Effect of an impurity on interband optical absorption in solids

Publisher Website
Google Scholar
Abstract
We explore the effect of an impurity on the contribution to the optical absorption in solids from electronic interband transitions. We view the impurity as a point probe which, through breakdown of wave-vector conservation, allows the incoming photon to probe critical points in the pure-crystal band structure not accessible by optical methods in the pure solid. After formulating the problem in a general manner, we present numerical studies of a one-dimensional two-band solid to illustrate how the impurity can "activate" critical points in the host band structure.