异质结位置对缓变集电结SiGe HBT性能的影响

研究了npn型SiGe HBT集电结附近的异质结位置对器件性能的影响.采用Taurus-Medici 2D器件模拟软件,在渐变集电结SiGe HBT的杂质分布不变的情况下,模拟了各种异质结位置时的器件直流增益特性和频率特性.同时比较了处于不同集电结偏压下的直流增益和截止频率.分析发现即使没有出现导带势垒,器件的直流和高频特性仍受SiGe层中性基区边界位置的影响.模拟结果对SiGe HBT的设计和分析都具有实际意义.

Influence of Heterojunction Position on SiGe HBTs with Graded BC Junctions

The influence of a heterojunction in the vicinity of a graded BC junction on the performance of npn SiGe HBTs is studied.SiGe HBTs differing only in heterojunction position in the vicinity of a graded BC junction are simulated by means of 2D Medici software for DC current gain and frequency characteristics.In addition,the simulated DC current gains and cut-off frequencies are compared at different collector-emitter bias voltages.Through the simulation results,both DC and HF device performance are found to be strongly impacted by degree of confinement of the neutral base in the SiGe layer,even in the absence of a conduction band barrier.This conclusion is of significance for designing and analyzing SiGe HBTs.