In-situ etching of GaAs/Al x Ga1− x As by CBr4

Abstract: In-situ etching of GaAs and Al x Ga1− x As in LP-MOVPE has been studied using carbon tetrabromide (CBr4). This source is routinely used by us as a source for carbon doping in GaAs and AlGaAs. The etching rate decreases with increasing AsH3 partial pressure. While the etch rate is nearly constant for GaAs between 600 and 700°C it strongly drops towards higher temperatures with higher Al content in the layers. A model based on blocking of the surface by non-volatile Al–Br compounds is proposed. The observed effects allow for selective in-situ etching of GaAs against AlGaAs. [Copyright &y& Elsevier]