Optical-absorption spectrum near the exciton band edge inCuGaS2at 5 K

The absorption spectrum of ${\mathrm{CuGaS}}_2$ near the fundamental absorption edge measured at 5 K has been analyzed taking into account both the discrete and continuum excitons. It has been shown that a transition from an acceptor level, originated by copper vacancies, to the conduction band occurs in this spectral region. It has been shown that the experimental slope of the optical-absorption curves, the strength of excitons, and the binding energies of excitons and acceptors are well accounted for by existing theoretical models. © 1996 The American Physical Society.