Sains Malaysiana, 2008;37:233-237.

Abstract

A set of hydrogenated nanocrystalline silicon (nc-Si:H) films prepared in a home-built plasma enhanced chemical vapour deposition (PECVD) system using the layer-by-layer (LBL) deposition technique have been studied. The 13.56 MHz rf power was varied from 20 W to 100 W to study the influence of rf power on the structural properties of the nc-Si:H films. The structure of the films was studied by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Appearance of XRD peaks at 2q angles of 28o and 56o which correspond to silicon orientation of (111) and (311) respectively were observed in all films deposited on c-Si substrate indicating evidence of crystallinity in the films. The crystallite sizes were in the range of 8 to 100 nm as determined using the Scherrer technique. The integrated intensities of absorption bands at 630 cm-1, 780 - 880 cm-1 and 2000 – 2090 cm-1 from FTIR spectrum which corresponds to various Si-H bonding configurations in the films were studied and were related to the presence of small clusters of nanocrystallites embedded in an amorphous matrix. Based on the dependence of amplitudes of Si-H vibrational modes on crystallite size and rf power, the properties and the role of hydrogen in nc-Si:H films prepared using the LBL technique were discussed.