Rapid thermal annealing of metastable and stable Si/Si 1-x Ge x heterojunction bipolar transistors

The effect of Rapid Thermal Annealing (RTA) treatment on the base and collector currents of Si/Si 1-x Ge x HBTs is investigated. Whilst the base current is improved by high temperature annealing, probably through annealing out of point defects (reducingE/B depletion region recombination), the collector current is degraded by the out-diffusion of boron from the base, creating parasitic barriers to injection. For some devices, the E/B depletion region recombination is reduced to such an extent that the base current is dominated by neutral base recombination.