GaAs/GaAlAs heterojunction bipolar transistors with cutoff frequencies above 10 GHz

This paper describes the fabrication and high-frequency performance of an npn GaAs/GaAlAs heterojunction bipolar transistor. The fabrication process utilized molecular beam epitaxy, and featured a nominal base layer thickness of 500Å. The cutoff frequency,ft, of the transistor was measured to be 11 GHz (a value which was limited by parasitic elements associated with bonding pads and bond-wires).