发表机构
Faculty of Physics and Physics Engineering, University of Science; Viet Nam National University Ho Chi Minh City; Advanced Materials Technology Institute Vietnam National University Ho Chi Minh City; University of Health Sciences (UHS), Viet Nam National University Ho Chi Minh City; Frontier Research Institute for Interdisciplinary Sciences, Tohoku University（物理与物理工程学院，科学大学; 越南国立大学胡志明市分校; 先进材料技术研究所，越南国立大学胡志明市分校; 卫生科学学院（UHS），越南国立大学胡志明市分校; 前沿跨学科学研究院，东北大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究结合密度泛函理论、SSCHA和玻尔兹曼输运计算，揭示了单层SnSe中非谐声子重整化对热电功率因子的影响，并确定了保持PF的缺陷浓度上限。
AI 中文摘要
单层硒化锡（SnSe）表现出依赖于相的非谐晶格动力学，然而这些动力学对热电功率因子（PF）和点缺陷容忍性的影响仍未解决。我们结合密度泛函理论、随机自洽谐波近似（SSCHA）以及包含电子-声子和电子-缺陷散射的玻尔兹曼输运计算，研究了单层$\alpha$-SnSe（Pnma）和$\beta$-SnSe（Cmcm）。在动态稳定的$\alpha$-SnSe中，SSCHA重整化了有限温度声子，而未改变定性的n型输运图像。在$\beta$-SnSe中，SSCHA在800-1000 K下消除了Cmcm相的谐波软模不稳定性，从而实现了高温输运计算；LO/TO-2是主要的电子散射通道。在接近$10^{12}$ cm$^{-2}$的低密度窗口中，n型PF在800-900 K时达到15-19 $\mu\mathrm{W}/(\mathrm{K}^{2}\cdot\mathrm{cm})$，并主要由于更高的电导率而超过p型PF。硒空位（$V_{\mathrm{Se}}$）产生的电子-缺陷散射比锡空位（$V_{\mathrm{Sn}}$）更弱，并且在两种相中p型输运的缺陷容忍性低于n型。我们定义了一个操作性的临界缺陷浓度$C_{\mathrm{crit}}$，在该浓度下PF相对于相应的无缺陷值降低15%。对于具有$V_{\mathrm{Sn}}$的p型$\alpha$-SnSe，最低的$C_{\mathrm{crit}}$为$8.841\times10^{-5}$（约88 ppm）；对于具有$V_{\mathrm{Se}}$的n型$\beta$-SnSe，在高达$5\times10^{-3}$（5000 ppm）时未达到15%阈值。这些结果区分了稳定$\alpha$-SnSe中的有限温度声子重整化与$\beta$-SnSe中的非谐稳定化，并为保持PF提供了缺陷浓度限制。
英文摘要
Monolayer tin selenide (SnSe) exhibits phase-dependent anharmonic lattice dynamics, yet their consequences for the thermoelectric power factor (PF) and point-defect tolerance remain unresolved. We combine density functional theory, the stochastic self-consistent harmonic approximation (SSCHA), and Boltzmann transport calculations including electron-phonon and electron-defect scattering to investigate monolayer $α$-SnSe (Pnma) and $β$-SnSe (Cmcm). In dynamically stable $α$-SnSe, SSCHA renormalizes the finite-temperature phonons without changing the qualitative n-type transport picture. In $β$-SnSe, SSCHA removes the harmonic soft-mode instability of the Cmcm phase at 800-1000 K, and thereby enables high-temperature transport calculations; LO/TO-2 is the principal electron-scattering channel. In the lower-density window near $10^{12}$ cm$^{-2}$, the n-type PF reaches 15-19 $μ\mathrm{W}/(\mathrm{K}^{2}\cdot\mathrm{cm})$ at 800-900 K and exceeds the p-type PF primarily because of the higher electrical conductivity. Se vacancies ($V_{\mathrm{Se}}$) produce weaker electron-defect scattering than Sn vacancies ($V_{\mathrm{Sn}}$), and p-type transport is less defect tolerant than n-type transport in both phases. We define an operational critical defect concentration, $C_{\mathrm{crit}}$, at which the PF decreases by 15% relative to the corresponding defect-free value. The lowest $C_{\mathrm{crit}}$ is $8.841\times10^{-5}$ (approximately 88 ppm) for p-type $α$-SnSe with $V_{\mathrm{Sn}}$; for n-type $β$-SnSe with $V_{\mathrm{Se}}$, the 15% threshold is not reached up to $5\times10^{-3}$ (5000 ppm). These results distinguish finite-temperature phonon renormalization in stable $α$-SnSe from anharmonic stabilization in $β$-SnSe and provide defect-concentration limits for preserving the PF.
Comments13 pages, 4 figures, 1 table
