An in situ examination of atomic layer deposited alumina/InAs(100) interfaces

Undoped InAs(100) wafers were either passivated with sulfur from a (NH4)2Sx solution or etched with NH4OH and then characterized with monochromatic x-ray photoelectron spectroscopy (XPS) before and after in situ deposition of Al2O3 by atomic layer deposition. Sulfur passivation minimized oxidation. Trimethyl aluminum (TMA) exposure reduced trivalent indium and arsenic oxidation states. The In1+ chemical state persisted while elemental arsenic remained at the Al2O3/InAs interface prior to TMA exposure and possibly a mixture of As–As and As–Al bonds were present afterwards. The In 3d5/2 peak line shape from bulk InAs differed from previous XPS experiments on epitaxial InxGa1−xAs.