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

Bromineion-beam-assisted etching produces smooth vertical sidewalls in GaAs, GaP, InP, AlSb, and GaSb as well as in the usual alloys formed from these materials. Care must be taken, however, during etching to match the specific material system with an appropriate substrate etch temperature. For example, vertical walls were obtained using substrate temperatures in the range of 150 to 200°C with InP, 80 to 140°C with GaAs and GaP, and below 30°C with AlSb and GaSb. GaN has also been etched with the 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 various technologically important III-V binaries, ternaries, and quaternaries can be etched. Etch rates of most of the materials can be varied from several nm/min to 0.16 µm/min through the bromine flow rate, Ar⁺ ion beam density and energy, and the substrate temperature. Bromine ion-beam-assisted etching also appears to have an advantage over chlorine ion-beam-assisted etching 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 results obtained from etching a number of III-V binaries, alloys, and heterostructures. [ABSTRACT FROM AUTHOR]