Abstract

The graded base InGaAs//InP heterostructure bipolar transistors (HBTs)were passivated by the low-temperature plasma deposited iNx .The current gain was found to increase after the passivation.The study of the Gummel plots shows that the passivation results in the reduction of both the collector current and base current,while the decrease of the base current is more significant.This causes the increase of the current gain.Nitrogen plasma treatment results in the increase of the current gain,while Silane plasma treatment results in a small reduction of the current gain.The influence of the plasmas of the two sources on the HBTs ’ performance are investigated..In- situ ellipsometer study showed that at the initial state of SiNx deposition,the SiNx deposition rate was zero,and nitrogen plasma has strong effects on the passivation of HBTs and results in the increase of the current gain. surface recombination,these cause the increase of the base current and the decrease of current gain.