Influence of process pressure on HW-CVD deposited a-SiC:H films

Hydrogenated amorphous silicon carbon (a-SiC:H) films were deposited using pure SiH(4) and C(2)H(2) without hydrogen dilution by hot wire chemical vapor deposition (HW-CVD) technique. The compositional, optical, and structural properties of these films are systematically studied as a function of process pressure. The device quality a-SiC:H films with similar to 55% carbon content were deposited at a deposition rate 0.5 angstrom/s at low process pressure. However, a-SiC:H films deposited at higher process pressures show degradation in their structural and its network properties. The FTIR spectroscopic analysis has shown that there is a decrease in Si-C, Si-H and C-H bond densities at high process pressure. The hydrogen content (C(H)) in the films was found to be similar to 8 at.% over the entire range of process pressure studied. The band gap, however was found similar to 2.5 eV higher. High band gap at low hydrogen content has observed which may be due to presence of higher carbon incorporation. Raman spectroscopic analysis showed that structural disorder increases with increase in the process pressure. (c) 2006 Elsevier B.V. All rights reserved.