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基于异质结漂移－扩散模型，考虑Ｆｅｒｍｉ－Ｄｉｒａｃ统计和重掺杂能带窄变（ＢＧＮ）效应，对具有非均匀掺杂基区的ＡｌＧａＡｓ／ＧａＡｓＨＢＴ进行了数值模拟．结果表明，当基区非均匀程度较大时，非均匀掺杂引起的基区自建场远大于ＢＧＮ效应产生的反向场．基区非均匀掺杂能提高电流增益，但提高的幅度随非均匀程度的增加而减慢．基区非均匀掺杂可明显改善截止频率ｆＴ，但同时也增加了集电结空间电荷区渡越时间τｃ，ｓｃＲ，使得ｆＴ在非均匀程度较大时开始下降．发射极－集电极ｏｆｆｓｅｔ电压在一定的非均匀程度下达到最佳值．本文还提出了ＡｌＧａＡｓ／ＧａＡｓＨＢＴ基区非均匀掺杂设计的最佳条件．
Based on the heterogeneous junction drift-diffusion model, considering the Fermi-Dirac statistics and the effect of narrow band gap (BGN) of heavily doped band, the numerical simulation of AlGaAs / GaAs HBT with non-uniform doping basal region was carried out. The results show that when the nonuniformity of the base region is large, the self-built ground due to nonuniform doping is much larger than that of the BGN effect. Nonuniform doping of the base region can increase the current gain, but the amplitude of the increase slows with the increase of the non-uniformity. Inhomogeneous doping can improve the cut-off frequency fT obviously, but also increase the crossing time τc and scR of the charge-domain charge region of the collector junction, which makes the fT begin to decline when the non-uniformity is large. The emitter-collector offset voltage achieves the optimum value with a certain degree of inhomogeneity. In this paper, the optimal conditions for heterogeneous doping of AlGaAs / GaAs HBT base region are also proposed.