Magnetron enhanced reactive ion etching of GaAs in CH₄/H₂/Ar: Surface damage study/H₂/Ar: Surface damage study

An investigation was performed of surface region etch-induced damage of GaAs magnetron reactive ion etched in CH₄/H₂/Ar gas mixtures. Transmission electron microscope measurements revealed the presence of etch-induced defects which extended 4.3, 7.2, and 8.7 nm below the surface for Ar concentrations of 0%, 10%, and 20%, respectively, in the gas mixture. Auger electron spectroscopy measurements showed that etching produced an As-deficient surface region extending approximately 10 nm below the surface. The amount of As deficiency increased with Ar concentration, but was relatively unaffected by postetch annealing at 400 °C for 30 s. Changes in Schottky barrier surface potential (Di, upon etching and subsequent annealing can be explained by a combination of H passivation effects and As removal from the surface, whereas changes in Schottky barrier diode ideality factor n can be explained by the presence of etch-induced surface region defects such as donorlike As vacancies and deep level recombination centers, both of which are passivated by H.