禁带变窄效应对突变AlGaAs/GaAs HBT电流影响的研究

The Numerical Study on Currents for Band Gap Narrowing in Abrupt AlGaAs/GaAs HBT

重掺杂使导带、价带带边同时发生了收缩,从而产生禁带变窄效应(BGN)。对于基区重掺杂Npn突变AlGaAs/GaAsHBT,BGN引起导带和价带突变界面势垒形状及高度都发生了改变,这对基区、集电区电流产生重要的影响。文中基于Jain-Roulston禁带收缩模型及热场发射-扩散载流子输运机制,对这一现象进行了深入的研究。通过与其它计算程序常用的几种BGN模型比较得出为了更好描述电流传输,利用Jain-Roulston的BGN模型,考虑禁带变窄量在导带、价带有不同的分配,从而对电流有不同的影响是必要的。

Heavy impurity doping makes the conduction and valence bands shift, and brings about the so-called Band Gap Narrowing(BGN). Due to BGN, the form and height of energy barriers in abrupt HBT is disturbed,which changes the values of the currents flowing through its interfaces. In this work,the real bandgap narrowing is distributed between the conduction and valence bands according to Jain-Roulston model, and its effects on the base and collector currents of AlGaAs/GaAs HBT is analysis. This analysis is carried out through so-called Thermionic-Field-Diffusion model which combines the drift-diffusion transport in the bulk of the transistor with the thermionic emission and tunneling at the base-emitter interface. By comparison,it can be concluded that using more accurate bandgap modeling is important for a better description of the currents.