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4.4 Analysis of HBT Behavior After Electrothermal Stress

In this section simulations of one-finger power InGaP/GaAs HBTs before and after both electrical and thermal stress aging are presented. The influence of the ledge thickness and of the surface charges on the device performance and its impact on reliability is analyzed. Possible explanations of device degradation mechanisms, e.g. the effect of vanishing negative surface charges on the ledge/SiN interface, are proposed.


Vassil Palankovski