Dislocation-related optical absorption in plastically deformed GaN

Abstract

Optical absorption spectra have been measured for plastically deformed GaN to investigate effects of dislocations. The interband absorption edge has been observed to shift noticeably to lower photon energy by deformation, which has been analyzed based on a model of the Franz-Keldysh effect by the electric fields associated with charged dislocations. This model has satisfactorily reproduced the observed absorption spectra. In a lower energy region, a decrease in free-carrier absorption by deformation has been observed, which is partly attributable to the decrease in carrier concentration by carrier trapping at dislocation states.