Efficient Oxygen‐Vacancy Suppression and Electrical Stabilization of Solution‐Processed In₂O₃:Q (Q = S, Se) Thin‐Film Transistor with Chalcogen Alloying

Abstract

Transparent oxide semiconductors are successfully implemented as thin‐film transistors (TFTs) for large‐area display applications with superior electrical performance in comparison with that of conventional amorphous silicon. However, further development of high‐performance oxide semiconductors is hindered by the trade‐off between mobility and stability. Mixed metal composition containing heavy metal cations shows high‐mobility/low‐stability and light metal cations exhibits low‐mobility/high‐stability. A novel material design strategy for realizing a high‐performance oxide semiconductor for TFTs through partial substitution of Se or S for O in In2O3 is reported. In contrast to the conventional small‐sized Ga substitution for suppressing oxygen vacancies, the replacement of O by Se or S results in lattice stabilization and oxygen‐vacancy suppression, consequently stabilizing Se‐ or S‐incorporated In2O3 TFTs. In2O3:Se TFTs exhibit an average field‐effect mobility of 6.1 cm2 V−1s−1, ON/OFF current ratio (Ion/Ioff) of 108, and excellent operational stability with threshold voltage shift values of <0.10 V at a positive and negative bias stress for 10 000 s. Furthermore, the seven‐stage ring oscillator circuit operating at a supply bias of 20 V exhibits an oscillation frequency of >805 kHz and a corresponding propagation delay of <90 ns per stage.

Doping of Indium Oxide Semiconductor Film Prepared Using an Environmentally Friendly Aqueous Solution Process with Sub-1% Molybdenum to Improve Device Performance and Stability

“…It is important to note that, except for the W dopant, to efficiently tune the device parameters, much higher dopant concentrations were required compared to our work. In all cases, μ deteriorated as the doping concentration increased, but depending on the goal of the device optimization, some studies could achieve good performance without significantly sacrificing the mobility. ,, In other cases, including this study, however, to achieve an advantageous change in the V Th or V On , the dopant concentration had to be selected such that the optimized device exhibits significantly lower μ than the device with pristine In 2 O 3 . , Interestingly, in the majority of the previous studies, V Th or V On was tuned in the positive direction. In the case of our study, the shift in the V Th and V On was negative, demonstrating that MoO 3 opens a new possibility by enabling the tuning of the threshold voltage in the negative direction.…”

“…41,50,51 In other cases, including this study, however, to achieve an advantageous change in the V Th or V On , the dopant concentration had to be selected such that the optimized device exhibits significantly lower μ than the device with pristine In 2 O 3 . 42,43 Interestingly, in the majority of the previous studies, V Th or V On was tuned in the positive direction. In the case of our study, the shift in the V Th and V On was negative, demonstrating that MoO 3 opens a new possibility by enabling the tuning of the threshold voltage in the negative direction.…”

“…Doped films were prepared from dimethyl sulfoxide with acetylacetone additive at 400 °C. They reported reduced deep trap density owing to the suppression of oxygen vacancy formation, while avoiding a decrease in mobility …”

All solution-processed hafnium rich hybrid dielectrics for hysteresis free metal-oxide thin-film transistors

“…5 Therefore, the complete performance of TFTs totally depends on both semiconductor and dielectric materials including electrodes, and recently, significant efforts have been made to develop novel materials for these new device applications. For this, numerous oxide semiconductors such as a-IGZO, 6–8 In 2 O 3 , 9–11 and a-IGTO 12–14 have been extensively investigated by solution deposition methods due to their low fabrication cost, high optical transparency, high mobility, electrical stability, and robust operation for reliable metal oxide TFTs. At the same time, the investigation of dielectric materials progressed very slowly even though they are one of the crucial components in TFTs.…”

Optimization of solution-processed amorphous cadmium gallium oxide for high-performance thin-film transistors

“…Compared with conventional amorphous silicon or emerging alternatives, metal oxide semiconductors exhibit excellent properties, such as high electron mobilities even in the amorphous state, high optical transparency, high uniformity over a large area, and facile compositional control. 8–12 Several methods of depositing metal oxide semiconductors as thin films have been reported, including chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and solution-based deposition. Although vacuum processes, such as CVD, PVD, and ALD, are known to afford better control over the film thickness and morphology, 13 these methods generally require high-cost equipment and expensive precursors and are limited by low throughput and a fixed material composition.…”