采用差分法求解有效质量方程,考虑轻重空穴的混合效应及应变效应,对三种不同形状的量子阱的能带结构、价带态密度、跃迁矩阵元进行了比较。在阱宽相同的条件下,方阱有最大的限制能力,但抛物阱和三角阱有更平坦的态密度曲线,使得以抛物阱和三角阱为有源区的激光器和半导体激光放大器可以有较低的透明电流密度。同时价带子带的耦合强烈改变了跃迁矩阵元,这对量子阱的增益特性会产生影响。

By solving the effective mass equations using the difference method, taking into account the strain effects and valence band mixing effect, we have compared the band structures, DOS′s of valence band and the optical matrix elements for different shaped wells. With the same well width, rectangular well has the strongest confinement on carriers, but parabolic and triangular wells have flatter DOS curves, which are more analogous to step like DOS. Thus laser diode and semiconductor laser amplifier with these two kinds of wells as active layers may have lower transparent current densities. The mixing between valence subbands has greatly changed the optical matrix element, so it will have influence on the gain characteristics of quantum wells.