CHEMICAL-COMPOSITION BY AUGER SPUTTER-DEPTH PROFILES OF GAAS OXIDE LAYERS FORMED AFTER CHEMICAL OR AR+ ION ETCHINGS

The oxide formation on the GaAs(100) surface after different etching procedures has been studied using Auger sputter-depth profiles. The etching procedures were either chemical etching (H3PO4/H2O2/H2O or NH3/H2O2/H2O) or low-energy (100 eV) Ar+ ion beam etching. An attempt to a quantitative determination of the concentration profiles has been made using the sequential layer sputtering (SLS) model, taking into account the statistical nature of the ion sputtering and the Auger electron escape depth. The chemical composition and the oxide coverage on the GaAs surface have been deduced from the concentration profiles of the elements Ga, As and 0. The oxide composition has been also studied after a thermal annealing and compared to an atmospheric native oxide.