减弱SiGe HBT势垒效应

Measures to Alleviate Heterojunction Barrier Effects of SiGe HBT

讨论了基区Ge分布、集电极电流密度对势垒高度的影响,分析了减弱势垒效应的方法.计算结果表明:基区Ge分布对势垒高度有很大的影响,随着BC结处Ge含量的增大,势垒高度也迅速增大,并且使得基区渡越时间也迅速增大;当集电极电流密度增加时,势垒高度有着明显的饱和趋势;通过集电结处Ge组分缓变,并不能很好地减弱势垒效应的影响,而采用将Ge组分引入到集电区的方法可以有效地推迟势垒效应的发生.

The effects of Ge profile and collector current density on barrier height and the measures to alleviate the heterojunction barrier effects are studied. Results show that barrier height increases rapidly with the larger base Ge fraction grading, and barrier height exhibits apparent saturation trend as collector current density increases. Moreover, small Ge fraction grading can＇t alleviate the HBE effectively, and Ge introduced into the collector can delay the HBE.