Chemically assisted ion-beam etching processes have been examined using Cl-2, CH3I, and IBr3 for application in manufacturing optoelectronic devices. Although the etch rate was one of the properties compared, more attention was directed towards clean, smooth surfaces and exact reproduction of the desired geometry. The main effort was directed towards etching of laser mirrors, which require perpendicular sides of the structure with respect to the substrate plane. It was found that a low substrate temperature of 0 to 10 degrees C is the key for obtaining the desired surface quality and that a perpendicular sidewall can only be obtained by tilting the semiconductor wafer. This is in contrast to GaAs where temperature and beam energy strongly determine the angle of the structure walls relative to the wafer plane.