A new method of fabricating gallium arsenide MOS devices with improved electrical properties is discussed. The device consists of a gallium arsenide substrate overlaid with a gallium arsenic oxide, a thin aluminum oxide, and a metallic contact. The oxide layers are fabricated using a plasma oxidizing process. These MOS devices show very high breakdown voltages (typically ≈±4×106V/cm) and have low surface‐state densities (≈5×1010cm−2).