TIME RESOLVED OPTICAL SPECTROSCOPY IN AMORPHOUS SILICON AND CHALCOGENIDES

Abstract
Time resolved optical spectroscopy has become a valuable technique for studying the nature of electronic states in solids. Over the past few years, amorphous solids have been investigated using a variety of optical techniques over a very large time scale ranging from ~10^-12 sec to 10^-2 sec. We will review some of the important results obtained in amorphous silicon and chalcogenides by time resolved optical spectroscopy and discuss their implications. In particular, we will discuss time resolved luminescence studies and their interpretation in terms of defect and polaron models. We will also present results on transient photoinduced absorption in which the response of amorphous solids has been measured from ~1 psec to ~1 msec. In both these discussions, we will emphasize the similarities and differences between chalcogenide glasses and amorphous silicon.