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A simple lai ge-signal model, Extended Ebers-Moll (kl kf) model. is successfully used to accurately describe thy HBT nonlinear responses A unique and efficient pri iiedure that combines the DC, small-signal intrinsic, and parasitic extraction algorithms is developed to accilrately determine the Ef*M parameters This model

Migration enhanced epitaxy (MEE) was used in this work to grow p+-GaAs at the substrate temperature of 300 °C for the base of AlGaAs/GaAs heterojunction bipolar transistors. The results indicated that the low-temperature MEE-grown p+-GaAs epitaxial layers (p=1×1019–1×1020 cm−3) exhibited a crystalline quality comparable to those grown by standard MBE at a substrate temperature of 570 °C. AlGaAs/GaAs HBTs with low-temperature MEE-grown bases doped at p≊2×1019 cm−3 were fabricated by using a self-alignment technique. For the devices with the conventional MBE-grown base, secondary ion mass spectroscopy depth profiles showed a significant Be diffusion into the AlGaAs emitter and as a consequence, the devices showed no current gain. For the devices with the low-temperature MBE-grown base, there was a negligible Be penetration into the emitter and the devices exhibited a common-emitter dc current gain of 13.

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