Compositional dependence of absorption edges in evaporated Pb_(1-x)GeTe thin films as infrared short-wavelength cutoff filters

摘要

Semiconductors which exhibit a very rapid transition from opacity to transparency at the intrinsic edge are particularly useful in making excellent absorption filters. In this paper, we report the investigation on composition dependence of absorption edges in the evaporated Pb_(1-x)Ge_xTe thin films, which will be of a potentiality to fabricate a single-layer infrared short-wavelength cutoff filter by means of controlling the composition and processes. It is revealed that for thin films with an identical Te concentration, the absorption edges will shift towards short-wavelength with the increase of Ge concentration x in films; whereas, for those with a similar Ge concentration within a small range of deviation, the edges will also shift towards the short-wavelength with Te concentration approach to stoichiometry.