The high-performance ZnO thin-film transistors (TFTs) were fabricated on indium tin oxide glass with high-capacitance atomic layer deposition (ALD)-processed ZrO₂ as the gate dielectric. The 5-nm ultrathin ZrO₂ film showed a very high areal capacitance of 820 nF/cm² at 20 Hz, a relatively high breakdown field of 14 MV/cm, and low surface root-mean-square (rms) roughness of 0.22 nm, making it possible for ZnO/ZrO₂ TFT to not only be operated by an ultralow operating voltage of 1 V but also present a near theoretical limit subthreshold swing of 69 mV/dec. Furthermore, the ZnO TFT with a 5-nm ZrO₂ gate dielectric exhibited excellent performance, such as a high Ion/Ioff of 10⁷, large field effect mobility of 36.8 cm²/Vs, low-density of trapping states (Ntrap) of 1.6 x 10¹¹ eV⁻¹cm⁻², and negligible hysteresis. In addition, the electron transport mode was built to explain the high mobility of nanocrystalline ZnO TFT. As a result, the ultralow operating voltage TFTs exhibited great potential for low-powered electronics applications.

The p-type Li:NiO_x thin films were successfully fabricated through the SUV route at 150 °C.

In this article, solution-processed zinc-tin-oxide (ZTO), indium-zinc-tin-oxide (IZTO), and yttrium-doped indium-zinc-tin-oxide (IZTO:Y) thin film transistors (TFTs) were investigated. The results indicate that the field effect mobility of the ZTO TFTs is enhanced by indium doping, whereas leading to the degradation of stability. Y-doping IZTO TFTs were also studied aiming to improve the stability of IZTO TFTs. The IZTO:Y shows a relatively higher transmittance in the visible light region compared to the nondoped IZTO, which could be due to the decrease of shallow defect levels caused by oxygen vacancy in the bandgap. Based on the X-ray photoelectron spectroscopy analysis, the oxygen vacancy concentration of IZTO:Y thin films decreases dramatically from 36.5% to 18.5% with Y incorporation. Moreover, the stability of IZTO:Y TFTs under positive bias stress (PBS) is also significantly improved. The device with 5-mol% Y element shows a low threshold voltage shift of 0.7 V compared to 2.6 V of IZTO TFT. The improvement in stability and electrical properties of IZTO TFTs are attributed to the Y doping, which can suppress the oxygen vacancy defects. Therefore, the high stability and excellent electrical performance of Y-doped IZTO TFTs have shown great application potential in transparent devices.

We developed a novel method to fabricate Zr-doped ZnO (ZrZnO) thin films via low-temperature atomic layer deposition technique. ZrZnO films were deposited by diethylzinc (DEZ)/tetrakiszirconium (TDMAZr)/H₂O cycles instead of the traditional DEZ/H₂O/TDMAZr/H₂O cycles and applied in thin-film transistors (TFTs). It is found that ZrZnO-TFTs with a Zn-Zr-O:ZnO atomic ratio of 1:49, i.e., ZrZnO (1:49) exhibit excellent properties, such as a minimum subthreshold swing value of 0.37 V/dec, a maximum Ion/Ioff value of 2.4 x 10⁷, a larger mobility of 12.38 cm²/V· s, and a smaller threshold voltage shift (Δ Vth) of 0.61 V under temperature stress from 25 °C to 105 °C, which are superior compared with TFTs with ZnO channel doped by ZrO₂ layer. The stability of ZnO TFTs was improved greatly by Zr-Zn-O doping. Moreover, the field-effect mobility of ZrZnO-TFTs was rarely influenced. Temperature-stress test was carried out to build up the correlation model in terms of the defect structures, subgap states, and stability. These results could provide a new access to understand the device instability of ZrZnO TFTs.

In this paper, top-gate thin-film transistors (TFTs) of two stacked double-channel layers derived from atomic layer deposition in combination with the plasma-enhanced chemical vapor deposition (PECVD) process were fabricated. The Hall measurement shows that the Hall mobility of the indium gallium oxide (IGO)/indium gallium zinc oxide (IGZO) active layer is 1.6 times more that of the amorphous In-rich IGZO/IGZO layer due to superior carrier percolation conduction paths from the polycrystalline IGO layer. Furthermore, x-ray photoelectron spectroscopy analysis indicates that the IGO/IGZO film has much less oxygen vacancy concentration, which is advantageous in improving not only mobility but also stability. The optimized IGO/IGZO TFT showed both high mobility (38.0 cm2 V−1 s−1) and high stability (ΔVTH = +0.14 V) of a positive bias stress under post-deposition annealing at 250 °C. This strategy provides a feasible process for realizing high-performance TFTs that is compatible with ALD-derived oxides and commercial PECVD techniques in the industry.