晶粒尺寸分布对纳米晶硅薄膜喇曼散射谱的影响

Large Effects of Nanocrystal Size Distribution on Raman Scattering Spectra of nc-Si: H Films

用热丝助化学汽相反应法沉积了nc－Si：H薄膜，测量了它的喇曼散射谱，由透射电子显微镜直接测量了晶粒的大小和分布．应用声子强限制模型和球形粒子假设，并考虑到纳米晶粒的分布对样品的喇曼散射谱进行了拟合．结果表明，在考虑到纳米粒子的尺寸分布后，采用指数权重函数比采用高斯型权重函数更接近于实验测量的喇曼谱．

nc-Si: H films have been deposited by hot wire chemical vapor deposition (HWCVD) technique. The nanocrystal size distribution in these films have been directly measured by transmission electron microscopy (TEM) observation. By using the strong phonon confinement model and assuming the nanocrystals have spherical shape, the Raman spectra of these films have been fitted with different phonon weighting functions after considering the size distribution. It is shown that the calculated spectra with the exponential function are in better agreement with experimental data than those with Gaussian weighting function.