Cd) nanowires have been epitaxially grown on magnesium-doped p-GaN by electrochemical deposition. The Zn1-xTMxO/p-GaN heterojunction was integrated in a LED structure. Nanowires act as the light emitters and waveguides. At room temperature, TM-doped ZnO based LEDs exhibit low-threshold emission voltage and electroluminescence emission shifted from ultraviolet to violet-blue spectral region compared to pure ZnO LEDs. The emission wavelength can be tuned by changing the transition metal (TM) content in the ZnO nanomaterial and the shift is discussed, including insights from DFT computational investigations.

Integrated Spectral Low Noise Image Sensor with Nanowire Polarization Filters for Low Contrast Imaging

DTIC Science & Technology

2015-11-05

AFRL-AFOSR-VA-TR-2015-0359 Integrated Spectral Low Noise Image Sensor with Nanowire Polarization Filters for Low Contrast Imaging Viktor Gruev...To) 02/15/2011 - 08/15/2015 4. TITLE AND SUBTITLE Integrated Spectral Low Noise Image Sensor with Nanowire Polarization Filters for Low Contrast...investigate alternative spectral imaging architectures based on my previous experience in this research area. I will develop nanowire polarization

UV radiation and CH4 gas detection with a single ZnO:Pd nanowire

NASA Astrophysics Data System (ADS)

Lupan, O.; Adelung, R.; Postica, V.; Ababii, N.; Chow, L.; Viana, B.; Pauporté, T.

2017-02-01

There is an increasing demand for sensors to monitor environmental levels of ultraviolet (UV) radiation and pollutant gases. In this work, an individual nanowire of Pd modified ZnO nanowire (ZnO:Pd NW) was integrated in a nanosensor device for efficient and fast detection of UV light and CH4 gas at room temperature. Crystalline ZnO:Pd nanowire/nanorod arrays were synthesized onto fluorine doped tin oxide (FTO) substrates by electrochemical deposition (ECD) at relative low-temperatures (90 °C) with different concentrations of PdCl2 in electrolyte solution and investigated by SEM and EDX. Nanodevices were fabricated using dual beam focused electron/ion beam (FIB/SEM) system and showed improved UV radiation response compared to pristine ZnO NW, reported previously by our group. The UV response was increased by one order in magnitude (≈ 11) for ZnO:Pd NW. Gas sensing measurements demonstrated a higher gas response and rapidity to methane (CH4 gas, 100 ppm) at room temperature, showing promising results for multifunctional applications. Also, due to miniature size and ultra-low power consumption of these sensors, it is possible to integrate them into portable devices easily, such as smartphones, digital clock, flame detection, missile lunching and other smart devices.

Aligned hierarchical Ag/ZnO nano-heterostructure arrays via electrohydrodynamic nanowire template for enhanced gas-sensing properties.

PubMed

Yin, Zhouping; Wang, Xiaomei; Sun, Fazhe; Tong, Xiaohu; Zhu, Chen; Lv, Qiying; Ye, Dong; Wang, Shuai; Luo, Wei; Huang, YongAn

2017-09-22

Gas sensing performance can be improved significantly by the increase in both the effective gas exposure area and the surface reactivitiy of ZnO nanorods. Here, we propose aligned hierarchical Ag/ZnO nano-heterostructure arrays (h-Ag/ZnO-NAs) via electrohydrodynamic nanowire template, together with a subsequent hydrothermal synthesis and photoreduction reaction. The h-Ag/ZnO-NAs scatter at top for higher specific surface areas with the air, simultaneously contact at root for the electrical conduction. Besides, the ZnO nanorods are uniformly coated with dispersed Ag nanoparticles, resulting in a tremendous enhancement of the surface reactivity. Compared with pure ZnO, such h-Ag/ZnO-NAs exhibit lower electrical resistance and faster responses. Moreover, they demonstrate enhanced NO 2 gas sensing properties. Self-assembly via electrohydrodynamic nanowire template paves a new way for the preparation of high performance gas sensors.

A novel ethanol gas sensor-ZnS/ cyclohexylamine hybrid nanowires.

PubMed

Xu, Lin; Song, Hongwei; Zhang, Tong; Fan, Huitao; Fan, Libo; Wang, Yu; Dong, Biao; Bai, Xue

2011-03-01

We fabricated a novel ethanol gas sensor based on organic-inorganic ZnS/cyclohexylamine (CHA) nanowires via a solvothermal route. The sensor exhibited significantly better performance with response time of approximately 0.6 s and recovery time of approximately 10 s even under a low ethanol concentration and the high surface area, small nanofiber diameter, and hybrid nature made the ZnS/CHA nanowire gas sensor have high sensitivity to ethanol gas at a lower operating current of 160 mA. Moreover, the gas sensing mechanism was proposed on the basis of the two simultaneous steps to explain the adsorbing process due to the hybrid nature. This work indicates that the ZnS/CHA hybrid can be a novel candidate for the ethanol gas sensor with high performance.

Formation of Ordered and Disordered Dielectric/metal Nanowire Arrays and their Plasmonic Behavior

DTIC Science & Technology

2007-01-01

sheath geometry. 2. EXPERIMENTAL PROCEDURES Several different nanowire systems have been grown, including random Ga2O3 nanowires, InAs...nanowires, ZnO nanowires, as well as Au lines produced by e-beam lithography. The growth of the Ga2O3 nanowires was achieved by the controlled oxidation...CLOSELY-SPACED PARALLEL ZnO NANOWIRES AND CROSSED Ga2O3 NANOWIRES. As discussed above, due to the far separation of the gold colloid catalyst in the

Micropatternable Double-Faced ZnO Nanoflowers for Flexible Gas Sensor.

PubMed

Kim, Jong-Woo; Porte, Yoann; Ko, Kyung Yong; Kim, Hyungjun; Myoung, Jae-Min

2017-09-27

Micropatternable double-faced (DF) zinc oxide (ZnO) nanoflowers (NFs) for flexible gas sensors have been successfully fabricated on a polyimide (PI) substrate with single-walled carbon nanotubes (SWCNTs) as electrode. The fabricated sensor comprises ZnO nanoshells laid out on a PI substrate at regular intervals, on which ZnO nanorods (NRs) were grown in- and outside the shells to maximize the surface area and form a connected network. This three-dimensional network structure possesses multiple gas diffusion channels and the micropatterned island structure allows the stability of the flexible devices to be enhanced by dispersing the strain into the empty spaces of the substrate. Moreover, the micropatterning technique on a flexible substrate enables highly integrated nanodevices to be fabricated. The SWCNTs were chosen as the electrode for their flexibility and the Schottky barrier they form with ZnO, improving the sensing performance. The devices exhibited high selectivity toward NO 2 as well as outstanding sensing characteristics with a stable response of 218.1, fast rising and decay times of 25.0 and 14.1 s, respectively, and percent recovery greater than 98% upon NO 2 exposure. The superior sensing properties arose from a combination of high surface area, numerous active junction points, donor point defects in the ZnO NRs, and the use of the SWCNT electrode. Furthermore, the DF-ZnO NF gas sensor showed sustainable mechanical stability. Despite the physical degradation observed, the devices still demonstrated outstanding sensing characteristics after 10 000 bending cycles at a curvature radius of 5 mm.

In situ biasing and off-axis electron holography of a ZnO nanowire

NASA Astrophysics Data System (ADS)

den Hertog, Martien; Donatini, Fabrice; McLeod, Robert; Monroy, Eva; Sartel, Corinne; Sallet, Vincent; Pernot, Julien

2018-01-01

Quantitative characterization of electrically active dopants and surface charges in nano-objects is challenging, since most characterization techniques using electrons [1-3], ions [4] or field ionization effects [5-7] study the chemical presence of dopants, which are not necessarily electrically active. We perform cathodoluminescence and voltage contrast experiments on a contacted and biased ZnO nanowire with a Schottky contact and measure the depletion length as a function of reverse bias. We compare these results with state-of-the-art off-axis electron holography in combination with electrical in situ biasing on the same nanowire. The extension of the depletion length under bias observed in scanning electron microscopy based techniques is unusual as it follows a linear rather than square root dependence, and is therefore difficult to model by bulk equations or finite element simulations. In contrast, the analysis of the axial depletion length observed by holography may be compared with three-dimensional simulations, which allows estimating an n-doping level of 1 × 1018 cm-3 and negative sidewall surface charge of 2.5 × 1012 cm-2 of the nanowire, resulting in a radial surface depletion to a depth of 36 nm. We found excellent agreement between the simulated diameter of the undepleted core and the active thickness observed in the experimental data. By combining TEM holography experiments and finite element simulation of the NW electrostatics, the bulk-like character of the nanowire core is revealed.

Bottle-brush-shaped heterostructures of NiO-ZnO nanowires: growth study and sensing properties

NASA Astrophysics Data System (ADS)

Baratto, C.; Kumar, R.; Comini, E.; Ferroni, M.; Campanini, M.

2017-11-01

We present here heterostructured ZnO-NiO nanowires (NWs), constituted by a core of single crystalline ZnO NWs, covered by poly-crystalline NiO nanorods (NRs). The bottle-brush shape was investigated by scanning electron microscopy and transmission electron microscope, confirming that a columnar growth of NiO occurred over the ZnO core, with a preferred orientation of NiO over ZnO NWs. The heterostructured devices are proposed for gas sensing application. Bare ZnO NWs and heterostructured sensors with two different thicknesses of NiO poly-crystalline NRs were analysed for acetone, ethanol, NO2 and H2 detection. All sensors maintained n-type sensing mechanism, with improved sensing performance for lower thickness of NiO, due to high catalytic activity of NiO. The sensing dynamic is also strongly modified by the presence of heterojunction of NiO/ZnO, with a reduction of response and recovery times towards ethanol and acetone at 400 °C.

Acoustoelectric Effect on the Responses of SAW Sensors Coated with Electrospun ZnO Nanostructured Thin Film

PubMed Central

Tasaltin, Cihat; Ebeoglu, Mehmet Ali; Ozturk, Zafer Ziya

2012-01-01

In this study, zinc oxide (ZnO) was a very good candidate for improving the sensitivity of gas sensor technology. The preparation of an electrospun ZnO nanostructured thin film on a 433 MHz Rayleigh wave based Surface Acoustic Wave (SAW) sensor and the investigation of the acoustoelectric effect on the responses of the SAW sensor are reported. We prepared an electrospun ZnO nanostructured thin film on the SAW devices by using an electrospray technique. To investigate the dependency of the sensor response on the structure and the number of the ZnO nanoparticles, SAW sensors were prepared with different coating loads. The coating frequency shifts were adjusted to fall between 100 kHz and 2.4 MHz. The sensor measurements were performed against VOCs such as acetone, trichloroethylene, chloroform, ethanol, n-propanol and methanol vapor. The sensor responses of n-propanol have opposite characteristics to the other VOCs, and we attributed these characteristics to the elastic effect/acoustoelectric effect.

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

NASA Astrophysics Data System (ADS)

McAlpine, Michael C.; Ahmad, Habib; Wang, Dunwei; Heath, James R.

2007-05-01

The development of a robust method for integrating high-performance semiconductors on flexible plastics could enable exciting avenues in fundamental research and novel applications. One area of vital relevance is chemical and biological sensing, which if implemented on biocompatible substrates, could yield breakthroughs in implantable or wearable monitoring systems. Semiconducting nanowires (and nanotubes) are particularly sensitive chemical sensors because of their high surface-to-volume ratios. Here, we present a scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto plastic to yield highly ordered films for low-power sensor chips. The nanowires are excellent field-effect transistors, and, as sensors, exhibit parts-per-billion sensitivity to NO2, a hazardous pollutant. We also use SiO2 surface chemistries to construct a `nano-electronic nose' library, which can distinguish acetone and hexane vapours via distributed responses. The excellent sensing performance coupled with bendable plastic could open up opportunities in portable, wearable or even implantable sensors.

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

PubMed Central

McAlpine, Michael C.; Ahmad, Habib; Wang, Dunwei; Heath, James R.

2013-01-01

The development of a robust method for integrating high-performance semiconductors on flexible plastics could enable exciting avenues in fundamental research and novel applications. One area of vital relevance is chemical and biological sensing, which if implemented on biocompatible substrates, could yield breakthroughs in implantable or wearable monitoring systems. Semiconducting nanowires (and nanotubes) are particularly sensitive chemical sensors because of their high surface-to-volume ratios. Here, we present a scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto plastic to yield highly ordered films for low-power sensor chips. The nanowires are excellent field-effect transistors, and, as sensors, exhibit parts-per-billion sensitivity to NO2, a hazardous pollutant. We also use SiO2 surface chemistries to construct a ‘nano-electronic nose’ library, which can distinguish acetone and hexane vapours via distributed responses. The excellent sensing performance coupled with bendable plastic could open up opportunities in portable, wearable or even implantable sensors. PMID:17450146

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors.

PubMed

McAlpine, Michael C; Ahmad, Habib; Wang, Dunwei; Heath, James R

2007-05-01

The development of a robust method for integrating high-performance semiconductors on flexible plastics could enable exciting avenues in fundamental research and novel applications. One area of vital relevance is chemical and biological sensing, which if implemented on biocompatible substrates, could yield breakthroughs in implantable or wearable monitoring systems. Semiconducting nanowires (and nanotubes) are particularly sensitive chemical sensors because of their high surface-to-volume ratios. Here, we present a scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto plastic to yield highly ordered films for low-power sensor chips. The nanowires are excellent field-effect transistors, and, as sensors, exhibit parts-per-billion sensitivity to NO2, a hazardous pollutant. We also use SiO2 surface chemistries to construct a 'nano-electronic nose' library, which can distinguish acetone and hexane vapours via distributed responses. The excellent sensing performance coupled with bendable plastic could open up opportunities in portable, wearable or even implantable sensors.

High-Density ZnO Nanowires as a Reversible Myogenic-Differentiation Switch.

PubMed

Errico, Vito; Arrabito, Giuseppe; Fornetti, Ersilia; Fuoco, Claudia; Testa, Stefano; Saggio, Giovanni; Rufini, Stefano; Cannata, Stefano; Desideri, Alessandro; Falconi, Christian; Gargioli, Cesare

2018-04-25

Mesoangioblasts are outstanding candidates for stem-cell therapy and are already being explored in clinical trials. However, a crucial challenge in regenerative medicine is the limited availability of undifferentiated myogenic progenitor cells because growth is typically accompanied by differentiation. Here reversible myogenic-differentiation switching during proliferation is achieved by functionalizing the glass substrate with high-density ZnO nanowires (NWs). Specifically, mesoangioblasts grown on ZnO NWs present a spherical viable undifferentiated cell state without lamellopodia formation during the entire observation time (8 days). Consistently, the myosin heavy chain, typically expressed in skeletal muscle tissue and differentiated myogenic progenitors, is completely absent. Remarkably, NWs do not induce any damage while they reversibly block differentiation, so that the differentiation capabilities are completely recovered upon cell removal from the NW-functionalized substrate and replating on standard culture glass. This is the first evidence of a reversible myogenic-differentiation switch that does not affect the viability. These results can be the first step toward for the in vitro growth of a large number of undifferentiated stem/progenitor cells and therefore can represent a breakthrough for cell-based therapy and tissue engineering.

Atomic Layer Deposition of Nickel on ZnO Nanowire Arrays for High-Performance Supercapacitors.

PubMed

Ren, Qing-Hua; Zhang, Yan; Lu, Hong-Liang; Wang, Yong-Ping; Liu, Wen-Jun; Ji, Xin-Ming; Devi, Anjana; Jiang, An-Quan; Zhang, David Wei

2018-01-10

A novel hybrid core-shell structure of ZnO nanowires (NWs)/Ni as a pseudocapacitor electrode was successfully fabricated by atomic layer deposition of a nickel shell, and its capacitive performance was systemically investigated. Transmission electron microscopy and X-ray photoelectron spectroscopy results indicated that the NiO was formed at the interface between ZnO and Ni where the Ni was oxidized by ZnO during the ALD of the Ni layer. Electrochemical measurement results revealed that the Ti/ZnO NWs/Ni (1500 cycles) electrode with a 30 nm thick Ni-NiO shell layer had the best supercapacitor properties including ultrahigh specific capacitance (∼2440 F g -1 ), good rate capability (80.5%) under high current charge-discharge conditions, and a relatively better cycling stability (86.7% of the initial value remained after 750 cycles at 10 A g -1 ). These attractive capacitive behaviors are mainly attributed to the unique core-shell structure and the combined effect of ZnO NW arrays as short charge transfer pathways for ion diffusion and electron transfer as well as conductive Ni serving as channel for the fast electron transport to Ti substrate. This high-performance Ti/ZnO NWs/Ni hybrid structure is expected to be one of a promising electrodes for high-performance supercapacitor applications.

Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles.

PubMed

Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

2018-06-22

Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles

NASA Astrophysics Data System (ADS)

Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

2018-06-01

Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

Novel Gas Sensor Based on ZnO Nanorod Circular Arrays for C2H5OH Gas Detection.

PubMed

Jianjiao, Zhang; Hongyan, Yue; Erjun, Guo; Shaolin, Zhang; Liping, Wang; Chunyu, Zhang; Xin, Gao; Jing, Chang; Hong, Zhang

2015-03-01

Novel side-heating gas sensor based on ZnO nanorod circular arrays was firstly fabricated by hydrothermal treatment assisted with a kind of simple dip-coating technique. The structure and morphologies of ZnO nanorods were characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), respectively. XRD result indicates that the obtained ZnO nanorods have good crystalline with the hexagonal wurtzite structure. SEM result indicates that ZnO nanorod arrays are vertically growth on the surface of ceramic tube of side-heating sensor with controlled diameter and length, narrow size distribution and high orientation. The gas sensing properties of ZnO nanorod circular arrays are also evaluated. Comparative to the sensor based on scattered ZnO nanorods responding to 25 ppm H2, CO, C6H5CH3 and C2H5OH gas, respectively, the sensing values of high orientation gas sensor are generally increased by 5%. This novel sensor has good application promising for the fabrication of cost effective and high performance gas sensors.

A highly flexible platform for nanowire sensor assembly using a combination of optically induced and conventional dielectrophoresis.

PubMed

Lin, Yen-Heng; Ho, Kai-Siang; Yang, Chin-Tien; Wang, Jung-Hao; Lai, Chao-Sung

2014-06-02

The number and position of assembled nanowires cannot be controlled using most nanowire sensor assembling methods. In this paper, we demonstrate a high-yield, highly flexible platform for nanowire sensor assembly using a combination of optically induced dielectrophoresis (ODEP) and conventional dielectrophoresis (DEP). With the ODEP platform, optical images can be used as virtual electrodes to locally turn on a non-contact DEP force and manipulate a micron- or nano-scale substance suspended in fluid. Nanowires were first moved next to the previously deposited metal electrodes using optical images and, then, were attracted to and arranged in the gap between two electrodes through DEP forces generated by switching on alternating current signals to the metal electrodes. A single nanowire can be assembled within 24 seconds using this approach. In addition, the number of nanowires in a single nanowire sensor can be controlled, and the assembly of a single nanowire on each of the adjacent electrodes can also be achieved. The electrical properties of the assembled nanowires were characterized by IV curve measurement. Additionally, the contact resistance between the nanowires and electrodes and the stickiness between the nanowires and substrates were further investigated in this study.

Enhanced photoelectric performance in self-powered UV detectors based on ZnO nanowires with plasmonic Au nanoparticles scattered electrolyte

NASA Astrophysics Data System (ADS)

Zeng, Yiyu; Ye, Zhizhen; Lu, Bin; Dai, Wei; Pan, Xinhua

2016-04-01

Vertically aligned ZnO nanowires (NWs) were grown on a fluorine-doped tin-oxide-coated glass substrate by a hydrothermal method. Au nanoparticles were well dispersed in the mixed solution of ethanol and deionized water. A simple self-powered ultraviolet detector based on solid-liquid heterojunction was fabricated, utilizing ZnO NWs as active photoanode and such prepared mixed solution as electrolyte. The introduction of Au nanoparticles results in considerable improvements in the responsivity and sensitivity of the device compared with the one using deionized water as electrolyte, which is attributed to the enhanced light harvesting by Au nanoparticles.

Characterization of planar pn heterojunction diodes constructed with Cu2O nanoparticle films and single ZnO nanowires.

PubMed

Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

2013-05-01

In this study, we fabricate planar pn heterojunction diodes composed of Cu2O nanoparticle (NP) films and single ZnO nanowires (NWs) on SiO2 (300 nm)/Si substrates and investigate their characteristics in the dark and under the illumination of white light and 325 nm wavelength light. The diode at bias voltages of +/- 1 V shows rectification ratios of 10 (in the dark) and 34 (under the illumination of white light). On the other hand, the diode exposed to the 325 nm wavelength light exhibits Ohmic characteristics which are associated with efficient photocurrent generation in both the Cu2O NP film and the single ZnO NW.

Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor

NASA Astrophysics Data System (ADS)

Khun, K.; Ibupoto, Z. H.; Chey, C. O.; Lu, Jun.; Nur, O.; Willander, M.

2013-03-01

In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and L-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 ± 0.52 mV/decade, for a wide range of concentrations from 1.00 × 10-6 to 5.00 × 10-2 M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

Facile synthesis of highly uniform Mn/Co-codoped ZnO nanowires: optical, electrical, and magnetic properties.

PubMed

Li, Huifeng; Huang, Yunhua; Zhang, Qi; Qiao, Yi; Gu, Yousong; Liu, Jing; Zhang, Yue

2011-02-01

In this article, Co/Mn-codoped ZnO nanowires (NWs) were successfully synthesized on a silicon substrate by the thermal evaporation method with Au catalyst. The X-ray diffraction pattern indicated that the Co/Mn-codoped ZnO NWs are a hexagonal wurtzite structure without a second phase, and energy dispersive X-ray spectroscopy revealed that the Co and Mn ions were introduced into the ZnO NWs with the content of ∼0.8 at% and ∼1.2 at%, respectively. Photoluminescence spectra and Raman spectra showed that the Co/Mn were doped into the NWs and resulted in the shift of the near-band-edge emission. Moreover, the novel Raman peak at 519.3 cm(-1) has suggested that the two kinds of cations via doping could affect the local polarizability. Compared with the undoped ZnO NW, the electrical measurement showed that the Co/Mn-codoping enhanced the conductivity by an order of magnitude due to the presence of Co, Mn cations. The electron mobility and carrier concentration of a fabricated field effect transistor (FET) device is 679 cm2 V(-1) s(-1) and 2×10(18) cm(-3), respectively. Furthermore, the M-H curve demonstrated that the Co/Mn-codoped ZnO NWs have obvious ferromagnetic characteristics at room temperature. Our study enhances the understanding of the novel performances of transition-metal codoped ZnO NWs and also provides a potential way to fabricate optoelectronic devices.

Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study.

PubMed

Pimentel, Ana; Ferreira, Sofia Henriques; Nunes, Daniela; Calmeiro, Tomas; Martins, Rodrigo; Fortunato, Elvira

2016-04-20

The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C.

Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study

PubMed Central

Pimentel, Ana; Ferreira, Sofia Henriques; Nunes, Daniela; Calmeiro, Tomas; Martins, Rodrigo; Fortunato, Elvira

2016-01-01

The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C. PMID:28773423

TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

NASA Astrophysics Data System (ADS)

Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan; Xie, Xi

2017-12-01

Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.

TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

PubMed Central

Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan

2017-01-01

Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials. PMID:29308265

Predictive simulations and optimization of nanowire field-effect PSA sensors including screening

NASA Astrophysics Data System (ADS)

Baumgartner, Stefan; Heitzinger, Clemens; Vacic, Aleksandar; Reed, Mark A.

2013-06-01

We apply our self-consistent PDE model for the electrical response of field-effect sensors to the 3D simulation of nanowire PSA (prostate-specific antigen) sensors. The charge concentration in the biofunctionalized boundary layer at the semiconductor-electrolyte interface is calculated using the propka algorithm, and the screening of the biomolecules by the free ions in the liquid is modeled by a sensitivity factor. This comprehensive approach yields excellent agreement with experimental current-voltage characteristics without any fitting parameters. Having verified the numerical model in this manner, we study the sensitivity of nanowire PSA sensors by changing device parameters, making it possible to optimize the devices and revealing the attributes of the optimal field-effect sensor.

Surface plasmon aided high sensitive non-enzymatic glucose sensor using Au/NiAu multilayered nanowire arrays.

PubMed

Wang, Lanfang; Zhu, Weiqi; Lu, Wenbo; Qin, Xiufang; Xu, Xiaohong

2018-07-15

A novel plasmon aided non-enzymatic glucose sensor was first constructed based on the unique half-rough Au/NiAu multilayered nanowire arrays. These multilayered and half-rough nanowires provide high chemical activity and large surface area for glucose oxidation in an alkaline solution. Under visible light irradiation, the surface plasmons originated from Au part enhance the electron transfer in the vertically aligned nanowires, leading to high sensitivity and wide detection range. The resulting sensor exhibits a wide glucose detection concentration range, low detection limit, and high sensitivity for plasmon aided non-enzymatic glucose sensor. Moreover, the detection sensitivity is enhanced by almost 2 folds compared to that in the dark, which significantly enhanced the performance of Au/NiAu multilayered nanowire arrays sensor. An excellent selectivity and acceptable stability were also achieved. These results indicate that surface plasmon aided nanostructures are promising new platforms for the construction of non-enzymatic glucose sensors. Copyright © 2018 Elsevier B.V. All rights reserved.

SAW Humidity Sensor Sensitivity Enhancement via Electrospraying of Silver Nanowires

PubMed Central

Sayar Irani, Farid; Tunaboylu, Bahadir

2016-01-01

In this research, we investigated the influence of the surface coatings of silver nanowires on the sensitivity of surface acoustic wave (SAW) humidity sensors. Silver nanowires, with poly(vinylpyrrolidone) (PVP), which is a hydrophilic capping agent, were chemically synthesized, with an average length of 15 µm and an average diameter of 60 nm. Humidity sensors, with 433 MHz frequency dual-port resonator Rayleigh-SAW devices, were coated by silver nanowires (AgNWs) using the electrospray coating method. It was demonstrated that increasing thickness of coated AgNW on the surfaces of SAW devices results in increased sensitivity. The highest frequency shift (262 kHz) in these SAW devices was obtained with an injection of 0.5 mL of the AgNW solution with a concentration of 0.5 mg/mL at an injection rate of 1 mL/h. It also showed the highest humidity sensitivity among the other prepared SAW devices. PMID:27916870

A wearable and highly sensitive pressure sensor with ultrathin gold nanowires

NASA Astrophysics Data System (ADS)

Gong, Shu; Schwalb, Willem; Wang, Yongwei; Chen, Yi; Tang, Yue; Si, Jye; Shirinzadeh, Bijan; Cheng, Wenlong

2014-02-01

Ultrathin gold nanowires are mechanically flexible yet robust, which are novel building blocks with potential applications in future wearable optoelectronic devices. Here we report an efficient, low-cost fabrication strategy to construct a highly sensitive, flexible pressure sensor by sandwiching ultrathin gold nanowire-impregnated tissue paper between two thin polydimethylsiloxane sheets. The entire device fabrication process is scalable, enabling facile large-area integration and patterning for mapping spatial pressure distribution. Our gold nanowires-based pressure sensors can be operated at a battery voltage of 1.5 V with low energy consumption (<30 μW), and are able to detect pressing forces as low as 13 Pa with fast response time (<17 ms), high sensitivity (>1.14 kPa-1) and high stability (>50,000 loading-unloading cycles). In addition, our sensor can resolve pressing, bending, torsional forces and acoustic vibrations. The superior sensing properties in conjunction with mechanical flexibility and robustness enabled real-time monitoring of blood pulses as well as detection of small vibration forces from music.

