Compensation :in GaAs/GaAlAs Heterostructures by Ion Implantation Comparison of Oxygen and Boron

Abstract

AbstractIon implantation has been used to form an insulating layer in GaAs/GaAlAs heterostructures for bipolar transistor applications with the aim of reducing the base-collector capacitance. Two ions have been compared : boron and oxygen. In both cases magnesium has been implanted to contact the base layer and rapid thermal annealing has been used to activate this dopant. We show that the base-collector capacitance can be lowered by a factor of ∼,2 with oxygen, but high oxygen doses (≥, 1014 ions/cm2 ) are necessary to obtain reproducible results. The capacitance is lowere!6 by 2 a factor of ∼4 with optimized boron dose. With high boron doses (≥ 1013 /cm2 ) we have decreased the capacitance by a factor of 16 but the defects created during the implantation affect the properties of the emitter and base layer.