In2O3 Nanofibers Research Articles

Low-Temperature Fabrication of Nontoxic Indium Oxide Nanofibers and Their Application in Field-Effect Transistors

In this letter, the water-induced (WI) In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanofibers were prepared by electrospinning using poly(vinyl alcohol) as polymer. The field effect transistors (FETs) based on In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanofibers were integrated, and the annealing dependence of the FETs performance was investigated. It is found that the FET based on WI In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanofibers annealed at 380°C for 1 h (In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -380-1h) exhibits a field-effect mobility (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> ) of 1.53 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs, and an ON/ OFF current ratio (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ) of ~8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> . Interestingly, the electrical performance of the FET based on WI In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanofibers annealed at 280°C for 10 h (In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -280-10h) is comparable with the FET based on In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -380-1h. To further improve the electrical performance of the FETs processed at low temperature, the FET based on In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -280-10h as the channel and the aqueous-route derived ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> as dielectric was integrated. The optimized FET exhibits a μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> of 5.8 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs, an I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> of ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> , and a subthreshold swing (SS) of 150 mV/decade. This nontoxic and fully water-inducement approach is highly expected for the fabrication of low-temperature and flexible circuitry.

Surface functionalization of porous In2O3 nanofibers with Zn nanoparticles for enhanced low-temperature NO2 sensing properties

Different from the dominant method of surface modification of metal oxide sensing materials with noble metals, a simple and low-cost method is developed by using Zn nanoparticles as a surface modifier in this work. The first step involves the fabrication of porous In2O3 nanofibers by an electrospinning technique, and then Zn nanoparticles decorated In2O3 nanofibers are constructed by a simple thermal evaporation method. An increase in surface O2- species absorbing capability and a decrease in sensor resistance are observed by surface modification of In2O3 nanofibers with Zn nanoparticles. In comparison with pure In2O3 nanofibers, this kind of Zn–In2O3 composite nanofibers display higher response and better selectivity to NO2. The response of Zn–In2O3 nanofibers is up to 130.00–5 ppm NO2 at 50 °C, which is 13.7 times higher than that of pure In2O3. From our perspective, the improved NO2 sensing performances of Zn–In2O3 composite nanofibers are mainly attributed to the enhanced resistance modulation because of the formation of ohmic contacts between Zn nanoparticles and In2O3 nanoparticles.

Mechanism and characteristics of Au-functionalized SnO2/In2O3 nanofibers for highly sensitive CO detection

In this study, SnO2 doped In2O3 nanofibers were prepared using an electrospinning method and subjected to a series of analyses using TGA, XRD, SEM, TEM, and XPS. The gold nanoparticles were then sputtered onto nanofibers for use in a carbon monoxide (CO) gas sensor. The gas sensing results show that 4 wt% SnO2 doped In2O3 nanofibers with gold coating for 20 s (gold particle size of about 14 ± 3 nm) have the best CO sensing response. The best CO gas response is 29.2%, with good recovery and reproducibility.

Researching the crystal phase effect on gas sensing performance in In2O3 nanofibers

Phase structure, specific surface area and composition have great influence on the gas sensing performance, however the dominant factor is still unknown. In this study, In2O3 nanofiber (NF) and In2O3 flower-like nanofibers (FNF) with different phase structures, specific surface areas and morphologies are investigated to obtain in-depth understanding of how different factors alters gas sensing performances. In2O3 NF exhibits the best gas sensing performance towards 100 ppm acetone gas at 180 °C with high sensitivity (72), good selectivity and ultra-fast response speed (1 s), while In2O3 FNF shows distinct enhancement of sensing performances toward formaldehyde (14.3 times higher than the sensitivity of In2O3 NF) and obviously decrease in acetone response at 180 °C. Such gas sensing behaviors can be attributed to the difference in the oxidation abilities of chemical absorbed oxygen species induced by the variation of phase structure. Our findings not only promote the understanding of sensing reaction process but also pave a new pathway for the design of high-selectivity gas sensors.

