Properties of Al2O3 optical coatings on GaAs produced by oxidation of epitaxial AlAs/GaAs films

Abstract
Auger analysis of oxidized AlAs epitaxial layers grown by molecular‐beam epitaxy reveals that the composition of the films is stoichiometric Al2O3. High optical quality of the films is demonstrated by optical reflection and transmission measurements. A reflectivity of 6% is measured for an antireflection coating on GaAs. Leakage currents in the nA range and resistivities ≳5×1011 Ω cm are deduced from current‐voltage measurements. Capacitance‐voltage measurements on metal‐oxide‐semiconductor structures using the Al2O3 films obtained by oxidizing AlAs, reveal a significant reduction of the interface state density as compared to conventional, electron beam evaporated Al2O3.