A method for suppressing impurities in GaN thin films grown via plasma-enhanced atomic deposition (PEALD) through the in situ pretreatment of Si (100) substrate with plasma was developed. This approach leads to a superior GaN/Si (100) interface. After pretreatment, the thickness of the interfacial layer between GaN films and the substrates decreases from 2.0 to 1.6 nm, and the oxygen impurity content at the GaN/Si (100) interface reduces from 34 to 12%. The pretreated GaN films exhibit thinner amorphous transition GaN layer of 5.3 nm in comparison with those nonpretreated of 18.0 nm, which indicates the improvement of crystallinity of GaN. High-quality GaN films with enhanced density are obtained because of the pretreatment. This promising approach is considered to facilitate the growth of high-quality thin films via PEALD.
Keywords: Ar/N2/H2 plasma; GaN; GaN/Si (100) interface; PEALD; impurity; pretreatment.