Impact of AlSnO Back-Channel Layer on the Performance of AlSnO/InSnZnO Heterojunction Thin-Film Transistors

In this study, Al _{\text{0.1}} Sn _{\text{0.9}} O and Al _{\text{0.3}} Sn _{\text{0.7}} O are used as the back-channel materials of Al _{\textit{x}} Sn _{\text{1}-\textit{x}} O/InSnZnO heterojunction thin-film transistors (HTFTs) to investigate the effect of Al/Sn mole ratio on the electrical performance of Al _{\textit{x}} Sn _{\text{1}-\textit{x}} O/InSnZnO HTFTs. The Tauc plot, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) are used to characterize the bandgap energy, crystallinity, and oxygen vacancy content of the films. The results show that Al _{\text{0.3}} Sn _{\text{0.7}} O has a wider bandgap energy and fewer oxygen vacancies than Al _\text{0.1} Sn _{\text{0.9}} O. In addition, Al _{\text{0.1}} Sn _{\text{0.9}} O is polycrystalline, while Al _{\text{0.3}} Sn _{\text{0.7}} O is amorphous. This difference in crystallinity results in Al _{\text{0.1}} Sn _{\text{0.9}} O having higher electron mobility than Al _{\text{0.3}} Sn _{\text{0.7}} O. Therefore, Al _{\text{0.1}}