Abstract
Abstract The long-term current instability of GaAs-based heterojunction bipolar transistor (HBT) is studied, and the physical mechanism contributing to such a phenomenon will be tried to explain. First, We focus on AlGaAs/GaAs HBT long-term reliability performance and our main objective is to identify the origins of base current instability observed experimentally in Burn-in HBT and traps with different types、densities、location is considered in our two-demensional numerical simulation. Our results suggest that the commonly observed base current instability over the mid-voltage region is might due to stem from traps generated at the vicinity of emitter sidewall. Second, we analyzed InGaP/GaAs HBT long-term reliability issue by means of numerical simulation. Our simulation results suggest that it might be due to compensation of acceptor-like traps by H+ at the ledge/nitride interface and acceptor-like traps concentrations is decrease from 3e13cm-2 to 1e12cm-2 over the mid-voltage region. In addition, we also use InGaP material system which is well-known better reliability than AlGaAs material system to design power double heterojunction bipolar transistor(DHBT).In careful design of base-collector junction, the step-graded structure DHBT performance will approach SHBT. With smaller offset voltage, high breakdown voltage, high cut-off frequency and lower leakage, the new structure InGaP/GaAs DHBT will suitable to power amplifier application.