Compositional dependence of Raman scattering and photoluminescence emission in Cu[sub x]Ga[sub y]Se[sub 2] thin films.

Raman scattering and photoluminescence (PL) emission of Cu[sub x]Ga[sub y]Se[sub 2] thin films, grown by metalorganic chemical vapor deposition (MOCVD) on GaAs (100) and by physical vapor deposition (PVD) on Glass/Mo substrates, were studied at room and low temperatures as a function of composition. Line width changes of Raman bands in the temperature range 20–300 K indicate the formation of a more disordered Cu[sub x]Ga[sub y]Se[sub 2] phase with increasing Ga content. It is most likely that Raman bands observed at 193 and 199 cm-1 in the Ga-rich samples at low temperatures are associated with defect-related interface modes. The intensity increase of these bands and the photoluminescence intensity enhancement may be correlated to an increase in defect concentration in the Ga-rich phase. The radiative recombination in defect-rich Ga-rich samples with a higher degree of disorder apparently supports the PL emission. The observed changes are more pronounced in MOCVD than in PVD grown films. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]