Self-terminating thermal oxidation of AlAs epilayers grown on GaAs by molecular beam epitaxy

Metal-oxide-semiconductor (MOS) capacitors were prepared by thermal oxidation (wet and dry) of AlAs epilayers grown on GaAs using molecular beam epitaxy (MBE). This oxidation process was found to be self-terminated at the AlAs-GaAs interface. Together with the use of MBE for growing the AlAs-GaAs multilayer structures, the oxide films obtained were extremely uniform over areas ≳6 cm2, possessed sharp oxide-semiconductor interfaces, and precise film thicknesses. Capacitance-voltage measurements on these MOS capacitors displayed inversion behavior and showed little or no hysteresis for oxides prepared by dry oxidation. Measured fixed interface charge density was ∼ (4–6) ×1011 cm−2, while breakdown fields were ∼ (2–4) ×106 V/cm.