Deposition of In2O3 nanofibers on polyimide substrates to construct high-performance and flexible trimethylamine sensor

Flexible trimethylamine sensor has been realized based on In2O3 nanofibers via electrospinning and a deposition technique. The web-like In2O3 nanofibers with high length-to-diameter ratios are benefit for gas adsorption and desorption. High trimethylamine sensing properties are observed. The sensors can detect trimethylamine gas down to 1 ppm at 80 °C with the response up to 3.8. Additionally, rapid response (6 s) and recovery (10 s) behavior can also be obtained. Good reliability and flexibility are observed in 100 bending/extending cycles. Our results open a new route to construct flexible gas sensors in practice.

Hierarchical In2O3@SnO2 Core-Shell Nanofiber for High Efficiency Formaldehyde Detection.

In this work, three-dimensional (3D) hierarchical In2O3@SnO2 core-shell nanofiber (In2O3@SnO2) was designed and successfully prepared via a facile electrospinning and further hydrothermal methods. Vertically aligned SnO2 nanosheets uniformly grown on the outside surface of In2O3 nanofibers were clearly observed by field emission scanning electron microscopy. Besides, hierarchical core-shell nanostructure of In2O3@SnO2 was characterized by elemental maps using scanning transmission electron microscopy. The formaldehyde (HCHO) sensing performances of pure In2O3 nanofibers, SnO2 nanosheets, and In2O3@SnO2 core-shell nanocomposite were compared, and the In2O3@SnO2 nanocomposite possessed highest response value, fast response/recovery speed, best selectivity, and lowest HCHO detection limit. Specifically, the response value (Ra/Rg) of the In2O3@SnO2 nanocomposite reached 180.1 toward 100 ppm of HCHO gas, which was near 9 and 6 times higher than that of the pure In2O3 nanofibers (Ra/Rg = 19.7) and pure SnO2 nanosheets (Ra/Rg = 33.2), respectively. In addition, the gas sensor showed instantaneous response/recovery time (3/3.6 s) toward 100 ppm of HCHO at the optimal operation temperature of 120 °C. More importantly, the detection limit toward HCHO gas was as low as 10 ppb (Ra/Rg = 1.9), which could be used for trace HCHO gas detection. The excellent sensing properties of the In2O3@SnO2 were attributed to the synergistic effect of large specific surface areas of SnO2 nanosheet arrays, abundant adsorbed oxygen species on the surface, unique electron transformation between core-shell heterogeneous materials, and long electronic transmission channel of SnO2 transition layer. This work provides an efficient route for the preparation of novel hierarchical sensitive materials.

Enhanced gas sensing performance based on p-NiS/n-In2O3 heterojunction nanocomposites

Heterostructured semiconductor materials, combining the collective advantages of individuals and synergistic properties, have spurred great interest as a new paradigm toward detecting of volatile organic compounds recently. Direct use of NiS as a sensing material is impractical because the structure of NiS is unstable, exhibiting an undesirable sensing performance. Herein, we firstly report its incorporation into an ethanol gas sensor with a conventional n-type sensitive material of In2O3, and the gas sensing performance of the NiS@In2O3 nanocomposites has been significantly enhanced. Nanofiber-like NiS and In2O3 were fabricated via a synergetic approach of electrospinning and calcination processes. The diameters of crystalline NiS and In2O3 are about 150 nm and 120 nm, respectively. Then, the NiS@In2O3 nanocomposites were prepared via re-calcination of as-prepared NiS and In2O3 nanofibers. The results show that the sensor based on NiS@In2O3 exhibits a detecting limit of as low as 5 ppm and a short response time of 8 s at the optimum temperature of 300 ºC, which outstripped that (13 s) of pristine In2O3 and pure NiS sensors (21 s) for the detection of ethanol gas. The remarkable improvement of sensing performance can be attributed to the p-n heterojunction in multi-component phases of NiS and In2O3.

