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Thin-film transistors (TFTs) with bilayer channels were used to improve the field-effect mobility and bias stress stability of the TFTs. Homogeneous structures were fabricated by the combination of a carrier deficient layer made of In2O3 thin film annealed in oxygen atmosphere (InO:O) and an electron injection layer made of In2O3 thin film annealed in air (InO:A). Compared with the InO:A/InO:A TFT with only air annealing, the field-effect mobility of InO:O/ InO:A TFT with two-step annealing process was improved from 0.04 to 5.11 cm2/Vs, the on/off current ratio was ameliorated from 4.6 × 105 to 7.6 × 107 A, while the VTH is decreased from 12.5 to 4.7 V under the positive bias stressing (PBS). It is confirmed that the excessive oxygen vacancies are produced by annealing the thin film in the air. The electrical performance of the InO:O/InO:A TFTs with two-step annealing process is greatly improved due to the formation of a low defect state and high carrier concentration electron transport layer, through the combination of the carrier transport layer and the carrier injection layer. These optimized electrical properties indicate an important step toward achieving transparent, high performance, and low-temperature metal oxides TFTs. [ABSTRACT FROM AUTHOR]

In this report, In2O3 nanofiber networks (NFNs) were prepared by electrospinning and the field-effect transistors (FETs) based on In2O3 NFNs were fabricated. The effects of plasma treatment on the electrical performance of the FETs based on In2O3 NFNs were investigated. It is found that the oxygen vacancy in In2O3 NFNs can be tuned by the plasma treatment and the electrical performance of the FETs can be tuned accordingly. In this work, X-ray photoelectron spectroscopy was employed to investigate the chemical stoichiometry in In2O3 nanofibers with respect to plasma treatment conditions. The electrical performances of the FETs based on In2O3 NFNs treated by various plasma treatment conditions were systematically studied. It is found that, compared to those without O2 plasma treatment, the FET based on In2O3 NFNs treated by O2 plasma at 120 W for 5 min exhibits high electrical performance, including the variation of threshold voltage from −22.34 to 7.81 V and current on/off ratio from $\sim 10^{{3}}$ to $\sim 10^{{7}}$ and a $\mu _{\text {FE}}$ of 1.51 cm2 /Vs. This result demonstrates that moderate plasma treatment can be adopted to improve the electrical performance of the FETs based on metal oxide NFNs. [ABSTRACT FROM AUTHOR]

Electrospinning technique is considered to be one of the most powerful approaches for the preparation of one-dimensional (1D) metal oxide nanofiber networks (NFNs). In this report, In2O3 NFNs were fabricated by electrospinning using polymethyl methacrylate (PMMA) as polymer and epoxy resin as additive. Benefiting from the excellent chemical properties of PMMA, In2O3 NFNs with impact stacking were prepared at a relatively low annealing temperature by a welding process. The welded In2O3 NFNs were characterized by various techniques and the electrical performance of the field-effect transistors (FETs) based on the welded In2O3 NFNs were systematically investigated. It is observed that the FET based on In2O3 NFNs annealed at 320 °C, with a nanofiber density of $0.4\,\,\mu \text{m}^{-{1}}$ exhibits high electrical performance, including an ${I}_{ {\mathrm{{ON}}}}/{I}_{ {\mathrm{{OFF}}}}$ of $\sim {5}\times {10}^{{7}}$ , a $\mu _{\text {FE}}$ of 1.27 cm2/V s, an on voltage of −8 V and a hysteresis of 5 V. A device array with ${4}\times {5}$ units was fabricated and tested, confirming the excellent reliability and reproducibility of the FET. [ABSTRACT FROM AUTHOR]

Emulating the essential synaptic working principles using a three-terminal synaptic transistor has been an important research field in recent years. Electrospun metal oxide nanofibers have been regarded as promising blocks for large-area, low-cost, and one-dimensional (1D) electronic devices. In this letter, zinc-tin oxide (ZnSnO) nanofibers were fabricated by electrospinning, and the synaptic transistors based on ZnSnO nanofibers were integrated. To mimic the synaptic behavior of human brain, LiClO4 dissolved in polyethylene oxide was used as the gate electrolyte in the synaptic transistors. The plasticities, including short term and long term, are mimicked with the help of electrolyte ion dynamics under low and large bias voltage, and an energy consumption of as low as 0.44 pJ per event is observed. This work demonstrates a new approach for establishing the large-scale, energy-efficient 1D artificial synapses for neuromorphic networks. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Here, a simple, nontoxic, and inexpensive 'water-inducement' technique for the fabrication of oxide thin films at low annealing temperatures is reported. For water-induced (WI) precursor solution, the solvent is composed of water without additional organic additives and catalysts. The thermogravimetric analysis indicates that the annealing temperature can be lowered by prolonging the annealing time. A systematic study is carried out to reveal the annealing condition dependence on the performance of the thin-film transistors (TFTs). The WI indium-zinc oxide (IZO) TFT integrated on SiO2 dielectric, annealed at 300 °C for 2 h, exhibits a saturation mobility of 3.35 cm2 V−1 s−1 and an on-to-off current ratio of ≈108. Interestingly, through prolonging the annealing time to 4 h, the electrical parameters of IZO TFTs annealed at 230 °C are comparable with the TFTs annealed at 300 °C. Finally, fully WI IZO TFT based on YO x dielectric is integrated and investigated. This TFT device can be regarded as 'green electronics' in a true sense, because no organic-related additives are used during the whole device fabrication process. The as-fabricated IZO/YO x TFT exhibits excellent electron transport characteristics with low operating voltage (≈1.5 V), small subthreshold swing voltage of 65 mV dec−1 and the mobility in excess of 25 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]