INP-HBTS WITH GOOD HIGH-FREQUENCY PERFORMANCE AT LOW COLLECTOR CURRENTS USING SILICON-NITRIDE PLANARISATION

A fabrication process for small area HBTs with a self-aligned base con tact has been developed, based on silicon nitride planarisation. The m ean current gain for 130 realised devices ranged from 40 for the small est devices, to 71 for the largest, with a standard deviation of <10%. The transit frequency was 94.7 +/- 2.6GHz, and the maximum frequency of oscillation 95.1 +/- 4.4GHz, at a collector current of only 0.3 mA. The extremely good high frequency performance at low currents and hig h uniformity improves the competitiveness using InP-based HBTs for fab rication of complex integrated circuits.