Improved formaldehyde gas sensing properties of well-controlled Au nanoparticle-decorated In2O3 nanofibers integrated on low power MEMS platform

Approaches for the fabrication of a low power-operable formaldehyde (HCHO) gas sensor with high sensitivity and selectivity were performed by the utilization of an effective micro-structured platform with a micro-heater to reach high temperature with low heating power as well as by the integration of indium oxide (In2O3) nanofibers decorated with well-dispersed Au nanoparticles as a sensing material. Homogeneous In2O3 nanofibers with the large specific surface area were prepared by the electrospinning following by calcination process. Au nanoparticles with the well-controlled size as a catalyst were synthesized on the surface of In2O3 nanofibers. The Au-decorated In2O3 nanofibers were reliably integrated as sensing materials on the bridge-type micro-platform including micro-heaters and micro-electrodes. The micro-platform designed to maintain high temperature with low power consumption was fabricated by a microelectromechanical system (MEMS) technique. The micro-platform gas sensor consisting with Au-In2O3 nanofibers were fabricated effectively to detect HCHO gases with high sensitivity and selectivity. The HCHO gas sensing behaviors were schematically studied as a function of the gas concentration, the size of the adsorbed Au nanoparticles, the applied power to raise the temperature of a sensing part and the kind of target gases.

Combustion synthesis of electrospun LaInO nanofiber for high-performance field-effect transistors

One-dimensional semiconductor nanofibers are regarded as ideal materials for electronics due to their distinctive morphology and characteristics. In this work, La-doped indium oxide (LaInO) nanofibers are fabricated as the channel layer to reduce O vacancies and the density of interface trap states; this is clearly confirmed by investigating the stability under positive bias stress and the capacitance–voltage for field-effect transistors (FETs). The In2O3 nanofiber FETs optimized by doping with 5 mol% La exhibit excellent electrical performance with a mobility of 4.95 cm2 V–1 s–1 and an on/off current ratio of 1.1 × 108. In order to further enhance the electrical performance of LaInO nanofiber FETs, ZrAlOx film, which has a high dielectric constant, is employed as the insulator for the LaInO nanofiber FETs. The LaInO nanofiber FETs with ZrAlOx insulator have a high mobility of 13.5 cm2 V–1 s–1. These findings clearly indicate the great promise of La-doped In2O3 nanofibers in future one-dimensional nanoelectronics.

Sub-ppm acetic acid gas sensor based on In2O3 nanofibers

Metal oxide semiconductor sensors based on nanocrystalline In2O3 and its composites are found to be very sensitive in detecting low-concentration (~ 5 ppm) gases such as ozone, nitrogen dioxide, formaldehyde and butane. Here, we successfully obtained fiber-shaped In2O3 crystalline nanofibers via electrospun and calcination routes. The gas sensing properties of the In2O3 nanofibers were studied by exposing them to the acetic acid vapor with different concentrations from 500 ppb to 2000 ppm at the optimum operating temperature (250 °C). The device possesses ultra-high response of 66.7 toward 2000 ppm acetic acid vapor, low response and recovery times of 25 s and 37 s (100 ppm), respectively, and significant selectivity to acetic acid at 100 ppm. In particular, the sensor based on In2O3 nanofibers has very low detection limit and can reach 500 ppb. Therefore, the presented In2O3 nanofiber sensor can be used in practice in acetic acid detection area in the future.

Rationally designed mesoporous In2O3 nanofibers functionalized Pt catalysts for high-performance acetone gas sensors

Here, we demonstrate a facile design and simple fabrication of acetone gas sensors based on one-dimensional (1D) porous platinum (Pt)-doped In2O3 nanofiber structure. Be first to try to immerse electrospun polystyrene (PS) nanofibers (NFs) into a precursor solution followed by an annealing process, the as-prepared composite NFs can readily turn into Pt-In2O3 porous NFs. The obtained Pt-In2O3 porous NFs exhibit the mesoporous size of 4–6 nm and high specific surface area of 212.3 m2 g-1. We observed that the spillover effect of Pt nanoparticles and the large-surface-area of the porous structure can effectively enhance catalytic sensing response to acetone with a lower limit of 10 part-per-billion (ppb) at a low working temperature of 180 °C. More importantly, the proposed NFs-based sensor shows rapid response and recovery time (6/9 s), higher selectivity toward acetone against other interfering gases, reversibility and time stability (50 days) compared to its counterparts. In addition, the proposed sensor shows a fast response and recovery time, maintaining 70% of the initial response even in 85% relative humidity (RH) environment. These results demonstrate the potential feasibility that the Pt-In2O3 porous NFs act as a promising sensing platform for monitoring acetone at ppb levels in human breath.

