The Urbach focus and hydrogenated amorphous silicon

摘要

We critically examine the validity of the Urbach "focus" concept for the case of hydrogenated amorphous silicon. Our approach involves an analysis of a broad assortment of hydrogenated amorphous silicon experimental optical absorption data from many different sources. We find that these experimental data are consistent with the notion of the Urbach focus concept. The implications of this conclusion are explored.