First-principles calculation of intrinsic defect chemistry and self-doping in PbTe
First-principles calculation of intrinsic defect chemistry and self-doping in PbTe
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DOI：
10.1038/s41524-017-0047-6
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发表时间：
2017-10-10
影响因子：
9.7
通讯作者：
Stevanovic, Vladan
中科院分区：
文献类型：
--
作者：
Goyal, Anuj;Gorai, Prashun;Stevanovic, Vladan
半导体的掺杂能力本质上受到本征缺陷化学的限制。在许多热电材料中，由于强自旋 - 轨道相互作用导致的窄带隙使得对本征缺陷化学和自掺杂进行精确的原子级预测在计算上具有挑战性。在此，我们使用不同层次的理论对PbTe中的点缺陷进行建模，并将结果相互比较，同时与大量实验数据进行对比。我们发现，要准确重现PbTe的本征缺陷化学和已知的自掺杂行为，关键在于：(a)超越密度泛函理论中的半局域广义梯度近似（GGA），(b)包含自旋 - 轨道耦合，以及(c)利用多体GW理论来描述各个能带边的位置。包含自旋 - 轨道耦合的杂化HSE泛函，结合来自G(0)W(0)的能带边移动，是唯一一种能够准确捕捉PbTe的本征导电类型随合成条件的变化以及测量到的载流子浓度的方法，且无需实验输入。我们的结果再次证实了各个能带边位置在缺陷计算中的关键作用，并表明在这种具有挑战性的窄带隙材料中可以准确预测掺杂能力。
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 G(0)W(0) 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.