多晶硅发射极晶体管的低温频率特性研究

本文考虑低温下半导体中载流子冻析效应和浅能级杂质的陷阱效应等因素,分析了多晶硅发射极晶体管的低温频率特性。研究表明,受载流子冻析效应的影响,基区电阻在低温下随温度下降接近于指数上升,使晶体管的频率性能变环;而由于浅能级杂质的陷阱效应,低温下基区和发射区渡越时间变长,截止频率下降。这些因素在低温器件设计中应予重视。

INVESTIGATION OF LOW TEMPERATURE FREQUENCY CHARACTERISTICS OF POLYSILICON EMITTER BIPOLAR TRANSISTORS

The low temperature frequency characteristics of polysilicon emitter bipolar transistors are investigated, considered the carrier freezingout effect and trapping effect of shallow energy impurities in semiconductors. It shows that the base sheet resistance Rdb increases quasi-exponentially at low temperature due to carrier freezingout, which results in the degradation of frequency characteristics of the transistors at low temperature. The base and emitter transit time increase and the cutoff frequency decreases at low temperature due to the trapping effect of shallow energy level impurities. Those should be considered carefully in the design of devices for low temperature operation.