ETCHING OF ALXGA1-XAS (0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1) BY TRISDIMETHYLAMINOARSINE

The etching of AlxGa1-xAs 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 AlxGa1-xAs rapidly decreased along with an increase in x, reaching almost zero at x = 1. At a substrate temperature of 600 degrees C, where the R(e) for GaAs was 0.33 monolayer(ML)/s, the R(e) of AlxGa1-xAs 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.