DEPOSITION OF WIDE BAND GAP DLC FILMS USING RF PECVD AT VERY LOW POWER

Abstract

Wide band gap diamond-like carbon films (DLCs) are deposited on silicon (1 0 0) substrates using capacitive coupled radio frequency plasma-enhanced chemical vapor deposition (R. F. PECVD) technique. The deposition of films is carried out at a constant pressure (similar to 5 x 10(-2) mbar) using acetylene precursor diluted with argon at constant R. F. power of 5 W. Raman spectroscopy of deposited DLC films shows broad G peak near 1550 cm(-1) and a weak D peak near 1320 cm(1). FTIR plot of DLC films shows a peak near 2900 cm(-1) corresponding to C-H stretching mode and peaks below 2000 cm(-1) corresponding to C-C modes and C-H bending modes. Maximum hardness of the deposited films is found to be similar to 15 GPa. Band gap of the DLC films is similar to 3.5 eV. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) pictures show that the deposited films are amorphous. Deposition mechanism of wide band gap DLC film is explained on the basis of subplantation model.