Large effects of nano-crystal size distribution on Raman scattering spectra of nc-Si:H films

nc-Si:H films have been deposited by hot wire chemical vapor deposition (HWCVD) technique. The nano-crystal 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 nano-crystals 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 weighing function.