MAGNETRON ENHANCED REACTIVE ION ETCHING OF GAAS IN CH4 H2/AR - SURFACE DAMAGE STUDY/

An investigation was performed of surface region etch-induced damage o f GaAs magnetron reactive ion etched in CH4/H-2/Ar gas mixtures. Trans mission 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 m ixture. Auger electron spectroscopy measurements showed that etching p roduced an As-deficient surface region extending approximately 10 nm b elow the surface. The amount of As deficiency increased with Ar concen tration, but was relatively unaffected by postetch annealing at 400-de grees-C for 30 s. Changes in Schottky barrier surface potential PHI(b) upon etching and subsequent annealing can be explained by a combinati on of H passivation effects and As removal from the surface, whereas c hanges 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.