Raman microspectroscopy of a silicon solar cell

A fully finished, aluminum back-surface field, multi crystalline silicon solar cell was analyzed using Raman microspectroscopy. New insights into the process and material quality of the finished device is obtained. First, the image scan obtained on the multi crystalline silicon surface is reflective of the textured surface contributing to the surface topology. Second, the analysis helps to identify differences in the Raman spectra of the remnant saw marks on the silicon surface when compared to a textured silicon surface. Third, Raman analysis of the silver line shows a clear silver oxide signal that is detected up to 25 μm away from the edge of the silver line thus, quantifying the quality and effectiveness of the screen-printing and firing process. Finally, inclusions embedded inside the silicon surface are unambiguously identified as nanocrystalline silicon. Using confocal Raman microspectroscopy 3D tomography of the inclusions are constructed and the state of compressive stress around these particulates are measured. Taken together, these results demonstrate Raman microspectroscopy as a valuable tool for identification of micron-scale feature sizes and defects, otherwise too small to be identified using current metrology techniques.