First-principles exploration of defect-pairs in GaN  

作　　者：He Li Menglin Huang Shiyou Chen 

机构地区：[1]Key Laboratory of Polar Materials and Devices(MOE)and Department of Electronics,East China Normal University,Shanghai 200241,China [2]Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China

出　　处：《Journal of Semiconductors》2020年第3期23-31,共9页半导体学报（英文版）

基　　金：supported by the Science Challenge Project (TZ2018004);National Natural Science Foundation of China (NSFC) under grant Nos. 61722402 and 91833302;National Key Research and Development Program of China (2016YFB0700700);Shanghai Academic/Technology Research Leader (19XD1421300);Fok Ying Tung Education Foundation (161060);the Fundamental Research Funds for the Central Universities

摘　　要：Using first-principles calculations,we explored all the 21 defect-pairs in GaN and considered 6 configurations with different defect-defect distances for each defect-pair.15 defect-pairs with short defect–defect distances are found to be stable during structural relaxation,so they can exist in the GaN lattice once formed during the irradiation of high-energy particles.9 defect-pairs have formation energies lower than 10 eV in the neutral state.The vacancy-pair VN–VN is found to have very low formation energies,as low as 0 eV in p-type and Ga-rich GaN,and act as efficient donors producing two deep donor levels,which can limit the p-type doping and minority carrier lifetime in GaN.VN–VN has been overlooked in the previous study of defects in GaN.Most of these defect-pairs act as donors and produce a large number of defect levels in the band gap.Their formation energies and concentrations are sensitive to the chemical potentials of Ga and N,so their influences on the electrical and optical properties of Ga-rich and N-rich GaN after irradiation should differ significantly.These results about the defect-pairs provide fundamental data for understanding the radiation damage mechanism in GaN and simulating the defect formation and diffusion behavior under irradiation.Using first-principles calculations, we explored all the 21 defect-pairs in Ga N and considered 6 configurations with different defect-defect distances for each defect-pair. 15 defect-pairs with short defect–defect distances are found to be stable during structural relaxation, so they can exist in the GaN lattice once formed during the irradiation of high-energy particles. 9 defect-pairs have formation energies lower than 10 e V in the neutral state. The vacancy-pair V_N–V_N is found to have very low formation energies, as low as 0 e V in p-type and Ga-rich Ga N, and act as efficient donors producing two deep donor levels, which can limit the p-type doping and minority carrier lifetime in GaN. V_N–V_N has been overlooked in the previous study of defects in GaN. Most of these defect-pairs act as donors and produce a large number of defect levels in the band gap. Their formation energies and concentrations are sensitive to the chemical potentials of Ga and N, so their influences on the electrical and optical properties of Ga-rich and N-rich GaN after irradiation should differ significantly. These results about the defect-pairs provide fundamental data for understanding the radiation damage mechanism in Ga N and simulating the defect formation and diffusion behavior under irradiation.

关 键 词：GAN first-principles calculations radiation damage defect-pairs point defects 

分 类 号：TN304[电子电信—物理电子学] O469[理学—凝聚态物理]