Non-classical logic inverter coupling a ZnO nanowire-based Schottky barrier transistor and adjacent Schottky diode.

PubMed

Hosseini Shokouh, Seyed Hossein; Raza, Syed Raza Ali; Lee, Hee Sung; Im, Seongil

2014-08-21

On a single ZnO nanowire (NW), we fabricated an inverter-type device comprising a Schottky diode (SD) and field-effect transistor (FET), aiming at 1-dimensional (1D) electronic circuits with low power consumption. The SD and adjacent FET worked respectively as the load and driver, so that voltage signals could be easily extracted as the output. In addition, NW FET with a transparent conducting oxide as top gate turned out to be very photosensitive, although ZnO NW SD was blind to visible light. Based on this, we could achieve an array of photo-inverter cells on one NW. Our non-classical inverter is regarded as quite practical for both logic and photo-sensing due to its performance as well as simple device configuration.

Advances in Hydrogen, Carbon Dioxide, and Hydrocarbon Gas Sensor Technology Using GaN and ZnO-Based Devices

PubMed Central

Anderson, Travis; Ren, Fan; Pearton, Stephen; Kang, Byoung Sam; Wang, Hung-Ta; Chang, Chih-Yang; Lin, Jenshan

2009-01-01

In this paper, we review our recent results in developing gas sensors for hydrogen using various device structures, including ZnO nanowires and GaN High Electron Mobility Transistors (HEMTs). ZnO nanowires are particularly interesting because they have a large surface area to volume ratio, which will improve sensitivity, and because they operate at low current levels, will have low power requirements in a sensor module. GaN-based devices offer the advantage of the HEMT structure, high temperature operation, and simple integration with existing fabrication technology and sensing systems. Improvements in sensitivity, recoverability, and reliability are presented. Also reported are demonstrations of detection of other gases, including CO2 and C2H4 using functionalized GaN HEMTs. This is critical for the development of lab-on-a-chip type systems and can provide a significant advance towards a market-ready sensor application. PMID:22408548

Highly sensitive NO2 sensor using brush-coated ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Chandra, Lalit; Dwivedi, R.; Mishra, V. N.

2017-10-01

This work reports the sensing properties of a ZnO nanoparticle (NP) based gas sensor. A sol-gel method was used for the synthesis of ZnO nanoparticles, and a brush coating technique for applying these in a thick film over the gold electrode. The structural properties of the ZnO film so developed have been studied using energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM), revealing a hexagonal wurtzite structure having particle size of ~25 to ~110 nm and roughness of ~136.303 nm. The sensitivity of the sensor to NO2, H2, CO, ethanol and propanol gases in the temperature range from 150 to 350 °C has been tested. Among all these gases, sensitivity to NO2 was found to be highest, at around fifty times greater than the next highest sensitivity, for ethanol gas. The sensor’s response to NO2 gas has been measured at ~945.12%/ppt (parts per thousand), with fast response time and recovery time at operating temperature 280 °C. The obtained result has been discussed with the help of surface and subsurface adsorption and desorption of NO2 molecules at the available trap sites (oxygen ions) on the ZnO nanoparticle surface. This sensor also exhibits excellent repeatability.

Effects of silver impurity on the structural, electrical, and optical properties of ZnO nanowires

PubMed Central

2011-01-01

1, 3, and 5 wt.% silver-doped ZnO (SZO) nanowires (NWs) are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002) to (103) plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 106, 1.34 × 106, and 3.04 × 105 Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A0X). Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in ZnO NWs by the atomic substitution of Ag with Zn in the lattice. PMID:21985620

Impedance spectroscopy of undoped and Cr-doped ZnO gas sensors under different oxygen concentrations

NASA Astrophysics Data System (ADS)

Al-Hardan, N.; Abdullah, M. J.; Aziz, A. Abdul

2011-08-01

Thin films of undoped and chromium (Cr)-doped zinc oxide (ZnO) were synthesized by RF reactive co-sputtering for oxygen gas sensing applications. The prepared films showed a highly c-axis oriented phase with a dominant (0 0 2) peak appeared at a Bragg angle of around 34.13 °, which was lower than that of the standard reference of ZnO powder (34.42 °). The peak shifted to a slightly higher angle with Cr doping. The operating temperature of the ZnO gas sensor was around 350 °C, which shifted to around 250 °C with Cr-doping. The response of the sensor to oxygen gas was enhanced by doping ZnO with 1 at.% Cr. Impedance spectroscopy analysis showed that the resistance due to grain boundaries significantly contributed to the characteristics of the gas sensor.

Catalyst-free growth of ZnO nanowires on ITO seed/glass by thermal evaporation method: Effects of ITO seed layer thickness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alsultany, Forat H., E-mail: foratusm@gmail.com; Ahmed, Naser M.; Hassan, Z.

A seed/catalyst-free growth of ZnO nanowires (ZnO-NWs) on a glass substrate were successfully fabricated using thermal evaporation technique. These nanowires were grown on ITO seed layers of different thicknesses of 25 and 75 nm, which were deposited on glass substrates by radio frequency (RF) magnetron sputtering. Prior to synthesized ITO nanowires, the sputtered ITO seeds were annealed using the continuous wave (CW) CO2 laser at 450 °C in air for 15 min. The effect of seed layer thickness on the morphological, structural, and optical properties of ZnO-NWs were systematically investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM),more » and UV-Vis spectrophotometer.« less

Luminescent ZnO quantum dots as an efficient sensor for free chlorine detection in water.

PubMed

Singh, Kulvinder; Mehta, S K

2016-04-21

Highly luminescent ZnO quantum dots (QDs) synthesized via a simple and facile route are used for the preparation of an optical sensor for the detection of free chlorine. The concentration of free chlorine greatly affects the PL emission of the ZnO QDs at 525 nm. Since hypochlorite gains electrons with high efficiency, it takes electrons from the oxygen vacancies of ZnO QDs, which gives rise to defect emission in ZnO QDs. UV-vis data analysis shows that free chlorine does not affect the optical absorption spectra of ZnO QDs. The optical sensing of free chlorine using ZnO QDs has several advantages, like quick response time, good selectivity and of course high sensitivity. The pH has very little effect on the PL emission of ZnO QDs. It does not interfere in the sensing mechanism for free chlorine. After 60 s, the response of the ZnO QDs remains stable. The present sensor shows high selectivity with respect to various common cations, as well as anions.

Upconversion luminescence from Er-N codoped of ZnO nanowires prepared by ion implantation method

NASA Astrophysics Data System (ADS)

Zhong, Kun; Xu, Jie; Su, Jing; Chen, Yu lin

2011-02-01

Nitrogen and erbium co-doped of ZnO nanowires (NWs) are fabricated by ion implantation and subsequent annealing in air. The incorporation of Er3+ and N+ ions is verified by energy dispersive X-ray spectroscopy (EDS) and Raman spectra. The samples exhibit upconversion photoluminescence around ∼550 nm and ∼660 nm under an excitation at 980 nm. It is discovered that the N-doped can drastically increase the upconversion photoluminescence intensity by modifying the local structure around Er3+ in ZnO matrix. The enhancement of the PL intensity by the N-doped is caused by the formation of ErO6-xNx octahedron complexes. With the increase of the annealing temperature (Ta), the Er3+ ions diffuse towards the surface of the NWs, which benefits the red emission and evokes the variation of intensity ratio owing to the existence of some organic groups.

Fabrication and characterization of SnO2/ZnO gas sensors for detecting toluene gas.

PubMed

Min, Byung-Sam; Park, Young-Ho; Lee, Chang-Seop

2014-11-01

This study investigates the use of SnO2, ZnO, Ag, Au, Cu, In, Pd, Ru and carbon black to improve the sensitivity of a gas sensor for detecting toluene gas. Metal-SnO2/ZnO thick films were screen-printed onto Al2O3 substrates with platinum electrodes. The physico-chemical properties of the sensor materials were characterized using SEM/EDS, XRD, and BET analyses. Measuring the electrical resistance of each sensor as a function of the gas concentration determined the sensing characteristics. The sensors were tested using toluene, benzene, xylene, ethanol, methanol, ammonia and trimethylamine vapors with concentrations of 1-2000 ppm. The gas sensing properties of metal-SnO2/ZnO thick films depended on the content and variety of metals and the content of carbon black. The optimum condition of sensor material for toluene gas detection is operation temperature 300 degrees C and when metal catalyst Cu and carbon black were added. The best sensitivity and selectivity for toluene gas at 300 degrees C resulted from doping with 5 wt.% carbon black, 1 wt.% Cu and 20 wt.% ZnO to SnO2.

A selective iodide ion sensor electrode based on functionalized ZnO nanotubes.

PubMed

Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

2013-02-04

In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10-6 to 1 × 10-1 M) and excellent sensitivity of -62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10-7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples.

A Selective Iodide Ion Sensor Electrode Based on Functionalized ZnO Nanotubes

PubMed Central

Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

2013-01-01

In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10−6 to 1 × 10−1 M) and excellent sensitivity of −62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10−7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples. PMID:23385412

Viral-templated nanocrystalline Pd nanowires for chemiresistive hydrogen (H2) sensors

NASA Astrophysics Data System (ADS)

Moon, Chung Hee; Yan, Yiran; Zhang, Miluo; Myung, Nosang V.; Haberer, Elaine D.

2014-08-01

A palladium (Pd) nanowire-based hydrogen (H2) sensor has been fabricated with a novel viral-templated assembly route. A filamentous M13 bacteriophage was used as the viral-template for assembly of Pd nanowires at ambient conditions. Scanning electron microscopy determined Pd nanowire distribution and morphology with the devices. The phage template concentration controlled the number of physical and electrical nanowire connections across the device. A greater phage concentration resulted in a higher connection density and thicker Pd deposition. A lower phage concentration generated devices which formed chain-like nanowires of Pd nanocrystals, whereas a higher phage concentration formed devices with a continuous mesh-like structure. The lower concentration devices showed 51-78% instantaneous response to 2000 ppm H2 and response time less than 30 s.

Growth Evolution and Characterization of PLD Zn(Mg)O Nanowire Arrays

NASA Astrophysics Data System (ADS)

Rahm, Andreas; Nobis, Thomas; Lorenz, Michael; Zimmermann, Gregor; Boukos, Nikos; Travlos, Anastasios; Grundmann, Marius

ZnO and Zn0.98Mg0.02O nanowires have been grown by high-pressure pulsed laser deposition on sapphire substrates covered with gold colloidal particles as nucleation sites. We present a detailed study of the nanowire size and length distribution and of the growth evolution. We find that the aspect ratio varies linearly with deposition time. The linearity coefficient is independent of the catalytic gold particle size and lateral nanowire density. The superior structural quality of the whiskers is proven by X-ray diffraction and transmission electron microscopy. The defect-free ZnO nanowires exhibit a FWHM(2θ-ω) of the ZnO(0002) reflection of 22 arcsec. We show (0-11) step habit planes on the side faces of the nanowires that are a few atomic steps in height. The microscopic homogeneity of the optical properties is confirmed by temperature-dependent cathodoluminescence.

Simple fabrication process for 2D ZnO nanowalls and their potential application as a methane sensor.

PubMed

Chen, Tse-Pu; Chang, Sheng-Po; Hung, Fei-Yi; Chang, Shoou-Jinn; Hu, Zhan-Shuo; Chen, Kuan-Jen

2013-03-20

Two-dimensional (2D) ZnO nanowalls were prepared on a glass substrate by a low-temperature thermal evaporation method, in which the fabrication process did not use a metal catalyst or the pre-deposition of a ZnO seed layer on the substrate. The nanowalls were characterized for their surface morphology, and the structural and optical properties were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL). The fabricated ZnO nanowalls have many advantages, such as low growth temperature and good crystal quality, while being fast, low cost, and easy to fabricate. Methane sensor measurements of the ZnO nanowalls show a high sensitivity to methane gas, and rapid response and recovery times. These unique characteristics are attributed to the high surface-to-volume ratio of the ZnO nanowalls. Thus, the ZnO nanowall methane sensor is a potential gas sensor candidate owing to its good performance.

Simple Fabrication Process for 2D ZnO Nanowalls and Their Potential Application as a Methane Sensor

PubMed Central

Chen, Tse-Pu; Chang, Sheng-Po; Hung, Fei-Yi; Chang, Shoou-Jinn; Hu, Zhan-Shuo; Chen, Kuan-Jen

2013-01-01

Two-dimensional (2D) ZnO nanowalls were prepared on a glass substrate by a low-temperature thermal evaporation method, in which the fabrication process did not use a metal catalyst or the pre-deposition of a ZnO seed layer on the substrate. The nanowalls were characterized for their surface morphology, and the structural and optical properties were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL). The fabricated ZnO nanowalls have many advantages, such as low growth temperature and good crystal quality, while being fast, low cost, and easy to fabricate. Methane sensor measurements of the ZnO nanowalls show a high sensitivity to methane gas, and rapid response and recovery times. These unique characteristics are attributed to the high surface-to-volume ratio of the ZnO nanowalls. Thus, the ZnO nanowall methane sensor is a potential gas sensor candidate owing to its good performance. PMID:23519350

Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application.

PubMed

Jia, Qianqian; Ji, Huiming; Zhang, Ying; Chen, Yalu; Sun, Xiaohong; Jin, Zhengguo

2014-07-15

Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

Disposable sensor based on enzyme-free Ni nanowire array electrode to detect glutamate.

PubMed

Jamal, Mamun; Hasan, Maksudul; Mathewson, Alan; Razeeb, Kafil M

2013-02-15

Enzyme free electrochemical sensor platform based on a vertically aligned nickel nanowire array (NiNAE) and Pt coated nickel nanowire array (Pt/NiNAE) have been developed to detect glutamate. Morphological characterisation of Ni electrodes was carried out using scanning and transmission electron microscopy combined with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNAE and the Pt/NiNAE for glutamate. It has been found that both NiNAE and Pt/NiNAE electrodes showed remarkably enhanced electrocatalytic activity towards glutamate compared to planar Ni electrodes, and showed higher catalytic activity when compared to other metallic nanostructure electrodes such as gold nanowire array electrodes (AuNAE) and Pt coated gold nanowire array electrode (Pt/AuNAE). The sensitivity of NiNAE and Pt/NiNAE has been found to be 65 and 96 μA mM(-1) cm(-2), respectively, which is approximately 6 to 9 times higher than the state of the art glutamate sensor. Under optimal detection conditions, the as prepared sensors exhibited linear behaviour for glutamate detection in the concentration up to 8mM for both NiNAE and Pt/NiNAE with a limit of detection of 68 and 83 μM, respectively. Experimental results show that the vertically aligned ordered nickel nanowire array electrode (NiNAE) has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform. Copyright © 2012 Elsevier B.V. All rights reserved.

Ultra-Fast Microwave Synthesis of ZnO Nanorods on Cellulose Substrates for UV Sensor Applications

PubMed Central

Pimentel, Ana; Samouco, Ana; Araújo, Andreia; Martins, Rodrigo; Fortunato, Elvira

2017-01-01

In the present work, tracing and Whatman papers were used as substrates to grow zinc oxide (ZnO) nanostructures. Cellulose-based substrates are cost-efficient, highly sensitive and environmentally friendly. ZnO nanostructures with hexagonal structure were synthesized by hydrothermal under microwave irradiation using an ultrafast approach, that is, a fixed synthesis time of 10 min. The effect of synthesis temperature on ZnO nanostructures was investigated from 70 to 130 °C. An Ultra Violet (UV)/Ozone treatment directly to the ZnO seed layer prior to microwave assisted synthesis revealed expressive differences regarding formation of the ZnO nanostructures. Structural characterization of the microwave synthesized materials was carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical characterization has also been performed. The time resolved photocurrent of the devices in response to the UV turn on/off was investigated and it has been observed that the ZnO nanorod arrays grown on Whatman paper substrate present a responsivity 3 times superior than the ones grown on tracing paper. By using ZnO nanorods, the surface area-to-volume ratio will increase and will improve the sensor sensibility, making these types of materials good candidates for low cost and disposable UV sensors. The sensors were exposed to bending tests, proving their high stability, flexibility and adaptability to different surfaces. PMID:29140304

Low-temperature growth of ZnO nanoparticles: photocatalyst and acetone sensor.

PubMed

Khan, Sher Bahadar; Faisal, M; Rahman, Mohammed M; Jamal, Aslam

2011-08-15

Well-crystalline ZnO nanoparticles (NPs) were synthesized in large-quantity via simple hydrothermal process using the aqueous mixtures of zinc chloride and ammonium hydroxide. The detailed structural properties were examined using X-ray diffraction pattern (XRD) and field emission scanning electron microscope (FESEM) which revealed that the synthesized NPs are well-crystalline and possessing wurtzite hexagonal phase. The NPs are almost spherical shape with the average diameters of ∼ 50 ± 10 nm. The quality and composition of the synthesized NPs were obtained using Fourier transform infrared (FTIR) and electron dispersed spectroscopy (EDS) which confirmed that the obtained NPs are pure ZnO and made with almost 1:1 stoichiometry of zinc and oxygen, respectively. The optical properties of ZnO NPs were investigated by UV-vis absorption spectroscopy. Synthesized ZnO NPs were extensively applied as a photocatalyst for the degradation of acridine orange (AO) and as a chemi-sensor for the electrochemical sensing of acetone in liquid phase. Almost complete degradation of AO has taken place after 80 min of irradiation time. The fabricated acetone sensor based on ZnO NPs exhibits good sensitivity (∼ 0.14065 μA cm(-2) mM(-1)) with lower detection limit (0.068 ± 0.01 mM) in short response time (10s). Copyright © 2011 Elsevier B.V. All rights reserved.

High performance NO2 sensor using MoS2 nanowires network

NASA Astrophysics Data System (ADS)

Kumar, Rahul; Goel, Neeraj; Kumar, Mahesh

2018-01-01

We report on a high-performance NO2 sensor based on a one dimensional MoS2 nanowire (NW) network. The MoS2 NW network was synthesized using chemical transport reaction through controlled turbulent vapor flow. The crystal structure and surface morphology of MoS2 NWs were confirmed by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Further, the sensing behavior of the nanowires was investigated at different temperatures for various concentrations of NO2 and the sensor exhibited about 2-fold enhanced sensitivity with a low detection limit of 4.6 ppb for NO2 at 60 °C compared to sensitivity at room temperature. Moreover, it showed a fast response (16 s) with complete recovery (172 s) at 60 °C, while sensitivity of the device was decreased at 120 °C. The efficient sensing with reliable selectivity toward NO2 of the nanowires is attributed to a combination of abundant active edge sites along with a large surface area and tuning of the potential barrier at the intersections of nanowires during adsorption/desorption of gas molecules.

High performance non-volatile ferroelectric copolymer memory based on a ZnO nanowire transistor fabricated on a transparent substrate

NASA Astrophysics Data System (ADS)

Nedic, Stanko; Tea Chun, Young; Hong, Woong-Ki; Chu, Daping; Welland, Mark

2014-01-01

A high performance ferroelectric non-volatile memory device based on a top-gate ZnO nanowire (NW) transistor fabricated on a glass substrate is demonstrated. The ZnO NW channel was spin-coated with a poly (vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) layer acting as a top-gate dielectric without buffer layer. Electrical conductance modulation and memory hysteresis are achieved by a gate electric field induced reversible electrical polarization switching of the P(VDF-TrFE) thin film. Furthermore, the fabricated device exhibits a memory window of ˜16.5 V, a high drain current on/off ratio of ˜105, a gate leakage current below ˜300 pA, and excellent retention characteristics for over 104 s.

Molybdenum disulfide nanoflake-zinc oxide nanowire hybrid photoinverter.

PubMed

Hosseini Shokouh, Seyed Hossein; Pezeshki, Atiye; Ali Raza, Syed Raza; Choi, Kyunghee; Min, Sung-Wook; Jeon, Pyo Jin; Lee, Hee Sung; Im, Seongil

2014-05-27

We demonstrate a hybrid inverter-type nanodevice composed of a MoS2 nanoflake field-effect transistor (FET) and ZnO nanowire Schottky diode on one substrate, aiming at a one-dimensional (1D)-two-dimensional (2D) hybrid integrated electronic circuit with multifunctional capacities of low power consumption, high gain, and photodetection. In the present work, we used a nanotransfer printing method using polydimethylsiloxane for the fabrication of patterned bottom-gate MoS2 nanoflake FETs, so that they could be placed near the ZnO nanowire Schottky diodes that were initially fabricated. The ZnO nanowire Schottky diode and MoS2 FET worked respectively as load and driver for a logic inverter, which exhibits a high voltage gain of ∼50 at a supply voltage of 5 V and also shows a low power consumption of less than 50 nW. Moreover, our inverter effectively operates as a photoinverter, detecting visible photons, since MoS2 FETs appear very photosensitive, while the serially connected ZnO nanowire Schottky diode was blind to visible light. Our 1D-2D hybrid nanoinverter would be quite promising for both logic and photosensing applications due to its performance and simple device configuration as well.

A selective potentiometric copper (II) ion sensor based on the functionalized ZnO nanorods.

PubMed

Khun, K; Ibupoto, Z H; Liu, X; Nur, O; Willander, M; Danielsson, B

2014-09-01

In this work, ZnO nanorods were hydrothermally grown on the gold-coated glass substrate and characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The ZnO nanorods were functionalized by two different approaches and performance of the sensor electrode was monitored. Fourier transform infrared spectroscopy (FTIR) was carried out for the confirmation of interaction between the ionophore molecules and ZnO nanorods. In addition to this, the surface of the electrode was characterized by X-ray photoelectron spectroscopy (XPS) showing the chemical and electronic state of the ionophore and ZnO nanorod components. The ionophore solution was prepared in the stabilizer, poly vinyl chloride (PVC) and additives, and then functionalized on the ZnO nanorods that have shown the Nernstian response with the slope of 31 mV/decade. However, the Cu2+ ion sensor was fabricated only by immobilizing the selective copper ion ionophore membrane without the use of PVC, plasticizers, additives and stabilizers and the sensor electrode showed a linear potentiometric response with a slope of 56.4 mV/decade within a large dynamic concentration range (from 1.0 x 10(-6) to 1.0 x 10(-1) M) of copper (II) nitrate solutions. The sensor showed excellent repeatability and reproducibility with response time of less than 10 s. The negligible response to potentially interfering metal ions such as calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe3+), zinc (Zn2+), and sodium (Na+) allows this sensor to be used in biological studies. It may also be used as an indicator electrode in the potentiometric titration.

One-dimensional ZnO nanostructures.

PubMed

Jayadevan, K P; Tseng, T Y

2012-06-01

The wide-gap semiconductor ZnO with nanostructures such as nanoparticle, nanorod, nanowire, nanobelt, nanotube has high potential for a variety of applications. This article reviews the fundamentals of one-dimensional ZnO nanostructures, including processing, structure, property, application and their processing-microstructure-property correlation. Various fabrication methods of the ZnO nanostructures including vapor-liquid-solid process, vapor-solid growth, solution growth, solvothermal growth, template-assisted growth and self-assembly are introduced. The characterization and properties of the ZnO nanostructures are described. The possible applications of these nanostructures are also discussed.

Highly sensitive H2 gas sensor of Co doped ZnO nanostructures

NASA Astrophysics Data System (ADS)

Bhati, Vijendra Singh; Ranwa, Sapana; Kumar, Mahesh

2018-04-01

In this report, the hydrogen gas sensing properties based on Co doped ZnO nanostructures are explored. The undoped and Co doped nanostructures were grown by RF magnetron sputtering system, and its structural, morphological, and hydrogen sensing behavior are investigated. The maximum relative response was occurred by the 2.5% Co doped ZnO nanostructures among undoped and other doped sensors. The enhancement of relative response might be due to large chemisorbed sites formation on the ZnO surface for the reaction to hydrogen gas.

Study on silver doped and undoped ZnO thin films working as capacitive sensor

NASA Astrophysics Data System (ADS)

Kiran, S.; Kumar, N. Santhosh; Kumar, S. K. Naveen

2013-06-01

Nanomaterials have been found to exhibit interesting properties like good conductivity, piezoelectricity, high band gap etc. among those metal oxide family, Zinc Oxide has become a material of interest among scientific community. In this paper, we present a method of fabricating capacitive sensors, in which Silver doped ZnO and pure ZnO nanoparticles act as active layer. For the synthesis of the nanoparticle, we followed biosynthesis method and wet chemical method for Ag and Ag doped ZnO nanoparticles respectively. Characterization has been done for both the particles. The XRD pattern taken for the Ag Doped ZnO nanoparticles confirmed the average size of the particles to be 15nm. AFM image of the sample is taken by doping on Silicon wafer. Also we have presented the results of CV characteristics and IV characteristics of the capacitive sensor.

All-carbon suspended nanowire sensors as a rapid highly-sensitive label-free chemiresistive biosensing platform.

