Influence of source and drain contacts on the properties of the indium-zinc oxide thin-film transistors based on anodic aluminum oxide gate dielectrics

Thin-film transistors (TFTs) based on indium-zinc oxide (IZO) active layer and anodic aluminum oxide (Al2O3) gate dielectric layer were fabricated. The influence of source and drain (S/D) contacts on TFT performance was investigated by comparing IZO–TFTs with different S/D electrodes. The TFT with Mo S/D electrodes had higher output current and lower threshold voltage, but had poorer subthreshold swing and lower effective electron mobility compared to that with ITO S/D electrodes. By using x-ray photoelectron spectroscopy (XPS) depth profile analyzing method, it was observed that Mo was diffusing seriously into IZO, resulting in the variation of the effective channel length, thereby causing serious short-channel effect, poor subshreshold swing, and bad uniformity of the TFTs with Mo S/D electrodes.