The architecture of high efficiency thin film solar cell involves integration of some nanometric layers, including buffer layer and protection layer, below the TCO (transparent conductive oxide) layer. Mainly the CdS with thicknesses in the range of 30-60 nm is used as buffer layer, while ZnO up to 20 nm is used as protection layer. Alternative Cd-free layers based on Zn(O,S), Zn(S,Se) and (Zn,Mg)O alloys have more recently been developed. In all cases, control of the thickness and composition of the layers are relevant to achieve high performance devices. However, assessment of these parameters is currently compromised by their nanometric thickness. In this framework, this work reviews the development of resonant Raman scattering methodologies for the quantitative assessment of the thickness and composition of the nanometric layers used for the thin film solar cells. Particularly, the solid solutions of (Zn,Mg)O layers with different thickness and Zn/Mg ratio were analyzed. Obtained data confirms the potential of Raman scattering based techniques for the non-destructive monitoring of nanometric layers in advanced high efficient devices.