PubMed

Thiha, Aung; Ibrahim, Fatimah; Muniandy, Shalini; Dinshaw, Ignatius Julian; Teh, Swe Jyan; Thong, Kwai Lin; Leo, Bey Fen; Madou, Marc

2018-06-01

Nanowire sensors offer great potential as highly sensitive electrochemical and electronic biosensors because of their small size, high aspect ratios, and electronic properties. Nevertheless, the available methods to fabricate carbon nanowires in a controlled manner remain limited to expensive techniques. This paper presents a simple fabrication technique for sub-100 nm suspended carbon nanowire sensors by integrating electrospinning and photolithography techniques. Carbon Microelectromechanical Systems (C-MEMS) fabrication techniques allow fabrication of high aspect ratio carbon structures by patterning photoresist polymers into desired shapes and subsequent carbonization of resultant structures by pyrolysis. In our sensor platform, suspended nanowires were deposited by electrospinning while photolithography was used to fabricate support structures. We have achieved suspended carbon nanowires with sub-100 nm diameters in this study. The sensor platform was then integrated with a microfluidic chip to form a lab-on-chip device for label-free chemiresistive biosensing. We have investigated this nanoelectronics label-free biosensor's performance towards bacterial sensing by functionalization with Salmonella-specific aptamer probes. The device was tested with varying concentrations of Salmonella Typhimurium to evaluate sensitivity and various other bacteria to investigate specificity. The results showed that the sensor is highly specific and sensitive in detection of Salmonella with a detection limit of 10 CFU mL -1 . Moreover, this proposed chemiresistive assay has a reduced turnaround time of 5 min and sample volume requirement of 5 µL which are much less than reported in the literature. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast-Response Single-Nanowire Photodetector Based on ZnO/WS2 Core/Shell Heterostructures.

PubMed

Butanovs, Edgars; Vlassov, Sergei; Kuzmin, Alexei; Piskunov, Sergei; Butikova, Jelena; Polyakov, Boris

2018-04-25

The surface plays an exceptionally important role in nanoscale materials, exerting a strong influence on their properties. Consequently, even a very thin coating can greatly improve the optoelectronic properties of nanostructures by modifying the light absorption and spatial distribution of charge carriers. To use these advantages, 1D/1D heterostructures of ZnO/WS 2 core/shell nanowires with a-few-layers-thick WS 2 shell were fabricated. These heterostructures were thoroughly characterized by scanning and transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Then, a single-nanowire photoresistive device was assembled by mechanically positioning ZnO/WS 2 core/shell nanowires onto gold electrodes inside a scanning electron microscope. The results show that a few layers of WS 2 significantly enhance the photosensitivity in the short wavelength range and drastically (almost 2 orders of magnitude) improve the photoresponse time of pure ZnO nanowires. The fast response time of ZnO/WS 2 core/shell nanowire was explained by electrons and holes sinking from ZnO nanowire into WS 2 shell, which serves as a charge carrier channel in the ZnO/WS 2 heterostructure. First-principles calculations suggest that the interface layer i-WS 2 , bridging ZnO nanowire surface and WS 2 shell, might play a role of energy barrier, preventing the backward diffusion of charge carriers into ZnO nanowire.

Increased short circuit current in organic photovoltaic using high-surface area electrode based on ZnO nanowires decorated with CdTe quantum dots.

PubMed

Aga, R S; Gunther, D; Ueda, A; Pan, Z; Collins, W E; Mu, R; Singer, K D

2009-11-18

A photosensitized high-surface area transparent electrode has been employed to increase the short circuit current of a photovoltaic device with a blend of poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM) as the active layer. This is achieved by directly growing ZnO nanowires on indium tin oxide (ITO) film via a physical vapor method. The nanowire surface is then decorated with CdTe quantum dots by pulsed electron-beam deposition (PED). The nanowires alone provided a 20-fold increase in the short circuit current under visible light illumination. This was further increased by a factor of approximately 1.5 by the photosensitization effect of CdTe, which has an optical absorption of up to 820 nm.

Enhanced NH3 gas sensing properties of a QCM sensor by increasing the length of vertically orientated ZnO nanorods

NASA Astrophysics Data System (ADS)

Minh, Vu Anh; Tuan, Le Anh; Huy, Tran Quang; Hung, Vu Ngoc; Quy, Nguyen Van

2013-01-01

Vertically aligned ZnO nanorods were directly synthesised on a gold electrode of quartz crystal microbalance (QCM) by a simple low-temperature hydrothermal method for a NH3 gas sensing application. The length of vertically aligned ZnO nanorods was increased to purpose enhancement in the gas sensing response of the sensor. The length of ZnO nanorods increased with an increase in growth time. The growth time of ZnO nanorods was systematically varied in the range of 1-4 h to examine the effect of the length of the ZnO nanorods on the gas sensing properties of the fabricated sensors. The gas sensing properties of sensors with different ZnO nanorods lengths was examined at room temperature for various concentrations of NH3 (50-800 ppm) in synthetic air. Enhancement in gas sensing response by increasing the length of ZnO nanorods was observed.

Piezoresistive Pressure Sensor Based on Synergistical Innerconnect Polyvinyl Alcohol Nanowires/Wrinkled Graphene Film.

PubMed

Liu, Weijie; Liu, Nishuang; Yue, Yang; Rao, Jiangyu; Cheng, Feng; Su, Jun; Liu, Zhitian; Gao, Yihua

2018-04-01

Piezoresistive sensor is a promising pressure sensor due to its attractive advantages including uncomplicated signal collection, simple manufacture, economical and practical characteristics. Here, a flexible and highly sensitive pressure sensor based on wrinkled graphene film (WGF)/innerconnected polyvinyl alcohol (PVA) nanowires/interdigital electrodes is fabricated. Due to the synergistic effect between WGF and innerconnected PVA nanowires, the as-prepared pressure sensor realizes a high sensitivity of 28.34 kPa -1 . In addition, the device is able to discern lightweight rice about 22.4 mg (≈2.24 Pa) and shows excellent durability and reliability after 6000 repeated loading and unloading cycles. What is more, the device can detect subtle pulse beat and monitor various human movement behaviors in real-time. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Local sensor based on nanowire field effect transistor from inhomogeneously doped silicon on insulator

NASA Astrophysics Data System (ADS)

Presnov, Denis E.; Bozhev, Ivan V.; Miakonkikh, Andrew V.; Simakin, Sergey G.; Trifonov, Artem S.; Krupenin, Vladimir A.

2018-02-01

We present the original method for fabricating a sensitive field/charge sensor based on field effect transistor (FET) with a nanowire channel that uses CMOS-compatible processes only. A FET with a kink-like silicon nanowire channel was fabricated from the inhomogeneously doped silicon on insulator wafer very close (˜100 nm) to the extremely sharp corner of a silicon chip forming local probe. The single e-beam lithographic process with a shadow deposition technique, followed by separate two reactive ion etching processes, was used to define the narrow semiconductor nanowire channel. The sensors charge sensitivity was evaluated to be in the range of 0.1-0.2 e /√{Hz } from the analysis of their transport and noise characteristics. The proposed method provides a good opportunity for the relatively simple manufacture of a local field sensor for measuring the electrical field distribution, potential profiles, and charge dynamics for a wide range of mesoscopic objects. Diagnostic systems and devices based on such sensors can be used in various fields of physics, chemistry, material science, biology, electronics, medicine, etc.

Exogenous Gene Integration for Microalgal Cell Transformation Using a Nanowire-Incorporated Microdevice.

PubMed

Bae, Sunwoong; Park, Seunghye; Kim, Jung; Choi, Jong Seob; Kim, Kyung Hoon; Kwon, Donguk; Jin, EonSeon; Park, Inkyu; Kim, Do Hyun; Seo, Tae Seok

2015-12-16

Superior green algal cells showing high lipid production and rapid growth rate are considered as an alternative for the next generation green energy resources. To achieve the biomass based energy generation, transformed microalgae with superlative properties should be developed through genetic engineering. Contrary to the normal cells, microalgae have rigid cell walls, so that target gene delivery into cells is challengeable. In this study, we report a ZnO nanowire-incorporated microdevice for a high throughput microalgal transformation. The proposed microdevice was equipped with not only a ZnO nanowire in the microchannel for gene delivery into cells but also a pneumatic polydimethylsiloxane (PDMS) microvalve to modulate the cellular attachment and detachment from the nanowire. As a model, hygromycin B resistance gene cassette (Hyg3) was functionalized on the hydrothermally grown ZnO nanowires through a disulfide bond and released into green algal cells, Chlamydomonas reinhardtii, by reductive cleavage. During Hyg3 gene delivery, a monolithic PDMS membrane was bent down, so that algal cells were pushed down toward ZnO nanowires. The supply of vacuum in the pneumatic line made the PDMS membrane bend up, enabling the gene delivered algal cells to be recovered from the outlet of the microchannel. We successfully confirmed Hyg3 gene integrated in microalgae by amplifying the inserted gene through polymerase chain reaction (PCR) and DNA sequencing. The efficiency of the gene delivery to algal cells using the ZnO nanowire-incorporated microdevice was 6.52 × 10(4)- and 9.66 × 10(4)-fold higher than that of a traditional glass bead beating and electroporation.

High-gain subnanowatt power consumption hybrid complementary logic inverter with WSe2 nanosheet and ZnO nanowire transistors on glass.

PubMed

Shokouh, Seyed Hossein Hosseini; Pezeshki, Atiye; Ali Raza, Syed Raza; Lee, Hee Sung; Min, Sung-Wook; Jeon, Pyo Jin; Shin, Jae Min; Im, Seongil

2015-01-07

A 1D-2D hybrid complementary logic inverter comprising of ZnO nanowire and WSe2 nanosheet field-effect transistors (FETs) is fabricated on glass, which shows excellent static and dynamic electrical performances with a voltage gain of ≈60, sub-nanowatt power consumption, and at least 1 kHz inverting speed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal Catalyst for Low-Temperature Growth of Controlled Zinc Oxide Nanowires on Arbitrary Substrates

PubMed Central

Kim, Baek Hyun; Kwon, Jae W.

2014-01-01

Zinc oxide nanowires generated by hydrothermal method present superior physical and chemical characteristics. Quality control of the growth has been very challenging and controlled growth is only achievable under very limited conditions using homogeneous seed layers with high temperature processes. Here we show the controlled ZnO nanowire growth on various organic and inorganic materials without the requirement of a homogeneous seed layer and a high temperature process. We also report the discovery of an important role of the electronegativity in the nanowire growth on arbitrary substrates. Using heterogeneous metal oxide interlayers with low-temperature hydrothermal methods, we demonstrate well-controlled ZnO nanowire arrays and single nanowires on flat or curved surfaces. A metal catalyst and heterogeneous metal oxide interlayers are found to determine lattice-match with ZnO and to largely influence the controlled alignment. These findings will contribute to the development of novel nanodevices using controlled nanowires. PMID:24625584

A CMOS-Compatible Poly-Si Nanowire Device with Hybrid Sensor/Memory Characteristics for System-on-Chip Applications

PubMed Central

Chen, Min-Cheng; Chen, Hao-Yu; Lin, Chia-Yi; Chien, Chao-Hsin; Hsieh, Tsung-Fan; Horng, Jim-Tong; Qiu, Jian-Tai; Huang, Chien-Chao; Ho, Chia-Hua; Yang, Fu-Liang

2012-01-01

This paper reports a versatile nano-sensor technology using “top-down” poly-silicon nanowire field-effect transistors (FETs) in the conventional Complementary Metal-Oxide Semiconductor (CMOS)-compatible semiconductor process. The nanowire manufacturing technique reduced nanowire width scaling to 50 nm without use of extra lithography equipment, and exhibited superior device uniformity. These n type polysilicon nanowire FETs have positive pH sensitivity (100 mV/pH) and sensitive deoxyribonucleic acid (DNA) detection ability (100 pM) at normal system operation voltages. Specially designed oxide-nitride-oxide buried oxide nanowire realizes an electrically Vth-adjustable sensor to compensate device variation. These nanowire FETs also enable non-volatile memory application for a large and steady Vth adjustment window (>2 V Programming/Erasing window). The CMOS-compatible manufacturing technique of polysilicon nanowire FETs offers a possible solution for commercial System-on-Chip biosensor application, which enables portable physiology monitoring and in situ recording. PMID:22666012

A facile fluorescent sensor based on silicon nanowires for dithionite

NASA Astrophysics Data System (ADS)

Cao, Xingxing; Mu, Lixuan; Chen, Min; She, Guangwei

2018-05-01

A facile and novel fluorescent sensor for dithionite has been constructed by simultaneously immobilizing dansyl group (fluorescence molecule) and dabsyl group (quencher and recognizing group) on the silicon nanowires (SiNWs) and SiNW arrays surface. This sensor for dithionite exhibited high selectivity and a good relationship of linearity between fluorescence intensities and dithionite concentrations from 0.1 to 1 mM. This approach is straightforward and does not require complicated synthesis, which can be extended to develop other sensors with similar rationale.

In situ monitoring of laser-assisted hydrothermal growth of ZnO nanowires: thermally deactivating growth kinetics.

PubMed

In, Jung Bin; Kwon, Hyuk-Jun; Lee, Daeho; Ko, Seung Hwan; Grigoropoulos, Costas P

2014-02-26

The laser-assisted hydrothermal growth kinetics of a cluster of ZnO nanowires are studied based on optical in situ growth monitoring. The growth yields are orders of magnitude higher than those of conventional hydrothermal methods that use bulk heating. This remarkable improvement is attributed to suppression of precursor depletion occurring by homogeneous growth reactions, as well as to enhanced mass transport. The obtained in situ data show gradually decaying growth kinetics even with negligible precursor consumption. It is revealed that the growth deceleration is caused by thermal deactivation resulting from heat dissipation through the growing nanowires. Finally, it is demonstrated that the tailored temporal modulation of the input power enables sustained growth to extended dimensions. These results provide a key to highly efficient use of growth precursors that has been pursued for industrial use of this functional metal oxide semiconductor. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Joule heating a palladium nanowire sensor for accelerated response and recovery to hydrogen gas.

PubMed

Yang, Fan; Taggart, David K; Penner, Reginald M

2010-07-05

The properties of a single heated palladium (Pd) nanowire for the detection of hydrogen gas (H(2)) are explored. In these experiments, a Pd nanowire, 48-98 microm in length, performs three functions in parallel: 1) Joule self-heating is used to elevate the nanowire temperature by up to 128 K, 2) the 4-contact wire resistance in the absence of H(2) is used to measure its temperature, and 3) the nanowire resistance in the presence of H(2) is correlated with its concentration, allowing it to function as a H(2) sensor. Compared with the room-temperature response of a Pd nanowire, the response of the heated nanowire to hydrogen is altered in two ways: First, the resistance change (DeltaR/R(0)) induced by H(2) exposure at any concentration is reduced by a factor of up to 30 and second, the rate of the resistance change - observed at the beginning ("response") and at the end ("recovery") of a pulse of H(2) - is increased by more than a factor of 50 at some H(2) concentrations. Heating nearly eliminates the retardation of response and recovery seen from 1-2% H(2), caused by the alpha --> beta phase transition of PdH(x), a pronounced effect for nanowires at room temperature. The activation energies associated with sensor response and recovery are measured and interpreted.

Three-dimensional mesoscale heterostructures of ZnO nanowire arrays epitaxially grown on CuGaO2 nanoplates as individual diodes.

PubMed

Forticaux, Audrey; Hacialioglu, Salih; DeGrave, John P; Dziedzic, Rafal; Jin, Song

2013-09-24

We report a three-dimensional (3D) mesoscale heterostructure composed of one-dimensional (1D) nanowire (NW) arrays epitaxially grown on two-dimensional (2D) nanoplates. Specifically, three facile syntheses are developed to assemble vertical ZnO NWs on CuGaO2 (CGO) nanoplates in mild aqueous solution conditions. The key to the successful 3D mesoscale integration is the preferential nucleation and heteroepitaxial growth of ZnO NWs on the CGO nanoplates. Using transmission electron microscopy, heteroepitaxy was found between the basal planes of CGO nanoplates and ZnO NWs, which are their respective (001) crystallographic planes, by the observation of a hexagonal Moiré fringes pattern resulting from the slight mismatch between the c planes of ZnO and CGO. Careful analysis shows that this pattern can be described by a hexagonal supercell with a lattice parameter of almost exactly 11 and 12 times the a lattice constants for ZnO and CGO, respectively. The electrical properties of the individual CGO-ZnO mesoscale heterostructures were measured using a current-sensing atomic force microscopy setup to confirm the rectifying p-n diode behavior expected from the band alignment of p-type CGO and n-type ZnO wide band gap semiconductors. These 3D mesoscale heterostructures represent a new motif in nanoassembly for the integration of nanomaterials into functional devices with potential applications in electronics, photonics, and energy.

Fabrication and characterization of Ga-doped ZnO / Si heterojunction nanodiodes

NASA Astrophysics Data System (ADS)

Akgul, Guvenc; Akgul, Funda Aksoy

2017-02-01

In this study, temperature-dependent electrical properties of n-type Ga-doped ZnO thin film / p-type Si nanowire heterojunction diodes were reported. Metal-assisted chemical etching (MACE) process was performed to fabricate Si nanowires. Ga-doped ZnO films were then deposited onto nanowires through chemical bath deposition (CBD) technique to build three-dimensional nanowire-based heterojunction diodes. Fabricated devices revealed significant diode characteristics in the temperature range of 220 - 360 K. Electrical measurements shown that diodes had a well-defined rectifying behavior with a good rectification ratio of 103 ±3 V at room temperature. Ideality factor (n) were changed from 2.2 to 1.2 with increasing temperature.

High-performance optical projection controllable ZnO nanorod arrays for microweighing sensors.

PubMed

Wang, Hongbo; Jiang, Shulan; Zhang, Lei; Yu, Bingjun; Chen, Duoli; Yang, Weiqing; Qian, Linmao

2018-03-08

Optical microweighing sensors are an essential component of micro-force measurements in physical, chemical, and biological detection fields, although, their limited detection range (less than 15°) severely hinders their wide application. Such a limitation is mainly attributed to the essential restrictions of traditional light reflection and optical waveguide modes. Here, we report a high-performance optical microweighing sensor based on the synergistic effects of both a new optical projection mode and a ZnO nanorod array sensor. Ascribed to the unique configuration design of this sensing method, this optical microweighing sensor has a wide detection range (more than 80°) and a high sensitivity of 90 nA deg -1 , which is much larger than that of conventional microcantilever-based optical microweighing sensors. Furthermore, the location of the UV light source can be adjusted within a few millimeters, meaning that the microweighing sensor does not need repetitive optical calibration. More importantly, for low height and small incident angles of the UV light source, we can obtain highly sensitive microweighing properties on account of the highly sensitive ZnO nanorod array-based UV sensor. Therefore, this kind of large detection range, non-contact, and non-destructive microweighing sensor has potential applications in air quality monitoring and chemical and biological detection.

A generic approach for vertical integration of nanowires.

PubMed

Latu-Romain, E; Gilet, P; Noel, P; Garcia, J; Ferret, P; Rosina, M; Feuillet, G; Lévy, F; Chelnokov, A

2008-08-27

We report on the collective integration technology of vertically aligned nanowires (NWs). Si and ZnO NWs have been used in order to develop a generic technological process. Both mineral and organic planarizations of the as-grown nanowires have been achieved. Chemical vapour deposition (CVD) oxides, spin on glass (SOG), and polymer have been investigated as filling materials. Polishing and/or etching of the composite structures have been set up so as to obtain a suitable morphology for the top and bottom electrical contacts. Electrical and optical characterizations of the integrated NWs have been performed. Contacts ohmicity has been demonstrated and specific contact resistances have been reported. The photoconducting properties of polymer-integrated ZnO NWs have also been investigated in the UV-visible range through collective electrical contacts. A small increase of the resistivity in the ZnO NWs under sub-bandgap illumination has been observed and discussed. A comparison of the photoluminescence (PL) spectra at 300 K of the as-grown and SOG-integrated ZnO nanowires has shown no significant impact of the integration process on the crystal quality of the NWs.

Temperature-dependent photoluminescence analysis of ZnO nanowire array annealed in air

NASA Astrophysics Data System (ADS)

Sun, Yanan; Gu, Xiuquan; Zhao, Yulong; Wang, Linmeng; Qiang, Yinghuai

2018-05-01

ZnO nanowire arrays (NWAs) were prepared on transparent conducting fluorine doped tin oxide (FTO) substrates through a facile hydrothermal method, followed by a 500 °C annealing to improve their crystalline qualities and photoelectrochemical (PEC) activities. It was found that the annealing didn't change the morphology, but resulted in a significant reduction of the donor concentration. Temperature-dependent photoluminescence (PL) was carried out for a comprehensive analysis of the effect from annealing. Noteworthy, four dominant peaks were identified from the 10 K spectrum of a 500 °C annealed sample, and they were assigned to FX, D0X, (e, D0) and (e, D0) -1LO, respectively. Of them, the FX emission was only existed below 130 K, while the room-temperature (RT) PL spectrum was dominated by the D0X emission.

Design of Highly Selective Gas Sensors via Physicochemical Modification of Oxide Nanowires: Overview

PubMed Central

Woo, Hyung-Sik; Na, Chan Woong; Lee, Jong-Heun

2016-01-01

Strategies for the enhancement of gas sensing properties, and specifically the improvement of gas selectivity of metal oxide semiconductor nanowire (NW) networks grown by chemical vapor deposition and thermal evaporation, are reviewed. Highly crystalline NWs grown by vapor-phase routes have various advantages, and thus have been applied in the field of gas sensors over the years. In particular, n-type NWs such as SnO2, ZnO, and In2O3 are widely studied because of their simple synthetic preparation and high gas response. However, due to their usually high responses to C2H5OH and NO2, the selective detection of other harmful and toxic gases using oxide NWs remains a challenging issue. Various strategies—such as doping/loading of noble metals, decorating/doping of catalytic metal oxides, and the formation of core–shell structures—have been explored to enhance gas selectivity and sensitivity, and are discussed herein. Additional methods such as the transformation of n-type into p-type NWs and the formation of catalyst-doped hierarchical structures by branch growth have also proven to be promising for the enhancement of gas selectivity. Accordingly, the physicochemical modification of oxide NWs via various methods provides new strategies to achieve the selective detection of a specific gas, and after further investigations, this approach could pave a new way in the field of NW-based semiconductor-type gas sensors. PMID:27657076

Piezo-Phototronic Matrix via a Nanowire Array.

PubMed

Zhang, Yang; Zhai, Junyi; Wang, Zhong Lin

2017-12-01

Piezoelectric semiconductors, such as ZnO and GaN, demonstrate multiproperty coupling effects toward various aspects of mechanical, electrical, and optical excitation. In particular, the three-way coupling among semiconducting, photoexcitation, and piezoelectric characteristics in wurtzite-structured semiconductors is established as a new field, which was first coined as piezo-phototronics by Wang in 2010. The piezo-phototronic effect can controllably modulate the charge-carrier generation, separation, transport, and/or recombination in optical-electronic processes by modifying the band structure at the metal-semiconductor or semiconductor-semiconductor heterojunction/interface. Here, the progress made in using the piezo-phototronic effect for enhancing photodetectors, pressure sensors, light-emitting diodes, and solar cells is reviewed. In comparison with previous works on a single piezoelectric semiconducting nanowire, piezo-phototronic nanodevices built using nanowire arrays provide a promising platform for fabricating integrated optoelectronics with the realization of high-spatial-resolution imaging and fast responsivity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surfactant-Templated Mesoporous Metal Oxide Nanowires

DOE PAGES

Luo, Hongmei; Lin, Qianglu; Baber, Stacy; ...

2010-01-01

We demore » monstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta 2 O 5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses.« less

Nanowire humidity optical sensor system based on fast Fourier transform technique

NASA Astrophysics Data System (ADS)

Rota-Rodrigo, S.; Pérez-Herrera, R.; Lopez-Aldaba, A.; López Bautista, M. C.; Esteban, O.; López-Amo, M.

2015-09-01

In this paper, a new sensor system for relative humidity measurements based on its interaction with the evanescent field of a nanowire is presented. The interrogation of the sensing head is carried out by monitoring the fast Fourier transform phase variations of one of the nanowire interference frequencies. This method is independent of the signal amplitude and also avoids the necessity of tracking the wavelength evolution in the spectrum, which can be a handicap when there are multiple interference frequency components with different sensitivities. The sensor is operated within a wide humidity range (20%-70% relative humidity) with a maximum sensitivity achieved of 0.14rad/% relative humidity. Finally, due to the system uses an optical interrogator as unique active element, the system presents a cost-effective feature.

Magnetoresistance manipulation and sign reversal in Mn-doped ZnO nanowires

DOE PAGES

Sapkota, Keshab R.; Chen, Weimin; Maloney, F. Scott; ...

2016-10-14

We report magnetoresistance (MR) manipulation and sign reversal induced by carrier concentration modulation in Mn-doped ZnO nanowires. At low temperatures positive magnetoresistance was initially observed. When the carrier concentration was increased through the application of a gate voltage, the magnetoresistance also increased and reached a maximum value. However, further increasing the carrier concentration caused the MR to decrease, and eventually an MR sign reversal from positive to negative was observed. An MR change from a maximum positive value of 25% to a minimum negative value of 7% was observed at 5 K and 50 KOe. The observed MR behavior wasmore » modeled by considering combined effects of quantum correction to carrier conductivity and bound magnetic polarons. Finally, this work could provide important insights into the mechanisms that govern magnetotransport in dilute magnetic oxides, and it also demonstrated an effective approach to manipulating magnetoresistance in these materials that have important spintronic applications.« less

Multisegment nanowire sensors for the detection of DNA molecules.

PubMed

Wang, Xu; Ozkan, Cengiz S

2008-02-01

We describe a novel application for detecting specific single strand DNA sequences using multisegment nanowires via a straightforward surface functionalization method. Nanowires comprising CdTe-Au-CdTe segments are fabricated using electrochemical deposition, and electrical characterization indicates a p-type behavior for the multisegment nanostructures, in a back-to-back Schottky diode configuration. Such nanostructures modified with thiol-terminated probe DNA fragments could function as high fidelity sensors for biomolecules at very low concentration. The gold segment is utilized for functionalization and binding of single strand DNA (ssDNA) fragments while the CdTe segments at both ends serve to modulate the equilibrium Fermi level of the heterojunction device upon hybridization of the complementary DNA fragments (cDNA) to the ssDNA over the Au segment. Employing such multisegment nanowires could lead to the fabrication more sophisticated and high multispecificity biosensors via selective functionalization of individual segments for biowarfare sensing and medical diagnostics applications.

