Scanlon David O, Morgan Benjamin J, Watson Graeme W
School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
J Chem Phys. 2009 Sep 28;131(12):124703. doi: 10.1063/1.3231869.
The exact nature of the hole traps reported deep in the band gap of Cu(2)O has been a topic of vigorous debate, with copper vacancies and oxygen interstitials both having been proposed as the relevant defects. In this article, the electronic structure of acceptor-forming defects in Cu(2)O, namely, copper vacancies and oxygen interstitials, is investigated using generalized gradient approximation (GGA) and GGA corrected for on-site Coulombic interactions (GGA+U). GGA produces notionally semimetallic defect complexes, which is not consistent with the experimentally known polaronic nature of conduction in Cu(2)O. GGA+U also predicts a semimetallic defect complex for the "simple" copper vacancy but predicts the "split" vacancy and both oxygen interstitials are characterized by localized polarons, with distinct single particle levels found in the band gap. For both methods, however, the positions of calculated transition levels are inconsistent with experimental ionization levels. Hence neither GGA nor GGA+U are successful in modeling p-type defects in Cu(2)O.
据报道，在Cu₂O的带隙深处存在的空穴陷阱的确切性质一直是激烈争论的话题，铜空位和氧间隙原子都被认为是相关缺陷。在本文中，使用广义梯度近似（GGA）和针对局域库仑相互作用校正的GGA（GGA+U），研究了Cu₂O中形成受主的缺陷（即铜空位和氧间隙原子）的电子结构。GGA产生名义上的半金属缺陷复合体，这与Cu₂O中已知的实验性极化子导电性质不一致。GGA+U也预测“简单”铜空位会形成半金属缺陷复合体，但预测“分裂”空位以及两种氧间隙原子都以局域极化子为特征，在带隙中发现了不同的单粒子能级。然而，对于这两种方法，计算出的跃迁能级位置都与实验电离能级不一致。因此，GGA和GGA+U在模拟Cu₂O中的p型缺陷方面都不成功。
