First-Principles Study on the Defect Physics of Ternary Chalcopyrite ZnGeP₂ through Hybrid Functional

Zinc germanium diphosphide (ZnGeP₂) is a chalcopyrite semiconductor that can be used for infrared frequency conversion applications. It is believed that the intrinsic defects are responsible for the defect-related absorptions and emissions observed in experiments, and the performance of the corresponding device is also limited by those defects. Here we study the defect physics in ZnGeP₂ using the density functional theory (DFT) calculations with a hybrid functional. We will firstly present the result of phase stability, which differs significantly from the previous result calculated by semi-local DFT. Ge_Zn, Zn_Ge, Ge_P, P_Ge antisites are the dominant point defects among all the Fermi level range and growth conditions. Under Zn-rich condition, the Fermi level is about 0.6 eV above valence band maximum (VBM), which shows the p-type conductivity, while under Ge-poor condition, the Fermi level is located at the middle of the band gap, consistent with the experiment results. We will also discuss the result of calculated optical transition that is related to photoluminescence peak and the possible impurities and defect complexes.