This work reports the surface and in-depth resolved Raman scattering analysis of polycrystalline CuInSe2 layers grown with different chemical composition, as function of the Cu to In content ratio (0.48 ≤ × ≤ 1.14). Measurements performed at the surface of the Cu-poor layers corroborate the formation of both Cu-poor Ordered Vacancy Compound (OVC) and CuAu ordered CuInSe2 phases for compositions corresponding to x ≤ 0.82 (OCV) and x ≤ 0.66 (CuAu), respectively. In-depth resolved measurements performed on the layers with lower Cu content have allowed observing a strong decrease with the depth of the intensity of the Raman peak from the chalcopyrite ordered CuInSe2 phase. This suggests a preferential formation of both OVC and CuAu ordered phases at the region close to the interface with the back Mo layer. On the other hand, the comparison between the spectra directly measured on the front and back surfaces of the layers -after removal of the layers from the Mo coated glass substrates- suggests also a worsening of the crystalline quality at the back region of the layers in the whole range of compositions.

This work reports the use of strategies based on Raman scattering for process monitoring of electrodeposited based S rich CuIn(S,Se)2 solar cells. Main vibrational modes in the Raman spectra are sensitive to features related to the crystalline quality, chemical composition and presence of secondary phases in the chalcopyrite layers, being all these features relevant for the optoelectronic properties of the final devices. Ex-situ and in-situ measurements during the electrochemical step allow the direct assessment on the formation of Se rich secondary phases which are related to the stoichiometry of the grown precursors. The analysis of the relative intensity of the spectral contribution from these phases allows early detection of deviations of precursor stoichiometry in relation to the optimum composition range in terms of solar cell efficiency. The applicability of the technique for the in-situ monitoring of the electrodeposition process is also discussed