A high frequency field effect transistor is made by first epitaxially growing semiconductor channel and drain layers over a source layer. An oxide layer is formed on the upper drain layer which acts as a mask during etching of the epitaxial layers. Anisotropic etching of the semiconductor forms a mesa configuration of the channel and drain layers which is overlapped by the upper oxide layer. Metal is then evaporated onto the mesa from a point opposite the oxide layer. The overhanging oxide layer masks part of the mesa, particularly the drain layer, to define precisely the area covered by the evaporated gate contact, as required for high frequency operation. Other embodiments are also described.