Effect of deposition condition and UV-ozone post-treatment on work function of DC magnetron sputtered AZO thin films

Abstract

Highly transparent and conductive aluminum-doped zinc oxide (AZO) thin films were successfully deposited on glass by DC magnetron sputtering. The effects of Al-doping content (1–4 at.%), substrate temperature (250–350 °C) and ultraviolet (UV)-ozone treatment time (0–20 min) on AZO film work function were systematically investigated. It was revealed that the AZO work function increased with the decrease of Al content, while it was almost insensitive to the substrate temperature. Moreover, the UV-ozone treatment significantly improved AZO work function, while the post-treatment time had no effect on AZO work function. Two factors, [OZnAl]/([Zn] + 1.5[Al]) ratio and carbon contamination on film surface, affected the AZO work function. It was suggested that AZO films with high [OZnAl]/([Zn] + 1.5[Al]) ratio and reduced carbon concentration, possessed high work function.