Raman scattering structural evaluation of CuInS2 thin films

This work reports the spectral characterisation of CuInS2 (CIS) layers for solar cell devices by Raman scattering. The Raman spectrum from CIS is char acterised by a dominant A, mode at approximately 290 cm(-1), being the posi tion and width of the mode sensitive to the CIS structural quality. Besides , layers with poor structural quality show the appearance in the spectra of an additional line, not allowed for chalcopyrite crystals, at approximatel y 305 cm(-1). The relative intensity of this line has been proposed as a fu rther marker for film quality. To deepen in the knowledge of the origin of this mode, Raman scattering measurements are performed in both polycrystall ine and epitaxial layers under different conditions, including resonant Ram an and different polarisation configurations. The origin of the mode is dis cussed in terms of (i) the presence of phases with different symmetry as Cu -Au ordering, and (ii) the possible existence of defect-related local vibra tional modes. (C) 2001 Elsevier Science B.V. All rights reserved.