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In this work, nitrogen‐doped zinc‐tin‐oxygen (ZnSnO:N) optoelectronic synaptic thin film transistors (TFTs) with superior visible light response are fabricated. Nitrogen doping narrows the bandgap of ZnSnO, which in turn broadens the absorption spectrum. Additionally, the reduction of non‐radiative centers in the channel layer prolongs the lifetime of the photogenerated electrons, resulting in enhancements to the photo response throughout the visible region. Optoelectronic synaptic devices based on ZnSnO:N TFTs can accurately replicate synaptic behaviors, including short‐term plasticity (STP) and long‐term plasticity (LTP). Furthermore, the ZnSnO:N optoelectronic synaptic TFT‐based array has the potential to improve image contrast. The ZnSnO:N TFT exhibits a considerable improvement in both visible light photosensitivity and synaptic plasticity. [ABSTRACT FROM AUTHOR]

In this article, this research demonstrates the influence of in-situ introduction of H2 into the working gas on the physical properties of post-annealed In2O3 thin films and the performance of associated devices. A gradual increase in the H2 ratio leads to improved film quality, as indicated by spectroscopic ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscope analyses showing a reduction in defect states such as band-tail states and VO in the film, and a smoother surface morphology with the root mean square roughness approximately 0.446 nm. Furthermore, this hydrogen doping effect results in a distinct shift in the device's threshold voltage toward the positive direction, and an improvement in the field-effect mobility and subthreshold swing. Consequently, a high-performance In2O3:H TFT is developed, exhibiting a field-effect mobility of 47.8 cm2/Vs, threshold voltage of −4.1 V and subthreshold swing of 0.25 V/dec. These findings highlight the potential of in-situ H doping as a promising approach to regulate In2O3-based TFTs. [ABSTRACT FROM AUTHOR]

The exploration of bionic neuromorphic chips, capable of processing sensory data in a human‐like manner, is both a trend and a challenge. There is a strong demand for phototransistors that offer broadband in‐sensor adaptability. This study introduces a bioinspired vision sensor based on InP quantum dots (QDs)/InSnZnO hybrid phototransistors. This novel design combines the excellent electrical transportation features of oxide semiconductors with the superior optoelectronic response of InP QDs. The resulting hybrid devices exhibit exceptional gate controllability and a robust visible‐light response. These characteristics enable the emulation of multiple functions of the human visual system and the accommodation of varying light intensity environments. Furthermore, the phototransistor array successfully replicates the scotopic and photopic adaptation recognition behaviors of the human retina. Notably, the device demonstrates faultless competency in image processing, achieving an impressive 93% accuracy for digit recognition. These findings contribute to the advancement of bionic neuromorphic chips and offer promising opportunities for future developments in the bioinspired visual system. [ABSTRACT FROM AUTHOR]

Amorphous oxide semiconductor thin‐film transistors (AOS TFTs) are ever‐increasingly utilized in displays. However, to bring high mobility and excellent stability together is a daunting challenge. Here, the carrier transport/relaxation bilayer stacked AOS TFTs are investigated to solve the mobility‐stability conflict. The charge transport layer (CTL) is made of amorphous In‐rich InSnZnO, which favors big average effective coordination number for all cations and more edge‐shared structures for better charge transport. Praseodymium‐doped InSnZnO is used as the charge relaxation layer (CRL), which substantially shortens the photoelectron lifetime as revealed by femtosecond transient absorption spectroscopy. The CTL and CRL with the thickness suitable for industrial production respectively afford minute potential barrier fluctuation for charge transport and fast relaxation for photo‐generated carriers, resulting in transistors with an ultrahigh mobility (75.5 cm2 V−1 s−1) and small negative‐bias‐illumination‐stress/positive‐bias‐temperature‐stress voltage shifts (−1.64/0.76 V). The design concept provides a promising route to address the mobility‐stability conflict for high‐end displays. [ABSTRACT FROM AUTHOR]

