A self-aligned enhancement mode metal-oxide-compound semiconductor field effect transistor (10) includes a lower oxide layer that is a mixture of Ga₂O, Ga₂O₃, and other gallium oxide compounds (30), and a second insulating layer that is positioned immediately on top of the gallium oxygen layer together positioned on upper surface (14) of a III-V compound semiconductor wafer structure (13). Together the lower gallium oxide compound layer and the second insulating layer form a gallium oxide gate insulating structure. The gallium oxide gate insulating structure and underlying compound semiconductor gallium arsenide layer (15) meet at an atomically abrupt interface at the surface of with the compound semiconductor wafer structure (14). The initial essentially gallium oxygen layer serves to passivate and protect the underlying compound semiconductor surface from the second insulating oxide layer. A refractory metal gate electrode layer (17) is positioned on upper surface (18) of the second insulating oxide layer. The refractory metal is stable on the second insulating oxide layer at elevated temperature. Self-aligned source and drain areas, and source and drain contacts (19, 20) are positioned on the source and drain areas (21, 22) of the device. Multiple devices are then positioned in proximity and the appropriate interconnection metal layers and insulators are utilized in concert with other passive circuit elements to form a integrated circuit structure.