AlGaN GaN heterojunction bipolar transistor

We demonstrate the first GaN bipolar transistor. An AlGaN/GaN HBT structure was grown by MOCVD on c-plane sapphire substrate. The emitter was grown with an Al0.1Ga0.9N barrier to increase the emitter injection efficiency. Cia RIE was used to pattern the emitter mesa, and selectively regrown base contact pads were implemented to reduce a contact barrier associated with RIE etch damage to the base surface. The current gain of the devices was measured to be as high as three with a base width of 200 nm, DC transistor characteristics were measured to 30 V V-CE in the common emitter configuration, with an offset voltage of 5 V, A gummel plot and base contact characteristics are also presented.