Self-aligned InGaP/GaAs heterojunction bipolar transistors for microwave power application

As an alternative to AlGaAs/GaAs heterojunction bipolar transistors (HBTs) for microwave applications, InGaP/GaAs HBTs with carbon-doped base layers grown by metal organic molecular beam epitaxy (MOMBE) with excellent DC, RF, and microwave performance are demonstrated. As previously reported, with a 700-AA-thick base layer (135- Omega /sq sheet resistance), a DC current gain of 25, and cutoff frequency and maximum frequency of oscillation above 70 GHz were measured for a 2- mu m*5- mu m emitter area device. A device with 12 cells, each consisting of a 2- mu m*15- mu m emitter area device for a total emitter area of 360 mu m/sup 2/, was power tested at 4 GHz under continuous-wave (CW) bias condition. The device delivered 0.6-W output power with 13-dB linear gain and a power-added efficiency of 50%. >