Photoluminescence and photoluminescence excitation study of CuGaTe2

Abstract
Photoluminescence (PL) and photoluminescence excitation measurements over a temperature range 12 K<T<300 K on high quality CuGaTe2 crystals grown by the vertical Bridgman method were completed. The whole PL spectrum consists of two regions. The first region includes PL bands E1 at 1.431 eV, E2 at 1.426 eV, and E3 at 1.417 eV, together with their phonon replicas while in the second region we have a PL band D0 at 1.338 eV with its well-resolved LO-phonon replicas (ℏωLO=26.5 meV). All these PL bands appear to be at higher energy than the lowest (fundamental) band gap energy EgA. The possible origin of observed PL bands is discussed.