Plasma-enhanced atomic layer deposition of aluminum-indium oxide thin films and associated device applications

In this study, aluminum-indium oxide (AIO) semiconductors were fabricated by plasma-enhanced atomic layer deposition (ALD) using trimethyl (dimethylamino)propyl dimethyl indium and trimethylaluminum as the indium and aluminum precursors, respectively. The ALD supercycle consists of n indium oxide subcycles and one aluminum oxide subcycle, where n is 6, 9, 19, or 29. As the number of indium oxide subcycles decrease, the aluminum concentration in the AIO thin film increases and diminishes the thin film crystallinity. In addition, the chemical binding states of the AIO thin film also change with the number of indium oxide subcycles. AIO thin films made with a high number of indium oxide subcycles show stable aluminum oxide bonding and low oxygen related defects. In contrast, AIO thin films deposited with a small number of indium oxide subcycles form unstable AlOx, InOx, and oxygen related defects. The control of aluminum concentration in AIO thin films is essential to control the defect sites in the thin film. Finally, thin film transistors using AIO thin films are fabricated, demonstrating 2.16 V, 6.07 cm2/V s, and 1.50 V/decade with an optimized number of indium oxide subcycles.