Experimental evaluation of the minimum detectable outdiffusion length for AlGaAs/GaAs HBTs

Triple mesa, Be-doped AlGaAs/GaAs HBTs were stressed at low temperature by forcing an emitter current density while the devices were biased in the forward active region. The effect on the d.c. characteristics was investigated and the results demonstrated that a base dopant outdiffusion is the degradation mechanism.By merging the experimental data with numerical simulations we obtained for the first time an experimental evaluation of the minimum detectable outdiffusion length. The measured value is in fair agreement with the theoretical value reported in the literature.