Semiconductor dopability is inherently limited by intrinsic defect chemistry.In many thermoelectric materials,narrow band gaps due to strong spin-orbit interactions make accurate atomic level predictions of intrinsic ...Semiconductor dopability is inherently limited by intrinsic defect chemistry.In many thermoelectric materials,narrow band gaps due to strong spin-orbit interactions make accurate atomic level predictions of intrinsic defect chemistry and self-doping computationally challenging.Here we use different levels of theory to model point defects in PbTe,and compare and contrast the results against each other and a large body of experimental data.We find that to accurately reproduce the intrinsic defect chemistry and known self-doping behavior of PbTe,it is essential to(a)go beyond the semi-local GGA approximation to density functional theory,(b)include spin-orbit coupling,and(c)utilize many-body GW theory to describe the positions of individual band edges.The hybrid HSE functional with spin-orbit coupling included,in combination with the band edge shifts from G0W0 is the only approach that accurately captures both the intrinsic conductivity type of PbTe as function of synthesis conditions as well as the measured charge carrier concentrations,without the need for experimental inputs.Our results reaffirm the critical role of the position of individual band edges in defect calculations,and demonstrate that dopability can be accurately predicted in such challenging narrow band gap materials.展开更多
基金funded by the National Science Foundation(NSF)Grant No.DMR-1309980funded by the NSF DMR program,Grant No.1334713sponsored by the DOE Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory(NREL).
文摘Semiconductor dopability is inherently limited by intrinsic defect chemistry.In many thermoelectric materials,narrow band gaps due to strong spin-orbit interactions make accurate atomic level predictions of intrinsic defect chemistry and self-doping computationally challenging.Here we use different levels of theory to model point defects in PbTe,and compare and contrast the results against each other and a large body of experimental data.We find that to accurately reproduce the intrinsic defect chemistry and known self-doping behavior of PbTe,it is essential to(a)go beyond the semi-local GGA approximation to density functional theory,(b)include spin-orbit coupling,and(c)utilize many-body GW theory to describe the positions of individual band edges.The hybrid HSE functional with spin-orbit coupling included,in combination with the band edge shifts from G0W0 is the only approach that accurately captures both the intrinsic conductivity type of PbTe as function of synthesis conditions as well as the measured charge carrier concentrations,without the need for experimental inputs.Our results reaffirm the critical role of the position of individual band edges in defect calculations,and demonstrate that dopability can be accurately predicted in such challenging narrow band gap materials.