High‐performance bilayer In2O3/IGZO thin‐film transistors (TFTs) fabricated by pulsed laser deposition are reported. The TFTs exhibit an on/off current ratio of 109, a reversed subthreshold slope (ss) of 0.08 V dec−1, and a high saturation mobility of 47.9 cm2 V−1 s−1. The reliability of the mobility values is critically validated and assessed by four‐probe measurements, the transfer‐length method, and the temperature‐dependence. X‐ray photoelectron spectra are combined with C–V measurements to characterize the interface, and the results show that a two‐dimensional electron gas (2DEG)‐like state accumulates at the In2O3/IGZO interface. However, this state only forms in the subthreshold region and does not cause the high carrier mobility in the region above the threshold. Instead, the enhanced carrier mobility results from the intrinsic high mobility of the In2O3, the smooth surface, and the low‐defect states in the In2O3/IGZO bilayer with a good percolation transport path. [ABSTRACT FROM AUTHOR]

In this work, amorphous praseodymium-doped In-Sn-Zn-O (ITZO-Pr) thin-film transistors (TFTs) were fabricated with improved negative-bias illumination stress (NBIS) stability under different radio frequency (RF) magnetron sputtering powers. The optimized ITZO-Pr TFTs presented field effect mobility ($\boldsymbol {\mu }_{\text{FE}}$) of 20.9 cm $^{2}\cdot {}\text{V}^{-1}\cdot {}\text{s}$ −1, steep subthreshold (SS) of 0.27 V/dec, and small threshold voltage shift (${\Delta } {V}_{\text{th}} = -2.12$ V) under NBIS (−20 V, 3600 s). All Pr-doped devices exhibited a reduction in light responsivity of more than one order of magnitude compared with ITZO TFTs. Moreover, after Pr doping, relaxation processes of photoelectrons changed and then the activation energy (${E}_{\text{a}}$) of light-induced electrons relaxation decreased, which enhanced the NBIS stability of ITZO TFTs effectively. [ABSTRACT FROM AUTHOR]

High-field-effect-mobility InSnZnO thin-film transistors (TFTs) are prepared through Al-induced microstructure regularization (AIMR) at an annealing temperature lower to 400 °C. Spherical crystalline particles are distributed throughout the back channel near the Al layer, while an amorphous phase still represents the front channel but with enhanced microstructure ordering. Especially, the packing density is distinctly increased, and oxygen vacancies are largely reduced. The optimized TFT exhibits excellent performance with a steep sub-threshold swing of 0.18 V/dec, a high on/off current ratio of 2.5 × 108, a threshold voltage of −0.21 V, and a small threshold voltage shift of −0.24 V under negative bias stress (−20 V, 3600 s), especially a remarkable field-effect mobility boosted to 53.2 cm2/V s compared to 19.1 cm2/V s for the TFT without the Al layer. After Al removal, the TFT performance shows no obvious degradation, implying good compatibility of the AIMR technique to the current device process. [ABSTRACT FROM AUTHOR]

In this work, we study the intrinsic connection between target quality and performance of sputtered In-Sn-Zn-O (ITZO) thin-film transistors. Using a dense target, the ITZO device overall performance can be improved synergistically. The optimized device exhibits a steep subthreshold swing of 0.13 V/decade, a high on/off current ratio of 2.47 × 108, a threshold voltage of −0.03 V, a saturation field-effect mobility (μFE) of 36.1 cm2/Vs, and a small threshold voltage shift (Δ Vth) of −0.55 V under negative bias stress (−20 V, 3600 s). In contrast, the μFE shows a reverse trend to Δ Vth when using a target with a relatively small density and poor crystallinity. In this case, although the amount of oxygen vacancy in the films can be reduced for better stability via increasing the sputtering power, the film density observably drops due to serious preferential sputtering, leading to smaller μFE. [ABSTRACT FROM AUTHOR]

