InP-collector double-heterojunction bipolar transistors by valved phosphorus cracker

We report the growth and device characterization of InAlAs/InGaAs/InP doubl e-heterojunction bipolar transistors in a solid source molecular beam epita xy system with a valved-phosphorus cracker. Linearly graded InGaAlAs base-c ollector and emitter-base junctions were used. Photoreflectance characteriz ation shows excellent growth reproducibility. The dc current-voltage charac teristics of a 1.5x10 mu m(2) device indicate high breakdown voltage, low o ffset voltage, and good linearity. Breakdown voltage of an InP-collector de vice with compositionally graded base-collector junction is 19 V compared t o 11 V for an InGaAs-collector device. By comparison, a chirped superlattic e base-collector junction shows significant current oscillations due to the carrier tunneling effect. High-frequency performance was similar to previo usly reported InGaAs-collector devices; unity current-gain frequency and un ity maximum-available power gain frequency are 75 and 140 GHz, respectively . (C) 1999 American Vacuum Society. [S0734-211X(99)01403-1].