An SiGe heterojunction bipolar transistor with very high open-base breakdown voltage

An SiGe heterojunction bipolar transistor having a very high open-base breakdown voltage (BV
CEO
), which is close to the hard breakdown voltage (BV
CBO
), is introduced. This is achieved by draining the hot holes generated from impact ionization to the substrate. The carrier transport in those proposed devices is intensively investigated by device simulations which were confirmed by the electrical characteristics of our processed devices. The positive and constant base current over a large range of collector voltages (until BV
CBO
) will improve the issues of electro-thermal reliability and distortion normally associated with a negative base current at voltages beyond BV
CEO
, which is very attractive for RF power amplifiers.