Semiconductor alloys exhibit a strong dependence of effective thermal conductivity on measurement frequency. So far this quasi-ballistic behaviour has only been interpreted phenomenologically, providing limited insight into the underlying thermal transport dynamics. Here, we show that quasi-ballistic heat conduction in semiconductor alloys is governed by Lévy superdiffusion. By solving the Boltzmann transport equation (BTE) with ab initio phonon dispersions and scattering rates, we reveal a transport regime with fractal space dimension $1 < α< 2$ and superlinear time evolution of mean square energy displacement $σ^2(t) \sim t^β (1 < β< 2)$. The characteristic exponents are directly interconnected with the order $n$ of the dominant phonon scattering mechanism $τ\sim ω^{-n} (n>3)$ and cumulative conductivity spectra $κ_Σ(τ;Λ)\sim (τ;Λ)^γ$ resolved for relaxation times or mean free paths through simple relations $α= 3-β= 1 + 3/n = 2 - γ$. The quasi-ballistic transport inside alloys is no longer governed by Brownian motion, but instead dominated by Lévy dynamics. This has important implications for the interpretation of thermoreflectance (TR) measurements with modified Fourier theory. Experimental $α$ values for InGaAs and SiGe, determined through TR analysis with a novel Lévy heat formalism, match ab initio BTE predictions within a few percent. Our findings lead to a deeper and more accurate quantitative understanding of the physics of nanoscale heat flow experiments.
Impact of band-anticrossing on band-to-band tunneling in highly-mismatched semiconductor alloys
我们从理论上分析了带间隧穿（BTBT）在高度失配，窄隙稀氮化物和铋化物合金，和量化的影响的N-或Bi-引起的扰动的能带结构-由于带反交叉（BAC）与局部杂质状态-上的电场依赖的BTBT产生率。对于这类半导体，由于BAC相互作用产生的强带边非抛物性，支持广泛采用的直接BTBT凯恩模型的假设被打破。通过数值计算的基础上的Wentzel-Kramers-Brillouin近似，我们表明，BAC导致，在固定的带隙，以减少（增加）BTBT电流在低（高）施加的电场相比，在传统的InAs $_{1-x}$ Sb $_{x}$合金。我们的分析表明，BTBT在InN $_{x}$ As $_{1-x}$和InAs $_{1-x}$ Bi $_{x}$是由场依赖的竞争的影响N（Bi）的掺入（i）的色散的复杂的带连接的价带和导带，这在低场强占主导地位，和（ii）的导（价）带边的状态密度，这在高场强占主导地位。我们的研究结果在雪崩光电二极管和隧穿场效应晶体管的应用的影响进行了讨论。
Theoretical analysis of influence of random alloy fluctuations on the opto-electronic properties of site-controlled (111)-oriented InGaAs/GaAs quantum dots
Hysteretic electrical transport in BaTiO$_3$/Ba$_{1-x}$Sr$_x$TiO$_3$/Ge heterostructures
我们目前的电输运测量异质结构组成的BaTiO $_3$和Ba $_{1-x}$ Sr $_x$ TiO $_3$外延生长在Ge上。Sr合金化赋予BaTiO $_3$压缩应变，这使得能够克服BaTiO $_3$和Ge之间的热膨胀失配以实现$c$轴取向生长。BaTiO $_3$和Ba $_{1-x}$ Sr $_x$ TiO $_3$的导带几乎与Ge的导带对齐，这有利于电子输运。通过电介质堆叠的电输运测量表现出整流行为和滞后，其中后者与铁电开关一致。
First principles phase diagram calculation and theoretical investigation of electronic structure properties of $\mathrm{KCuTe_{1-x}Se_{x}}$ for photocathode applications
本研究通过第一性原理计算 KCuTe₁₋ₓSeₓ 的温度-成分相图与电子结构，证明其在 322 K 以上形成六方固溶体，并具备高迁移率、强光吸收及合适析氢能级对齐，适用于光电阴极。
Pt-induced semimetallic transport and enhanced thermoelectric response in the half-Heusler alloy YNi_{0.5}Pt_{0.5}Bi
Indian Institute of Technology Delhi（印度德里理工学院）；Harbin Institute of Technology（哈尔滨工业大学）；Chalmers University of Technology（查尔姆斯理工大学）；Damanhour University（达曼胡尔大学）；Max-Planck-Institut für Chemische Physik fester Stoffe（马克斯·普朗克固体化学物理研究所）；Tohoku University（东北大学）