Toluene Gas Sensing Properties of Pt-Nanoparticle-Decorated Indium Oxide Nanofibers on a Low-Power Consumable Bridge-Type Micro-Platform

Pt-decorated In2O3 nanofibers with tailored size and morphology were synthesized as sensing materials for a highly sensitive toluene gas sensor. The bridge-type micro-platforms, including micro-heaters and micro-electrodes for the integration of In2O3 nanofibers-based sensing materials, were designed to demonstrate the sensing at high temperature with low power consumption. The gas sensing properties of the fabricated toluene gas sensor were systematically investigated by controlling the power of the micro-heater and the concentration of the toluene gas. Additionally, the enhanced sensing properties for various gas concentrations of toluene were investigated for Pt-nanoparticle-decorated In2O3 nanofibers.

Study on Preparation and Photocurrent Response Properties of In/In2O3/TiO2 Nanotubes Arrays Compound Heterojunction Semiconductor

TNTs were prepared in ethylene glycol with 0.5wt%NH4F and 1.5Vol%H2O by the anode potential of 60V. In/In2O3/TiO2 nanotube arrays (TNTs) heterojunction semiconductor was prepared by two electrochemical steps of reduction and oxidation in 0.01 mol/L InCl3 ethanol solution. The element In and In2O3 nanofibers were distributed in and on the TNTs by SEM figures. By the photocurrent results, TNTs photocurrent response was reinforced by In2O3 and In modification in UV and visible light region. The monochromatic incident photon-to-electron conversion efficiency (IPCE) reached to 58% under the 350nm light radiation and was nearly 5 times that of TNTs. Two oxidation phases were got from the photocurrent data (the energy band gap Eg = 3.08eV and Eg = 2.2 eV), which was propitious to the absorption light red shift and response under the visible light. The flat band potentials shifted to electric positive direction for In/TNTs prepared by one step of reduction or In/In2O3/TNTs prepared by two steps of reduction and oxidation according to the Mott-Schottky curve. The donor density (ND) of the In/In2O3/TNTs was slightly higher than TNTs and the ND of In/TNTs was the highest for 14.6 times that of TNTs. The results show that heterojunction is formed between In2O3 and TNTs to promote visible light absorption and carrier separation. A great deal of element In makes the photo generated electrons and holes recombination to reduce the photocurrent response, but a small amount of element In can reduce the Eg of semiconductor and promote the absorption light to red shift for TNTs. The transfer mechanism of In and In2O3 modified by TNTs was discussed.

Zeolitic imidazolate framework-8 (ZIF-8)-coated In2O3 nanofibers as an efficient sensing material for ppb-level NO2 detection

The development of NO2 gas sensors is of great importance for air quality monitoring and human health. In this work, In2O3 and zeolitic imidazolate framework-8 (ZIF-8) heterostructures were synthesized and designed as efficient sensing materials for NO2 detection. The ZIF-8 nanocrystals were uniformly deposited on In2O3 nanofibers (NFs) by using a self-template strategy, where In2O3/ZnO NFs act as the source of Zn2+ for the formation of ZIF-8 and as the template. By tuning the amount of Zn2+ in the composite NFs, different morphologies from In2O3 NFs with minimal ZIF-8 loading to an In2O3/ZIF-8 core-shell complex were obtained. The optimized In2O3/ZIF-8 NFs show a remarkably high response to 1 ppm NO2 (Rg/Ra = 16.4) and enhanced humidity resistance due to the hydrophobicity of ZIF-8 in comparison with those of the pristine In2O3 NF sensor (Rg/Ra = 4.9) at 140 °C. The gas sensing mechanism of In2O3/ZIF-8, which is based on electron transduction, surface chemistry, and the functional interface between the loaded ZIF-8 and In2O3 matrix, was proposed. Additionally, the large number of pores, which were formed by the in situ conversion of ZnO grains in the matrix, ensures that all parts of the In2O3 NFs are accessible to gases. This facile strategy paves the way for the design of metal oxide/MOF complex architectures with tunable metal centers for various applications, including gas sensing.

