Effect of technical parameter on optical constants of amorphous silicon thin film

In this paper, a series of a-Si:H thin films for about 350 nanometers in thickness were deposited on K9 glass substrate by means of plasma enhanced chemical vapor deposition (PECVD) . During deposition process, there are many factors which influence the optical properties of films. The importance among them includes RF power, substrate temperature and working gas pressure. Technical parameters affect the contents of hydrogen in a-Si:H film. Hydrogen plays a critical role in enhancing the ordering of the film network in a-Si, which can increase nucleation sites and reduce crystallization temperature effectively. The optical constants (n, k) of films were obtained with Forouhi Bloomer (FB) model in spectra ellipsometer (SE) and the absorption coefficient α was deduced from α=4πk/λ.