A self-aligned InP/GalnAs single heterojunction bipolar transistor（HBT） is investigated using a novel T-shaped emitter. A U-shaped emitter layout,selective wet etching,laterally etched undercut, and an air-bridge are applied in this process. The device, which has a 2μm×12μm U-shaped emitter area,demonstrates a common-emitter DC current gain of 170,an offset voltage of 0.2V,a knee voltage of 0.5V, and an open-base breakdown voltage of over 2V. The HBT exhibits good microwave performance with a current gain cutoff frequency of 85GHz and a maximum oscillation frequency of 72GHz, These results indicate that these InP/InGaAs SHBTs are suitable for low-voltage,low-power,and high-frequency applications.
An emitter self-aligned InP-based single heterojunction bipolar transistor with a cutoff frequency （fT） of 162GHz is reported. The emitter size is 0.8μm × 12μm, the maximum DC gain is 120, the offset voltage is 0.10V,and the typical breakdown voltage at Ic = 0. 1μA is 3.8V. This device is suitable for high-speed low-power applications,such as OEIC receivers and analog-to-digital converters.
