High-performance bipolar microwave transistor
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorNax N. Yoder
Life of this patent
Estimating the term…
Abstract
A high-frequency transistor and method of making same wherein the parasitic apacitance between base and collector is reduced. The collector layer of GaAs is impregnated with boron ions to form an insulative region under the base contact structure thereby reducing the capacitance in this region and leaving only the region underlying the emitter structure as the active transistor region.
Claims4
An improved bipolar transistor of the type having a collector layer lying on one side of a substrate and an ohmic contact lying on the other side thereof, a base layer lying on the collector layer, an emitter structure including a tunnel barrier layer lying on a center region of the base layer, an emitter layer lying on the tunnel barrier layer and another ohmic contact lying on the emitter layer, and a base contact structure including a contact layer lying on outer regions of the base layer and a metal layer lying on the contact layer, the emitter and base contact structures being spaced from each other, wherein the improvement comprises:
- forming a semi-insulative region in the collector layer underlying the base contact structure, so that the region through which charge carriers travel from the emitter structure through the base layer into the collector layer is restricted substantially to the center region of the base layer underlying the tunnel barrier layer of the emitter structure.
Dependencies are inferred from the claim text.