Etching of AlxGa1-xAs (0≤x≤1) by Trisdimethylaminoarsine

Abstract
The etching of Al x Ga1- x As by trisdimethylaminoarsine (TDMAAs) in an ultra-high-vacuum chamber of molecular-beam epitaxy (MBE) was investigated in relation to the Al composition (x) dependence. The etching rate (R e) of Al x Ga1- x As rapidly decreased along with an increase in x, reaching almost zero at x=1. At a substrate temperature of 600° C, where the R e for GaAs was 0.33 monolayer(ML)/s, the R e of Al x Ga1- x As with x above 0.06 was one order of magnitude smaller than that for GaAs. In situ Auger electron spectroscopy revealed that the surfaces of AlGaAs exposed to TDMAAs changed to Al-rich surfaces, showing that the Al-rich layer formed as a result of the selective desorption of Ga atoms from the AlGaAs surface terminated the progression of etching.