Correlation between the base–emitter interface crystalline quality and the current gain in InGaP/GaAs HBTs grown by MOVPE

Abstract

We demonstrated that the InGaP emitter ledge passivation in InGaP/GaAs heterojunction bipolar transistor (HBT) could suppress the recombination components in I B induced by the extrinsic base surface and the defects activated by the current stress. Similar suppression of I B by the current stress was found in unpassivated HBT with the 2 min growth interruption at the base–emitter interface under PH 3 partial pressure and we attributed this to the existence of an intermediate layer at the base–emitter interface that would improve the interface crystalline quality and reduce the recombination component of I B induced by defects at the base–emitter edge. Unpassivated HBT with the shorter post-growth annealing in time in hydrogen atmosphere, however, showed the increase in the current gain β with the current stress because of the burn-in effect rather than the decrease in β due to the increase of I B induced by defects.