Search

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]

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]

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]

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]