Density functional and quasiparticle band-structure calculations forGaxAl1−xNandGaxIn1−xNalloys
Density functional and quasiparticle band-structure calculations forGaxAl1−xNandGaxIn1−xNalloys
复制标题
GaxAl1−xN 和 GaxIn1−xNalloys 的密度泛函和准粒子能带结构计算
DOI：
10.1103/physrevb.68.075203
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发表时间：
2003
影响因子：
3.7
通讯作者：
J. Pollmann
中科院分区：
文献类型：
--
作者：
F. Sökeland;M. Rohlfing;P. Krüger;J. Pollmann
采用三种不同的从头算方法研究了两种宽带隙半导体合金Ga x Al 1 - x N和Ga x In 1 - x N的电子结构。局部密度计算在密度泛函理论使用常规以及自相互作用校正伪势和准粒子带结构计算进行。随机合金问题是在虚拟晶体近似和团簇展开近似中处理的。一个主要问题是对基本带隙的组成依赖性的弯曲的评估。结果表明，Ga x Al 1 - x N合金的带隙弯曲在虚晶体近似下得到了很好的描述。相反，对于Ga x In 1 - x N，该近似不能正确描述带隙的组成依赖性，因为它忽略了重要的局部结构弛豫。这些在星团膨胀近似中被考虑在内。我们的结果表明，在这两种合金中，带隙表现出与成分相关的弯曲函数，而不是恒定的弯曲参数。
We investigate the electronic structure of two wide-band-gap semiconductor alloys Ga x Al 1 - x N and Ga x In 1 - x N, employing three different ab initio band-structure approaches. Local density calculations within density functional theory using conventional as well as self-interaction-corrected pseudopotentials and quasiparticle band-structure calculations are carried out. The stochastical alloy problem is treated within the virtual crystal approximation, as well as within a cluster expansion approximation. One main issue is the evaluation of the bowing of the composition dependence of the fundamental band gap. It turns out that the band-gap bowing for Ga x Al 1 - x N alloys is described reasonably well within the virtual crystal approximation. For Ga x In 1 - x N, on the contrary, that approximation does not correctly describe the composition dependence of the band gap because it neglects significant local structural relaxations. These are taken into account in the cluster expansion approximation. Our results indicate that in both alloys the band gap exhibits a composition-dependent bowing function rather than a constant bowing parameter.