Comparative Study of Wet and Dry Oxides on Polycrystalline GaAs by AES,SIMS and XPS

Complementary Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and X-ray photoelectron spectroscopy (XPS) are used to evaluate low-temperature wet and dry oxides and the oxide/semiconductor interfaces on polycrystalline GaAs. The dry oxides are discovered to be primarily Ga//2O//3 and are relatively uniform in composition. The wet oxides are less uniform and mixed, with a more abrupt transition region that the dry oxide/GaAs interface. XPS data verify the presence of Ga//2O//3 in the dry oxide. In comparison, Ga//2O//3, As//2O//5 are detected in the wet oxide layer. SIMS shows higher trace impurity concentrations in the wet oxide with some buildup at the oxide/GaAs interface. The relative performance of solar cells fabricated from these structures is discussed.