Native oxide stabilization of AlAs-GaAs heterostructures

Data are presented on the stabilization of AlAs-GaAs heterostructures against atmospheric (destructive) hydrolysis using the native oxide that can be formed (N2+H2O, 400 °C, 3 h) on the AlAs layer. The ∼0.1-μm-thick native oxide formed from the AlAs layer is shown to be stable with aging (∼100 days), while unoxidized samples degrade through the AlAs (0.1 μm) down into the GaAs as deep as ∼1 μm. Relative to oxides formed (∼25 °C) on AlAs (or AlxGa1−xAs, x ≳ 0.7) under atmospheric conditions (hydrolysis), oxides formed (via N2 +H2O) at higher temperatures (≳400 °C) are much more stable and seal the underlying crystal (e.g., GaAs).