講演情報
[7p-N105-3]Anharmonicity-Induced Enhancement of Thermal Transport in SiGe Alloyed Nanowires
〇(D)Wei Zhang1,2, Shiyun Xiong3, Yangyu Guo2, Hongliang Yi2, Sebastian Volz1,4, Masahiro Nomura1 (1.IIS Univ. of Tokyo, 2.Harbin Inst. Technol., 3.Guangdong Univ. of Technol., 4.LIMMS Univ. of Tokyo)
キーワード：
localization effects、inelastic scattering、SiGe nanowires
Semiconductor alloys exhibit significant potential as thermoelectric materials, enabled by their ordered crystalline structure. In addition, the presence of mass disorder significantly reduces lattice thermal transport while exerting minimal effect on electron behavior. In the case of SiGe nanowires (SiGe NWs), the discernible mass difference between components results in intense phonon scattering. As is generally recognized, the introduction of disorder substantially influences phonon transport through elastic scattering, thereby substantially reducing thermal conductivity. However, the role of system anharmonicity in affecting thermal transport within SiGe NWs remains to be elucidated. In this research, we perform ballistic non-equilibrium Green's function (NEGF) and non-equilibrium molecular dynamics (NEMD) simulations, to demonstrate that introducing anharmonicity in SiGe NWs could unexpectedly enhance thermal conductance of the system by up to 47%. We further observed that as the concentration of Ge was increased to over 10%, the influence of systemic anharmonicity on heat transport within SiGe NWs measuring several nanometers in length became discernible, and this effect was gradually amplified with increasing length. Spectral analysis of phonon heat transport reveals that the enhancement of heat transport by anharmonicity is mainly due to the augmentation of low frequency phonon transmission and an increase in mean free path below 2 THz. In addition, the presence of anharmonicity results in an increase in Anderson localization length, which subsequently reduces the number of localized phonon modes, and also exercises corresponding enhancement on heat transport. Our research has enhanced the understanding of phonon heat transport in low-dimensional disordered systems, providing substantial theoretical guidance for the control of thermal conductivity of semiconductor materials.