Analysis of degradation induced by silicon nitride InP/InGaAs heterojunction bipolar transistors

The Si
₃
N
₄
layer deposited by PECVD at 300degC to passivate InP/InGaAs HBTs induces extra charges densities in the peripheral mesa emitter-base heterojunction. The changes in the effective emitter-base doping concentrations were determined by a new method which used the simultaneous analysis of the collector current density and the collector current ideality factor, measured at a fixed emitter-base voltage.