The effect of carbon on neutral base recombination in high-speed SiGeC heterojunction bipolar transistors

This paper deals with the introduction of high carbon doses in the base of SiGeC HBTs to create neutral base recombination (NBR). The base current IB was increased by a factor of 10, with significant enhancement of the collector-to-emitter breakdown voltage BVCEO. The transit frequency fT was kept nearly constant, which enabled the fT × BVCEO product to be pushed up. The analysis is followed by 1/f noise measurements, temperature analysis and device simulations to demonstrate a trap saturation effect. Electrical bandgap measurements enable us to discern whether carbon is inserted in substitutional or interstitial sites.