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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]

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]

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]

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]

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]