摘要
本文定量地模拟了硅双极晶体管电流增益和特征频率与集电极电流在77K和300K时的关系，计算结果与实验相吻合．结果表明在77K时，电流增益大注入效应由基区电导调制效应和发射区电流集边效应决定，而在300K时则由有效基区展宽效应决定，特征频率在300K时主要由基区渡越时间决定，而在77K时，由于发射区禁带变窄效应非常明显，以至于发射区少于存贮时间可能成为主要因素．低温下特征频率蜕变的主要原因是禁带变窄效应，而不是低温浅能级杂质陷阱效应．
The current gain and cutoff frequency of silicon bipolar transistor have beenquantitatively modeled at 77K and 300K. The obtained results are in agreement with theexperimental data. The current gain is mainly determined by the conductivity modulationeffect and the emitter current crowding effect at 77K. At 3oOK, it is determined by theeffective base widening effect. For the cutoff frequency, it is mainly determined by the basetransit time at 300K, and at 77K, the emitter transit time may be dominant for the largebandgap narrowing effect in emitter. The bandgap narrowing effect is the main reason forthe great decrease of the cutoff frequency with the decrease of temperature, instead of thelow temperature trapping effect by the compensated impurities with the shallow energylevels.
基金
国家自然科学基金
关键词
硅双极晶体管
电流增益
特征频率
Electric currents
Gain control
Semiconducting silicon
Simulation