Amorphous Ga2O3:CdO thin films and their thin-film transistor (TFT) photodetectors were fabricated via a simple and low-cost spin-coating method. The film optical bandgap and TFT electrical parameters can be effectively regulated via changing the Cd content. The optimized Ga2O3:CdO TFT photodetector exhibited a responsivity of 2.17 A/W and a high UV/vis. rejection of 1.88 × 104 under 260 nm at small working biases, which are comparable or even superior to the recently reported results. Systematic comparison between metal-semiconductor-metal- and TFT-type photodetectors further confirmed that our TFT photodetectors had superior detective performance and lower electrical power consumption. [ABSTRACT FROM AUTHOR]

Optoelectronic synapse, well coupling the optical and electrical signals in one device, is an important building block in neuromorphic hardware library. Herein, optoelectronic synaptic devices are demonstrated based on a unique amorphous oxide semiconductor (InGaCdO [IGCO]) that can be spiked by broadband light signals from ultraviolet to near‐infrared region, approaching the wavelength of 1000 nm. These optically stimulated synaptic devices are based on the conventional bottom‐gate thin‐film transistor (TFT) configuration, providing the beneficial process/structural compatibility with the flat‐panel display industry. The IGCO TFTs, showing an ultrahigh field‐effect mobility up to 106 cm2 V−1 s−1, can well simulate a series of basic synaptic functionalities via changing the pulse intensity, number, and frequency. The device plasticity originates from the dynamic ionization and neutralization of oxygen vacancy‐related defects. Also, the mechanism underlying this dynamic process is discussed in detail, verifying that oxygen vacancy can turn to its ionized state by directly absorbing a photon having enough energy or with the aid of holes. The relatively higher carrier mobility, smaller bandgap, and larger activation energy of oxygen vacancy for the IGCO together facilitate the achievement of broadband optoelectronic synaptic devices. [ABSTRACT FROM AUTHOR]

Dielectrics fabrication on rough substrates, always leading to microstructural defects and detrimental dielectric properties eventually, is a great challenge for academic endeavors in this field. We report here on self-flattening AlO x :Y dielectric thin films processed by a facile aqueous solution method. The obtained AlO x :Y dielectrics are dense, large-area uniform, and amenable to accurate control of film thickness by repeating the deposition cycles. In particular, an atomically smooth surface with a RMS of 0.10 nm was realized for the AlO x :Y film with a thickness of 14.5 nm on Si wafer, yielding a low leakage current density of 7.9 × 10-8 A cm-2@2 MV/cm, a dielectric constant of 8.8 @100 Hz, and an attenuated dielectric dispersion property. The interactions between pre-baked YO x underlayer and later-dropped AlO x precursor were comprehensively investigated, in order to understand the film growth mechanism and the origin of self-flattening effect. Fortunately, this self-flattening effect is also applicable to other substrates. A RMS of 0.81 nm was achieved on ITO glasses, and the height distribution profile of the film surface was found to follow symmetric Gaussian distribution. This preparation routine was also examined by device verification in the fully-transparent thin-film transistors. The combination of ease of preparation and attractive physical properties would provide a green-route solution platform for dielectric synthesis, for interface engineering, and for well-performed devices on rough substrates. [ABSTRACT FROM AUTHOR]

Thin-film transistors (TFTs) with ScInO or MgScInO semiconductors were fabricated with the annealing temperature of only 150 °C. Compared with ScInO TFT, MgScInO TFT exhibited much better stability under negative-bias temperature stress (NBTS) at 60 °C with negative turn-on voltage (${V}_{ \mathrm{\scriptscriptstyle ON}}$) shift of −0.6 V at the initial stress stage (≤;900 s) and then positive $V_{ \mathrm{\scriptscriptstyle ON}}$ shift (>900 s). First-principles calculations show that the oxygen vacancies (${V}_{\text {O}}$) tend to be bounded with Mg and form Mg– ${V}_{\text {O}}$ pairs with activating (or binding) energy of greater than 0.1369 eV, which is ascribed to the NBTS stability improvement for MgScInO TFT. [ABSTRACT FROM AUTHOR]

