Ge组分分布对基区杂质非均匀分布的SiGe HBT温度特性的影响

众所周知, 双极型晶体管的设计主要是基区的设计. 一般而言, 基区的杂质分布是非均匀的. 本文首先研究了非均匀的杂质高斯分布对器件温度分布、增益和截止频率的温度特性的影响, 发现增益和截止频率具有正温度系数, 体内温度较高. 随后研究了基区Ge组分分布对这些器件参数的影响. 均匀Ge组分分布和梯形Ge组分分布的SiGe 异质结双极型晶体管增益和截止频率具有负温度系数, 具有较好的体内温度分布. 进一步的研究表明, 具有梯形Ge组分分布的SiGe 异质结双极型晶体管, 由于Ge组分缓变引入了少子加速电场, 不但使它的增益和截止频率具有较高的值, 而且保持了较弱的温度敏感性, 在增益、特征频率大小及其温度敏感性、体内温度分布达到了很好的折中.

Effects of Ge profile on thermal characteristics of SiGe heterojunction bipolar transistor with non-uniform doping profile in base region

As is well known, base region is the design focus of bipolar junction transistor (BJT). Generally, the doping distribution in base is non-uniform. In this paper, the effects of different Gaussian dopings in the base on bulk temperature distribution, temperature dependences of current gain and cut-off frequency are first studied. It is found that current gain and cut-off frequency of BJT have positive temperature coefficients, and the temperature in bulk is high. Then, the effect of Ge composition distribution on these device parameters is investigated. It is found that the SiGe heterojunction bipolar transistors (HBTs) with box Ge composition distribution and trapezoidal Ge composition distribution have negative temperature coefficients of current gain and cut-off frequency, and have good bulk temperature distributions. Furthermore, the SiGe HBT with trapezoidal Ge profile has higher current gain and cut-off frequency, and its temperature insensitivity is kept. The good trade-off is made among the magnitudes of current gain and cut-off frequency, temperature sensitivity and bulk temperature distribution.