The electrical recovery behaviors of the amorphous InGaZnO thin-film transistors (a-IGZO TFTs) after positive gate-bias stress (PBS) are investigated. The TFTs show an evident sub-threshold swing (SS) degradation after the PBS removal when the channel layer is deposited at relatively high oxygen flow rates, although they exhibit a parallel positive shift in the transfer characteristics during the PBS. It is inferred that the SS degradation results from the oxygen interstitial defects created in the a-IGZO channel during the PBS, which are in the octahedral configuration and are usually more easily created in the oxygen-rich a-IGZO channel layer. They are electrically inactive during the PBS due to the “negative U” behavior and then become relaxed and electrically active during the recovery process, leading to the SS degradation during the recovery process.

High-performance ZnO thin-film transistors (TFTs) have been successfully fabricated by atomic layer deposition (ALD) with a maximum temperature of 200 °C. The impacts of deposition and annealing temperature on the characteristics of devices were discussed. ZnO thin films show a (002) preferred orientation at the high growth temperature. The carrier concentrations of ZnO TFTs can be optimized by appropriate growth temperature and annealing treatments. Subthreshold swing (SS) and hysteresis windows of TFTs are improved after annealing in dry O₂ due to the reduction in traps at ZnO/SiO₂ interface or/and within the ZnO channel. The ZnO TFT deposited at 150 °C with 200 °C annealing in oxygen demonstrates excellent electrical characteristics with high saturation mobility μ sat of 7.8 cm²V⁻¹s⁻¹, small SS of 127 mV/decade, high Ion/Ioff of 2.8 x 10⁹, and good contact between source/drain electrodes. The high-performance ZnO TFTs with low processing temperatures have great potential in application for flexible electronics.

In this work, we have successfully fabricated bottom gate fully transparent tin-doped zinc oxide thin film transistors (TZO TFTs) fabricated on flexible plastic substrate at low temperature by RF magnetron sputtering. The effect of O₂/Ar gas flow ratio during channel deposition on the electrical properties of TZO TFTs was investigated, and we found that the O₂/Ar gas flow ratio have a great influence on the electrical properties. TZO TFTs on flexible substrate has very nice electrical characteristics with a low off-state current (I_off) of 3 pA, a high on/off current ratio of 2 × 10⁷, a high saturation mobility (μ_sat) of 66.7 cm²/V•s, a steep subthreshold slope (SS) of 333 mV/decade and a threshold voltage (V_th) of 1.2 V. Root-Mean-Square (RMS) roughness of TZO thin film is about 0.52 nm. The transmittance of TZO thin film is about 98%. These results highlight that the excellent device performance can be realized in TZO film and TZO TFT can be a promising candidate for flexible displays.

We fabricated ZnO channel/Al₂O₃ gate dielectric thin-film transistors (TFTs) by atomic layer deposition (ALD) continuous growth process. The effects of the channel and the dielectric continuous growth on the performance of TFTs were investigated. Compared with noncontinuous growth ZnO/Al₂O₃ films, continuous growth ZnO/Al₂ O₃ films with no obvious buffer layer and less residual O-H bonds possess superior ZnO/Al₂ O₃ interface quality. The continuous growth TFTs exhibit a field-effect mobility of 19.6 cm² V⁻¹ s⁻¹, a subthreshold swing of 0.13 V dec⁻¹, a high Ion/Ioff of 4.1 x 10⁷, a hysteresis window of 0.09 V, and an excellent uniformity of electrical characteristics. Continuous growth TFTs also demonstrate better stability with minor shifts of ΔVth 0.6 V [positive bias stress (PBS)] and ΔVth -0.3 V [negative bias stress (NBS)]. The faster falling rates of activation energy for continuous growth TFTs indicate that the total trap density is reduced through the continuous growth of active layer and dielectric layer. Our results suggest that the ALD-based continuous growth process could enhance the performance of TFTs.

In this work, fully transparent high performance double-channel indium-tin-oxide/Al–Sn–Zn–O thin-film transistors (ITO/ATZO TFTs) are successfully fabricated on glass by radio frequency (RF) magnetron sputtering. The ITO layer acts as the bottom channel layer to increase the channel carrier concentration. The top ATZO channel layer, which is deposited via high oxygen partial pressure in the sputtering process, is useful to control the minimum off-state current. After annealing, the ITO/ATZO TFT demonstrates outstanding electrical performances, including a high ON/OFF current ratio (I_on/I_off) of 3.5 × 10⁸, a steep threshold swing (SS) of 142.2 mV/decade, a superior saturation mobility (μ_sat) of 246.0 cm²/Vs, and a threshold voltage V_T of 0.5 V. The operation mechanisms for double-channel structures are also clarified.

InSnO (ITO) thin-film transistors (TFTs) attract much attention in fields of displays and low-cost integrated circuits (IC). In the present work, we demonstrate the high-performance, robust ITO TFTs that fabricated at process temperature no higher than 100 °C. The influences of channel thickness (t_ITO, respectively, 6, 9, 12, and 15 nm) on device performance and positive bias stress (PBS) stability of the ITO TFTs are examined. We found that content of oxygen defects positively correlates with t_ITO, leading to increases of both trap states as well as carrier concentration and synthetically determining electrical properties of the ITO TFTs. Interestingly, the ITO TFTs with a t_ITO of 9 nm exhibit the best performance and PBS stability, and typical electrical properties include a field-effect mobility (µ_FE) of 37.69 cm²/Vs, a V_on of −2.3 V, a SS of 167.49 mV/decade, and an on–off current ratio over 10⁷. This work paves the way for practical application of the ITO TFTs.