Modulating Electrical Performances of In2O3 Nanofiber Channel Thin Film Transistors via Sr Doping

AbstractAlthough In2O3 nanofibers (NFs) are considered as one of the fundamental building blocks for future electronics, the further development of these NFs devices is still seriously hindered by the large leakage current, low on/off current ratio (Ion/Ioff), and large negative threshold voltage (VTH) due to the excess carriers existed in the NFs. A simple one‐step electrospinning process is employed here to effectively control the carrier concentration of In2O3 NFs by selectively doping strontium (Sr) element to improve their electrical device performance. The optimal devices (3.6 mol% Sr doping concentration) can yield the high field‐effect mobility (μfe ≈ 3.67 cm2 V−1 s−1), superior Ion/Ioff ratio (≈108), and operation in the energy‐efficient enhancement‐mode. High‐κ Al2O3 thin films can also be employed as the gate dielectric to give the gate voltage greatly reduced by 10× (from 40 to 4 V) and the μfe substantially increased by 4.8× (to 17.2 cm2 V−1 s−1). The electrospun E‐mode Sr‐In2O3 NF field‐effect transistors (NFFETs) can as well be integrated into full swing of inverters with excellent performances, further elucidating the significant advance of this electrospinning technique toward practical applications for future low‐cost, energy‐efficient, large‐scale, and high‐performance electronics.

Discriminative detection of indoor volatile organic compounds using a sensor array based on pure and Fe-doped In2O3 nanofibers

Representative indoor volatile organic compounds (VOCs) such as benzene, xylene, toluene, formaldehyde, and ethanol need to be detected in a highly sensitive and discriminative manner because of their different impact on human health. In this study, pure and 0.05, 0.1, 0.3, and 0.5 at% Fe-doped In2O3 nanofibers were prepared by electrospinning and their gas sensing characteristics toward the aforementioned VOCs were investigated. The doping of In2O3 nanofiber sensor with 0.05 and 0.1 at% Fe shifted the temperature to show the maximum responses to benzene, xylene, and toluene, and reduced responses to ethanol and formaldehyde, thus demonstrating changed gas selectivity. The gas sensing characteristics of 0.5 at% Fe-doped In2O3 nanofiber sensor were substantially different from those of the other sensors. Significantly different gas sensing patterns of pure and Fe-doped In2O3 sensors could be used to discriminate between the five different VOCs at 375 °C and to distinguish between the aromatic and non-aromatic gases at all sensing temperatures. The mechanism underlying the Fe-induced change in gas sensing characteristics has been discussed in relation to the variation of catalytic activity, morphology, oxygen adsorption, and charge carrier concentration.

Ultra-sensitive sensing platform based on Pt-ZnO-In2O3 nanofibers for detection of acetone

Ultra-small Pt nanoparticles functionalized In2O3 nanofibers have been designed by using a new catalyst loading platform (Pt@ZIF-8), which involves three steps including the synthesis of ZIF-8 nanoparticles, the preparation of Pt@ZIF-8 and the subsequent transformation to Pt-ZnO-In2O3 composite nanofibers by electrospinning. The experimental results demonstrate that the average sizes of Pt nanoparticles obtained in this way are only ∼3 nm, which is helpful to obtain highly sensitive gas sensors due to the ultra-small Pt nanoparticles. Gas sensing investigations indicate that the sensor based on Pt-ZnO-In2O3 nanofibers exhibit the superior acetone response (Ra/Rg = 57.1 to 100 ppm at 300 °C), ultra-fast response and recovery time (1/44s) and low detection limit (0.5 ppm). In this study, the excellent acetone gas sensing property of Pt-ZnO-In2O3 nanofibers attributes to the chemical sensitization and electrical sensitization of the ultra-small Pt nanoparticles, the n-n heterojunctions between ZnO and In2O3, and the p-n heterojunction produced between p-type PtO2 and n-type In2O3 (ZnO).

