UV-Raman scattering assessment of ZnO:Al layers from Cu(In, Ga)Se2 based solar cells: Application for fast on-line process monitoring

In this paper, we present a non destructive optical methodology based on the use of pre-resonant UV-Raman scattering measurements, which allows for the on-line fast characterization of ZnO:Al (AZO) transparent conductive oxide (TCO). The experimental data corroborate the possibility to obtain by this methodology reliable information about the electrical properties of the TCO layers. The UV-Raman spectra of AZO are characterized by the presence of a defect-induced band. The relative intensity of this band in the spectra shows a clear correlation with the TCO resistivity. This methodology has been tested in real case devices, showing its potential for its implementation as on-line control tool for TCO's in the photovoltaic industry.