Effective scheme to determine accurate defect formation energies and charge transition levels of point defects in semiconductors

摘要

We propose an effective method to accurately determine the defect formation energy E_f and charge transition level ε of the point defects using exclusively cohesive energy E_(coh) and the fundamental band gap E_g of pristine host materials. We find that E_f of the point defects can be effectively separated into geometric and electronic contributions with a functional form: E_f = χEcoh + λE_g, where χ and λ are dictated by the geometric and electronic factors of the point defects (χ and λ are defect dependent). Such a linear combination of Ecoh and Eg reproduces E_f with an accuracy better than 5% for electronic structure methods ranging from hybrid densityfunctional theory (DFT) to many-body random-phase approximation (RPA) and experiments. Accordingly, ε is also determined by Ecoh/E_g and the defect geometric/electronic factors. The identified correlation is rather general for monovacancies and interstitials, which holds in a wide variety of semiconductors covering Si, Ge, phosphorenes, ZnO, GaAs, and InP, and enables one to obtain reliable values of E_f and ε of the point defects for RPA and experiments based on semilocal DFT calculations.