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本文介绍了对Si/Si_(1-x)Ge_x异质结双极晶体管(HBT)和硅双极结晶体管(BJT)高频性能进行模拟比较的结果,其结构参数是为获得最高f_T≈f_(max)设计的。模拟研究表明,(1)Si/Si_(1-x)Ge_xHBT具有64GHz的峰值f_T(=f_(max)),它比Si BJT提高了16.4％;(2)发射极充电时间对高频性能有相当大的影响,即使电流密度高达80kAcm~(-2)时也是如此;(3)SiGe基区组分梯度和基区掺杂分布强烈影响着f_T和f_(max)。研究发现高斯梯度分布具有最高的峰值f_T=f_(max),据估计其峰值截止频率比均匀掺杂分布高30％;(4)高频性能对集电极设计的依赖关系表明,要在f_T、f_(max)和BV_(CBO)间进行折衷处理;并且(5)通过降低发射区或基区掺杂浓度,可设计出f_T超过100GHz的Si_(1-x)Ge_xHBT。同样,通过提高基区掺杂浓度和降低非本征电容和电阻,可实现100GHz的f_(max)。
In this paper, the simulation results of high frequency performance of Si / Si_ (1-x) Ge_x heterojunction bipolar transistor (HBT) and silicon bipolar junction transistor (BJT) are introduced. The structural parameters are obtained to obtain the highest f_T≈f_ (max) design. Simulation results show that (1) Si / Si_ (1-x) Ge_xHBT has a peak f_T (= f max) of 64 GHz which is 16.4% higher than that of Si BJT; (2) (3) The gradient and base doping distribution of SiGe strongly influence the f_T and f_ (max). The results show that the Gaussian gradient distribution has the highest peak value f_T = f_max, and the peak cut-off frequency is estimated to be 30% higher than the uniform doping distribution. (4) The dependence of the high frequency performance on the collector design shows that for the f_T, (5) Si_ (1-x) Ge_xHBT with f_T over 100 GHz can be designed by reducing the emission area or base doping concentration. Also, the f max of 100 GHz can be achieved by increasing the base doping concentration and reducing the extrinsic capacitance and resistance.