High Performance Amorphous In_0.5Ga_0.5O Thin‐Film Transistor Embedded with Nanocrystalline In₂O₃ Dots for Flexible Display Application

Abstract

High‐performance, coplanar amorphous In0.5Ga0.5O (a‐IGO) thin film transistor (TFT) on a polyimide (PI) substrate deposited by spray pyrolysis (SP) is reported. The SP a‐IGO film deposited at 370 °C has less than 8% nanocrystalline‐In2O3 dots and a mass density of 6.6 g cm−3. The a‐IGO TFT on PI exhibits linear mobility over 30 cm2 V−1 s−1 and a negligible shift in threshold voltage (ΔVTH = <0.3 V) under positive bias (+20 V) at 60 °C for 1 h. The TFT performance is stable even when bent to a radius of ≈1 mm. The X‐ray photoelectron spectroscopy results of the SP a‐IGO deposited at 370 °C indicate the O‐vacancy (Vo) related defects of 25.79% and hydroxyl (OH) at less than 3%, indicating a good active/gate insulator interface. A seven‐stage ring oscillator made of SP a‐IGO TFTs exhibits a high oscillation frequency (>2.3 MHz) with a low propagation delay time of ≈30 ns per stage at a supply voltage (VDD) of 15 V. The fabricated gate shift register circuit works up to the last stage without any decrement of the input voltage (15 V) with rising and falling times less than 0.8 µs. Therefore, the coplanar a‐IGO TFT by SP deposited at 370 °C is a promising candidate for low‐cost, flexible TFT backplanes of foldable electronics.

All‐Solution‐Processed InGaO/PbI2 Heterojunction for Self‐Powered Omnidirectional Near‐Ultraviolet Photodetection and Imaging

“…As a typical oxide semiconductor, indium–gallium‐oxide (InGaO) is attracted much attention in next‐generation electronics and optoelectronics in the past decades, owing to its high mobility, wide bandgap, and chemical stability. [ 1–5 ] It is fantastic to find that stoichiometry and crystallinity both play important roles in the corresponding mobility and bandgap. [ 6–8 ] Generally speaking, with a larger In content, InGaO possesses higher mobility, a narrower bandgap, owing to the unique orbital of In.…”

“…Although amorphous InGaO film has been widely studied in electrical devices, its ultraviolet photodetection behaviors are studied limited in the literature. [ 4,19 ] This is because the famous persistent photocurrent (PPC) phenomenon, which is prevalent in oxide semiconductors, severely limits the ultraviolet photodetection performance of amorphous InGaO film, resulting in a slow photoresponse speed. [ 20–22 ] Generally speaking, the PPC phenomenon originates from the ionized oxygen vacancies, which prevent the recombination of photogenerated carriers.…”

Toward Smart, Flexible, and Omnidirectional Self-Powered Photodetection by an All-Solution-Processed In2O3/Pbl2 Heterojunction

“…Meanwhile, the amorphous structure can avoid the absence of grain boundaries and is conducive to obtaining a compact, uniform, and smooth film, making In 2 O 3 films insensitive to chemical bond distortion and stress, promising the next-generation flexible, stretchable, and omnidirectional devices . Several methods have been reported to prepare amorphous In 2 O 3 films, including plasma-enhanced chemical vapor deposition, magnetron cosputtering, atomic layer deposition, and halide vapor phase epitaxy . Recently, a solution approach has been proposed to prepare amorphous In 2 O 3 films, which is complementary metal oxide semiconductor compatible and has the features of large area preparation and high-throughput production, − promising the application of amorphous In 2 O 3 films in the next-generation electronics and optoelectronics. ,, …”

“…Indium oxide (In 2 O 3 ), as a typical oxide semiconductor, has drawn enormous attention for use in next-generation electronics and optoelectronics due to its suitable band gap, tunable electrical conductivity, inherent transparency, and low resistivity. − Benefiting from the unique orbital of In, the electron effective mass is low, enabling the realization of high mobility of In 2 O 3 . It is worth mentioning that the unique properties of In cations are still effective in the amorphous structure, − endowing the amorphous In 2 O 3 films with excellent electrical and optoelectronic properties. Meanwhile, the amorphous structure can avoid the absence of grain boundaries and is conducive to obtaining a compact, uniform, and smooth film, making In 2 O 3 films insensitive to chemical bond distortion and stress, promising the next-generation flexible, stretchable, and omnidirectional devices .…”

“…Although amorphous In 2 O 3 films have been widely studied in electrical devices, their photodetection performance is rarely reported due to the famous persistent photocurrent (PPC) phenomenon. ,, The PPC phenomenon originates from the ionized oxygen vacancies and is prevalent in oxide semiconductors, which prevents the recombination of photogenerated carriers after removing the light signal, resulting in a slow photoresponse speed and unstable dynamic photoresponse. ,− On the other hand, it is well-known that the In cation is a creator of oxygen vacancy (Vo) due to the weak In–O bond strength, and Vo acts as an electron source site . Hence, the electron concentration in amorphous films is high, resulting in a large dark current and a small I light / I dark ratio in photodetectors.…”