Effects of Deposition Conditions on Properties of a-Si1-xCx:H Diagnosed Using Optical Emission Spectroscopy

Abstract

The effects of both plasma conditions and substrate temperatures on the properties of a-Si_1-x C _x :H obtained by a glow-discharge plasma with SiH₄-C₂H₄-H₂ were investigated using deposition rates of Si and C atoms and in-situ optical-emission spectroscopy. The deposition rates of Si and C atoms were calculated from the deposition rates of a-Si_1-x C _x :H (x=0.5-0.99) films with the measured values of the densities of the films. The deposition rate of C atoms is proportional to the emission intensity of CH^* from a plasma; this shows that CH^* is a good indicator of the decomposition of C₂H₄. The decomposition of C₂H₄ is reduced in a C₂H₄-rich gas composition, which causes a decrease in the deposition rate of C atoms and an increase in the average number of H atoms attached to C atoms in the film. The increase of H atoms in the film provides a low density and a large optical energy gap.