The reactive ion etching characteristics of AlGaN/GaN SLs and etch-induced damage study of n-GaN using Cl_2/SiCl_4/Ar plasma

摘要

In this study, the etching characteristics of Al_xGa_(1-x)N/GaN superlattices with x = 0.11 and 0.21 of Al and n-GaN with Cl_2/SiCl_4/Ar plasma using reactive ion etching (RIE) system were investigated. By varying gas ratio and rf power, it was found that SiCl_4 is an effective getter to remove residual oxygen in the chamber and has a strong physical sputtering effect to remove the oxide layer during the etching, and a nearly nonselective smooth etching of Al_xGa_(1-x)N/GaN SLs with the high etch rate of 220 nm/min could be obtained. X-ray photoelectron spectroscopy (XPS) and Hall measurements were employed together to reveal the correlation between stoichiometry and electrical changes of n-GaN induced by plasma etching. Combining with N_2O plasma post-etch treatments to restore etched surfaces, those results suggested that oxygen not only influences morphology of the Al-containing samples, but also electrical properties of n-GaN by changing the status of oxygen-related defects, which may play crucial roles in determining the nature of the damage.