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,f
t
, of the transistor was measured to be 11 GHz (a value which was limited by parasitic elements associated with bonding pads and bond-wires).