SELF-ALIGNED INGAP GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS FOR MICROWAVE-POWER APPLICATION/

As an alternative to AlGaAs/GaAs heterojunction bipolar transistors (H BT's) for microwave applications, InGaP/GaAs HBT's with carbon-doped b ase layers grown by metal organic molecular beam epitaxy (MOMBE) are d emonstrated with excellent dc, RF, and microwave performance. As previ ously reported, with a 700-angstrom-thick base layer (135-OMEGA/square sheet resistance), a dc current gain of 25, and cutoff frequency and maximum frequency of oscillation above 70 GHz were measured for a 2 X 5-mum2 emitter area device. A device with 12 cells, each consisting of a 2 x 15-mum2 emitter area device for a total emitter area of 360 mum 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%.