Current-Induced Degradation of AlGaAs/GaAs Heterojunction Bipolar Transistors and Its Suppression by Thermal Annealing in As Overpressure

Current-induced degradation of current-voltage (I-V) characteristics in AlGaAs/GaAs heterojunction bipolar transistors (HBTs) with Be-doped base layers is investigated. Large shifts of emitter-base on-voltage (ΔVBE) are observed during high current operation. The behavior of degradation is qualitatively explained in terms of interstitial Be diffusion in combination with the electron-hole recombination process. Thermal annealing in As overpressure can successfully stabilize the characteristics. Degradation is not observed in AlGaAs/GaAs HBTs with C-doped base layers without the Zn diffusion process.