Selective etching and photoetching of {100} gallium arsenide in CrO 3-HF aqueous solutions : I. Influence of composition on etching behaviour

Abstract

The etch rate and surface morphology of n-type, Si doped, ‘100’ GaAs versus composition of CrO 3-HF-H 2O mixtures were studied. Two ternary diagrams: (i) with and (ii) without laser illumination, have been drawn and described. Particular attention was paid to finding mixtures suitable for shallow revealing of defects in thin epitaxial layers and in bulk GaAs. High resolution etch patterns have been obtained after photoetching (etch depth 0.1 to 0.2 μm) and after etching without illumination (etch depth 0.5 to 5 μm). Defects can also be revealed on semi-insulating and p-type GaAs, although the sensitivity is then decreased and an etch depth of 0.5 to 1 μm is required to produce well resolved surface patterns. This “Sirtl-like” defect revealing system (DSL) has been calibrated and confronted with the well known AB etch and ABI-DABL systems [Saitoh et al., J. Electrochem. Soc. 122 (1975) 670; Munoz-Yague and Bafleur, J. Crystal Growth 53 (1981) 239].