In2O3 nanofibers surface modified by low-temperature RF plasma and their gas sensing properties

Hierarchical structure In2O3 nanofibers were synthesized by traditional electrospinning technology. Then, In2O3 nanofibers were treated 30 min by using low-temperature RF oxygen plasma and hydrogen plasma, respectively. The morphology, structure, composition and element content of the In2O3 nanofibers modified by oxygen plasma and hydrogen plasma were characterized and analyzed by XRD, SEM, BET and XPS. After modification by plasma, the morphology, structure and element contents of the In2O3 nanofibers were significantly changed. Gas sensors were fabricated based on In2O3 nanofibers modified by oxygen plasma and hydrogen plasma, respectively. Gas sensing properties of modified In2O3 sensors were investigated by a static test system to a variety of VOC gases in the concentration range of 0.3–500 ppm. The test result shows that In2O3 gas sensor modified by oxygen plasma exhibits excellent acetone sensing properties, It indicates that surface adsorption properties of In2O3 nanofibers can be improved by surface modification technology using low-temperature RF plasma, so as to improve the gas sensing properties of sensors.

High-performance field-effect transistors based on gadolinium doped indium oxide nanofibers and their application in logic gate

One-dimensional metal oxide nanofibers have been regarded as promising building blocks for large area low cost electronic devices. As one of the representative metal oxide semiconducting materials, In2O3 based materials have attracted much interest due to their excellent electrical and optical properties. However, most of the field-effect transistors (FETs) based on In2O3 nanofibers usually operate in a depletion mode, which lead to large power consumption and a complicated integrated circuit design. In this report, gadolinium (Gd) doped In2O3 (InGdO) nanofibers were fabricated by electrospinning and applied as channels in the FETs. By optimizing the doping concentration and the nanofiber density, the device performance could be precisely manipulated. It was found that the FETs based on InGdO nanofibers, with a Gd doping concentration of 3% and a nanofiber density of 2.9 μm−1, exhibited the best device performance, including a field-effect mobility (μFE) of 2.83 cm2/V s, an on/off current ratio of ∼4 × 108, a threshold voltage (VTH) of 5.8 V, and a subthreshold swing (SS) of 2.4 V/decade. By employing the high-k ZrOx thin films as the gate dielectrics in the FETs, the μFE, VTH and SS can be further improved to be 17.4 cm2/V s, 0.7 V and 160 mV/decade, respectively. Finally, an inverter based on the InGdO nanofibers/ZrOx FETs was constructed and a gain of ∼11 was achieved.

Improved NO2 sensing properties at low temperature using reduced graphene oxide nanosheet–In2O3 heterojunction nanofibers

Pure In2O3 and reduced graphene oxide (rGO)–In2O3 composite nanofibers are prepared by a facile electrospinning technique. Low-temperature gas-sensing properties to NO2 of the produced nanofibers are evaluated. Our results indicate that in comparison with pure In2O3 nanofibers, the rGO–In2O3 heterojunction nanofibers display much better sensing properties in response, selectivity and detection limit to NO2. Moreover, the weight ratios of rGO to In2O3 are used as a parameter to estimate the best gas-sensing properties of rGO–In2O3 nanofibers. Consequently, the heterojunction nanofibers with an optimized amount of rGO (2.2 wt%) exhibit the highest response of 42 to 5 ppm NO2 at the low operating temperature of 50 °C, which is 4.4 times higher than that of pristine In2O3. From our perspective, the enhanced sensing properties of the composite nanofibers can be mainly attributed to the formation of p–n heterojunctions between rGO and In2O3, and ultrahigh specific surface area as well as strong gas adsorption capacity of rGO nanosheets. These excellent gas-sensing properties make the rGO–In2O3 heterojunction nanofibers attractive to application for low-temperature NO2 gas sensors.