Interference fringe-free transmission spectroscopy of amorphous thin films

Based on optical fundamentals, we present in this article a practical metho d to obtain an interference fringe-free transmission spectrum for hydrogena ted amorphous solid thin films. From this spectrum, reliable optical proper ties, such as the Urbach edge and optical band gap of the thin films, can b e extrapolated directly. In terms of the Brewster angle accuracy, the margi ns of error of the proposed method due to material dispersion are less than +/-1% for hydrogenated amorphous silicon and less than +/-1.2% for hydroge nated amorphous silicon nitride. These figures are less than the detectable limit of the proposed method. (C) 2000 American Institute of Physics. [S00 21-8979(00)02720-1].