Diamond metal base/permeable base transistor and method of making same

Abstract

A diamond transistor includes a base layer formed of a conductive material which is lattice matched to diamond, and which is embedded between two epitaxial diamond layers to form a monolithic heterostructure. An emitter contact is electrically connected to one diamond layer and a collector contact is electrically connected to the other diamond layer. The base layer may be a solid base layer, in which case a metal base transistor is formed. Alternatively, the base layer may be a patterned base layer having a grid of laterally spaced apart conductor lines, in which case a permeable base transistor is formed. Alternatively, the epitaxial diamond layers may be doped diamond layers of the same conductivity type. The epitaxial diamond layers may be undoped diamond layers formed between highly doped diamond layers, with the collector and emitter contacts being formed on the highly doped diamond layers to provide low resistance contacts. The transistor is preferably formed by epitaxially forming a first undoped diamond layer on a first heavily doped diamond layer. A metal base electrode is then epitaxially formed on the first undoped diamond layer. A second undoped diamond layer is epitaxially formed on the metal base electrode. A second heavily doped diamond layer is then formed on the second undoped diamond layer, and emitter and collector contacts are formed on the exposed faces of the respective heavily doped monocrystalline diamond layers.