National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
Phys Rev Lett. 2010 Jun 11;104(23):236403. doi: 10.1103/PhysRevLett.104.236403.
Random substitutional A(x)B(1-x) alloys lack formal translational symmetry and thus cannot be described by the language of band-structure dispersion E(k(→)). Yet, many alloy experiments are interpreted phenomenologically precisely by constructs derived from wave vector k(→), e.g., effective masses or van Hove singularities. Here we use large supercells with randomly distributed A and B atoms, whereby many different local environments are allowed to coexist, and transform the eigenstates into an effective band structure (EBS) in the primitive cell using a spectral decomposition. The resulting EBS reveals the extent to which band characteristics are preserved or lost at different compositions, band indices, and k(→) points, showing in (In,Ga)N the rapid disintegration of the valence band Bloch character and in Ga(N,P) the appearance of a pinned impurity band.
随机取代 A(x)B(1-x) 合金缺乏正规的平移对称性，因此不能用能带结构色散 E(k(→))的语言来描述。然而，许多合金实验通过从波矢 k(→)导出的构造物，例如有效质量或范霍夫奇点，被精确地从唯象学上加以解释。这里我们用含有随机分布的 A 和 B 原子的大超胞，其中允许许多不同的局域环境同时存在，并使用谱分解将本征态转化为原胞中的有效能带结构（EBS）。所得到的 EBS 揭示了在不同组成、能带指数和 k(→)点处，能带特征得以保持或丢失的程度，表明在 InGaN 中，价带 Bloch 特征迅速瓦解，而在 Ga(N,P)中出现固定的杂质能带。
