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在Ｓｉ１－ＺＧｅＺ基区ＨＢＴ中，Ｇｅ组份Ｚ缓变（进而能隙缓变）产生自建电场，基区杂质浓度向发射极侧的减小产生了阻滞电场，基区杂质浓度向集电极侧的减小产生了加速电场．文中研究了这些电场对基区渡越时间的影响．研究结果表明，随基区发射极侧杂质浓度的不同，因阻滞电场而产生的延迟时间占基区总渡越时间的４０％～８０％．同时还发现，选用无阻滞电场产生的基区杂质分布，采用大的Ｇｅ组份线性缓变和利用集电结空间电荷区电子速度过冲效应，可望得到截止频率大于１００ＧＨｚ的Ｓｉ１－ＺＧｅＺ基区ＨＢＴ
In Si1-ZGeZ base HBT, the Ge component Z is slowly changing (and then the energy gap is slowly changed) to generate a self-built electric field. The reduction of the base impurity concentration to the emitter side produces a retarding electric field. The reduction of the electrode side produces an accelerating electric field. In this paper, the effect of these electric fields on the base transit time is studied. The results show that with the difference of impurity concentration in the emitter side of the base region, the delay time due to the retarding electric field accounts for 40% -80% of the total transit time of the base region. At the same time, it is also found that the Si1-ZGeZ with a cut-off frequency of more than 100 GHz can be obtained by selecting the base impurity distribution generated by the un-retarded electric field, adopting the linear grading of the large Ge component and utilizing the electronic speed overshoot effect of the charge region in the collector junction space Base area HBT