Field effect transistor using diamond

Abstract

A field effect transistor in accordance with the present invention comprises a buffer layer made of a highly resistant diamond on a substrate; an active layer which is made of a conductive diamond on the buffer layer and has such a dopant concentration that conduction of carriers is metallically dominated thereby and such a thickness that dopant distribution is two-dimensionally aligned thereby; a cap layer made of a highly resistant diamond on the active layer; a gate electrode layer formed on the cap layer so as to make Schottky contact therewith; and a source electrode layer and a drain electrode layer which make ohmic contact with a laminate structure of said buffer, active and cap layers. Namely, the active layer is formed as a so-called .delta.-dope layer or pulse-dope layer doped with a conductive dopant, while being held between both highly resistant buffer and cap layers. Accordingly, even when the dopant concentration in the conductive diamond layer is increased, a high gain, as an excellent controllability and an excellent temperature-stability in operation characteristics can be obtained.