Interference fringe-free transmission spectroscopy of amorphous thin films

Based on optical fundamentals, we present in this article a practical method to obtain an interference fringe-free transmission spectrum for hydrogenated amorphous solid thin films. From this spectrum, reliable optical properties, such as the Urbach edge and optical band gap of the thin films, can be extrapolated directly. In terms of the Brewster angle accuracy, the margins of error of the proposed method due to material dispersion are less than +/-1% for hydrogenated amorphous silicon and less than +/-1.2% for hydrogenated amorphous silicon nitride. These figures are less than the detectable limit of the proposed method. (C) 2000 American Institute of Physics. [S0021-8979(00)02720-1].