Dry etch induced defects and H passivation of GaAs surfaces produced by Ch₄/H₂/Ar plasmas

An investigation was performed of surface region etch-induced damage of GaAs magnetron reactive ion etched in CH₄/H₂/Ar gas mixtures for 10% and 20% Ar concentrations. Schottky barrier I-V measurements showed that changes in surface potential (φ_b) upon etching and subsequent annealing can be explained by a combination of H passivation effects and As removal from the surface region. Changes in Schottky barrier ideality factor (n) can be explained by the presence of etch-induced surface region defects such as donor-like As vacancies and deep level recombination centers, both of which are passivated by H. Schottky barrier C-V measurements indicated that H passivation extends about 0.3 μm below the surface. Rapid thermal annealing at 400°C for 30 s was effective in removing most of the H passivation effects.