Transistor device and method

A field-effect transistor device, including: a semiconductor heterostructure comprising, in a vertically stacked configuration, a semiconductor gate layer between semiconductor source and drain layers, the layers being separated by heterosteps; the gate layer having a thickness of less than about 100 Angstroms; and source, gate, and drain electrodes respectively coupled with said source, gate, and drain layers. Separation of the gate by heterosteps, rather than an oxide layer, has very substantial advantages.