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 wi th an Al0.1Ga0.9N barrier to increase the emitter injection efficiency. Cia RIE was used to pattern the emitter mesa, and selectively regrown base con tact pads were implemented to reduce a contact barrier associated with RIE etch damage to the base surface. The current gain of the devices was measur ed to be as high as three with a base width of 200 nm, DC transistor charac teristics were measured to 30 V V-CE in the common emitter configuration, w ith an offset voltage of 5 V, A gummel plot and base contact characteristic s are also presented.