Resonant Raman Effect on a CuGaSe2 Crystal Grown by the Traveling Heater Method

Abstract

Resonant Raman scattering phenomena in the case of CuGaSe2 crystals grown by the traveling heater method have been investigated. Seven resonant Raman peaks which are assigned to one A1, one B2(L) and five E(L) modes, have been observed over a wide excitation energy range (1.54–1.66 eV). The enhancement of these Raman peaks is due to incoming resonance mediated by the donor–acceptor pair transition states which are observed as a luminescence peak. The breakdown of the Raman selection rule is attributed to the resonance effect. Temperature dependence of Raman intensity also suggests that the transition states of the donor–acceptor pair act as intermediate states of the resonant Raman scattering.