Structural, chemical and optical features of nanocrystalline Si films prepared by PECVD techniques

The nanostructural and chemical features of nanocrystalline Si (nc-Si) films, which were prepared by plasma-enhanced chemical vapor deposition (PECVD), were investigated in terms of various deposition conditions such as reaction gas fractions and substrate temperature. Such features were related with the photoluminescence (PL) phenomena of the nc-Si films. The phase of the nc-Si films prepared at room temperature is somewhere between amorphous and crystalline states, containing about 2 nm size nanocrystallites, which are well passivated by hydrogen. These films exhibit significant PL intensities near blue light region; the PL peaks shift to lower wavelength with decreasing nanocrystallite size.