CBr4-based in-situ etching of GaAs, assisted with TMAl and TMGa

• GaAs is etched with CBr4 in LP-MOVPE.
• TMGa addition leads to a superposition of etching and growth.
• TMAl inhibits defect formation and – at low temperature – enhances the etch rate.

In-situ etching of GaAs with CBr4 in metalorganic vapor phase epitaxy has been investigated at different temperatures using in-situ reflectivity to measure the etch rates. Deep (150 nm) etching of epitaxially-grown GaAs leads to the development of etch pits on the surface, corresponding to the emerging points of threading dislocations. Addition of trimethylgallium (TMGa) leads to a linear superposition of growth and etching. Trimethylaluminium (TMAl) added in moderate quantity enhances the etch rate and inhibits the development of etch pits. A model description for the enhanced etch rate is presented.