In-situ monitoring of the selective etching of antimonides in GaSb/AlSb/InAs heterostructures using Raman spectroscopy

The in-situ real-time monitoring of the selective etching of semiconductor structures with a Raman microprobe system is demonstrated for the first time. The technique that is applied to GaSb/AlSb/InAs heterostructures allows the accurate timing of the etching as well as a study of the chemistry of the etching process and can be applied to many problems in processing of compound semiconductors. During etching of AlSb a surface layer rich in Sb builds up that slows down the etch rate whereas GaSb is etched without producing this residue layer. The origin of the antimony layer is explained.