Visible light-sensitive APTES-bound ZnO nanowire toward a potent nanoinjector sensing biomolecules in a living cell

NASA Astrophysics Data System (ADS)

Lee, Jooran; Choi, Sunyoung; Bae, Seon Joo; Yoon, Seok Min; Choi, Joon Sig; Yoon, Minjoong

2013-10-01

Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon interaction with a complementary sequence-based double stranded (ds) DNA, whereas it is not significantly affected by non-complementary ds DNA. Further, the tip of a single APTES-ZnO NW can be inserted into the subcellular region of living HEK 293 cells without significant toxicity, and it can also detect the enhancement of the tip emission from subcellular regions with high spatial resolution. These results indicate that the single APTES-ZnO NW would be useful as a potent nanoinjector which can guide visible light into intracellular compartments of mammalian cells, and can also detect nanoscopic optical signal changes induced by interaction with the subcellular specific target biomolecules without separate optical probes.Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon

Study of quantum confinement effects in ZnO nanostructures

NASA Astrophysics Data System (ADS)

Movlarooy, Tayebeh

2018-03-01

Motivation to fact that zinc oxide nanowires and nanotubes with successful synthesis and the mechanism of formation, stability and electronic properties have been investigated; in this study the structural, electronic properties and quantum confinement effects of zinc oxide nanotubes and nanowires with different diameters are discussed. The calculations within density functional theory and the pseudo potential approximation are done. The electronic structure and energy gap for Armchair and zigzag ZnO nanotubes with a diameter of about 4 to 55 Angstrom and ZnO nanowires with a diameter range of 4 to 23 Å is calculated. The results revealed that due to the quantum confinement effects, by reducing the diameter of nanowires and nanotubes, the energy gap increases. Zinc oxide semiconductor nanostructures since having direct band gap with size-dependent and quantum confinement effect are recommended as an appropriate candidate for making nanoscale optoelectronic devices.

Importance of the Debye Screening Length on Nanowire Field Effect Transistor Sensors

PubMed Central

Stern, Eric; Wagner, Robin; Sigworth, Fred J.; Breaker, Ronald; Fahmy, Tarek M.; Reed, Mark A.

2009-01-01

Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors. PMID:17914853

Importance of the Debye screening length on nanowire field effect transistor sensors.

PubMed

Stern, Eric; Wagner, Robin; Sigworth, Fred J; Breaker, Ronald; Fahmy, Tarek M; Reed, Mark A

2007-11-01

Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors.

EDITORIAL: Nanowires for energy Nanowires for energy

NASA Astrophysics Data System (ADS)

LaPierre, Ray; Sunkara, Mahendra

2012-05-01

This special issue of Nanotechnology focuses on studies illustrating the application of nanowires for energy including solar cells, efficient lighting and water splitting. Over the next three decades, nanotechnology will make significant contributions towards meeting the increased energy needs of the planet, now known as the TeraWatt challenge. Nanowires in particular are poised to contribute significantly in this development as presented in the review by Hiralal et al [1]. Nanowires exhibit light trapping properties that can act as a broadband anti-reflection coating to enhance the efficiency of solar cells. In this issue, Li et al [2] and Wang et al [3] present the optical properties of silicon nanowire and nanocone arrays. In addition to enhanced optical properties, core-shell nanowires also have the potential for efficient charge carrier collection across the nanowire diameter as presented in the contribution by Yu et al [4] for radial junction a-Si solar cells. Hybrid approaches that combine organic and inorganic materials also have potential for high efficiency photovoltaics. A Si-based hybrid solar cell is presented by Zhang et al [5] with a photoconversion efficiency of over 7%. The quintessential example of hybrid solar cells is the dye-sensitized solar cell (DSSC) where an organic absorber (dye) coats an inorganic material (typically a ZnO nanostructure). Herman et al [6] present a method of enhancing the efficiency of a DSSC by increasing the hetero-interfacial area with a unique hierarchical weeping willow ZnO structure. The increased surface area allows for higher dye loading, light harvesting, and reduced charge recombination through direct conduction along the ZnO branches. Another unique ZnO growth method is presented by Calestani et al [7] using a solution-free and catalyst-free approach by pulsed electron deposition (PED). Nanowires can also make more efficient use of electrical power. Light emitting diodes, for example, will eventually become the

Growth of antimony doped P-type zinc oxide nanowires for optoelectronics

DOEpatents

Wang, Zhong Lin; Pradel, Ken

2016-09-27

In a method of growing p-type nanowires, a nanowire growth solution of zinc nitrate (Zn(NO.sub.3).sub.2), hexamethylenetetramine (HMTA) and polyethylenemine (800 M.sub.w PEI) is prepared. A dopant solution to the growth solution, the dopant solution including an equal molar ration of sodium hydroxide (NaOH), glycolic acid (C.sub.2H.sub.4O.sub.3) and antimony acetate (Sb(CH.sub.3COO).sub.3) in water is prepared. The dopant solution and the growth solution combine to generate a resulting solution that includes antimony to zinc in a ratio of between 0.2% molar to 2.0% molar, the resulting solution having a top surface. An ammonia solution is added to the resulting solution. A ZnO seed layer is applied to a substrate and the substrate is placed into the top surface of the resulting solution with the ZnO seed layer facing downwardly for a predetermined time until Sb-doped ZnO nanowires having a length of at least 5 .mu.m have grown from the ZnO seed layer.

The Present State of Amperometric Nanowire Sensors for Chemical and Biological Detection

DTIC Science & Technology

2006-10-01

reported for a multi(nano)wire carbon monoxide 6 sensor (17). A single gallium oxide nanowire ethanol sensor with a 2.5 second response time has also...Covington, J. A.; Gardner, J. W.; Bartlett, P. N.; Toh, C-S. Conductive polymer gate FET devices for vapour sensing. IEE Proceedings - Circuits...detecting organic vapours . Sensors and Actuators B 2001, 77 (1–2), 155–162. 48. Malliaras G.; Friend, R. An organic electronics primer. Physics

Semiconductor Nanowires and Nanotubes for Energy Conversion

NASA Astrophysics Data System (ADS)

Fardy, Melissa Anne

Se nanowires allowed their thermoelectric properties to be controllably tuned by increasing their carrier concentration or hole mobility. After optimal annealing, single PbSe nanowires exhibited a thermoelectric figure of merit (ZT) of 0.12 at 300 K. In addition, using a field-effect gated device, the Seebeck coefficient of single PbSe nanowires could be tuned from 64 to 193 muV˙K-1. This direct electrical field control of the electrical conductivity and Seebeck coefficient suggests a powerful strategy for optimizing ZT in thermoelectric devices and these results represent the first demonstration of field-effect modulation of the thermoelectric figure of merit in a single semiconductor nanowire. This novel strategy for thermoelectric property modulation could prove especially important in optimizing the thermoelectric properties of semiconductors where reproducible doping is difficult to achieve. Recent theoretical work has shown large enhancements in ZT for single-crystal nanowires containing nanoscale interfaces along their lengths. M2O3(ZnO) n ( M = In, Ga, Fe) superlattice nanowires were synthesized via a novel solid-state diffusion approach to investigate this possible enhancement. Using atomic resolution Z-contrast STEM imaging a detailed structural analysis was performed on In2-xGaxO3(ZnO) n nanowires, leading to the discovery that octahedral inclusions within the superlattice structure are likely generated through a defect-assisted process. Single-nanowire thermal and electrical measurements on In2-x GaxO3(ZnO)n reveal a simultaneous improvement in all contributing factors to the thermoelectric figure of merit, giving an order of magnitude enhancement over similar bulk materials at room temperature. This is the first report of enhancement of all three thermoelectric parameters (Seebeck coefficient, electrical conductivity, and thermal resistivity) for a nanowire system. Photoelectrochemical water splitting is another exciting renewable energy application that can

A facile synthesis of mesoporous Pdsbnd ZnO nanocomposites as efficient chemical sensor

NASA Astrophysics Data System (ADS)

Ismail, Adel A.; Harraz, Farid A.; Faisal, M.; El-Toni, Ahmed Mohamed; Al-Hajry, A.; Al-Assiri, M. S.

2016-07-01

Mesoporous ZnO was synthesized through the sol-gel method in the presence of triblock co-polymer Pluronic (F-127) template as the structure directing agent. Palladium nanoparticles were photochemically reduced and deposited onto mesoporous ZnO to obtain 1 wt.% Pd/ZnO nanocomposite. Structural and morphological analysis revealed high homogeneity and monodispersity of Pd nanoclusters with small particle sizes ∼ 2-5 nm onto mesoporous ZnO. The electrochemical detection of ethanol in aqueous solutions was conducted at the newly developed Pd/ZnO modified glassy carbon electrode (GCE) by the current-potential (IV) and cyclic voltammetry (CV) techniques and compared with bare GCE or pure ZnO. The presence of Pd dopant greatly enhances the sensitivity of ZnO, and the obtained mesoporous Pd/ZnO sensor has an excellent performance for precision detection of ethanol in aqueous solution with low concentration. The sensitivity was found to be 33.08 μAcm-2 mM-1 at lower concentration zone (0.05-0.8 mM) and 2.13 μAcm-2 mM-1 at higher concentration zone (0.8-12 mM), with a limit of detection (LOD) 19.2 μM. The kinetics study of ethanol oxidation revealed a characteristic feature for a mixed surface and diffusion-controlled process. These excellent sensing characteristics make the mesoporous Pd/ZnO nanocomposite a good candidate for the production of high-performance electrochemical sensors at low ethanol concentration in aqueous solution.

ZnO/ZnSxSe1-x core/shell nanowire arrays as photoelectrodes with efficient visible light absorption

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Safdar, Muhammad; Niu, Mutong; Zhang, Jinping; Huang, Ying; He, Jun

2012-08-01

ZnO/ZnSxSe1-x core/shell nanowires have been synthesized on n+-type silicon substrate via a two-step chemical vapor deposition method. Transmission electron microscopy reveals that ZnSxSe1-x can be deposited on the entire surface of ZnO nanowire, forming coaxial heterojunction along ZnO nanowire with very smooth shell surface and high shell thickness uniformity. The photoelectrode after deposition of the ternary alloy shell significantly improves visible light absorption efficiency. Electrochemical impedance spectroscopy results explicitly indicate that the introduction of ZnSxSe1-x shell to ZnO nanowires effectively improves the photogenerated charge separation process. Our finding opens up an efficient means for achieving high efficient energy conversion devices.

Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

2015-11-01

The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

A Wearable Hydration Sensor with Conformal Nanowire Electrodes.

PubMed

Yao, Shanshan; Myers, Amanda; Malhotra, Abhishek; Lin, Feiyan; Bozkurt, Alper; Muth, John F; Zhu, Yong

2017-03-01

A wearable skin hydration sensor in the form of a capacitor is demonstrated based on skin impedance measurement. The capacitor consists of two interdigitated or parallel electrodes that are made of silver nanowires (AgNWs) in a polydimethylsiloxane (PDMS) matrix. The flexible and stretchable nature of the AgNW/PDMS electrode allows conformal contact to the skin. The hydration sensor is insensitive to the external humidity change and is calibrated against a commercial skin hydration system on an artificial skin over a wide hydration range. The hydration sensor is packaged into a flexible wristband, together with a network analyzer chip, a button cell battery, and an ultralow power microprocessor with Bluetooth. In addition, a chest patch consisting of a strain sensor, three electrocardiography electrodes, and a skin hydration sensor is developed for multimodal sensing. The wearable wristband and chest patch may be used for low-cost, wireless, and continuous monitoring of skin hydration and other health parameters. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coupling of semiconductor nanowires with neurons and their interfacial structure.

PubMed

Lee, Ki-Young; Shim, Sojung; Kim, Il-Soo; Oh, Hwangyou; Kim, Sunoh; Ahn, Jae-Pyeong; Park, Seung-Han; Rhim, Hyewhon; Choi, Heon-Jin

2009-12-04

We report on the compatibility of various nanowires with hippocampal neurons and the structural study of the neuron-nanowire interface. Si, Ge, SiGe, and GaN nanowires are compatible with hippocampal neurons due to their native oxide, but ZnO nanowires are toxic to neuron due to a release of Zn ion. The interfaces of fixed Si nanowire and hippocampal neuron, cross-sectional samples, were prepared by focused ion beam and observed by transmission electron microscopy. The results showed that the processes of neuron were adhered well on the nanowire without cleft.

Water- and humidity-enhanced UV detector by using p-type La-doped ZnO nanowires on flexible polyimide substrate.

PubMed

Hsu, Cheng-Liang; Li, Hsieh-Heng; Hsueh, Ting-Jen

2013-11-13

High-density La-doped ZnO nanowires (NWs) were grown hydrothermally on flexible polyimide substrate. The length and diameter of the NWs were around 860 nm and 80-160 nm, respectively. All XRD peaks of the La-doped sample shift to a larger angle. The strong PL peak of the La-doped sample is 380 nm, which is close to the 3.3 eV ZnO bandgap. That PL dominated indicates that the La-doped sample has a great amount of oxygen vacancies. The lattice constants ~0.514 nm of the ZnO:La NW were smaller when measured by HR-TEM. The EDX spectrum determined that the La-doped sample contains approximately 1.27 at % La. The La-doped sample was found to be p-type by Hall Effect measurement. The dark current of the p-ZnO:La NWs decreased with increased relative humidity (RH), while the photocurrent of the p-ZnO:La nanowires increased with increased RH. The higher RH environment was improved that UV response performance. Based on the highest 98% RH, the photocurrent/dark current ratio was around 47.73. The UV response of water drops on the p-ZnO:La NWs was around 2 orders compared to 40% RH. In a water environment, the photocurrent/dark current ratio of p-ZnO:La NWs was 212.1, which is the maximum UV response.

Sponge-Templated Macroporous Graphene Network for Piezoelectric ZnO Nanogenerator.

PubMed

Li, Xinda; Chen, Yi; Kumar, Amit; Mahmoud, Ahmed; Nychka, John A; Chung, Hyun-Joong

2015-09-23

We report a simple approach to fabricate zinc oxide (ZnO) nanowire based electricity generators on three-dimensional (3D) graphene networks by utilizing a commercial polyurethane (PU) sponge as a structural template. Here, a 3D network of graphene oxide is deposited from solution on the template and then is chemically reduced. Following steps of ZnO nanowire growth, polydimethylsiloxane (PDMS) backfilling and electrode lamination completes the fabrication processes. When compared to conventional generators with 2D planar geometry, the sponge template provides a 3D structure that has a potential to increase power density per unit area. The modified one-pot ZnO synthesis method allows the whole process to be inexpensive and environmentally benign. The nanogenerator yields an open circuit voltage of ∼0.5 V and short circuit current density of ∼2 μA/cm(2), while the output was found to be consistent after ∼3000 cycles. Finite element analysis of stress distribution showed that external stress is concentrated to deform ZnO nanowires by orders of magnitude compared to surrounding PU and PDMS, in agreement with our experiment. It is shown that the backfilled PDMS plays a crucial role for the stress concentration, which leads to an efficient electricity generation.

A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires.

PubMed

Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

2015-02-21

The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa(-1). The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.

Ultraviolet Electroluminescence from ZnS@ZnO Core-Shell Nanowires/p-GaN Introduced by Exciton Localization.

PubMed

Fang, Xuan; Wei, Zhipeng; Yang, Yahui; Chen, Rui; Li, Yongfeng; Tang, Jilong; Fang, Dan; Jia, Huimin; Wang, Dengkui; Fan, Jie; Ma, Xiaohui; Yao, Bin; Wang, Xiaohua

2016-01-27

We investigate the electroluminescence (EL) from light emitting diodes (LEDs) of ZnO nanowires/p-GaN structure and ZnS@ZnO core-shell nanowires/p-GaN structure. With the increase of forward bias, the emission peak of ZnO nanowires/p-GaN structure heterojunction shows a blue-shift, while the ZnS@ZnO core-shell nanowires/p-GaN structure demonstrates a changing EL emission; the ultraviolet (UV) emission at 378 nm can be observed. This discrepancy is related to the localized states introduced by ZnS particles, which results in a different carrier recombination process near the interfaces of the heterojunction. The localized states capture the carriers in ZnO nanowires and convert them to localized excitons under high forward bias. A strong UV emission due to localized excitons can be observed. Our results indicated that utilizing localized excitons should be a new route toward ZnO-based ultraviolet LEDs with high efficiency.

Highly Sensitive and Selective Ethanol Sensor Fabricated with In-Doped 3DOM ZnO.

PubMed

Wang, Zhihua; Tian, Ziwei; Han, Dongmei; Gu, Fubo

2016-03-02

ZnO is an important n-type semiconductor sensing material. Currently, much attention has been attracted to finding an effective method to prepare ZnO nanomaterials with high sensing sensitivity and excellent selectivity. A three-dimensionally ordered macroporous (3DOM) ZnO nanostructure with a large surface area is beneficial to gas and electron transfer, which can enhance the gas sensitivity of ZnO. Indium (In) doping is an effective way to improve the sensing properties of ZnO. In this paper, In-doped 3DOM ZnO with enhanced sensitivity and selectivity has been synthesized by using a colloidal crystal templating method. The 3DOM ZnO with 5 at. % of In-doping exhibits the highest sensitivity (∼88) to 100 ppm ethanol at 250 °C, which is approximately 3 times higher than that of pure 3DOM ZnO. The huge improvement to the sensitivity to ethanol was attributed to the increase in the surface area and the electron carrier concentration. The doping by In introduces more electrons into the matrix, which is helpful for increasing the amount of adsorbed oxygen, leading to high sensitivity. The In-doped 3DOM ZnO is a promising material for a new type of ethanol sensor.

Facial development of high performance room temperature NO2 gas sensors based on ZnO nanowalls decorated rGO nanosheets

NASA Astrophysics Data System (ADS)

Liu, Zongyuan; Yu, Lingmin; Guo, Fen; Liu, Sheng; Qi, Lijun; Shan, Minyu; Fan, Xinhui

2017-11-01

A highly sensitive NO2 gas sensor based on ZnO nanowalls decorated rGO nanosheets was fabricated using a thermal reduction and soft solution process. The highly developed interconnected microporous networks of ZnO nanowalls were anchored homogeneously on the surface of reduced graphene oxide (rGO). Sensors fabricated with heterojunction structures achieved a higher response (S = 9.61) and shorter response-recovery (25 s, 15 s) behavior at room temperature to 50 ppm level NO2 effectively in contrast to those sensors based on net ZnO nanowalls or rGO layers. The stability and selectivity of ZnO/rGO heterojunction were carried out. Meanwhile, the effects of humidity on ZnO/rGO heterojunction gas sensor were investigated. The more preferable sensing performance of ZnO/rGO heterojunction to NO2 was discussed. It can be surmised that this NO2 gas sensor has potential for use as a portable room temperature gas sensor.

Analysis of ultraviolet photo-response of ZnO nanostructures prepared by electrodeposition and atomic layer deposition

NASA Astrophysics Data System (ADS)

Makhlouf, Houssin; Karam, Chantal; Lamouchi, Amina; Tingry, Sophie; Miele, Philippe; Habchi, Roland; Chtourou, Radhouane; Bechelany, Mikhael

2018-06-01

In this work, ZnO nanowires (ZnO NWs) and urchin-like ZnO nanowires (U-ZnO NWs) based on self-assembled ordered polystyrene sphere (PS) were successfully prepared by combining atomic layer deposition (ALD) and electrochemical deposition (ECD) processes to build UV photosensors. The photo-response of the prepared samples was investigated and compared. The growth of the nanowires on self-assembled, ordered PS introduces a significant modification on the morphology, crystal orientation and grain size of U-ZnO NWs compared to randomly, vertically aligned ZnO NWs, and therefore improves the photo-response of U-ZnO NWs. The photocurrent may be produced by either a surface or bulk-related process. For ZnO NW-based photosensors, the photocurrent was monitored by a surface related process, whereas, it was mainly governed by a bulk related process for U-ZnO NWs, resulting in a higher and faster photo-response. The study of the rise and decay time constants for both materials showed that these parameters were strikingly sensitive to the optical properties.

Nanowire Electron Scattering Spectroscopy

NASA Technical Reports Server (NTRS)

Hunt, Brian; Bronikowsky, Michael; Wong, Eric; VonAllmen, Paul; Oyafuso, Fablano

2009-01-01

Nanowire electron scattering spectroscopy (NESS) has been proposed as the basis of a class of ultra-small, ultralow-power sensors that could be used to detect and identify chemical compounds present in extremely small quantities. State-of-the-art nanowire chemical sensors have already been demonstrated to be capable of detecting a variety of compounds in femtomolar quantities. However, to date, chemically specific sensing of molecules using these sensors has required the use of chemically functionalized nanowires with receptors tailored to individual molecules of interest. While potentially effective, this functionalization requires labor-intensive treatment of many nanowires to sense a broad spectrum of molecules. In contrast, NESS would eliminate the need for chemical functionalization of nanowires and would enable the use of the same sensor to detect and identify multiple compounds. NESS is analogous to Raman spectroscopy, the main difference being that in NESS, one would utilize inelastic scattering of electrons instead of photons to determine molecular vibrational energy levels. More specifically, in NESS, one would exploit inelastic scattering of electrons by low-lying vibrational quantum states of molecules attached to a nanowire or nanotube.

Large-area fabrication of patterned ZnO-nanowire arrays using light stamping lithography.

PubMed

Hwang, Jae K; Cho, Sangho; Seo, Eun K; Myoung, Jae M; Sung, Myung M

2009-12-01

We demonstrate selective adsorption and alignment of ZnO nanowires on patterned poly(dimethylsiloxane) (PDMS) thin layers with (aminopropyl)siloxane self-assembled monolayers (SAMs). Light stamping lithography (LSL) was used to prepare patterned PDMS thin layers as neutral passivation regions on Si substrates. (3-Aminopropyl)triethoxysilane-based SAMs were selectively formed only on regions exposing the silanol groups of the Si substrates. The patterned positively charged amino groups define and direct the selective adsorption of ZnO nanowires with negative surface charges in the protic solvent. This procedure can be adopted in automated printing machines that generate patterned ZnO-nanowire arrays on large-area substrates. To demonstrate its usefulness, the LSL method was applied to prepare ZnO-nanowire transistor arrays on 4-in. Si wafers.

Fluorinated copper phthalocyanine nanowires for enhancing interfacial electron transport in organic solar cells.

PubMed

Yoon, Seok Min; Lou, Sylvia J; Loser, Stephen; Smith, Jeremy; Chen, Lin X; Facchetti, Antonio; Marks, Tobin J; Marks, Tobin

2012-12-12

Zinc oxide is a promising candidate as an interfacial layer (IFL) in inverted organic photovoltaic (OPV) cells due to the n-type semiconducting properties as well as chemical and environmental stability. Such ZnO layers collect electrons at the transparent electrode, typically indium tin oxide (ITO). However, the significant resistivity of ZnO IFLs and an energetic mismatch between the ZnO and the ITO layers hinder optimum charge collection. Here we report that inserting nanoscopic copper hexadecafluorophthalocyanine (F(16)CuPc) layers, as thin films or nanowires, between the ITO anode and the ZnO IFL increases OPV performance by enhancing interfacial electron transport. In inverted P3HT:PC(61)BM cells, insertion of F(16)CuPc nanowires increases the short circuit current density (J(sc)) versus cells with only ZnO layers, yielding an enhanced power conversion efficiency (PCE) of ∼3.6% vs ∼3.0% for a control without the nanowire layer. Similar effects are observed for inverted PTB7:PC(71)BM cells where the PCE is increased from 8.1% to 8.6%. X-ray scattering, optical, and electrical measurements indicate that the performance enhancement is ascribable to both favorable alignment of the nanowire π-π stacking axes parallel to the photocurrent flow and to the increased interfacial layer-active layer contact area. These findings identify a promising strategy to enhance inverted OPV performance by inserting anisotropic nanostructures with π-π stacking aligned in the photocurrent flow direction.

A room temperature ethanol sensor made from p-type Sb-doped SnO2 nanowires.

PubMed

Wu, Jyh Ming

2010-06-11

A p-type ethanol sensor with a response time of approximately 8.3 s at room temperature was produced by SnO(2):Sb nanowires. The electrical properties of p-type SnO(2) nanowires are stable with a hole concentration of 1.544 x 10(17) cm(-3) and a field-effect mobility of 22 cm(2) V(-2) S(-1). X-ray photoelectron spectroscopy (XPS) and Hall measurement revealed that as-synthesized nanowires exhibit p-type behavior. A comprehensive investigation of the p-type sensing mechanism is reported.

Silicon nanowire sensor for DNA detection and sequencing: an ab initio simulation

NASA Astrophysics Data System (ADS)

Lu, Wenchang; Li, Yan; Hodak, Miroslav; Xiao, Zhongcan; Bernholc, Jerry

Electrical sensors able to detect DNA replication and determine its sequence would enable fast and relatively cheap diagnosis of gene-related vulnerabilities and cancers. At present, it is already possible to electrically monitor DNA replication events using a Klenow fragment of polymerase I attached to a carbon nanotube. Since devices based on Si nanowires would be much easier to produce in quantity, we examine theoretically the sensitivity of a Si nanowire/Klenow fragment for electrical detection of nucleotide addition. A highly parallel real-space multigrid code is used for DFT-based non-equilibrium Green's function calculations involving up to 16,000 atoms, employing highly-accurate variationally-optimized localized orbitals. We find that the open and closed Klenow fragment configurations, prior and during nucleotide addition, respectively, screen the Si nanowire differently and result in a detectable current difference. The sensitivity is the largest in the subthreshold regime while the absolute current difference is maximized in the turn-on state. The sensitivity decreases with an increase of the nanowire size, as expected, but the current difference between different enzymatic states is nearly independent on the nanowire size up to 800 Å2 cross section.

Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

PubMed Central

Li, Zhiyang; Leung, Calvin; Gao, Fan; Gu, Zhiyong

2015-01-01

In this paper, vertically aligned Pt nanowire arrays (PtNWA) with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H2O2) detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO) template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM−1·cm−2) among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water) was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors. PMID:26404303

Glucose biosensor based on functionalized ZnO nanowire/graphite films dispersed on a Pt electrode

NASA Astrophysics Data System (ADS)

Gallay, P.; Tosi, E.; Madrid, R.; Tirado, M.; Comedi, D.

2016-10-01

We present a glucose biosensor based on ZnO nanowire self-sustained films grown on compacted graphite flakes by the vapor transport method. Nanowire/graphite films were fragmented in water, filtered to form a colloidal suspension, subsequently functionalized with glucose oxidase and finally transferred to a metal electrode (Pt). The obtained devices were evaluated using scanning electron microscopy, energy-dispersive x-ray spectroscopy, cyclic voltammetry and chronoamperometry. The electrochemical responses of the devices were determined in buffer solutions with successive glucose aggregates using a tripolar electrode system. The nanostructured biosensors showed excellent analytical performance, with linear response to glucose concentrations, high sensitivity of up to ≈17 μA cm-2 mM-1 in the 0.03-1.52 mM glucose concentration range, relatively low Michaelis-Menten constant, excellent reproducibility and a fast response. The detection limits are more than an order of magnitude lower than those achievable in commercial biosensors for glucose control, which is promising for the development of glucose monitoring methods that do not require blood extraction from potentially diabetic patients. The strong detection enhancements provided by the functionalized nanostructures are much larger than the electrode surface-area increase and are discussed in terms of the physical and chemical mechanisms involved in the detection and transduction processes.

