Dispersion model for optical constants of a-Si:H

The optical constants of hydrogenated amorphous silicon (a-Si:H) deposited by plasma enhanced chemical vapor deposition (PECVD) have been obtained using the Forouhi–Bloomer (FB) model and the Tauc–Lorentz (TL) model, respectively. It is indicated that there are some discrepancies between the results derived from the FB model and the TL model. Based on the theory background of the two models, a detailed analysis on these discrepancies has been carried out. Finally, we have proposed a modified FB model to reduce the physical imperfection of the original FB model. This model can better fit the optical constants of a wide variety of amorphous silicon with different microstructures.