【摘要】 声子限制效应会引起本征硅纳米线拉曼光谱红移及不对称宽化,但研究发现其并非引起硅纳米线拉曼光谱改变的主要因素。研究表明,由于在拉曼光谱测量中,通常使用的入射激光功率都在5mW以上,激光加热会导致很高的局部温度,从而引起拉曼光谱大幅度红移并对称宽化,这是硅纳米线拉曼光谱红移的主要影响因素。另外,激光功率很高时,由激光激发的载流子会与声子发生Fano型干涉,从而使硅纳米线拉曼光谱发生Fano型红移和不对称宽化。除此之外,对小直径本征硅纳米线,声子限制效应导致波矢选择定弛则弛豫,使不在布里渊区中心的声子也可以参与拉曼散射,因而其拉曼光谱中除常见的几个拉曼峰外还会出现新拉曼峰。更多还原

【Abstract】 Phonon confinement effect results in an redshift and asymmetric broadening in the low-frequency side of Raman spectra of intrinsic silicon nanowires(SiNWs), but is not the only factor impacting the Raman spectrum of SiNWs. At high incidence laser power densities, laser heating gives a redshift and symmetric broadening, and Fano interference between the scattering from the k=0 optic phonon and the electronic continuum scattering from laser-induced carriers gives an asymmetric line shape, i.e. Fano line shape. Furthermore, due to phonon confinement effect, the fundamental k=0 Raman selection rule is relaxed, allowing phonons away from the Brillouin zone center to participate Raman scattering too, therefore, some new weak Raman signals appear at about 604 and 423 cm-1 in addition to the usual silicon peaks at 520, 302 and 964 cm-1 for silicon nanowires with small diameter.更多还原