Large-scale fabrication of vertically aligned ZnO nanowire arrays

DOEpatents

Wang, Zhong L; Das, Suman; Xu, Sheng; Yuan, Dajun; Guo, Rui; Wei, Yaguang; Wu, Wenzhuo

2013-02-05

In a method for growing a nanowire array, a photoresist layer is placed onto a nanowire growth layer configured for growing nanowires therefrom. The photoresist layer is exposed to a coherent light interference pattern that includes periodically alternately spaced dark bands and light bands along a first orientation. The photoresist layer exposed to the coherent light interference pattern along a second orientation, transverse to the first orientation. The photoresist layer developed so as to remove photoresist from areas corresponding to areas of intersection of the dark bands of the interference pattern along the first orientation and the dark bands of the interference pattern along the second orientation, thereby leaving an ordered array of holes passing through the photoresist layer. The photoresist layer and the nanowire growth layer are placed into a nanowire growth environment, thereby growing nanowires from the nanowire growth layer through the array of holes.

Electric field-assisted deposition of nanowires on carbon nanotubes for nanoelectronics and sensor applications.

PubMed

Sivakumar, Kousik; Panchapakesan, Balaji

2005-02-01

Manipulation and control of matter at the nanoscale and atomic scale levels are crucial for the success of nanoscale sensors and actuators. The ability to control and synthesize multilayer structures using carbon nanotubes that will enable the building of electronic devices within a nanotube is still in its infancy. In this paper, we present results on selective electric field-assisted deposition of metals on carbon nanotubes realizing metallic nanowire structures. Silver and platinum nanowires have been fabricated using this approach for their applications in chemical sensing as catalytic materials to sniff toxic agents and in the area of biomedical nanotechnology for construction of artificial muscles. Electric field-assisted deposition allows the deposition of metals with a high degree of selectivity on carbon nanotubes by manipulating the charges on the surface of the nanotubes and forming electrostatic double-layer supercapacitors. Deposition of metals primarily occurred due to electrochemical reduction, electrophoresis, and electro-osmosis inside the walls of the nanotube. SEM and TEM investigations revealed silver and platinum nanowires between 10 nm and 100 nm in diameter. The present technique is versatile and enables the fabrication of a host of different types of metallic and semiconducting nanowires using carbon nanotube templates for nanoelectronics and a myriad of sensor applications.

Zinc oxide nanowire-poly(methyl methacrylate) dielectric layers for polymer capacitive pressure sensors.

PubMed

Chen, Yan-Sheng; Hsieh, Gen-Wen; Chen, Shih-Ping; Tseng, Pin-Yen; Wang, Cheng-Wei

2015-01-14

Polymer capacitive pressure sensors based on a dielectric composite layer of zinc oxide nanowire and poly(methyl methacrylate) show pressure sensitivity in the range of 2.63 × 10(-3) to 9.95 × 10(-3) cm(2) gf(-1). This represents an increase of capacitance change by as much as a factor of 23 over pristine polymer devices. An ultralight load of only 10 mg (corresponding to an applied pressure of ∼0.01 gf cm(-2)) can be clearly recognized, demonstrating remarkable characteristics of these nanowire-polymer capacitive pressure sensors. In addition, optical transmittance of the dielectric composite layer is approximately 90% in the visible wavelength region. Their low processing temperature, transparency, and flexible dielectric film makes them a highly promising means for flexible touching and pressure-sensing applications.

Efficient acetone sensor based on Ni-doped ZnO nanostructures prepared by spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Darunkar, Swapnil S.; Acharya, Smita A.

2018-05-01

Ni-doped ZnO thin film was prepared by home-built spray pyrolysis unit for the detection of acetone at 300°C. Scanning electron microscopic (SEM) images of as-developed thin film of undoped ZnO exhibits large quantity of spherical, non-agglomerated particles with uniform size while in Ni-doped ZnO, particles are quite non-uniform in nature. The particle size estimated by using image J are obtained to be around 20-200 nm. Ni-doping effect on band gaps are determined by UV-vis optical spectroscopy and band gap of Ni-doped ZnO is found to be 3.046 eV. Nickel doping exceptionally enhances the sensing response of ZnO as compared to undoped ZnO system. The major role of the Ni-doping is to create more active sites for chemisorbed oxygen on the surface of sensor and correspondingly, to improve the sensing response. The 6 at.% of Ni-doped ZnO exhibits the highest response (92%) for 100 ppm acetone at 300 °C.

Taheri-Saramad x-ray detector (TSXD): a novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane.

PubMed

Taheri, A; Saramad, S; Ghalenoei, S; Setayeshi, S

2014-01-01

A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 μm, respectively.

Light-controlling, flexible and transparent ethanol gas sensor based on ZnO nanoparticles for wearable devices

PubMed Central

Zheng, Z. Q.; Yao, J. D.; Wang, B.; Yang, G. W.

2015-01-01

In recent years, owing to the significant applications of health monitoring, wearable electronic devices such as smart watches, smart glass and wearable cameras have been growing rapidly. Gas sensor is an important part of wearable electronic devices for detecting pollutant, toxic, and combustible gases. However, in order to apply to wearable electronic devices, the gas sensor needs flexible, transparent, and working at room temperature, which are not available for traditional gas sensors. Here, we for the first time fabricate a light-controlling, flexible, transparentand working at room-temperature ethanol gas sensor by using commercial ZnO nanoparticles. The fabricated sensor not only exhibits fast and excellent photoresponse, but also shows high sensing response to ethanol under UV irradiation. Meanwhile, its transmittance exceeds 62% in the visible spectral range, and the sensing performance keeps the same even bent it at a curvature angle of 90o. Additionally, using commercial ZnO nanoparticles provides a facile and low-cost route to fabricate wearable electronic devices. PMID:26076705

Light-controlling, flexible and transparent ethanol gas sensor based on ZnO nanoparticles for wearable devices.

PubMed

Zheng, Z Q; Yao, J D; Wang, B; Yang, G W

2015-06-16

In recent years, owing to the significant applications of health monitoring, wearable electronic devices such as smart watches, smart glass and wearable cameras have been growing rapidly. Gas sensor is an important part of wearable electronic devices for detecting pollutant, toxic, and combustible gases. However, in order to apply to wearable electronic devices, the gas sensor needs flexible, transparent, and working at room temperature, which are not available for traditional gas sensors. Here, we for the first time fabricate a light-controlling, flexible, transparent, and working at room-temperature ethanol gas sensor by using commercial ZnO nanoparticles. The fabricated sensor not only exhibits fast and excellent photoresponse, but also shows high sensing response to ethanol under UV irradiation. Meanwhile, its transmittance exceeds 62% in the visible spectral range, and the sensing performance keeps the same even bent it at a curvature angle of 90(o). Additionally, using commercial ZnO nanoparticles provides a facile and low-cost route to fabricate wearable electronic devices.

Plasmonic Behavior of Ag/Dielectric Nanowires and the Effect of Geometry

DTIC Science & Technology

2009-07-01

in- cluding random Ga2O3 nanowires, ZnO nanowires, as well as Au lines produced by e-beam lithography. The growth of the Ga2O3 nanowires was achieved...PLASMONIC PROPERTIES As discussed above, we have developed a SERS substrate, consisting of Ga2O3 nanowire core/Ag metal sheath nano- structures, which have...signal. As is evident, the nanowire composites are about two orders of magnitude more sensitive than the Mesophotonics substrate. Since these Ga2O3 /Ag

Simultaneous tuning of electric field intensity and structural properties of ZnO: Graphene nanostructures for FOSPR based nicotine sensor.

PubMed

Tabassum, Rana; Gupta, Banshi D

2017-05-15

We report theoretical and experimental realization of a SPR based fiber optic nicotine sensor having coatings of silver and graphene doped ZnO nanostructure onto the unclad core of the optical fiber. The volume fraction (f) of graphene in ZnO was optimized using simulation of electric field intensity. Four types of graphene doped ZnO nanostructures viz. nanocomposites, nanoflowers, nanotubes and nanofibers were prepared using optimized value of f. The morphology, photoluminescence (PL) spectra and UV-vis spectra of these nanostructures were studied. The peak PL intensity was found to be highest for ZnO: graphene nanofibers. The optimized value of f in ZnO: graphene nanofiber was reconfirmed using UV-vis spectroscopy. The experiments were performed on the fiber optic probe fabricated with Ag/ZnO: graphene layer and optimized parameters for in-situ detection of nicotine. The interaction of nicotine with ZnO: graphene nanostructures alters the dielectric function of ZnO: graphene nanostructure which is manifested in terms of shift in resonance wavelength. From the sensing signal, the performance parameters were measured including sensitivity, limit of detection (LOD), limit of quantification (LOQ), stability, repeatability and selectivity. The real sample prepared using cigarette tobacco leaves and analyzed using the fabricated sensor makes it suitable for practical applications. The achieved values of LOD and LOQ are found to be unrivalled in comparison to the reported ones. The sensor possesses additional advantages such as, immunity to electromagnetic interference, low cost, capability of online monitoring, remote sensing. Copyright © 2017 Elsevier B.V. All rights reserved.

The Zn12O12 cluster-assembled nanowires as a highly sensitive and selective gas sensor for NO and NO2.

PubMed

Yong, Yongliang; Su, Xiangying; Zhou, Qingxiao; Kuang, Yanmin; Li, Xiaohong

2017-12-13

Motivated by the recent realization of cluster-assembled nanomaterials as gas sensors, first-principles calculations are carried out to explore the stability and electronic properties of Zn 12 O 12 cluster-assembled nanowires and the adsorption behaviors of environmental gases on the Zn 12 O 12 -based nanowires, including CO, NO, NO 2 , SO 2 , NH 3 , CH 4 , CO 2 , O 2 and H 2 . Our results indicate that the ultrathin Zn 12 O 12 cluster-assembled nanowires are particularly thermodynamic stable at room temperature. The CO, NO, NO 2 , SO 2 , and NH 3 molecules are all chemisorbed on the Zn 12 O 12 -based nanowires with reasonable adsorption energies, but CH 4 , CO 2 , O 2 and H 2 molecules are only physically adsorbed on the nanowire. The electronic properties of the Zn 12 O 12 -based nanowire present dramatic changes after the adsorption of the NO and NO 2 molecules, especially their electric conductivity and magnetic properties, however, the other molecules adsorption hardly change the electric conductivity of the nanowire. Meanwhile, the recovery time of the nanowire sensor at T = 300 K is estimated at 1.5 μs and 16.7 μs for NO and NO 2 molecules, respectively. Furthermore, the sensitivities of NO and NO 2 are much larger than that of the other molecules. Our results thus conclude that the Zn 12 O 12 -based nanowire is a potential candidate for gas sensors with highly sensitivity for NO and NO 2 .

Zinc phthalocyanine nanowires based flexible sensor for room temperature Cl2 detection

NASA Astrophysics Data System (ADS)

Devi, Pooja; Saini, Rajan; Singh, Rajinder; Mahajan, A.; Bedi, R. K.; Aswal, D. K.; Debnath, A. K.

2018-04-01

We have fabricated highly sensitive and Cl2 selective flexible sensor by depositing solution processed zinc phthalocyanine nanowires onto the flexible PET substrate and studied its Cl2 sensing characteristics in Cl2 concentration range 5-1500 ppb. The flexible sensor has a minimum detection limit as low as 5 ppb of Cl2 and response as high as 550% within 10 seconds. Interestingly, the sensor exhibited enhanced and faster response kinetics under bending conditions. The gas sensing mechanism of sensor has been discussed on the basis of XPS and Raman spectroscopic studies which revealed that zinc ions were the preferred sites for Cl2 interactions.

Origin of magnetic properties in carbon implanted ZnO nanowires.

PubMed

Wang, Y F; Shao, Y C; Hsieh, S H; Chang, Y K; Yeh, P H; Hsueh, H C; Chiou, J W; Wang, H T; Ray, S C; Tsai, H M; Pao, C W; Chen, C H; Lin, H J; Lee, J F; Wu, C T; Wu, J J; Chang, Y M; Asokan, K; Chae, K H; Ohigashi, T; Takagi, Y; Yokoyama, T; Kosugi, N; Pong, W F

2018-05-17

Various synchrotron radiation-based spectroscopic and microscopic techniques are used to elucidate the room-temperature ferromagnetism of carbon-doped ZnO-nanowires (ZnO-C:NW) via a mild C + ion implantation method. The photoluminescence and magnetic hysteresis loops reveal that the implantation of C reduces the number of intrinsic surface defects and increases the saturated magnetization of ZnO-NW. The interstitial implanted C ions constitute the majority of defects in ZnO-C:NW as confirmed by the X-ray absorption spectroscopic studies. The X-ray magnetic circular dichroism spectra of O and C K-edge respectively indicate there is a reduction in the number of unpaired/dangling O 2p bonds in the surface region of ZnO-C:NW and the C 2p-derived states of the implanted C ions strongly affect the net spin polarization in the surface and bulk regions of ZnO-C:NW. Furthermore, these findings corroborate well with the first-principles calculations of C-implanted ZnO in surface and bulk regions, which highlight the stability of implanted C for the suppression and enhancement of the ferromagnetism of the ZnO-C:NW in the surface region and bulk phase, respectively.

Sulfur-Doped Zinc Oxide (ZnO) Nanostars: Synthesis and Simulation of Growth Mechanism

DTIC Science & Technology

2011-10-01

Zinc Oxide ( ZnO ) Nanostars: Synthesis and Simulation of Growth Mechanism Jinhyun Cho1, Qiubao Lin2,3, Sungwoo...characterization, and ab initio simulations of star-shaped hexagonal zinc oxide ( ZnO ) nanowires. The ZnO nanostructures were synthesized by a low...Introduction Zinc oxide ( ZnO ) is a wide bandgap (3.37 eV), Ⅱ–Ⅵ semiconductor of great interest for optoelectronic applications [1–3]. Its

Application of Chemical Doping and Architectural Design Principles To Fabricate Nanowire Co2Ni3ZnO8 Arrays for Aqueous Asymmetric Supercapacitors.

PubMed

Liu, Qi; Yang, Bin; Liu, Jingyuan; Yuan, Yi; Zhang, Hongsen; Liu, Lianhe; Wang, Jun; Li, Rumin

2016-08-10

Electrode materials derived from transition metal oxides have a serious problem of low electron transfer rate, which restricts their practical application. However, chemically doped graphene transforms the chemical bonding configuration to enhance electron transfer rate and, therefore, facilitates the successful fabrication of Co2Ni3ZnO8 nanowire arrays. In addition, the Co2Ni3ZnO8 electrode materials, considered as Ni and Zn ions doped into Co3O4, have a high electron transfer rate and electrochemical response capability, because the doping increases the degree of crystal defect and reaction of Co/Ni ions with the electrolyte. Hence, the Co2Ni3ZnO8 electrode exhibits a high rate property and excellent electrochemical cycle stability, as determined by electrochemical analysis of the relationship between specific capacitance, IR drop, Coulomb efficiency, and different current densities. From the results of a three-electrode system of electrochemical measurement, the Co2Ni3ZnO8 electrode demonstrates a specific capacitance of 1115 F g(-1) and retains 89.9% capacitance after 2000 cycles at a current density of 4 A g(-1). The energy density of the asymmetric supercapacitor (AC//Co2Ni3ZnO8) is 54.04 W h kg(-1) at the power density of 3200 W kg(-1).

All-printable band-edge modulated ZnO nanowire photodetectors with ultra-high detectivity

PubMed Central

Liu, Xi; Gu, Leilei; Zhang, Qianpeng; Wu, Jiyuan; Long, Yunze; Fan, Zhiyong

2014-01-01

High-performance photodetectors are critical for high-speed optical communication and environmental sensing, and flexible photodetectors can be used for a wide range of portable or wearable applications. Here we demonstrate the all-printable fabrication of polycrystalline nanowire-based high-performance photodetectors on flexible substrates. Systematic investigations have shown their ultra-high photoconductive gain, responsivity and detectivity up to 3.3 × 1017 Jones. Further analysis shows that their high performance originates from the unique band-edge modulation along the nanowire axial direction, where the existence of Schottky barriers in series leads to highly suppressed dark current of the device and also gives rise to fast photoelectric response to low-intensity optical signal owing to barrier height modulation. The discovered rationale in this work can be utilized as guideline to design high-performance photodetectors with other nanomaterial systems. The developed fabrication scheme opens up possibility for future flexible and high-performance integrated optoelectronic sensor circuitry. PMID:24898081

All-printable band-edge modulated ZnO nanowire photodetectors with ultra-high detectivity.

PubMed

Liu, Xi; Gu, Leilei; Zhang, Qianpeng; Wu, Jiyuan; Long, Yunze; Fan, Zhiyong

2014-06-05

High-performance photodetectors are critical for high-speed optical communication and environmental sensing, and flexible photodetectors can be used for a wide range of portable or wearable applications. Here we demonstrate the all-printable fabrication of polycrystalline nanowire-based high-performance photodetectors on flexible substrates. Systematic investigations have shown their ultra-high photoconductive gain, responsivity and detectivity up to 3.3 × 10(17) Jones. Further analysis shows that their high performance originates from the unique band-edge modulation along the nanowire axial direction, where the existence of Schottky barriers in series leads to highly suppressed dark current of the device and also gives rise to fast photoelectric response to low-intensity optical signal owing to barrier height modulation. The discovered rationale in this work can be utilized as guideline to design high-performance photodetectors with other nanomaterial systems. The developed fabrication scheme opens up possibility for future flexible and high-performance integrated optoelectronic sensor circuitry.

New generation of α-MnO2 nanowires @PDMS composite as a hydrogen gas sensor

NASA Astrophysics Data System (ADS)

Hamidi, Seyedeh Mehri; Mosivand, Alireza; Mahboubi, Mina; Arabi, Hadi; Azad, Narin; Jamal, Murtada Riyadh

2018-03-01

New hydrogen gas sensor has been prepared by α-MnO2 nanowires in polydimethylsiloxane matrix. For this purpose, the high aspect ratio α-MnO2 nanowires has been prepared by the aid of hydrothermal method and then dispersed into poly-dimethyl siloxane polymer media. For gas sensing, the samples have been exposed under different gas concentrations from 0 to 5%. The sensor responses have been examined by normalized ellipsometric parameter with respect to the chamber filled with N2 Gas. Our results indicate linear behavior of resonance wavelength in ellipsometric parameter as a function of gas concentrations which can open a new insight for the sample's capability to hydrogen gas sensing applications.

Humidity Sensing Properties of Paper Substrates and Their Passivation with ZnO Nanoparticles for Sensor Applications

PubMed Central

Niarchos, Georgios; Dubourg, Georges; Afroudakis, Georgios; Georgopoulos, Markos; Tsouti, Vasiliki; Makarona, Eleni; Crnojevic-Bengin, Vesna; Tsamis, Christos

2017-01-01

In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a mask-less laser patterning method on simple commercial printing papers. Initial resistive measurements indicate that a paper substrate with a porous surface can be used as a cost-effective, sensitive and disposable humidity sensor in the 20% to 70% relative humidity (RH) range. Successive spin-coated layers of ZnO nanoparticles then, control the effect of humidity. Using this approach, the sensors become passive to relative humidity changes, paving the way to the development of ZnO-based gas sensors on paper substrates insensitive to humidity. PMID:28273847

Metal oxide nanostructures: preparation, characterization and functional applications as chemical sensors.

PubMed

Zappa, Dario; Bertuna, Angela; Comini, Elisabetta; Kaur, Navpreet; Poli, Nicola; Sberveglieri, Veronica; Sberveglieri, Giorgio

2017-01-01

Preparation and characterization of different metal oxide (NiO, WO 3 , ZnO, SnO 2 and Nb 2 O 5 ) nanostructures for chemical sensing are presented. p-Type (NiO) and n-type (WO 3 , SnO 2 , ZnO and Nb 2 O 5 ) metal oxide nanostructures were grown on alumina substrates using evaporation-condensation, thermal oxidation and hydrothermal techniques. Surface morphologies and crystal structures were investigated through scanning electron microscopy and Raman spectroscopy. Furthermore, different batches of sensors have been prepared, and their sensing performances towards carbon monoxide and nitrogen dioxide have been explored. Moreover, metal oxide nanowires have been integrated into an electronic nose and successfully applied to discriminate between drinking and contaminated water.

Layer-by-layer-assembled quantum dot multilayer sensitizers: how the number of layers affects the photovoltaic properties of one-dimensional ZnO nanowire electrodes.

PubMed

Jin, Ho; Choi, Sukyung; Lim, Sang-Hoon; Rhee, Shi-Woo; Lee, Hyo Joong; Kim, Sungjee

2014-01-13

Layer cake: Multilayered CdSe quantum dot (QD) sensitizers are layer-by-layer assembled onto ZnO nanowires by making use of electrostatic interactions to study the effect of the layer number on the photovoltaic properties. The photovoltaic performance of QD-sensitized solar cells critically depends on this number as a result of the balance between light-harvesting efficiency and carrier-recombination probability. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental study on structural, optoelectronic and room temperature sensing performance of Nickel doped ZnO based ethanol sensors

NASA Astrophysics Data System (ADS)

Sudha, M.; Radha, S.; Kirubaveni, S.; Kiruthika, R.; Govindaraj, R.; Santhosh, N.

2018-04-01

Nano crystalline undoped (1Z) Zinc Oxide (ZnO) and 5, 10 and 15 Wt. % (1ZN, 2ZN and 3ZN) of Nickel doped ZnO based sensors were fabricated using the hydrothermal approach on Fluorine doped Tin Oxide (FTO) glass substrates. X-ray diffraction (XRD) analysis proved the hexagonal Wurtzite structure of ZnO. Parametric variations in terms of dislocation density, bond length, lattice parameters and micro strain with respect to dopant concentration were analysed. The prominent variations in the crystallite size, optical band gap and Photoluminescence peak ratio of devices fabricated was observed. The Field Emission Scanning Electron Microscope (FESEM) images showed a change in diameter and density of the nanorods. The effect of the operating temperature, concentration of ethanol and the different doping levels of sensitivity, response and recovery time were investigated. It was inferred that 376% of sensitivity with a very quick response and recovery time of <5 s and 10 s respectively at 150 °C of 3ZN sensor has better performance compared to other three sensors. Also 3ZN sensor showed improved sensitivity of 114%, even at room temperature with response and recovery time of 35 s and 45 s respectively.

An investigation into the role of polyethyleneimine in chemical bath deposition of zinc oxide nanowires

NASA Astrophysics Data System (ADS)

Eskandari, Alireza; Abdizadeh, Hossein; Pourshaban, Erfan; Golobostanfard, Mohammad Reza

2018-01-01

Zinc oxide nanowires are considered as promising materials for wide range of optoelectrical and chemical devices, thanks to their desirable structural and optoelectrical properties. Over the past decade, chemical bath deposition (CBD) has been widely used to synthesize these nanostructures due to its low cost and controllability. Since improving the aspect ratio and length of nanowires is a vital issue in growing one-dimensional nanostructures, the influence of polyethyleneimine (PEI) as a complexing and chelating agent on the structural, morphological, and optoelectrical properties of ZnO nanowires has been studied in this report. As-grown ZnO nanowires synthesized by mixing deionized water, zinc acetate dihydrate, hexamethylenetetramine, and PEI were characterized with field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD), and photoluminescence spectroscopy (PL). FESEM results unambiguously show that increasing PEI concentration (from 0 to 0.2 g in 50 ml DI water) reduces the diameter and density of nanowires from ˜120 to 56 nm and from ˜85% to 65%, respectively. Interestingly, although adding more PEI decreases nanowires diameter, over-increasing of PEI brings about an inappropriate nanostructures growth. Moreover, XRD patterns demonstrate that all the samples have wurtzite structure with a preferred orientation along c-axis which may be improved or deteriorated by adding PEI into the chemical bath. Accordingly, it is crucial to optimize the amount of PEI in CBD method. Near-band edge (NBE) region in PL spectrum also confirms wide bandgap of ZnO (˜3.3 eV). In addition, comparing the appearance of PEI free with PEI assisted solutions show a considerable difference in their colors, which may be attributed to the formation of new chemical compounds. Considering these results, PEI plays a couple of determining roles in synthesizing ZnO nanowires; making nanowires thinner, with selectively absorption to the non-polar, lateral facets of

Wearable, wireless gas sensors using highly stretchable and transparent structures of nanowires and graphene

NASA Astrophysics Data System (ADS)

Park, Jihun; Kim, Joohee; Kim, Kukjoo; Kim, So-Yun; Cheong, Woon Hyung; Park, Kyeongmin; Song, Joo Hyeb; Namgoong, Gyeongho; Kim, Jae Joon; Heo, Jaeyeong; Bien, Franklin; Park, Jang-Ung

2016-05-01

Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area.Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01468b

Skin inspired fractal strain sensors using a copper nanowire and graphite microflake hybrid conductive network.

PubMed

Jason, Naveen N; Wang, Stephen J; Bhanushali, Sushrut; Cheng, Wenlong

2016-09-22

This work demonstrates a facile "paint-on" approach to fabricate highly stretchable and highly sensitive strain sensors by combining one-dimensional copper nanowire networks with two-dimensional graphite microflakes. This paint-on approach allows for the fabrication of electronic skin (e-skin) patches which can directly replicate with high fidelity the human skin surface they are on, regardless of the topological complexity. This leads to high accuracy for detecting biometric signals for applications in personalised wearable sensors. The copper nanowires contribute to high stretchability and the graphite flakes offer high sensitivity, and their hybrid coating offers the advantages of both. To understand the topological effects on the sensing performance, we utilized fractal shaped elastomeric substrates and systematically compared their stretchability and sensitivity. We could achieve a high stretchability of up to 600% and a maximum gauge factor of 3000. Our simple yet efficient paint-on approach enabled facile fine-tuning of sensitivity/stretchability simply by adjusting ratios of 1D vs. 2D materials in the hybrid coating, and the topological structural designs. This capability leads to a wide range of biomedical sensors demonstrated here, including pulse sensors, prosthetic hands, and a wireless ankle motion sensor.

