Effects of Cu:Al ratios and SiO2 substrates on PE-MOCVD copper aluminium oxide semiconductor thin films

Abstract

Transparent p-type Cu-Al-O thin films were prepared by plasma-enhanced metal-organic chemical vapor deposition technique. Cu-Al-O thin films were grown on za??cut single-crystal quartz, with the nominal Cu:Al ratios ranged from 1:1 to 6:1. It was observed that properties of the films, especially electrical conductivity and optical transmittance, were affected by the ratios of Cu:Al. The most conductive film, with a conductivity of 0.289 S cm-1 and a transmittance as high as 80%, was obtained with a nominal Cu:Al ratio of 1.5:1.It was observed that under a nominal Cu:Al ratio of 3:1, the crystalline films grown on single-crystal quartz were as conductive as 0.036 S cm-1. However, the amorphous or nanocrystal films grown on amorphous SiO2 substrates were insulators. It was also noted that the single-crystal quartz substrate was preferred for crystalline growth of films; while the amorphous or nanocrystal films were inclined to grow on amorphous SiO2 substrates.