Wet chemical MESA etching of InGaP and GaAs with solutions based on HCl, CH3COOH, and H2O2

Solutions consisting of 1 HCl:10 CH3COOH:xH2O2 are used for MESA etching of InGaP epitaxial layers on GaAs substrates. The etch rate of InGaP and GaAs and hence the selectivity of the etching solution depends on the H2O2 content. The etch rate of the etching solution is also strongly affected by temperature. In large unmasked areas 1HCl:10 CH3COOH:1 H2O2 etches InGaP inhomogeneously near mask edges. Edges etched in the (111) direction are found to be suitable for MESA isolation on (001) InGaP epitaxial layers grown on GaAs. The 1 HCl:10 CH3COOH:1H2O2 etching solution is sufficiently selective for the etching of InGaP grown on GaAs substrate.