Crystallographic dependence of the lateral undercut wet etching rate of InGaP in HCl

The crystallographic dependence of the lateral etch rate in 12 M HCl of InGaP lattice matched to GaAs has been measured. The etch rate at 20 degreesC is found to have twofold rotational symmetry about [100] and varies between <0.01 mu m/min for mesas oriented along [011] directions and similar to 0.9 mu m/min for mesas 55 degrees and 125 degrees from [011] towards [0<(1)over bar>1]. Etch fronts consist of {111}A planes. The etch rate also depends on the direction of etch step flow, suggesting that reconstruction plays an important role during InGaP wet etching. (C) 2003 American Institute of Physics.