In the research of III-nitride semiconductors (represented by GaN) materials and device, how to control and utilize defects is one of important topics. In the past, the dislocations are most concerned. With the realization of the GaN single crystal substrate and the decrease of dislocation density, the point defects in nitride material will be widespread concerned. Especially in the research of carrier recombination mechanism, the point defects and related complexes have gradually been considered as the main determinant in the nonradiative recombination. The study of these physical problems is the foundation of further exerting nitride semiconductor material superiority.

Recently, Dr. Lin Shi and Dr. Ke Xu, at Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, in collaboration with Dr. Lin-Wang Wang, at Lawrence Berkeley National Laboratory, use different approximations to calculate the capture coefficients of two complex defects GaP:Zn_Ga-O_P and GaN:Zn_Ga-V_N. In this study, all the parameters, including atomic structure, formation energy and electron-phonon coupling constants, have been calculated by ab initio density functional theory. All the phonon modes are considered. Compared with different methods, the capture coefficients calculated by the static coupling theory are 4.30×10^-8and 1.46×10^-7cm³/s for GaP:Zn_Ga-O_P and GaN:Zn_Ga-V_N, which are in good agreement with the experiment results. They also provided arguments for why the static coupling theory should be used to calculate the nonradiative decays of semiconductors. The related work was published in Phys. Rev. B 91, 205315 (2015), and has been selected by the editors of PRB to be an Editors' Suggestion. 

This work was supported by the National Natural Science Foundation of China under (Grant No. 11374328, 61325022, 11327804), the National Basic Research Program of China (973 Program No. 2012CB619305), and the Foundation of CNIC, CAS under Grant No. XXH12503-02-03-2(03).