High-Performance Fully Thermal ALD-Processed IGZO Thin Film Transistors

To enable ultrahigh-resolution displays, there is an urgent requirement for novel structures and processes that enhance the performance of thin film transistors (TFTs). Thermal atomic layer deposition (TH-ALD) emerges as a promising technique due to its capabilities in achieving controlled composition and large-area deposition. Here, we report a method for the vertical dimension control of ultrahigh performance indium-gallium-zinc-oxide (IGZO) TFTs fabricated via TH-ALD. By carefully adjusting the ratio and stacking sequence of InO $_{\text{x}}$ , GaO $_{\text{x}}$ , and ZnO $_{\text{x}}$ layers, our devices demonstrate outstanding performance characteristics. These include a field-effect mobility of 26.5 cm $^{\text{2}}$ /Vs, a threshold voltage of $-$ 0.06 V, an $\textit{I}_{\text{on}}$ / $\textit{I}_{\text{off}}$ ratio of 10 $^{\text{7}}$ , and a subthreshold swing (SS) of 0.15 V/decade, while maintaining a reasonable carrier density level of approximately 10 $^{\text{18}}$ cm $^{-\text{3}}$ . Based on the evaluation of physical, chemical, and optical analyses, a systematic investigation is conducted into how deposition routes affect performance, with the purpose of strategically improving overall performance and preventing problems like conductivity similar to that of conductors or insulators. The results indicate that IGZO TFTs fabricated via TH-ALD hold great potential advantages in ultrahigh-resolution displays industry.