Investigation on dielectrophoretic assembly of nanostructures and its application on chemical sensors

NASA Astrophysics Data System (ADS)

Tao, Quan

Because of their extraordinary characteristics such as quantum confinement and large surface-tovolume ratio, semiconducting nanostructures such as nanowires or nanotubes hold great potential in sensing chemical vapors. Nanowire or nanotube based gas sensors usually possess appealing advantages such as high sensitivity, high stability, fast recovery time, and electrically controllable properties. To better predict the composition and concentration of target gas, nanostructures made from heterogeneous materials are employed to provide more predictors. In recent years, nanowires and nanotubes can be synthesized routinely through different methods. The techniques of fabricating nanowire or nanotube based sensor arrays, however, encounter obstacles and deserve further investigations. Dielectrophoresis (DEP), which refers to the motion of submicron particles inside a non-uniform electric field, has long been recognized as a nondestructive, easily implementable, and efficient approach to manipulate nanostructures onto electronic circuitries. However, due to our limited understandings, devices fabricated through DEP often end up with unpredictable number of arbitrarily aligned nanostructures. In this study, we first optimize the classical DEP formulas such that it can be applied to a more general case that a nanostructure is subjected to a non-uniform electric field with arbitrary orientation. A comprehensive model is then constructed to investigate the trajectory and alignment of DEP assembled nanostructures, which can be verified by experimental observations. The simulation results assist us to fabricate a gas sensor array with zinc oxide (ZnO) nanowires and carbon nanotubes (CNTs). It is then demonstrated that the device can well sense ammonia (NH3) at room temperature, which circumvents the usually required high temperature condition for nanowire based gas sensor application. An effective approach to recover the device using DC biases to locally heat up the

Ultraviolet Light-Assisted Copper Oxide Nanowires Hydrogen Gas Sensor

NASA Astrophysics Data System (ADS)

Sihar, Nabihah; Tiong, Teck Yaw; Dee, Chang Fu; Ooi, Poh Choon; Hamzah, Azrul Azlan; Mohamed, Mohd Ambri; Majlis, Burhanuddin Yeop

2018-05-01

We fabricated copper oxide nanowires (CuO NWs) ultraviolet (UV) light-assisted hydrogen gas sensor. The fabricated sensor shows promising sensor response behavior towards 100 ppm of H2 at room temperature and elevated temperature at 100 °C when exposed to UV light (3.0 mW/cm2). One hundred-cycle device stability test has been performed, and it is found that for sample elevated at 100 °C, the UV-activated sample achieved stability in the first cycle as compared to the sample without UV irradiation which needed about 10 cycles to achieve stability at the initial stage, whereas the sample tested at room temperature was able to stabilize with the aid of UV irradiation. This indicates that with the aid of UV light, after some "warming up" time, it is possible for the conventional CuO NW sensor which normally work at elevated temperature to function at room temperature because UV source is speculated to play a dominant role to increase the interaction of the surface of CuO NWs and hydrogen gas molecules absorbed after the light exposure.

Tattoolike Polyaniline Microparticle-Doped Gold Nanowire Patches as Highly Durable Wearable Sensors.

PubMed

Gong, Shu; Lai, Daniel T H; Wang, Yan; Yap, Lim Wei; Si, Kae Jye; Shi, Qianqian; Jason, Naveen Noah; Sridhar, Tam; Uddin, Hemayet; Cheng, Wenlong

2015-09-09

Wearable and highly sensitive strain sensors are essential components of electronic skin for future biomonitoring and human machine interfaces. Here we report a low-cost yet efficient strategy to dope polyaniline microparticles into gold nanowire (AuNW) films, leading to 10 times enhancement in conductivity and ∼8 times improvement in sensitivity. Simultaneously, tattoolike wearable sensors could be fabricated simply by a direct "draw-on" strategy with a Chinese penbrush. The stretchability of the sensors could be enhanced from 99.7% to 149.6% by designing curved tattoo with different radius of curvatures. We also demonstrated roller coating method to encapusulate AuNWs sensors, exhibiting excellent water resistibility and durability. Because of improved conductivity of our sensors, they can directly interface with existing wireless circuitry, allowing for fabrication of wireless flexion sensors for a human finger-controlled robotic arm system.

Monolithic carbon structures including suspended single nanowires and nanomeshes as a sensor platform

PubMed Central

2013-01-01

With the development of nanomaterial-based nanodevices, it became inevitable to develop cost-effective and simple nanofabrication technologies enabling the formation of nanomaterial assembly in a controllable manner. Herein, we present suspended monolithic carbon single nanowires and nanomeshes bridging two bulk carbon posts, fabricated in a designed manner using two successive UV exposure steps and a single pyrolysis step. The pyrolysis step is accompanied with a significant volume reduction, resulting in the shrinkage of micro-sized photoresist structures into nanoscale carbon structures. Even with the significant elongation of the suspended carbon nanowire induced by the volume reduction of the bulk carbon posts, the resultant tensional stress along the nanowire is not significant but grows along the wire thickness; this tensional stress gradient and the bent supports of the bridge-like carbon nanowire enhance structural robustness and alleviate the stiction problem that suspended nanostructures frequently experience. The feasibility of the suspended carbon nanostructures as a sensor platform was demonstrated by testing its electrochemical behavior, conductivity-temperature relationship, and hydrogen gas sensing capability. PMID:24256942

ZnO Nanostructures for Tissue Engineering Applications

PubMed Central

Laurenti, Marco; Cauda, Valentina

2017-01-01

This review focuses on the most recent applications of zinc oxide (ZnO) nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair. PMID:29113133

Application of ZnO Nanoparticle as Sulphide Gas Sensor Using UV/VIS/NIR-Spectrophotometer

NASA Astrophysics Data System (ADS)

Juliasih, N.; Buchari; Noviandri, I.

2017-04-01

The nanoparticle of metal oxides has great unique characteristics that applicable to the wide industrial as sensors and catalysts for reducing environmental pollution. Sulphide gas monitors and detectors are required for assessing safety aspects, due to its toxicity level. A thin film of ZnO as the sulphide gas sensor was synthesised by the simple method of chemical liquid deposition with variation of annealing temperature from 200 ºC to 500 ºC, and characterised by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and UV/VIS/NIR-Spectrophotometer. Characterization studies showed nanoparticle size from the range 62 - 92 nm of diameters. The application this ZnO thin film to sulfide gas, detected by UV/VIS/NIR Spectrophotometer with diffuse reflectance, showed specific chemical reaction by the shifting of maximum % Reflectance peak. The gas sensing using this method is applicable at room.

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts.

PubMed

Ibrahim, Ahmed A; Tiwari, Preeti; Al-Assiri, M S; Al-Salami, A E; Umar, Ahmad; Kumar, Rajesh; Kim, S H; Ansari, Z A; Baskoutas, S

2017-07-13

Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE). Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM -1 ·cm -2 ), a lower limit of detection at 7.8 µM, a regression coefficient ( R ²) of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM -1 ·cm -2 , an experimental Limit of detection (LOD) of 0.125 mM, and a linear dynamic range (LDR) of 1.0 mM-5.0 mM were observed for the fabricated picric acid sensor.

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts

PubMed Central

Ibrahim, Ahmed A.; Tiwari, Preeti; Al-Assiri, M. S.; Al-Salami, A. E.; Umar, Ahmad; Kumar, Rajesh; Kim, S. H.; Ansari, Z. A.; Baskoutas, S.

2017-01-01

Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE). Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM−1·cm−2), a lower limit of detection at 7.8 µM, a regression coefficient (R2) of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM−1·cm−2, an experimental Limit of detection (LOD) of 0.125 mM, and a linear dynamic range (LDR) of 1.0 mM–5.0 mM were observed for the fabricated picric acid sensor. PMID:28773151

Temperature dependent current transport of Pd/ZnO nanowire Schottky diodes

NASA Astrophysics Data System (ADS)

Gayen, R. N.; Bhattacharyya, S. R.; Jana, P.

2014-09-01

Zinc oxide (ZnO) nanowire based Schottky barrier diodes are fabricated by depositing Pd metal contact on top of vertically well-aligned ZnO nanowire arrays. A vertical array of ZnO nanowires on indium tin oxide (ITO) coated glass substrates is synthesized by hybrid wet chemical route. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) measurement confirm the formation of stoichiometric well-aligned hexagonal (h-ZnO) nanowire arrays with wurtzite structure. Temperature dependent current-voltage (I-V) measurements on palladium-ZnO (Pd/ZnO) nanowire Schottky junctions in the temperature range 303-383 K exhibit excellent rectifying character. From these nonlinear I-V plots, different electrical parameters of diode-like reverse saturation current, barrier height and ideality factor are determined as a function of temperature assuming pure thermionic emission model. The ideality factor is found to decrease while the barrier height increases with the increase in temperature. The series resistance values calculated from Cheung’s functions also show temperature dependency. Such behavior can be attributed to the presence of defects that traps carriers, and barrier height inhomogeneity at the interface of the barrier junction. After barrier height inhomogeneity correction, considering a Gaussian distributed barrier height fluctuation across the Pd/ZnO interface, the estimated values of mean barrier height and modified Richardson constant are more closely matched to the theoretically predicted value for Pd/ZnO Schottky barrier diodes. The variation of density of interface states as a function of interface state energy is also calculated.

Detecting Airborne Mercury by Use of Gold Nanowires

NASA Technical Reports Server (NTRS)

Ryan, Margaret; Shevade, Abhijit; Kisor, Adam; Homer, Margie; Soler, Jessica; Mung, Nosang; Nix, Megan

2009-01-01

Like the palladium chloride (PdCl2) films described in the immediately preceding article, gold nanowire sensors have been found to be useful for detecting airborne elemental mercury at concentrations on the order of parts per billion (ppb). Also like the PdCl2 films, gold nanowire sensors can be regenerated under conditions much milder than those necessary for regeneration of gold films that have been used as airborne-Hg sensors. The interest in nanowire sensors in general is prompted by the expectation that nanowires of a given material covering a given surface may exhibit greater sensitivity than does a film of the same material because nanowires have a greater surface area. In preparation for experiments to demonstrate this sensor concept, sensors were fabricated by depositing gold nanowires, variously, on microhotplate or microarray sensor substrates. In the experiments, the electrical resistances were measured while the sensors were exposed to air at a temperature of 25 C and relative humidity of about 30 percent containing mercury at various concentrations from 2 to 70 ppb (see figure). The results of this and other experiments have been interpreted as signifying that sensors of this type can detect mercury at ppb concentrations in room-temperature air and can be regenerated by exposure to clean flowing air at temperatures <40 C.

Optimization of dielectric matrix for ZnO nanowire based nanogenerators

NASA Astrophysics Data System (ADS)

Kannan, Santhosh; Parmar, Mitesh; Tao, Ran; Ardila, Gustavo; Mouis, Mireille

2016-11-01

This paper reports the role of selection of suitable dielectric layer in nanogenerator (NG) structure and its influence on the output performance. The basic NG structure is a composite material integrating hydrothermally grown vertical piezoelectric zinc oxide (ZnO) nanowires (NWs) into a dielectric matrix. To accomplish this study, three materials - poly methyl methacrylate (PMMA), silicon nitride (Si3N4) and aluminium oxide (Al2O3) are selected, processed and used as matrix dielectric in NGs. Scanning electron microscopy (SEM) analysis shows the well-aligned NWs with a diameter of 200±50 nm and length of 3.5±0.3 μm. This was followed by dielectric material deposition as a matrix material. After fabricating NG devices, the output generated voltage under manual and automatic bending were recorded, observed and analyzed for the selection of the best dielectric material to obtain an optimum output. The maximum peak-to-peak open-circuit voltage output for PMMA, Si3N4 and Al2O3 under manual bending was recorded as approximately 880 mV, 1.2 V and 2.1 V respectively. These preliminary results confirm the predicted effect of using more rigid dielectrics as matrix material for the NGs. The generated voltage is increased by about 70% using Si3N4 or Al2O3, instead of a less rigid material as PMMA.

CuO-Decorated ZnO Hierarchical Nanostructures as Efficient and Established Sensing Materials for H2S Gas Sensors

PubMed Central

Vuong, Nguyen Minh; Chinh, Nguyen Duc; Huy, Bui The; Lee, Yong-Ill

2016-01-01

Highly sensitive hydrogen sulfide (H2S) gas sensors were developed from CuO-decorated ZnO semiconducting hierarchical nanostructures. The ZnO hierarchical nanostructure was fabricated by an electrospinning method following hydrothermal and heat treatment. CuO decoration of ZnO hierarchical structures was carried out by a wet method. The H2S gas-sensing properties were examined at different working temperatures using various quantities of CuO as the variable. CuO decoration of the ZnO hierarchical structure was observed to promote sensitivity for H2S gas higher than 30 times at low working temperature (200 °C) compared with that in the nondecorated hierarchical structure. The sensing mechanism of the hybrid sensor structure is also discussed. The morphology and characteristics of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption, photoluminescence (PL), and electrical measurements. PMID:27231026

Interfacial engineering of CuO nanorod/ZnO nanowire hybrid nanostructure photoanode in dye-sensitized solar cell

NASA Astrophysics Data System (ADS)

Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Baran, Sümeyra Seniha; Asgin, Mansur; Gur, Emre; Kocak, Yusuf

2018-01-01

Developing efficient and cost-effective photoanode plays a vital role determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Here, we demonstrate DSSCs that achieve relatively high power conversion efficiencies (PCEs) by using one-dimensional (1D) zinc oxide (ZnO) nanowires and copper (II) oxide (CuO) nanorods hybrid nanostructures. CuO nanorod-based thin films were prepared by hydrothermal method and used as a blocking layer on top of the ZnO nanowires' layer. The use of 1D ZnO nanowire/CuO nanorod hybrid nanostructures led to an exceptionally high photovoltaic performance of DSSCs with a remarkably high open-circuit voltage (0.764 V), short current density (14.76 mA/cm2 under AM1.5G conditions), and relatively high solar to power conversion efficiency (6.18%) . The enhancement of the solar to power conversion efficiency can be explained in terms of the lag effect of the interfacial recombination dynamics of CuO nanorod-blocking layer on ZnO nanowires. This work shows more economically feasible method to bring down the cost of the nano-hybrid cells and promises for the growth of other important materials to further enhance the solar to power conversion efficiency.

Conducting Polyaniline Nanowire and Its Applications in Chemiresistive Sensing

PubMed Central

Song, Edward; Choi, Jin-Woo

2013-01-01

One dimensional polyaniline nanowire is an electrically conducting polymer that can be used as an active layer for sensors whose conductivity change can be used to detect chemical or biological species. In this review, the basic properties of polyaniline nanowires including chemical structures, redox chemistry, and method of synthesis are discussed. A comprehensive literature survey on chemiresistive/conductometric sensors based on polyaniline nanowires is presented and recent developments in polyaniline nanowire-based sensors are summarized. Finally, the current limitations and the future prospect of polyaniline nanowires are discussed. PMID:28348347

Nano ZnO embedded in Chitosan matrix for vibration sensor application

NASA Astrophysics Data System (ADS)

Praveen, E.; Murugan, S.; Jayakumar, K.

2015-06-01

Biopolymer Chitosan is embedded with various concentration of ZnO nano particle and such a bio-nano composite electret has been fabricated by casting method. The morphological, structural, optical and electrical characterization of the bio-nano composite electret film have been carried out. Isolation and piezoelectric measurements of bio-nano composite have also been carried out indicating the possibility of using it as a mechanical sensor element.

Piezoelectric and optoelectronic properties of electrospinning hybrid PVDF and ZnO nanofibers

NASA Astrophysics Data System (ADS)

Ma, Jian; Zhang, Qian; Lin, Kabin; Zhou, Lei; Ni, Zhonghua

2018-03-01

Polyvinylidene fluoride (PVDF) is a unique ferroelectric polymer with significant promise for energy harvesting, data storage, and sensing applications. ZnO is a wide direct band gap semiconductor (3.37 eV), commonly used as ultraviolet photodetectors, nanoelectronics, photonicsand piezoelectric generators. In this study, we produced high output piezoelectric energy harvesting materials using hybrid PVDF/ZnO nanofibers deposited via electrospinning. The strong electric fields and stretching forces during the electrospinning process helps to align dipoles in the nanofiber crystal such that the nonpolar α-phase (random orientation of dipoles) is transformed into polar β-phase in produced nanofibers. The effect of the additional ZnO nanowires on the nanofiber β-phase composition and output voltage are investigated. The maximum output voltage generated by a single hybrid PVDF and ZnO nanofiber (33 wt% ZnO nanowires) is over 300% of the voltage produced by a single nanofiber made of pure PVDF. The ZnO NWs served not only as a piezoelectric material, but also as a semiconducting material. The electrical conductivity of the hybrid PVDF/ZnO nanofibers increased by more than a factor of 4 when exposed under ultraviolet (UV) light.

Development of a nanowire based titanium needle probe sensor for glucose monitoring

NASA Astrophysics Data System (ADS)

Deshpande, Devesh C.

glucose monitoring. The working electrode of the sensor comprised of vertically aligned, free standing Au nanowires to utilize the advantages of nanostructures. The sensor was fabricated on biocompatible titanium substrate using Micro/Nano fabrication processes such as Plasma Enhanced Chemical Vapor Deposition (PECVD), Electron Beam Evaporation, Lithography, aligned nanowire growth and wet and plasma etching. Arrays of free-standing nanowires were grown at room temperature and pressure using a novel template based growth process. After fabrication of the sensor, immobilization of an enzyme was carried out on the sensing electrode to ensure selectivity of the sensor to glucose. This was achieved by using self-assembled thiol monolayers and entrapment in a conducting polymer matrix. Glucose oxidase was used for this purpose, which catalyzed the conversion of glucose to gluconic acid, producing hydrogen peroxide in the process. Amperometry was used for glucose detection, in which a constant voltage was applied to the sensor. This potential oxidized the hydrogen peroxide and produced changes in the current which were correlated to the glucose concentration. This dissertation will address the importance of continuous glucose monitoring, current technology and problems faced, the design and fabrication of the sensor and electrochemical sensing to detect glucose levels in solution. Finally, the problems encountered during the process will be discussed and the future work will be detailed.

CdS/CdSe quantum dot shell decorated vertical ZnO nanowire arrays by spin-coating-based SILAR for photoelectrochemical cells and quantum-dot-sensitized solar cells.

PubMed

Zhang, Ran; Luo, Qiu-Ping; Chen, Hong-Yan; Yu, Xiao-Yun; Kuang, Dai-Bin; Su, Cheng-Yong

2012-04-23

A CdS/CdSe composite shell is assembled onto the surface of ZnO nanowire arrays with a simple spin-coating-based successive ionic layer adsorption and reaction method. The as-prepared photoelectrode exhibit a high photocurrent density in photoelectrochemical cells and also generates good power conversion efficiency in quantum-dot-sensitized solar cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface plasmon optical sensor with enhanced sensitivity using top ZnO thin film

NASA Astrophysics Data System (ADS)

Bao, Ming; Li, Ge; Jiang, Dongmei; Cheng, Wenjuan; Ma, Xueming

2012-05-01

Surface plasmon resonance (SPR) is one of the most sensitive label-free detection methods and has been used in a wide range of chemical and biochemical sensing. Upon using a 200 nm top layer of dielectric film with a high value of the real part ɛ' of the dielectric function, on top of an SPR sensor in the Kretschmann configuration, the sensitivity is improved. The refractive index effect of dielectric film on sensitivity is usually ignored. Dielectric films with different refractive indices were prepared by radio frequency magnetron (RF) sputtering and measured with spectroscopic ellipsometry (SE). The imaginary part ɛ'' of the top nanolayer permittivity needs to be small enough in order to reduce the losses and get sharper dips. The stability of the sensor is also improved because the nanolayer is protecting the Ag film from interacting with the environment. The response curves of the Ag/ZnO chips were obtained by using SPR sensor. Theoretical analysis of the sensitivity of the SPR sensors with different ZnO film refractive indices is presented and studied. Both experimental and simulation results show that the Ag/ZnO films exhibit an enhanced SPR over the pure Ag film with a narrower full width at half maximum (FWHM). It shows that the top ZnO layer is effective in enhancing the surface plasmon resonance and thus its sensitivity.

Composite nanowire networks for biological sensor platforms

NASA Astrophysics Data System (ADS)

Jabal, Jamie Marie Francisco

The main goal of this research is to design, fabricate, and test a nanomaterial-based platform adequate for the measurement of physiological changes in living cells. The two primary objectives toward this end are (1) the synthesis and selection of a suitable nanomaterial and (2) the demonstration of cellular response to a direct stimulus. Determining a useful nanomaterial morphology and behavior within a sensor configuration presented challenges based on cellular integration and access to electrochemical characterization. The prospect for feasible optimization and eventual scale-up in technology were also significant. Constraining criteria are that the nanomaterial detector must (a) be cheap and relatively easy to fabricate controllably, (b) encourage cell attachment, (c) exhibit consistent wettability over time, and (d) facilitate electrochemical processes. The ultimate goal would be to transfer a proof-of-principle and proof-of-design for a whole-cell sensor technology that is cost effective and has a potential for hand-held packaging. Initial tasks were to determine an effective and highly-functional nanomaterial for biosensors by assessing wettability, morphology and conductivity behavior of several candidate materials: gallium nitride nanowires, silicon dioxide nanosprings and nanowires, and titania nanofibers. Electrospinning poly(vinyl pyrrolidone)-coated titania nano- and microfibers (O20 nm--2 microm) into a pseudo-random network is controllable to a uniformity of 1--2° in contact angle. The final electrode can be prepared with a precise wettability ranging from partial wetting to ultrahydrophobic (170°) on a variety of substrates: glass, indium tin oxide, silicon, and aluminum. Fiber mats exhibit excellent mechanical stability against rinsing, and support the incubation of epithelial (skin) and pancreatic cells. Impedance spectroscopy on the whole-cell sensor shows resistive changes attributed to cell growth as well as complex frequency

An efficient BTX sensor based on ZnO nanoflowers grown by CBD method

NASA Astrophysics Data System (ADS)

Acharyya, D.; Bhattacharyya, P.

2015-04-01

In this paper, sensing performance of ZnO nanoflower like structures derived by chemical bath deposition method (CBD), towards Benzene Toluene and Xylene (BTX) vapors is reported. Relatively higher bath temperature (110 °C) and high pH value (pH: 11) of solution escort to higher growth rate along [0 0 0 1] plane of ZnO, which eventually resulted in pointed edge nanorod based flower like structures after 3 h. After detailed structural characterizations (field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD)), existence of different defect states (viz. oxygen vacancy (Vo), Zinc vacancy (VZn) and Zinc interstitials (Zni)) were authenticated by Photoluminescence (PL) spectroscopy. BTX sensing performance, employing the nanoflowers as the sensing layer, was carried out in resistive mode with two Pd lateral electrodes. The sensor study was performed at different temperatures (150-350 °C) in the concentration range of 0.5-700 ppm of the respective vapors. The highest normalized resistance response (NRR%) was achieved at 200 °C. At this optimum temperature, normalized resistance responses (39.3/92.6%, 45.8/96.9%, and 47.8/99% respectively) were found to be promising towards 0.5/700 ppm of benzene, toluene and xylene. The response time of the sensor towards the target species were also found to be appreciably fast (15 s, 6 s, and 5 s) towards 700 ppm of benzene, toluene and xylene respectively. Detailed sensing mechanism for BTX with such flower like ZnO structures was explained with the help of interaction of band structures (of ZnO) with the corresponding highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the target species.

ZnO nanoflower-based photoelectrochemical DNAzyme sensor for the detection of Pb2+.

PubMed

Zhang, Bintian; Lu, Lili; Hu, Qichang; Huang, Feng; Lin, Zhang

2014-06-15

Lead contamination is now widespread, and exposure to lead may cause adverse effects on human beings. In this study, a photoelectrochemical sensor based on flower-like ZnO nanostructures was developed for Pb(2+) detection, using a Pb(2+)-dependent DNAzyme as the recognition unit and a double-strand DNA intercalator, Ru(bpy)2(dppz)(2+) (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c] phenazine) as the photoelectrochemical signal reporter. The ZnO nanoflower was fabricated on an indium tin oxide (ITO) electrode by the convenient hydrothermal decomposition method. The morphology and photoelectrochemical property of the ZnO nanoflowers were characterized by SEM, XRD and photocurrent measurements. DNAzyme-substrate duplex was assembled on an ITO/ZnO electrode through electrostatic adsorption. In the presence of Pb(2+), RNA-cleavage activity of the DNAzyme was activated and its substrate strand was cleaved, resulting in the release of Ru(bpy)2(dppz)(2+) from the DNA film and the concomitant photocurrent decrease. The detection principle was verified by fluorescence measurements. Under the optimized conditions, a linear relationship between photocurrent and Pb(2+) concentration was obtained over the range of 0.5-20 nM, with a detection limit of 0.1 nM. Interference from other common metal ions was found negligible. Applicability of the sensor was demonstrated by analyzing lead level in human serum and Pb(2+) spiked water samples. This facile and economical sensor system showed high sensitivity and selectivity, thus can be potentially applied for on-site monitoring of lead contaminant. Copyright © 2014 Elsevier B.V. All rights reserved.

Spontaneous polarization induced electric field in zinc oxide nanowires and nanostars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farid, S., E-mail: sfarid3@uic.edu; Choi, M.; Datta, D.

We report on the detection mechanism of spontaneous polarization using electrostatic force microscopy in zinc oxide nanowires and nanostars grown by vapor-liquid-solid technique. Optical and structural properties are investigated in detail to understand the complex ZnO nanostructures comprehensively. Calculations are carried out to estimate the electric field from the change in interleave amplitude induced by the electrostatic force due to the spontaneous polarization effects. Attraction of the probe between the tip and the sample varies for different structures with a stronger attraction for nanostars as compared to nanowires. Strength of electric field is dependent on the orientation of nanowires andmore » nanostars c-axis with measured magnitude of electric field to be ∼10{sup 7 }V/m and 10{sup 8 }V/m respectively. This technique presents a unique detection mechanism of built-in spontaneous polarization and electric field from polar ZnO nanowires with applications in voltage gated ion channels, nano-bio interfaces, optoelectronic and photonic devices.« less

Zinc oxide inverse opal enzymatic biosensor

NASA Astrophysics Data System (ADS)

You, Xueqiu; Pikul, James H.; King, William P.; Pak, James J.

2013-06-01

We report ZnO inverse opal- and nanowire (NW)-based enzymatic glucose biosensors with extended linear detection ranges. The ZnO inverse opal sensors have 0.01-18 mM linear detection range, which is 2.5 times greater than that of ZnO NW sensors and 1.5 times greater than that of other reported ZnO sensors. This larger range is because of reduced glucose diffusivity through the inverse opal geometry. The ZnO inverse opal sensors have an average sensitivity of 22.5 μA/(mM cm2), which diminished by 10% after 35 days, are more stable than ZnO NW sensors whose sensitivity decreased by 10% after 7 days.

A patterned ZnO nanorod array/gas sensor fabricated by mechanoelectrospinning-assisted selective growth.

PubMed

Wang, Xiaomei; Sun, Fazhe; Huang, Yongan; Duan, Yongqing; Yin, Zhouping

2015-02-21

Micropatterned ZnO nanorod arrays were fabricated by the mechanoelectrospinning-assisted direct-writing process and the hydrothermal growth process, and utilized as gas sensors that exhibited excellent Ohmic behavior and sensitivity response to oxidizing gas NO2 at low concentrations (1-100 ppm).

