First-principles theory of nonradiative carrier capture via multiphonon emission
First-principles theory of nonradiative carrier capture via multiphonon emission
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DOI：
10.1103/physrevb.90.075202
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发表时间：
2014-08-18
影响因子：
3.7
通讯作者：
Van de Walle, Chris G.
中科院分区：
文献类型：
--
作者：
Alkauskas, Audrius;Yan, Qimin;Van de Walle, Chris G.
我们发展了一种实用的第一性原理方法来确定半导体缺陷处的非辐射载流子俘获系数。我们考虑通过多声子发射发生的跃迁。理论中的参数，包括电子-声子耦合矩阵元素，使用基于混合密度泛函理论的最先进的电子结构技术进行了一致的计算。它们提供了对体带结构以及缺陷几何形状和波函数的显著改进的描述。为了正确描述带电中心的载流子俘获过程，我们提出了一种在超胞计算框架下处理长程库仑相互作用对散射态影响的方法。我们还讨论了载流子捕获微扰处理的初始条件的选择。作为基准，我们将我们的理论应用于GaN和ZnO中的几个空穴捕获中心，这两种材料具有很高的技术重要性，其中缺陷的作用正在得到积极的研究。计算的空穴捕获系数与实验数据吻合较好。我们讨论了对宽禁带半导体中缺陷物理的认识，如电子-声子耦合的强度和不同声子模的作用。
We develop a practical first-principles methodology to determine nonradiative carrier capture coefficients at defects in semiconductors. We consider transitions that occur via multiphonon emission. Parameters in the theory, including electron-phonon coupling matrix elements, are computed consistently using state-of-the-art electronic structure techniques based on hybrid density functional theory. These provide a significantly improved description of bulk band structures, as well as defect geometries and wave functions. In order to properly describe carrier capture processes at charged centers, we put forward an approach to treat the effect of long-range Coulomb interactions on scattering states in the framework of supercell calculations. We also discuss the choice of initial conditions for a perturbative treatment of carrier capture. As a benchmark, we apply our theory to several hole-capturing centers in GaN and ZnO, materials of high technological importance in which the role of defects is being actively investigated. Calculated hole capture coefficients are in good agreement with experimental data. We discuss the insights gained into the physics of defects in wide-band-gap semiconductors, such as the strength of electron-phonon coupling and the role of different phonon modes.