双轴应变下GaN有效质量的计算及其对迁移率的影响

Electron effective mass of biaxially strained GaN and its effect on the mobility

通过计算双轴应变下氮化镓的电子能带结构,给出了GaN有效质量与应变的变化关系。在弛豫时间近似的条件下,这种关系决定了双轴应变AlGaN/GaN中二维电子气(2DEG)的迁移率的改变。在其他物理参量不变的情况下,这种二维电子气迁移率将随着张应变的增加而增加,并随着压应变的增加而减小。计算结果表明,张应变对2DEG迁移率的影响要比压应变大。此外,GaN有效质量的变化在低温时对迁移率的作用更明显。而在低温低浓度的条件下,迁移率却对有效质量的依赖很小。

By calculating the electronic band structure of biaxially strained GaN, we present the relation between electron effective mass and strain which determines the mobility of the two-dimensional electron gases （2DEG） in the biaxially strained AlGaN/GaN under the assumption of constant relaxation-time approximation. The 2DEG mobility increases with tensile strain and decreases with compressive strain with other parameters constant. Our calculations show that the effect of tensile strain on the 2DEG mobility is larger than that of compressive strain. Moreover, the effective mass has a stronger influence at low temperature than at high temperature. However, the mobility has weakly depended on the effective mass at low temperature and low density.