Highly sensitive hydrogen sulfide (H2 S) gas sensors from viral-templated nanocrystalline gold nanowires

NASA Astrophysics Data System (ADS)

Moon, Chung Hee; Zhang, Miluo; Myung, Nosang V.; Haberer, Elaine D.

2014-04-01

A facile, site-specific viral-templated assembly method was used to fabricate sensitive hydrogen sulfide (H2S) gas sensors at room temperature. A gold-binding M13 bacteriophage served to organize gold nanoparticles into linear arrays which were used as seeds for subsequent nanowire formation through electroless deposition. Nanowire widths and densities within the sensors were modified by electroless deposition time and phage concentration, respectively, to tune device resistance. Chemiresistive H2S gas sensors with superior room temperature sensing performance were produced with sensitivity of 654%/ppmv, theoretical lowest detection limit of 2 ppbv, and 70% recovery within 9 min for 0.025 ppmv. The role of the viral template and associated gold-binding peptide was elucidated by removing organics using a short O2 plasma treatment followed by an ethanol dip. The template and gold-binding peptide were crucial to electrical and sensor performance. Without surface organics, the resistance fell by several orders of magnitude, the sensitivity dropped by more than a factor of 100 to 6%/ppmv, the lower limit of detection increased, and no recovery was detected with dry air flow. Viral templates provide a novel, alternative fabrication route for highly sensitive, nanostructured H2S gas sensors.

Titanium dioxide nanowire sensor array integration on CMOS platform using deterministic assembly.

PubMed

Gall, Oren Z; Zhong, Xiahua; Schulman, Daniel S; Kang, Myungkoo; Razavieh, Ali; Mayer, Theresa S

2017-06-30

Nanosensor arrays have recently received significant attention due to their utility in a wide range of applications, including gas sensing, fuel cells, internet of things, and portable health monitoring systems. Less attention has been given to the production of sensor platforms in the μW range for ultra-low power applications. Here, we discuss how to scale the nanosensor energy demand by developing a process for integration of nanowire sensing arrays on a monolithic CMOS chip. This work demonstrates an off-chip nanowire fabrication method; subsequently nanowires link to a fused SiO 2 substrate using electric-field assisted directed assembly. The nanowire resistances shown in this work have the highest resistance uniformity reported to date of 18%, which enables a practical roadmap towards the coupling of nanosensors to CMOS circuits and signal processing systems. The article also presents the utility of optimizing annealing conditions of the off-chip metal-oxides prior to CMOS integration to avoid limitations of thermal budget and process incompatibility. In the context of the platform demonstrated here, directed assembly is a powerful tool that can realize highly uniform, cross-reactive arrays of different types of metal-oxide nanosensors suited for gas discrimination and signal processing systems.

Titanium dioxide nanowire sensor array integration on CMOS platform using deterministic assembly

NASA Astrophysics Data System (ADS)

Gall, Oren Z.; Zhong, Xiahua; Schulman, Daniel S.; Kang, Myungkoo; Razavieh, Ali; Mayer, Theresa S.

2017-06-01

Nanosensor arrays have recently received significant attention due to their utility in a wide range of applications, including gas sensing, fuel cells, internet of things, and portable health monitoring systems. Less attention has been given to the production of sensor platforms in the μW range for ultra-low power applications. Here, we discuss how to scale the nanosensor energy demand by developing a process for integration of nanowire sensing arrays on a monolithic CMOS chip. This work demonstrates an off-chip nanowire fabrication method; subsequently nanowires link to a fused SiO2 substrate using electric-field assisted directed assembly. The nanowire resistances shown in this work have the highest resistance uniformity reported to date of 18%, which enables a practical roadmap towards the coupling of nanosensors to CMOS circuits and signal processing systems. The article also presents the utility of optimizing annealing conditions of the off-chip metal-oxides prior to CMOS integration to avoid limitations of thermal budget and process incompatibility. In the context of the platform demonstrated here, directed assembly is a powerful tool that can realize highly uniform, cross-reactive arrays of different types of metal-oxide nanosensors suited for gas discrimination and signal processing systems.

High Aspect Ratio Perforated Co₃O₄ Nanowires Derived from Cobalt-Carbonate-Hydroxide Nanowires with Enhanced Sensing Performance.

PubMed

Zhou, Tuantuan; Gao, Wanlin; Wang, Qiang; Umar, Ahmad

2018-05-01

Herein, we report the facile synthesis of high-aspect ratio perforated Co3O4 nanowires derived from cobalt-carbonate-hydroxide (Co(CO3)0.5(OH) 0.11H2O) nanowires. The Co(CO3)0.5(OH) 0.11H2O nanowires were synthesized by simple hydrothermal process at 120 °C while annealing of such nanowires at 400 °C leads the formation of perforated Co3O4 nanowires. The prepared nanowires were characterized by several techniques which confirmed the high aspect ratio and well-crystallinity for the synthesized nanowires. For application point of view, the prepared perforated Co3O4 nanowires were used as efficient electrode material to fabricate highly sensitive and selective hydrazine chemical sensor. The electrochemical impedance spectroscopy (EIS) technique was employed to confirm the successful modification of the electrode. The key parameters of chemical sensor, such as detection limit, sensitivity, and linear range, have been systematically explored. The fabricated hydrazine sensor displayed a rather low detection limit of 4.52 μM (S/N = 3), a good sensitivity of 25.70 μA · mM-1, and a wide linear range of 16.97-358.34 μM.

Ultraviolet Light-Assisted Copper Oxide Nanowires Hydrogen Gas Sensor.

PubMed

Sihar, Nabihah; Tiong, Teck Yaw; Dee, Chang Fu; Ooi, Poh Choon; Hamzah, Azrul Azlan; Mohamed, Mohd Ambri; Majlis, Burhanuddin Yeop

2018-05-15

We fabricated copper oxide nanowires (CuO NWs) ultraviolet (UV) light-assisted hydrogen gas sensor. The fabricated sensor shows promising sensor response behavior towards 100 ppm of H 2 at room temperature and elevated temperature at 100 °C when exposed to UV light (3.0 mW/cm 2 ). One hundred-cycle device stability test has been performed, and it is found that for sample elevated at 100 °C, the UV-activated sample achieved stability in the first cycle as compared to the sample without UV irradiation which needed about 10 cycles to achieve stability at the initial stage, whereas the sample tested at room temperature was able to stabilize with the aid of UV irradiation. This indicates that with the aid of UV light, after some "warming up" time, it is possible for the conventional CuO NW sensor which normally work at elevated temperature to function at room temperature because UV source is speculated to play a dominant role to increase the interaction of the surface of CuO NWs and hydrogen gas molecules absorbed after the light exposure.

The clash of mechanical and electrical size-effects in ZnO nanowires and a double power law approach to elastic strain engineering of piezoelectric and piezotronic devices.

PubMed

Rinaldi, Antonio; Araneo, Rodolfo; Celozzi, Salvatore; Pea, Marialilia; Notargiacomo, Andrea

2014-09-10

The piezoelectric performance of ultra-strength ZnO nanowires (NWs) depends on the subtle interplay between electrical and mechanical size-effects. "Size-dependent" modeling of compressed NWs illustrates why experimentally observed mechanical stiffening can indeed collide with electrical size-effects when the size shrinks, thereby lowering the actual piezoelectric function from bulk estimates. "Smaller" is not necessarily "better" in nanotechnology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of Temperature and UV Irradiation on Dynamics of NO2 Sensors Based on ZnO Nanostructures

PubMed Central

Pustelny, Tadeusz

2017-01-01

The main object of this study is the improvement of the dynamics of NO2 sensors based on ZnO nanostructures. Investigations presented in this paper showed that the combination of temperature and ultraviolet (UV) activation of the sensors can significantly decrease the sensor response and regeneration times. In comparison with the single activation method (elevated temperature or UV), these times for 1 ppm of NO2 decreased from about 10 min (or more) to less than 40 s. In addition, at the optimal conditions (200 °C and UV), sensors were very stable, were fully scalable (in the range on NO2 concentration of 1–20 ppm) and baseline drift was significantly reduced. Furthermore, in this paper, extensive studies of the influence of temperature and carrier gas (nitrogen and air) on NO2 sensing properties of the ZnO nanostructures were conducted. The NO2 sensing mechanisms of the sensors operating at elevated temperatures and under UV irradiation were also discussed. Our study showed that sensor responses to NO2 and response/regeneration times are comparable from sensor to sensor in air and nitrogen conditions, which suggests that the proposed simple technology connected with well-chosen operation conditions is repeatable. The estimated limit of detection of the sensors is within the level of ≈800 ppb in nitrogen and ≈700 ppb in air. PMID:29019924

Separating light absorption layer from channel in ZnO vertical nanorod arrays based photodetectors for high-performance image sensors

NASA Astrophysics Data System (ADS)

Ma, Yang; Wu, Congjun; Xu, Zhihao; Wang, Fei; Wang, Min

2018-05-01

Photoconductor arrays with both high responsivity and large ON/OFF ratios are of great importance for the application of image sensors. Herein, a ZnO vertical nanorod array based photoconductor with a light absorption layer separated from the device channel has been designed, in which the photo-generated carriers along the axial ZnO nanorods drive to the external electrodes through nanorod-nanorod junctions in the dense layer at the bottom. This design allows us to enhance the photocurrent with unchanged dark current by increasing the ratio between the ZnO nanorod length and the thickness of the dense layer to achieve both high responsivity and large ON/OFF ratios. As a result, the as-fabricated devices possess a high responsivity of 1.3 × 105 A/W, a high ON/OFF ratio of 790, a high detectivity of 1.3 × 1013 Jones, and a low detectable light intensity of 1 μW/cm2. More importantly, the developed approach enables the integration of ZnO vertical nanorod array based photodetectors as image sensors with uniform device-to-device performance.

ZnO nanowire-based light-emitting diodes with tunable emission from near-UV to blue

NASA Astrophysics Data System (ADS)

Pauporté, Thierry; Lupan, Oleg; Viana, Bruno; le Bahers, T.

2013-03-01

Nanowires (NWs)-based light emitting diodes (LEDs) have drawn large interest due to many advantages compared to thin film based devices. We have successfully prepared epitaxial n-ZnO(NW)/p-GaN heterojunctions using low temperature soft electrochemical techniques. The structures have been used in LED devices and exhibited highly interesting performances. Moreover, the bandgap of ZnO has been tuned by Cu or Cd doping at controlled atomic concentration. A result was the controlled shift of the LED emission in the visible spectral wavelength region. Using DFT computing calculations, we have also shown that the bandgap narrowing has two different origins for Zn1-xCdxO (ZnO:Cd) and ZnO:Cu. In the first case, it is due to the crystal lattice expansion, whereas in the second case Cu-3d donor and Cu-3d combined to O-2p acceptor bands appear in the bandgap which broadnesses increase with the dopant concentration. This leads to the bandgap reduction.

Nanowire-nanopore transistor sensor for DNA detection during translocation

NASA Astrophysics Data System (ADS)

Xie, Ping; Xiong, Qihua; Fang, Ying; Qing, Quan; Lieber, Charles

2011-03-01

Nanopore sequencing, as a promising low cost, high throughput sequencing technique, has been proposed more than a decade ago. Due to the incompatibility between small ionic current signal and fast translocation speed and the technical difficulties on large scale integration of nanopore for direct ionic current sequencing, alternative methods rely on integrated DNA sensors have been proposed, such as using capacitive coupling or tunnelling current etc. But none of them have been experimentally demonstrated yet. Here we show that for the first time an amplified sensor signal has been experimentally recorded from a nanowire-nanopore field effect transistor sensor during DNA translocation. Independent multi-channel recording was also demonstrated for the first time. Our results suggest that the signal is from highly localized potential change caused by DNA translocation in none-balanced buffer condition. Given this method may produce larger signal for smaller nanopores, we hope our experiment can be a starting point for a new generation of nanopore sequencing devices with larger signal, higher bandwidth and large-scale multiplexing capability and finally realize the ultimate goal of low cost high throughput sequencing.

Light-Addressable Potentiometric Sensors using ZnO Nanorods as the Sensor Substrate for Bioanalytical Applications.

PubMed

Tu, Ying; Ahmad, Norlaily; Briscoe, Joe; Zhang, De-Wen; Krause, Steffi

2018-06-22

Light-addressable potentiometric sensors (LAPS) are of great interest in bioimaging applications such as the monitoring of concentrations in microfluidic channels or the investigation of metabolic and signaling events in living cells. By measuring the photocurrents at electrolyte-insulator-semiconductor (EIS) and electrolyte-semiconductor structures, LAPS can produce spatiotemporal images of chemical or biological analytes, electrical potentials and impedance. However, its commercial applications are often restricted by their limited AC photocurrents and resolution of LAPS images. Herein, for the first time, the use of 1D semiconducting oxides in the form of ZnO nanorods for LAPS imaging is explored to solve this issue. A significantly increased AC photocurrent with enhanced image resolution has been achieved based on ZnO nanorods, with a photocurrent of 45.7 ± 0.1 nA at a light intensity of 0.05 mW, a lateral resolution as low as 3.0 μm as demonstrated by images of a PMMA dot on ZnO nanorods and a pH sensitivity of 53 mV/pH. The suitability of the device for bioanalysis and bioimaging was demonstrated by monitoring the degradation of a thin poly(ester amide) film with the enzyme α-chymotrypsin using LAPS. This simple and robust route to fabricate LAPS substrates with excellent performance would provide tremendous opportunities for bioimaging.

Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

NASA Technical Reports Server (NTRS)

Sodano, Henry A.; Brett, Robert

2011-01-01

The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

Highly sensitive refractive index sensor based on a TiO₂ nanowire array.

PubMed

Li, Qiu-Shun; Xiang, Dong; Chang, Zhi-Min; Shi, Jian-Guo; Ma, Yao-Hong; Cai, Lei; Feng, Dong; Dong, Wen-Fei

2017-03-01

We propose a novel, highly sensitive refractive index (RI) sensor by means of combining the Kretschmann prism with a TiO₂ nanowire array and do not use a metallic layer in the Kretschmann configuration. Its RI sensing performance was investigated through measuring different concentrations of sodium chloride solution. Experimental results showed that, with increasing RI of liquid, the resonant wavelength in the reflectance spectrum redshifted gradually in the visible light range. There was a very good linear relationship between resonant wavelength and RI in the range of 1.3330 to 1.3546. More importantly, in contrast to the surface plasmon resonance (SPR) sensor, the interferometric sensors showed higher sensitivity to the external RI. In the case of the transverse magnetic mode, the RI sensitivity is up to 320,700.93 a.u./RIU (refractive index unit) by expression of light intensity, which is 9.55 times that of the SPR sensor. As for the transverse electric mode, it achieves 4371.76 nm/RIU by expression of the resonant wavelength, which is increased by a factor of 1.4 in comparison with the SPR sensor. Moreover, the experimental results have favorable repeatability. A TiO₂ nanowire array sensor has also other advantages, such as easy manufacturing, low cost, and in situ determination, etc. To our knowledge, this fact is reported for the first time. It has great potential applications in the field of biological and chemical sensing.

One step biofunctionalized electrospun multiwalled carbon nanotubes embedded zinc oxide nanowire interface for highly sensitive detection of carcinoma antigen-125.

PubMed

Paul, K Brince; Singh, Vikrant; Vanjari, Siva Rama Krishna; Singh, Shiv Govind

2017-02-15

Ovarian cancer is the most leading cause of cancer-related death in women . The carcinoma antigen-125, which is found on the surface of many ovarian cancer cells is known to be a gold standard clinical biomarker associated with life-threatening gynecological malignancy. In this work, we demonstrate a novel biosensor platform based on multiwalled carbon nanotubes embedded zinc oxide nanowire for the ultrasensitive detection of carcinoma antigen-125. Label free detection of the carcinoma antigen-125 was accomplished by differential voltammetry technique that demonstrated excellent sensitivity (90.14µA/(U/mL)/cm 2 ) with a detection limit of 0.00113UmL -1 concentration. The fabricated immunosensor exhibits good performance with wider detection range (0.001UmL -1 -1kUmL -1 ), reproducibility, selectivity, acceptable stability, and thus is a potential cost-effective methodology for point-of-care diagnosis. The multiwalled carbon nanotubes (MWCNTs) embedded highly oriented zinc oxide (ZnO) nanowires were synthesized by simple, low cost electrospinning technique. Compared to pure ZnO nanowires, electrochemical activity of MWCNTs embedded ZnO nanowires was found to be much higher. The calcination temperature was optimized to avoid any decomposition of the CNTs and to obtain multiwalled carbon nanotubes embedded highly crystalline ZnO nanowires. The salient feature of this biosensing platform is that one step calcination process is enough to create the functional groups on MWCNT-ZnO nanowire surface that are effective for the covalent conjugation of antibody without further surface modification. To the best of our knowledge, this is the first report on MWCNT-ZnO nanowire based immunosensor explored for the detection of cancer biomarker. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of Cu doping on the mechanical and optical properties of zinc oxide nanowires synthesized by hydrothermal route.

PubMed

Robak, Elżbieta; Coy, Emerson; Kotkowiak, Michał; Jurga, Stefan; Załęski, Karol; Drozdowski, Henryk

2016-04-29

Zinc oxide (ZnO) is a wide-bandgap semiconductor material with applications in a variety of fields such as electronics, optoelectronic and solar cells. However, much of these applications demand a reproducible, reliable and controllable synthesis method that takes special care of their functional properties. In this work ZnO and Cu-doped ZnO nanowires are obtained by an optimized hydrothermal method, following the promising results which ZnO nanostructures have shown in the past few years. The morphology of as-prepared and copper-doped ZnO nanostructures is investigated by means of scanning electron microscopy and high resolution transmission electron microscopy. X-ray diffraction is used to study the impact of doping on the crystalline structure of the wires. Furthermore, the mechanical properties (nanoindentation) and the functional properties (absorption and photoluminescence measurements) of ZnO nanostructures are examined in order to assess their applicability in photovoltaics, piezoelectric and hybrids nanodevices. This work shows a strong correlation between growing conditions, morphology, doping and mechanical as well as optical properties of ZnO nanowires.

Enhanced photoluminescence and field-emission behavior of vertically well aligned arrays of In-doped ZnO Nanowires.

PubMed

Ahmad, Mashkoor; Sun, Hongyu; Zhu, Jing

2011-04-01

Vertically oriented well-aligned Indium doped ZnO nanowires (NWs) have been successfully synthesized on Au-coated Zn substrate by controlled thermal evaporation. The effect of indium dopant on the optical and field-emission properties of these well-aligned ZnO NWs is investigated. The doped NWs are found to be single crystals grown along the c-axis. The composition of the doped NWs is confirmed by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and X-ray photospectroscopy (XPS). The photoluminescence (PL) spectra of doped NWs having a blue-shift in the UV region show a prominent tuning in the optical band gap, without any significant peak relating to intrinsic defects. The turn-on field of the field emission is found to be ∼2.4 V μm(-1) and an emission current density of 1.13 mA cm(-2) under the field of 5.9 V μm(-1). The field enhancement factor β is estimated to be 9490 ± 2, which is much higher than that of any previous report. Furthermore, the doped NWs exhibit good emission current stability with a variation of less than 5% during a 200 s under a field of 5.9 V μm(-1). The superior field emission properties are attributed to the good alignment, high aspect ratio, and better crystallinity of In-doped NWs. © 2011 American Chemical Society

Giant piezoelectric size effects in zinc oxide and gallium nitride nanowires. A first principles investigation.

PubMed

Agrawal, Ravi; Espinosa, Horacio D

2011-02-09

Nanowires made of materials with noncentrosymmetric crystal structure are under investigation for their piezoelectric properties and suitability as building blocks for next-generation self-powered nanodevices. In this work, we investigate the size dependence of piezoelectric coefficients in nanowires of two such materials - zinc oxide and gallium nitride. Nanowires, oriented along their polar axis, ranging from 0.6 to 2.4 nm in diameter were modeled quantum mechanically. A giant piezoelectric size effect is identified for both GaN and ZnO nanowires. However, GaN exhibits a larger and more extended size dependence than ZnO. The observed size effect is discussed in the context of charge redistribution near the free surfaces leading to changes in local polarization. The study reveals that local changes in polarization and reduction of unit cell volume with respect to bulk values lead to the observed size effect. These results have strong implication in the field of energy harvesting, as piezoelectric voltage output scales with the piezoelectric coefficient.

Gold nanowire assembling architecture for H2O2 electrochemical sensor.

PubMed

Guo, Shaojun; Wen, Dan; Dong, Shaojun; Wang, Erkang

2009-02-15

Morphological control of nanomaterials is of great interest due to their size and shape-dependent chemical and physical properties and very important applications in many fields such as biomedicine, sensors, electronics and others. In this paper, we reported a simple strategy for synthesizing gold nanowire assembling architecture at room temperature. It is found that two important factors, the proper volume ratio of ethanol to water and poly(vinyl pyrrolidone) (PVP), will play important roles in synthesizing flower-like short gold nanowire assembling spheres. Furthermore, the obtained flower-like gold assembling spheres with high surface-to-volume ratio have been employed as enhancing materials for electrochemical sensing H(2)O(2). The present electrochemical sensing platform exhibited good electrocatalytic activity towards the reduction of H(2)O(2). The detection limit for H(2)O(2) was found to be 1.2 microM, which was lower than certain enzyme-based biosensors.

Improvement of electroluminescence performance by integration of ZnO nanowires and single-crystalline films on ZnO/GaN heterojunction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zhifeng; Zhang, Yuantao, E-mail: zhangyt@jlu.edu.cn; Cui, Xijun

2014-03-31

Heterojunction light-emitting diodes based on n-ZnO nanowires/ZnO single-crystalline films/p-GaN structure have been demonstrated for an improved electroluminescence performance. A highly efficient ultraviolet emission was observed under forward bias. Compared with conventional n-ZnO/p-GaN structure, high internal quantum efficiency and light extraction efficiency were simultaneously considered in the proposed diode. In addition, the diode can work continuously for ∼10 h with only a slight degradation in harsh environments, indicating its good reliability and application prospect in the future. This route opens possibilities for the development of advanced nanoscale devices in which the advantages of ZnO single-crystalline films and nanostructures can be integrated together.

Quantum-interference transport through surface layers of indium-doped ZnO nanowires.

PubMed

Chiu, Shao-Pin; Lu, Jia Grace; Lin, Juhn-Jong

2013-06-21

We have fabricated indium-doped ZnO (IZO) nanowires (NWs) and carried out four-probe electrical-transport measurements on two individual NWs with geometric diameters of ≈70 and ≈90 nm in a wide temperature T interval of 1-70 K. The NWs reveal overall charge conduction behavior characteristic of disordered metals. In addition to the T dependence of resistance R, we have measured the magnetoresistance (MR) in magnetic fields applied either perpendicular or parallel to the NW axis. Our R(T) and MR data in different T intervals are consistent with the theoretical predictions of the one- (1D), two- (2D) or three-dimensional (3D) weak-localization (WL) and the electron-electron interaction (EEI) effects. In particular, a few dimensionality crossovers in the two effects are observed. These crossover phenomena are consistent with the model of a 'core-shell-like structure' in individual IZO NWs, where an outer shell of thickness t (~15-17 nm) is responsible for the quantum-interference transport. In the WL effect, as the electron dephasing length Lφ gradually decreases with increasing T from the lowest measurement temperatures, a 1D-to-2D dimensionality crossover takes place around a characteristic temperature where Lφ approximately equals d, an effective NW diameter which is slightly smaller than the geometric diameter. As T further increases, a 2D-to-3D dimensionality crossover occurs around another characteristic temperature where Lφ approximately equals t (ZnO NWs. This work also strongly

Composition and Band Gap Tailoring of Crystalline (GaN)1- x(ZnO) x Solid Solution Nanowires for Enhanced Photoelectrochemical Performance.

PubMed

Li, Jing; Liu, Baodan; Wu, Aimin; Yang, Bing; Yang, Wenjin; Liu, Fei; Zhang, Xinglai; An, Vladimir; Jiang, Xin

2018-05-07

Photoelectrochemical water splitting has emerged as an effective artificial photosynthesis technology to generate clean energy of H 2 from sunlight. The core issue in this reaction system is to develop a highly efficient photoanode with a large fraction of solar light absorption and greater active surface area. In this work, we take advantage of energy band engineering to synthesize (GaN) 1- x (ZnO) x solid solution nanowires with ZnO contents ranging from 10.3% to 47.6% and corresponding band gap tailoring from 3.08 to 2.77 eV on the basis of the Au-assisted VLS mechanism. The morphology of nanowires directly grown on the conductive substrate facilitates the charge transfer and simultaneously improves the surface reaction sites. As a result, a photocurrent approximately 10 times larger than that for a conventional powder-based photoanode is obtained, which indicates the potential of (GaN) 1- x (ZnO) x nanowires in the preparation of superior photoanodes for enhanced water splitting. It is anticipated that the water-splitting capability of (GaN) 1- x (ZnO) x nanowire can be further increased through alignment control for enhanced visible light absorption and reduction of charge transfer resistance.

A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

2012-03-01

A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ~1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures.

PubMed

Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

2012-04-21

A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ∼1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

Recent advances in large-scale assembly of semiconducting inorganic nanowires and nanofibers for electronics, sensors and photovoltaics.

PubMed

Long, Yun-Ze; Yu, Miao; Sun, Bin; Gu, Chang-Zhi; Fan, Zhiyong

2012-06-21

Semiconducting inorganic nanowires (NWs), nanotubes and nanofibers have been extensively explored in recent years as potential building blocks for nanoscale electronics, optoelectronics, chemical/biological/optical sensing, and energy harvesting, storage and conversion, etc. Besides the top-down approaches such as conventional lithography technologies, nanowires are commonly grown by the bottom-up approaches such as solution growth, template-guided synthesis, and vapor-liquid-solid process at a relatively low cost. Superior performance has been demonstrated using nanowires devices. However, most of the nanowire devices are limited to the demonstration of single devices, an initial step toward nanoelectronic circuits, not adequate for production on a large scale at low cost. Controlled and uniform assembly of nanowires with high scalability is still one of the major bottleneck challenges towards the materials and device integration for electronics. In this review, we aim to present recent progress toward nanowire device assembly technologies, including flow-assisted alignment, Langmuir-Blodgett assembly, bubble-blown technique, electric/magnetic- field-directed assembly, contact/roll printing, planar growth, bridging method, and electrospinning, etc. And their applications in high-performance, flexible electronics, sensors, photovoltaics, bioelectronic interfaces and nano-resonators are also presented.

