Enhancement of Current Gain at High Collector Current Densities for Silicon-Germanium Heterojunction Bipolar Transistors

Abstract

In this work, an NPN Si/SiGe/SiGe graded heterojunction bipolar transistor has been compared with contemporary NPN Si/SiGe/Si double heterojunction bipolar transistor for current gain performance at high collector current densities, using a 2-dimensional device simulator. The analysis predicts that the base-collector homojunction of the first transistor device structure is responsible for improved current gain at high collector current density in comparison with the conventional transistor device and provides the option of operation at higher collector current densities.