A comparative study of the passivation films on AlGaAs/GaAs heterojunctiondiodes and bipolar transistors

A series of Si-based thin films, including amorphous Si, SiC, as well as th e conventionalSiO(infinity) and SINinfinity, was investigated in terms of t he electrical characteristics of GaAs/Al0.3Ga0.7As heterostructure diodes a nd heterojunction bipolar transistors (HBTs). All the films were found effe ctive in reducing the leakage current and long term degradation, Less size- dependence of the current gain was found for the HBTs passivated by amorpho us Si and SIG. In addition, the devices passivated by amorphous Si and SIC films exhibited better performance during high power operation. This is att ributed to the high thermal conductivity of these two materials.