ANISOTROPIC PHOTOETCHING OF III-V-SEMICONDUCTORS .1. ELECTROCHEMISTRY

The mechanism and influence of photogalvanic interactions during localized photoetching of III-V semiconductors have been investigated. Starting from the cyclovoltammograms and etching kinetics in the dark and under uniform illumination, the chemistry of the mixed dark/illuminated system is discussed. Both in terms of current-potential curves and of band-energy diagrams, it is demonstrated how a geometrical separation of partial hole and electron currents can lead to the strong enhancement of etch rates under localized illumination. Some illustrative experiments are discussed, quantitatively. In the present work GaAs in acidic H2O2 and S2O82− solutions are used as model systems, but in addition some results from other III-V compounds and etchants are presented. © 1990, The Electrochemical Society, Inc. All rights reserved.