Passivation of InP/GaAsSb/InP double heterostructure bipolar transistors with ultra thin base layer by low-temperature deposited SiN_x

摘要

The InP/GaAsSb/InP double heterostructure bipolar transistors with 20-nm-thick base layer are passivated by low-temperature deposited SiN_x. The SiN_x passivation results in an increase of the current gain, seen from common-emitter I- V characteristics. An improvement of the Early voltage is also observed after the passivation. The study of the forward Gummel plots shows that the collector current keeps unchanged, while the base current decreases after SiN passivation. A decrease of the base current ideality factor is found by the SiN passivation. The passivation also results in an improvement of the base-collector junction. In contrast, the leakage current of the base-collector junction increases tow orders after passivation.