In this article, we fabricated amorphous InSnO thin film transistors (TFTs) with exceedingly high mobility and low thermal budget. The device is annealed only at a low temperature of 150 °C, a field-effect mobility (${\mu }_{FE}$ ) of 70.53 cm²/V s, a subthreshold swing of 0.25 V/decade, an on/off current ratio over 10⁸, and a reasonable threshold voltage shift under negative bias stress. The influence of thermal annealing on amorphous InSnO TFTs was investigated by systematically analyzing the crystallization, surface morphology, internal chemical state, and energy band relationship of the InSnO thin film. Amorphous InSnO films deposited at room temperature have a sparse and porous loose structure, which has carrier scattering caused by poor film quality, resulting in low mobility and few free carriers in the film. With the increase in the annealing temperature, the In and Sn metal cations are further oxidized, increasing the carrier concentration in the film and forming a dense M–O–M network when annealed at 150 °C. With the further increase in the annealing temperature, a large number of thermally excited free electrons make the device appear metal like conductivity. This paper expands the research on a high electron concentration InSnO material as the active layer and promotes the development of amorphous oxide semiconductors in high mobility and flexible TFTs.

To meet the demand for next-generation electronic products with excellent driving ability and high switching speed, using InSnO electrode material as a semiconductor channel layer is one of the attempts to improve the mobility of thin-film transistors (TFTs). However, instabilities in the environment limit the development of high-mobility semiconductors. In this work, an ultrathin hafnium (Hf)-doped InSnO (HITO) layer is prepared with enhanced stability, which is achieved by radio frequency magnetron cosputtering at low temperature. The HITO layer is deposited onto InSnO (ITO) to reduce the oxygen vacancies concentration, and thus, the trapping and detrapping issues at the surface of ITO channel are suppressed, leading to a high mobility of 76.21 cm $^{{2}}\text{V}^{{-{1}}}\text{s}^{-{1}}$ , a low threshold voltage of −0.86 V, and a steep subthreshold swing (SS) of 0.24 V/decade. The HITO layer is insensitive to water and oxygen and effectively blocks the permeability channel layer. The fabricated HITO/ITO TFTs obtain improved stability in positive bias stress (PBS) tests in humidity condition. The threshold voltage shifts under PBS at 85% relative humidity for 3600 s decreased from −8.2 to 0.97 V. This work provides a feasible method for low-cost, high-mobility oxide TFTs, and the whole process temperature control below 150 °C also expands its application in flexible electronic devices.

Despite increasing indium content improves the field-effect mobility of metal–oxide thin-film transistors (TFTs), it is usually accompanied by the deterioration in bias stability. In this work, we achieve enhanced mobility and stability together within a certain range by controlling the sputtering power in the co-sputtering system. Due to the difference in electronegativity and binding energy between indium and zinc, the increase of indium content at lower sputtering power reduces the oxygen vacancy defects and smooth interfacial quality. In $_{\text{0.45}}$ Zn $_{\text{0.42}}$ Sn $_{\text{0.13}}$ O TFTs exhibit excellent stability threshold voltage variation of only 0.58 and $-$ 0.12 V under positive bias stress (PBS) and negative bias stress (NBS). However, excess indium could lead to high carrier concentrations in the channel, which introduced new defects, while defects between active and gate insulator (GI) layer interface trap electrons and lead to decreased stability. In addition, the maximum temperature in this work does not exceed 150 $^{\circ}$ C and the transmittance of all thin films is greater than 80% in the visible range, which has great potential for application in the next generation of transparent flexible electronics. These results indicate that optimizing the ratio of indium doping is an effective strategy for achieving simultaneous enhancement of mobility and stability.

Oxide thin-film transistors (TFTs) with high mobility and excellent stability are extremely desired for advanced displays. In this work, we simultaneously enhanced the mobility and stability of In2O3 TFTs by nitrogen modification strategy, and systematically investigated the effects of nitrogen doping content on the structures and properties of In2O3 films and the TFT performance. With increasing amount of the nitrogen flow rate from 0 to 9 SCCM, crystallinity and surface quality are improved, while the oxygen defect, optical bandgap, and Urbach energy are decreased, gradually. At a suitable nitrogen flow rate of 6 SCCM, In2O3 films exhibit optimal comprehensive properties, such as high crystallinity, low surface roughness, and defect density, yielding significant enhancement in TFT performance. In particular, the N modified In2O3 TFT demonstrates a highest mobility of 24.96 cm2/V s, accompanied by superior positive and negative bias stability. And then, degradation mechanisms of the TFT stabilities are comprehensively revealed. The findings may be generalizable to other oxide electronics.