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Experimental results on heterojunction bipolar transistors made in liquid phase epitaxial (In,Ga)As and InP layers on InP substrates are described. The (In,Ga)As base layer was doped with manganese during growth and contacts were made to it by beryllium ion implantation. The maximum measured dc current gain β of these devices was in excess of 500. These devices also demonstrate for the first time in an InP-based system, the inverted emitter-down heterojunction transistor structure with a base contact, which yields a minimized collector-base junction area and should significantly improve high-frequency performance.