Field effect transistor devices and methods

A field-effect transistor device is provided, including: a substrate; a vertically stacked layered semiconductor structure on the substrate including the following layers: a first quantum well layer having laterally spaced-apart drain and source regions that are each delta-doped with a dopant of a first conductivity type, the drain and source regions being laterally separated by a channel region; and a second quantum well layer vertically spaced from the first quantum well layer by a gate spacing layer, the second quantum well layer having a gate region, above the channel region, which is delta-doped with a dopant; and couplings for applying electrical potentials with respect to said source, drain, and gate regions.