Bromine ion-beam-assisted etching of III-V semiconductors

Bromine ion-beam-assisted etching produces smooth vertical sidewalls in GaA s, GaP, InP, AlSb, and GaSb as well as in the usual alloys formed from thes e materials. Care must be taken, however, during etching to match the speci fic material system with an appropriate substrate etch temperature. Far exa mple, vertical walls were obtained using substrate temperatures in the rang e of 150 to 200 degrees C with InP, 80 to 140 degrees C with GaAs and GaP, and below 30 degrees C with AlSb and GaSb. GaN has also been etched with th e technique. Our etching experience and the vapor pressure data for bromine with group III and group V elements lead us to believe that all of the var ious technologically important III-V binaries, ternaries, and quaternaries can be etched. Etch rates of most of the materials can be varied from sever al nm/min to 0.16 mu m/min through the bromine flow rate, Ar+ ion beam dens ity and energy, and the substrate temperature. Bromine ion-beam-assisted et ching also appears to have an advantage over chlorine ion-beam-assisted etc hing in many situations, in that substrate temperature ranges can be found for which vertical sidewalls are, maintained while etching through layered structures composed of various alloys of the materials. Here we present res ults obtained from etching a number of III-V binaries, alloys, and heterost ructures.