[13p-N106-1~6] 22.1 Joint Session M "Phonon Engineering"

▼ [13p-N106-4] Effect of cluster size distribution in SiGe alloys on local phonon mode intensity

〇(D)Sylvia YukYee Chung¹, Motohiro Tomita^1,2, Junya Takizawa¹, Ryo Yokogawa^3,4, Atsushi Ogura^3,4, Haidong Wang⁵, Takanobu Watanabe^1,2 (1.Waseda University, 2.Comp. Res. Org., 3.Meiji Renew. Energy, 4.Meiji Univ., 5.Tsinghua University)

Keywords:phonon mode, sige alloy, molecular dynamics

A localised phonon mode in bulk SiGe alloy was recently discovered using inelastic x-ray scattering. A more in-depth investigation about the nature of this mode has yet to be conducted. Using molecular dynamics, the dependency of the local phonon mode intensities on cluster size was studied across a composition domain of Ge 20 ~ 80 %. By observing the phonon dispersion relations, it was revealed that the SiGe models with smaller Ge clusters produced the highest intensities of the local mode. Conversely, the models with large Ge and large Si clusters produced the lowest intensities of the local mode. The local mode is speculated to be a collective vibration, comprising the vibrational movement of Ge clusters, the surrounding Si-Si bonds, and the Si-Ge bonds that form in the periphery of the cluster. Additionally, the local mode appears in the Brillouin zone where the optical modes exist, indicating this mode is of optic nature.