In-situ Etching Of Gaas/al_xga(1-x)as By Cbr_4

摘要

In-situ etching of GaAs and Al_xGa(1-x)As in LP-MOVPE has been studied using carbon tetrabromide (CBr_4). This source is routinely used by us as a source for carbon doping in GaAs and AlGaAs. The etching rate decreases with increasing AsH_3 partial pressure. While the etch rate is nearly constant for GaAs between 600 and 700 ℃ 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.