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

PubMed Central

Ramachandran, K.; Raj kumar, T.; Babu, K. Justice; Gnana kumar, G.

2016-01-01

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM−1 cm−2, low detection limit of 1.2 μM, a wide linear range from 5 μM–10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability. PMID:27833123

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

NASA Astrophysics Data System (ADS)

Ramachandran, K.; Raj Kumar, T.; Babu, K. Justice; Gnana Kumar, G.

2016-11-01

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM-1 cm-2, low detection limit of 1.2 μM, a wide linear range from 5 μM-10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability.

Doping Ag in ZnO Nanorods to Improve the Performance of Related Enzymatic Glucose Sensors.

PubMed

Zhou, Fan; Jing, Weixuan; Liu, Pengcheng; Han, Dejun; Jiang, Zhuangde; Wei, Zhengying

2017-09-27

In this paper, the performance of a zinc oxide (ZnO) nanorod-based enzymatic glucose sensor was enhanced with silver (Ag)-doped ZnO (ZnO-Ag) nanorods. The effect of the doped Ag on the surface morphologies, wettability, and electron transfer capability of the ZnO-Ag nanorods, as well as the catalytic character of glucose oxidase (GOx) and the performance of the glucose sensor was investigated. The results indicate that the doped Ag slightly weakens the surface roughness and hydrophilicity of the ZnO-Ag nanorods, but remarkably increases their electron transfer ability and enhances the catalytic character of GOx. Consequently, the combined effects of the above influencing factors lead to a notable improvement of the performance of the glucose sensor, that is, the sensitivity increases and the detection limit decreases. The optimal amount of the doped Ag is determined to be 2 mM, and the corresponding glucose sensor exhibits a sensitivity of 3.85 μA/(mM·cm²), detection limit of 1.5 μM, linear range of 1.5 × 10 -3 -6.5 mM, and Michaelis-Menten constant of 3.87 mM. Moreover, the glucose sensor shows excellent selectivity to urea, ascorbic acid, and uric acid, in addition to displaying good storage stability. These results demonstrate that ZnO-Ag nanorods are promising matrix materials for the construction of other enzymatic biosensors.

Doping Ag in ZnO Nanorods to Improve the Performance of Related Enzymatic Glucose Sensors

PubMed Central

Zhou, Fan; Jing, Weixuan; Liu, Pengcheng; Han, Dejun; Jiang, Zhuangde; Wei, Zhengying

2017-01-01

In this paper, the performance of a zinc oxide (ZnO) nanorod-based enzymatic glucose sensor was enhanced with silver (Ag)-doped ZnO (ZnO-Ag) nanorods. The effect of the doped Ag on the surface morphologies, wettability, and electron transfer capability of the ZnO-Ag nanorods, as well as the catalytic character of glucose oxidase (GOx) and the performance of the glucose sensor was investigated. The results indicate that the doped Ag slightly weakens the surface roughness and hydrophilicity of the ZnO-Ag nanorods, but remarkably increases their electron transfer ability and enhances the catalytic character of GOx. Consequently, the combined effects of the above influencing factors lead to a notable improvement of the performance of the glucose sensor, that is, the sensitivity increases and the detection limit decreases. The optimal amount of the doped Ag is determined to be 2 mM, and the corresponding glucose sensor exhibits a sensitivity of 3.85 μA/(mM·cm2), detection limit of 1.5 μM, linear range of 1.5 × 10−3–6.5 mM, and Michaelis-Menten constant of 3.87 mM. Moreover, the glucose sensor shows excellent selectivity to urea, ascorbic acid, and uric acid, in addition to displaying good storage stability. These results demonstrate that ZnO-Ag nanorods are promising matrix materials for the construction of other enzymatic biosensors. PMID:28953217

Flexible piezotronic strain sensor.

PubMed

Zhou, Jun; Gu, Yudong; Fei, Peng; Mai, Wenjie; Gao, Yifan; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

2008-09-01

Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I- V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

Wearable, wireless gas sensors using highly stretchable and transparent structures of nanowires and graphene.

PubMed

Park, Jihun; Kim, Joohee; Kim, Kukjoo; Kim, So-Yun; Cheong, Woon Hyung; Park, Kyeongmin; Song, Joo Hyeb; Namgoong, GyeongHo; Kim, Jae Joon; Heo, Jaeyeong; Bien, Franklin; Park, Jang-Ung

2016-05-19

Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the 'Internet of Things' area.

Enhancing UV photoconductivity of ZnO nanobelt by polyacrylonitrile functionalization

NASA Astrophysics Data System (ADS)

He, J. H.; Lin, Yen H.; McConney, Michael E.; Tsukruk, Vladimir V.; Wang, Zhong L.; Bao, Gang

2007-10-01

UV photodetector fabricated using a single ZnO nanobelt (NB) has shown a photoresponse enhancement up to 750 times higher than that of a bare ZnO NB after coating with ˜20nm plasma polymerized acrylonitrile (PP-AN) nanoscale film. The mechanism for this colossal photoconductivity is suggested as a consequence of the efficient exciton dissociation under UV illumination due to enhanced electron transfer from valence band of ZnO NB to the PP-AN and then back to the conduction band of ZnO. This process has demonstrated an easy and effective method for improving the performance of the nanowire/NB-based devices, possibly leading to supersensitive UV detector for applications in imaging, photosensing, and intrachip optical interconnects.

A label-free electrochemical sensor for detection of mercury(II) ions based on the direct growth of guanine nanowire.

PubMed

Huang, Yan Li; Gao, Zhong Feng; Jia, Jing; Luo, Hong Qun; Li, Nian Bing

2016-05-05

A simple, sensitive and label-free electrochemical sensor is developed for detection of Hg(2+) based on the strong and stable T-Hg(2+)-T mismatches. In the presence of Mg(2+), the parallel G-quadruplex structures could be specifically recognized and precipitated in parallel conformation. Therefore, the guanine nanowire was generated on the electrode surface, triggering the electrochemical H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). In this research, a new method of signal amplification for the quantitative detection of Hg(2+) was described based on the direct growth of guanine nanowire via guanine nanowire. Under optimum conditions, Hg(2+) was detected in the range of 100 pM-100 nM, and the detection limit is 33 pM. Compared to the traditional single G-quadruplex label unit, this electrochemical sensor showed high sensitivity and selectivity for detecting Hg(2+). Copyright © 2016 Elsevier B.V. All rights reserved.

Ionic pH and glucose sensors fabricated using hydrothermal ZnO nanostructures

NASA Astrophysics Data System (ADS)

Wang, Jyh-Liang; Yang, Po-Yu; Hsieh, Tsang-Yen; Juan, Pi-Chun

2016-01-01

Hydrothermally synthesized aluminum-doped ZnO (AZO) nanostructures have been adopted in extended-gate field-effect transistor (EGFET) sensors to demonstrate the sensitive and stable pH and glucose sensing characteristics of AZO-nanostructured EGFET sensors. The AZO-nanostructured EGFET sensors exhibited the following superior pH sensing characteristics: a high current sensitivity of 0.96 µA1/2/pH, a high linearity of 0.9999, less distortion of output waveforms, a small hysteresis width of 4.83 mV, good long-term repeatability, and a wide sensing range from pHs 1 to 13. The glucose sensing characteristics of AZO-nanostructured biosensors exhibited the desired sensitivity of 60.5 µA·cm-2·mM-1 and a linearity of 0.9996 up to 13.9 mM. The attractive characteristics of high sensitivity, high linearity, and repeatability of using ionic AZO-nanostructured EGFET sensors indicate their potential use as electrochemical and disposable biosensors.

Fabrication of lateral electrodes on semiconductor nanowires through structurally matched insulation for functional optoelectronics.

PubMed

Sheng, Yun; Sun, Huabin; Wang, Jianyu; Gao, Fan; Wang, Junzhuan; Pan, Lijia; Pu, Lin; Zheng, Youdou; Shi, Yi

2013-01-18

A strategy of using structurally matched alumina insulation to produce lateral electrodes on semiconductor nanowires is presented. Nanowires in the architecture are structurally matched with alumina insulation using selective anodic oxidation. Lateral electrodes are fabricated by directly evaporating metallic atoms onto the opposite sides of the nanowires. The integrated architecture with lateral electrodes propels carriers to transport them across nanowires and is crucially beneficial to the injection/extraction in optoelectronics. The matched architecture and the insulating properties of the alumina layer are investigated experimentally. ZnO nanowires are functionalized into an ultraviolet photodiode as an example. The present strategy successfully implements an advantageous architecture and is significant in developing diverse semiconductor nanowires in optoelectronic applications.

Pt/ZnO nanoarray nanogenerator as self-powered active gas sensor with linear ethanol sensing at room temperature.

PubMed

Zhao, Yayu; Lai, Xuan; Deng, Ping; Nie, Yuxin; Zhang, Yan; Xing, Lili; Xue, Xinyu

2014-03-21

A self-powered gas sensor that can actively detect ethanol at room temperature has been realized from a Pt/ZnO nanoarray nanogenerator. Pt nanoparticles are uniformly distributed on the whole surface of ZnO nanowires. The piezoelectric output of Pt/ZnO nanoarrays can act not only as a power source, but also as a response signal to ethanol at room temperature. Upon exposure to dry air and 1500 ppm ethanol at room temperature, the piezoelectric output of the device under the same compressive strain is 0.672 and 0.419 V, respectively. Moreover, a linear dependence of the sensitivity on the ethanol concentration is observed. Such a linear ethanol sensing at room temperature can be attributed to the atmosphere-dependent variety of the screen effect on the piezoelectric output of ZnO nanowires, the catalytic properties of Pt nanoparticles, and the Schottky barriers at Pt/ZnO interfaces. The present results can stimulate research in the direction of designing new material systems for self-powered room-temperature gas sensing.

In situ TEM probing of crystallization form-dependent sodiation behavior in ZnO nanowires for sodium-ion batteries

DOE PAGES

Xu, Feng; Li, Zhengrui; Wu, Lijun; ...

2016-09-13

Development of sodium-ion battery (SIB) electrode materials currently lags behind electrodes in commercial lithium-ion batteries (LIBs). However, in the long term, development of SIB components is a valuable goal. Their similar, but not identical, chemistries require careful identification of the underlying sodiation mechanism in SIBs. Here in this study, we utilize in situ transmission electron microscopy to explore quite different sodiation behaviors even in similar electrode materials through real-time visualization of microstructure and phase evolution. Upon electrochemical sodiation, single-crystalline ZnO nanowires (sc-ZNWs) are found to undergo a step-by-step electrochemical displacement reaction, forming crystalline NaZn 13 nanograins dispersed in a Namore » 2O matrix. This process is characterized by a slowly propagating reaction front and the formation of heterogeneous interfaces inside the ZNWs due to non-uniform sodiation amorphization. In contrast, poly-crystalline ZNWs (pc-ZNWs) exhibited an ultrafast sodiation process, which can partly be ascribed to the availability of unobstructed ionic transport pathways among ZnO nanograins. Thus the reaction front and heterogeneous interfaces disappear. The in situ TEM results, supported by calculation of the ion diffusion coefficient, provide breakthrough insights into the dependence of ion diffusion kinetics on crystallization form. This points toward a goal of optimizing the microstructure of electrode materials in order to develop high performance SIBs.« less

Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future.

PubMed

Fennell, John F; Liu, Sophie F; Azzarelli, Joseph M; Weis, Jonathan G; Rochat, Sébastien; Mirica, Katherine A; Ravnsbæk, Jens B; Swager, Timothy M

2016-01-22

Chemiresistive sensors are becoming increasingly important as they offer an inexpensive option to conventional analytical instrumentation, they can be readily integrated into electronic devices, and they have low power requirements. Nanowires (NWs) are a major theme in chemosensor development. High surface area, interwire junctions, and restricted conduction pathways give intrinsically high sensitivity and new mechanisms to transduce the binding or action of analytes. This Review details the status of NW chemosensors with selected examples from the literature. We begin by proposing a principle for understanding electrical transport and transduction mechanisms in NW sensors. Next, we offer the reader a review of device performance parameters. Then, we consider the different NW types followed by a summary of NW assembly and different device platform architectures. Subsequently, we discuss NW functionalization strategies. Finally, we propose future developments in NW sensing to address selectivity, sensor drift, sensitivity, response analysis, and emerging applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fast response of carbon monoxide gas sensors using a highly porous network of ZnO nanoparticles decorated on 3D reduced graphene oxide

NASA Astrophysics Data System (ADS)

Ha, Nguyen Hai; Thinh, Dao Duc; Huong, Nguyen Thanh; Phuong, Nguyen Huy; Thach, Phan Duy; Hong, Hoang Si

2018-03-01

Zinc oxide (ZnO) nanoparticles loaded onto 3D reduced graphene oxide (3D-RGO) for carbon monoxide (CO) sensing were synthesized using hydrothermal method. The highly porous ZnO/3D-RGO configuration was stable without collapsing and was deposited on the micro-heater of the CO gas sensor. The resulting CO gas sensor displayed high sensitivity, fast response/recovery, and good linearity. The sensor achieved a response value of 85.2% for 1000 ppm CO at a working temperature of 200 °C. The response and recovery times of the sensor were 7 and 9 s for 1000 ppm CO at 200 °C. Similarly, the response value, response time, and recovery time of the sensor at room temperature were 27.5%, 14 s, and 15 s, respectively. The sensor demonstrated a distinct response to various CO concentrations in the range of 1-1000 ppm and good selectivity toward CO gas. In addition, the sensor exhibited good repeatability in multi-cycle and long-term stability.

Nanowire-based detector

DOEpatents

Berggren, Karl K; Hu, Xiaolong; Masciarelli, Daniele

2014-06-24

Systems, articles, and methods are provided related to nanowire-based detectors, which can be used for light detection in, for example, single-photon detectors. In one aspect, a variety of detectors are provided, for example one including an electrically superconductive nanowire or nanowires constructed and arranged to interact with photons to produce a detectable signal. In another aspect, fabrication methods are provided, including techniques to precisely reproduce patterns in subsequently formed layers of material using a relatively small number of fabrication steps. By precisely reproducing patterns in multiple material layers, one can form electrically insulating materials and electrically conductive materials in shapes such that incoming photons are redirected toward a nearby electrically superconductive materials (e.g., electrically superconductive nanowire(s)). For example, one or more resonance structures (e.g., comprising an electrically insulating material), which can trap electromagnetic radiation within its boundaries, can be positioned proximate the nanowire(s). The resonance structure can include, at its boundaries, electrically conductive material positioned proximate the electrically superconductive nanowire such that light that would otherwise be transmitted through the sensor is redirected toward the nanowire(s) and detected. In addition, electrically conductive material can be positioned proximate the electrically superconductive nanowire (e.g. at the aperture of the resonant structure), such that light is directed by scattering from this structure into the nanowire.

Porous Silicon Nanowires

PubMed Central

Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

2011-01-01

In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline porous silicon nanowires. The growth of porous silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The porous silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999

As-Grown Gallium Nitride Nanowire Electromechanical Resonators

NASA Astrophysics Data System (ADS)

Montague, Joshua R.

Technological development in recent years has led to a ubiquity of micro- and nano-scale electromechanical devices. Sensors for monitoring temperature, pressure, mass, etc., are now found in nearly all electronic devices at both the industrial and consumer levels. As has been true for integrated circuit electronics, these electromechanical devices have continued to be scaled down in size. For many nanometer-scale structures with large surface-to-volume ratio, dissipation (energy loss) becomes prohibitively large causing a decreasing sensitivity with decreasing sensor size. In this work, gallium nitride (GaN) nanowires are investigated as singly-clamped (cantilever) mechanical resonators with typical mechanical quality factors, Q (equal to the ratio of resonance frequency to peak full-width-at-half-maximum-power) and resonance frequencies, respectively, at or above 30,000, and near 1 MHz. These Q values---in vacuum at room temperature---indicate very low levels of dissipation; they are essentially the same as those for bulk quartz crystal resonators that form the basis of simple clocks and mass sensors. The GaN nanowires have lengths and diameters, respectively, of approximately 15 micrometers and hundreds of nanometers. As-grown GaN nanowire Q values are larger than other similarly-sized, bottom-up, cantilever resonators and this property makes them very attractive for use as resonant sensors. We demonstrate the capability of detecting sub-monolayer levels of atomic layer deposited (ALD) films, and the robust nature of the GaN nanowires structure that allows for their 'reuse' after removal of such layers. In addition to electron microscope-based measurement techniques, we demonstrate the successful capacitive detection of a single nanowire using microwave homodyne reflectometry. This technique is then extended to allow for simultaneous measurements of large ensembles of GaN nanowires on a single sample, providing statistical information about the distribution of

Preparation and characterization of ALD deposited ZnO thin films studied for gas sensors

NASA Astrophysics Data System (ADS)

Boyadjiev, S. I.; Georgieva, V.; Yordanov, R.; Raicheva, Z.; Szilágyi, I. M.

2016-11-01

Applying atomic layer deposition (ALD), very thin zinc oxide (ZnO) films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The gas sensing of the ZnO films to NO2 was tested in the concentration interval between 10 and 5000 ppm. On the basis of registered frequency change of the QCM, for each concentration the sorbed mass was calculated. Further characterization of the films was carried out by various techniques, i.e. by SEM-EDS, XRD, ellipsometry, and FTIR spectroscopy. Although being very thin, the films were gas sensitive to NO2 already at room temperature and could register very well as low concentrations as 100 ppm, while the sorption was fully reversible. Our results for very thin ALD ZnO films show that the described fast, simple and cost-effective technology could be implemented for producing gas sensors working at room temperature and being capable to detect in real time low concentrations of NO2.

Annealing Temperature Dependence of ZnO Nanostructures Grown by Facile Chemical Bath Deposition for EGFET pH Sensors

NASA Astrophysics Data System (ADS)

Bazilah Rosli, Aimi; Awang, Zaiki; Sobihana Shariffudin, Shafinaz; Herman, Sukreen Hana

2018-03-01

Zinc Oxide (ZnO) nanostructures were deposited using chemical bath deposition (CBD) technique in water bath at 95 °C for 4 h. Post-deposition heat treatment in air ambient at various temperature ranging from 200-600 °C for 30 min was applied in order to enhance the electrical properties of ZnO nanostructures as the sensing membrane of extended-gate field effect transistor (EGFET) pH sensor. The as-deposited sample was prepared for comparison. The samples were characterized in terms of physical and sensing properties. FESEM images showed that scattered ZnO nanorods were formed for the as-deposited sample, and the morphology of the ZnO nanorods changed to ZnO nanoflowers when the heat treatment was applied from 200-600 °C. For sensing properties, the samples heated at 300 °C showed the higher sensitivity which was 39.9 mV/pH with the linearity of 0.9792. The sensing properties was increased with the increasing annealing treatment temperature up to 300 °C before decreased drastically.

Quantum-interference transport through surface layers of indium-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Chiu, Shao-Pin; Lu, Jia Grace; Lin, Juhn-Jong

2013-06-01

We have fabricated indium-doped ZnO (IZO) nanowires (NWs) and carried out four-probe electrical-transport measurements on two individual NWs with geometric diameters of ≈70 and ≈90 nm in a wide temperature T interval of 1-70 K. The NWs reveal overall charge conduction behavior characteristic of disordered metals. In addition to the T dependence of resistance R, we have measured the magnetoresistance (MR) in magnetic fields applied either perpendicular or parallel to the NW axis. Our R(T) and MR data in different T intervals are consistent with the theoretical predictions of the one- (1D), two- (2D) or three-dimensional (3D) weak-localization (WL) and the electron-electron interaction (EEI) effects. In particular, a few dimensionality crossovers in the two effects are observed. These crossover phenomena are consistent with the model of a ‘core-shell-like structure’ in individual IZO NWs, where an outer shell of thickness t (≃15-17 nm) is responsible for the quantum-interference transport. In the WL effect, as the electron dephasing length Lφ gradually decreases with increasing T from the lowest measurement temperatures, a 1D-to-2D dimensionality crossover takes place around a characteristic temperature where Lφ approximately equals d, an effective NW diameter which is slightly smaller than the geometric diameter. As T further increases, a 2D-to-3D dimensionality crossover occurs around another characteristic temperature where Lφ approximately equals t (ZnO NWs. This work also strongly

Monolithic Integration of a Silicon Nanowire Field-Effect Transistors Array on a Complementary Metal-Oxide Semiconductor Chip for Biochemical Sensor Applications

PubMed Central

Livi, Paolo; Kwiat, Moria; Shadmani, Amir; Pevzner, Alexander; Navarra, Giulio; Rothe, Jörg; Stettler, Alexander; Chen, Yihui; Patolsky, Fernando; Hierlemann, Andreas

2017-01-01

We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I−V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized nanowire FETs. PMID:26348408

Monolithic integration of a silicon nanowire field-effect transistors array on a complementary metal-oxide semiconductor chip for biochemical sensor applications.

PubMed

Livi, Paolo; Kwiat, Moria; Shadmani, Amir; Pevzner, Alexander; Navarra, Giulio; Rothe, Jörg; Stettler, Alexander; Chen, Yihui; Patolsky, Fernando; Hierlemann, Andreas

2015-10-06

We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I-V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized nanowire FETs.

Bringing order to the world of nanowire devices by phase shift lithography.

PubMed

Subannajui, Kittitat; Güder, Firat; Zacharias, Margit

2011-09-14

Semiconductor nanowire devices have several properties which match future requirements of scaling down the size of electronics. In typical microelectronics production, a number of microstructures are aligned precisely on top of each other during the fabrication process. In the case of nanowires, this mandatory condition is still hard to achieve. A technological breakthrough is needed to accurately place nanowires at any specific position and then form devices in mass production. In this article, an upscalable process combining conventional micromachining with phase shift lithography will be demonstrated as a suitable tool for nanowire device technology. Vertical Si and ZnO nanowires are demonstrated on very large (several cm(2)) areas. We demonstrate how the nanowire positions can be controlled, and the resulting nanowires are used for device fabrication. As an example Si/ZnO heterojunction diode arrays are fabricated. The electrical characterization of the produced devices has also been performed to confirm the functionality of the fabricated diodes.

Surface/Interface Carrier-Transport Modulation for Constructing Photon-Alternative Ultraviolet Detectors Based on Self-Bending-Assembled ZnO Nanowires.

PubMed

Guo, Zhen; Zhou, Lianqun; Tang, Yuguo; Li, Lin; Zhang, Zhiqi; Yang, Hongbo; Ma, Hanbin; Nathan, Arokia; Zhao, Dongxu

2017-09-13

Surface/interface charge-carrier generation, diffusion, and recombination/transport modulation are especially important in the construction of photodetectors with high efficiency in the field of nanoscience. In the paper, a kind of ultraviolet (UV) detector is designed based on ZnO nanostructures considering photon-trapping, surface plasmonic resonance (SPR), piezophototronic effects, interface carrier-trapping/transport control, and collection. Through carefully optimized surface/interface carrier-transport modulation, a designed device with detectivity as high as 1.69 × 10 16 /1.71 × 10 16 cm·Hz 1/2 /W irradiating with 380 nm photons under ultralow bias of 0.2 V is realized by alternating nanoparticle/nanowire active layers, respectively, and the designed UV photodetectors show fast and slow recovery processes of 0.27 and 4.52 ms, respectively, which well-satisfy practical needs. Further, it is observed that UV photodetection could be performed within an alternative response by varying correlated key parameters, through efficient surface/interface carrier-transport modulation, spectrally resolved photoresponse of the detector revealing controlled detection in the UV region based on the ZnO nanomaterial, photodetection allowed or limited by varying the active layers, irradiation distance from one of the electrodes, standing states, or electric field. The detailed carrier generation, diffusion, and recombination/transport processes are well illustrated to explain charge-carrier dynamics contributing to the photoresponse behavior.

Zinc oxide nanowire gamma ray detector with high spatiotemporal resolution

NASA Astrophysics Data System (ADS)

Mayo, Daniel C.; Nolen, J. Ryan; Cook, Andrew; Mu, Richard R.; Haglund, Richard F.

2016-03-01

Conventional scintillation detectors are typically single crystals of heavy-metal oxides or halides doped with rare-earth ions that record the recombination of electron-hole pairs by photon emission in the visible to ultraviolet. However, the light yields are typically low enough to require photomultiplier detection with the attendant instrumental complications. Here we report initial studies of gamma ray detection by zinc oxide (ZnO) nanowires, grown by vapor-solid deposition. The nanowires grow along the c-axis in a wurtzite structure; they are typically 80 nm in diameter and have lengths of 1- 2 μm. The nanowires are single crystals of high quality, with a photoluminescence (PL) yield from band-edge exciton emission in the ultraviolet that is typically one hundred times larger than the PL yield from defect centers in the visible. Nanowire ensembles were irradiated by 662 keV gamma rays from a Cs-137 source for periods of up to ten hours; gamma rays in this energy range interact by Compton scattering, which in ZnO creates F+ centers that relax to form singly-charged positive oxygen vacancies. Following irradiation, we fit the PL spectra of the visible emission with a sum of Gaussians at the energies of the known defects. We find highly efficient PL from the irradiated area, with a figure of merit approaching 106 photons/s/MeV of deposited energy. Over a period of days, the singly charged O+ vacancies relax to the more stable doubly charged O++ vacancies. However, the overall defect PL returns to pre-irradiation values after about a week, as the vacancies diffuse to the surface of these very thin nanowires, indicating that a self-healing process restores the nanowires to their original state.

ZnO nanorod arrays and direct wire bonding on GaN surfaces for rapid fabrication of antireflective, high-temperature ultraviolet sensors

NASA Astrophysics Data System (ADS)

So, Hongyun; Senesky, Debbie G.

2016-11-01

Rapid, cost-effective, and simple fabrication/packaging of microscale gallium nitride (GaN) ultraviolet (UV) sensors are demonstrated using zinc oxide nanorod arrays (ZnO NRAs) as an antireflective layer and direct bonding of aluminum wires to the GaN surface. The presence of the ZnO NRAs on the GaN surface significantly reduced the reflectance to less than 1% in the UV and 4% in the visible light region. As a result, the devices fabricated with ZnO NRAs and mechanically stable aluminum bonding wires (pull strength of 3-5 gf) showed higher sensitivity (136.3% at room temperature and 148.2% increase at 250 °C) when compared with devices with bare (uncoated) GaN surfaces. In addition, the devices demonstrated reliable operation at high temperatures up to 300 °C, supporting the feasibility of simple and cost-effective UV sensors operating with higher sensitivity in high-temperature conditions, such as in combustion, downhole, and space exploration applications.

Stability Enhancement of Silver Nanowire Networks with Conformal ZnO Coatings Deposited by Atmospheric Pressure Spatial Atomic Layer Deposition.

PubMed