Statistical analysis of internal stresses and defect densities in multi-crystalline silicon thin film solar cells on glass using Macro-Raman spectroscopy

Macro-Raman spectroscopy is a technique that permits fast large area Raman analysis of materials. The fast collection of Raman signals is based on scanning the standard laser micro-spot across the sample by two orthogonally rotating piezo-mirrors resulting in a probing macro-spot the size of which is limited only by the opening of the used microscope objective. In the present paper, we show the instrument capabilities of the Macro-Raman spectrometer with respect to the statistical characterization of internal stresses (quantitatively), defect densities (qualitatively) and their correlation in multi-crystalline silicon (mc-Si) thin film solar cells on glass. While the lateral resolution decreases, the spectral information is preserved when integrating the Raman signal over increasingly large macro-spot sizes. The Macro-Raman results have been successfully used for the optimization of technological processes towards the lowest internal stresses and defect densities in thin film silicon solar cell materials. Our study demonstrates that Macro-Raman spectroscopy represents an advanced investigation method that can be applied both in a laboratory and factory environment for materials quality control.