Computationally predicted energies and properties of defects in GaN(计算预测GaN晶体缺陷的能量和性能)
John L. Lyons & Chris G. Van de Walle
npj Computational Materials 3, Article number: 12 (2017)
doi:10.1038/s41524-017-0014-2
Published online:24 March 2017
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摘要:理论计算技术的最新发展显著提高了基于密度泛函方法的计算预测能力。本文综述了这些技术进步如何改进了对GaN晶体中本征缺陷的理解。本文首先回顾了点缺陷的计算方法,并讨论了密度泛函理论带隙计算问题的解决如何影响本征缺陷的计算。特别地,本文考察了通过校正的半局域泛函(如广义梯度近似)在多大程度上可以准确描述缺陷结构的特征。本综述介绍了GaN中的空穴、空隙和反占位缺陷的性质,以及它们与常见杂质的相互作用。结合第一原理计算结果与实验表征,本文还讨论了本征缺陷及其复合物如何影响了氮化物器件的性能。总体而言,广义梯度近似等密度泛函方法与带-隙校正方法结合,可以获得准确定性结果。然而,这些计算方法在某些重要情况下,特别是在光学跃迁和局域载流子等体系有可能丢失了重要的物理现象。 the generalized gradient approximation), combined with correction schemes, can produce accurate results.The properties of vacancy, interstitial, and antisite defects in GaN are described, as well as their interaction with common impurities.We also connect the first-principles results to experimental observations, and discuss how native defects and their complexes impact the performance of nitride devices.Overall, we find that lower-cost functionals, such as the generalized gradient approximation, combined with band-edge correction schemes can produce results that are qualitatively correct. However, important physics may be missed in some important cases, particularly for optical transitions and when carrier localization occurs.
Abstract: Recent developments in theoretical techniques have significantly improved the predictive power of density-functional-based calculations. In this review, we discuss how such advancements have enabled improved understanding of native point defects in GaN.We review the methodologies for the calculation of point defects, and discuss how techniques for overcoming the band-gap problem of density functional theory affect native defect calculations. In particular, we examine to what extent calculations performed with semilocal functionals (such as