It is difficult to implement high-resolution layer-to-layer alignment by direct inkjet printing because of the limitation of position accuracy of the common inkjet printer. The poor alignment of conventional printers generally causes large parasitic overlap capacitances between the gate and source/drain (S/D) of thin-film transistors (TFTs), which degrades device operating speeds. In this paper, a self-aligned method was proposed to minimize the parasitic overlap capacitance. In this method, a hydrophobic fluoropolymers (Cytop) coffee stripe prepared by inkjet printing was utilized to define the gate electrodes, and to dewet deposited ink droplet for self-aligned S/D electrodes. This kind of inkjet-printed self-aligned TFTs with In0.95Sc0.05Ox channel layer have a parasitic overlap capacitance as small as 0.31–0.45 pF. The TFTs in array exhibited an on/off ratio larger than $\textsf {10}^{\textsf {7}}$ and a maximum saturation mobility of $\textsf {4.63}\,\,\textsf {cm}^{\textsf {2}}\,\,\textsf {V}^{-\textsf {1}}\textsf {s}^{-\textsf {1}}$. [ABSTRACT FROM AUTHOR]

Concerning the revolutionary future of electronic devices, high-performance solution-processable semiconductors have earned increasing academic and industrial research interests. In this paper, we synthesize In-Ga-Cd-O semiconductor thin films via a solution method. Transparent amorphous/nanocrystalline oxide thin films with small surface roughness have been grown by controlling the relative ratio of Cd-content. The present thin-film transistor with an optimized Cd-ratio exhibits a saturation field-effect mobility up to 10 cm² V-1 s-1, an on/off current ratio of ≈1.3×109, and a threshold voltage shift of ≈2.6 V under -5 V gate bias of 10 000 s, which are superior or comparable to those reported values of solution-processed conventional In-Ga-Zn-O counterparts. Our results indicate that the proposed In-Ga-Cd-O semiconductor would endow a promising transparent amorphous/nanocrystalline active material for electronic devices. [ABSTRACT FROM AUTHOR]

Chitosan (CS) dielectrics are in favor of packed CuI films with tiny grains on them under a robust ambient conditions, and hence facilitate transparent and flexible p-type CuI thin-film transistors with high mobility and on/off current ratio. Complementary inverters based on the CuI transistors demonstrate a voltage gain over 20. [Display omitted] • Flexible/transparent p-Type CuI TFTs are constructed, with μ FE up to 65 cm2V−1s−1 and I on / I off of 104. • Chitosan dielectrics facilitate easy coating of high-quality CuI films under permissive conditions. • Complementary inverters are demonstrated by combining p-type CuI and n -type ITO TFTs. High-performance transparent and low-process-temperature p-type devices are essential for portable and 'invisible' electronics. In this work, high-performance p-channel copper iodide (CuI) thin-film transistors (TFTs) with a bottom-gate structure are achieved via replacing traditional SiO 2 dielectric with Chitosan (CS, a kind of solid polymer electrolytes), with the threshold voltage down to −0.35 V, field-effect mobility (μ FE) up to 60 cm2V−1s−1 and on/off current ratio (I on / I off) beyond 103. The CuI films spin-coated on CS-dielectrics in the air with high humidity have smoother surface morphology, tinier grains, higher packing density and hence a higher μ FE , in sharp contrast with the SiO 2 case. In addition, the CuI films on CS-dielectrics demonstrate a work function ∼ 0.1 eV lower than that on SiO 2 , which implies a smaller hole concentration and higher I on / I off. And the low process temperature (<50 °C) facilitates the achievement of flexible and transparent CuI TFTs with μ FE and I on / I off comparable to those on rigid InSnO (ITO) glass. Furthermore, complementary inverters composed of p-type CuI and n -type ITO TFTs are demonstrated with clear inverting characteristics and voltage gain of over 20. [ABSTRACT FROM AUTHOR]

