A PROPOSED COLLECTOR DESIGN OF DOUBLE-HETEROJUNCTION BIPOLAR-TRANSISTORS FOR POWER APPLICATIONS

A new collector design for the AlGaAs/GaAs double heterostructure bipo lar transistor (DHBT) is proposed, analyzed, and simulated, The base-c ollector junction is linearly graded and terminated with a highly dope d thin layer to offset the adverse alloy grading electric held. Simple analytical formulas are derived to facilitate the implementation of t he design, A proof-of-principle simulation has been carried out for an X-band AlGaAs/GaAs power DHBT to confirm the design and the derived f ormula. The simulation shows the breakdown voltage can be increased fr om 30 V to about 45 V while the critical current density is about the same. It is also shown that, unlike other refined DHBT structures, the proposed structure does not require critical control in the fabricati on of the base-collector junction.