RECOMBINATION CURRENT REDUCTION IN ALGAAS GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS WITH POLYIMIDE DEPOSITION/

N-p-n AlGaAs/GaAs heterojunction bipolar transistors of various emitte r-mesa diameters have been fabricated to examine the effects on the re combination current with polyimide deposition. The recombination curre nt in these devices (when the ideality factor is close to 2) was propo rtional to the device perimeter before and after polyimide deposition. This suggests that the dominant component of the recombination curren t in these devices is the perimeter recombination current. A simple mo del was developed which allowed the contribution from the perimeter an d bulk recombination currents to be calculated. The common-emitter d.c . current gains of these devices increased correspondingly as recombin ation current decreased due to the polyimide deposition.