Fully transparent InZnO thin-film transistors (TFTs), with either a bottom gate or an in-plane gate device structure, were fabricated using the solution-processed SA proton conducting films as gate dielectrics. The self-assembled InZnO channel with different thickness by the gradient shadow mask was fabricated during the same batch radio-frequency magnetron sputtering. The threshold voltage can be modulated from −0.25 to +0.12 V and from −0.07 to +0.25 V by the channel layer thickness variations for the vertically-coupled and laterally-coupled InZnO TFTs, respectively. Accordingly, these InZnO TFTs can operate in either depletion or enhancement mode on the same chip. A general expression of the turn-on voltage in relation to the channel thickness is derived. The device performance with an on/off current ratio of ≥1.5 × 106, a subthreshold swing of down to 70 mV/decade, and a field-effect mobility of up to 34.3 cm2/V · s is exhibited. Our results demonstrate that the same batch channel processing is potentially applied in logic circuits or functional electronics. [ABSTRACT FROM AUTHOR]

The solution-processed sodium-alginate (SA) films, with nanoporous/nanochannel microstructure, possess a total absorbed water number of 10420 ± 395 molecules per square nanometer, which gives rise to a high proton conductivity of 4.0 × 10−4 S cm−1. When SA films used as gate dielectric in the thin film transistors, electric-double-layer (EDL) would be formed whether at the dielectric/channel or at dielectric/gate electrode interface, leading to a huge specific capacitance and low operating voltage for the TFTs. More importantly, due to the three-dimensional proton conducting characteristic, one can design the TFT device structure expediently from conventional vertical gate coupling to laterally coplanar gate coupling structure. The TFTs with ease-design device layout have potential applications in multifunctional electronic devices. [ABSTRACT FROM AUTHOR]

Tunable threshold voltage of a thin-film transistor (TFT) is highly desirable for designing multifunctional electronic circuits. In this letter, an ultrathin SnOx capping layer was adopted to modify the threshold voltage of bottom-gate amorphous indium–gallium–zinc-oxide (a-IGZO) TFTs. A threshold voltage shift from 15.2 to −9.0 V was observed as the SnOx thicknesses increased from 0 to 19 nm, accompanying by a sizable increase of the intrinsic electron concentration in the channel layer. It was believed that the SnOx capping layer can extract loosely bound oxygen from the a-IGZO, which was supported by the SnOx composition variation with its thickness. Combining an uncovered a-IGZO TFT with a SnOx capped a-IGZO TFT, an enhancement/depletion inverter with a voltage gain of up to 45.9 was successfully demonstrated. [ABSTRACT FROM AUTHOR]

InZnO thin-film transistors using high-κ Ta2O5 gate dielectric are presented and analysed. The large capacitance coupling effect of amorphous Ta2O5 results in fabricated devices with good electrical properties. However, an anomalous negative threshold voltage (Vth) shift under positive bias stress is observed. It is suggested that electron detrapping from the high-κ Ta2O5 dielectric to the gate electrode is responsible for this Vth shift, which is supported both by the logarithmical dependence of the Vth change on the duration of the bias stress and device simulation extracted trapped charges involved. [ABSTRACT FROM AUTHOR]

We report a facile and low-temperature aqueous route for the fabrication of various oxide thin films (Al 2 O 3 , In 2 O 3 and InZnO). A detail study is carried out to reveal the formation and properties of these sol-gel-derived thin films. The results show that the water-based oxide thin films undergo the decomposition of nitrate group as well as conversion of metal hydroxides to form metal oxide framework. High quality oxide thin film could be achieved at low temperature by this aqueous route. Furthermore, these oxide thin films are integrated to form thin-film transistors (TFTs) and the electrical performance is systematically studied. In particular, we successfully demonstrate In 2 O 3 /Al 2 O 3 TFTs with high mobility of 30.88 cm 2 V −1 s −1 and low operation voltage of 4 V at a maximum processing temperature of 250 °C. [ABSTRACT FROM AUTHOR]