Investigation on Different Surface Modifications Using Laser Texturing

One of the important factors that determines the performance of a crystalline silicon solar cell is the surface structuring. Surface not only affects the electrical properties with recombination but also the optical properties via light trapping. To minimize reflection from the flat surface and improve light trapping, the crystalline silicon wafers must be textured. For monocrystalline Si cells, anisotropic alkaline etchants are commonly used to create pyramids on the surface. However, this method is not suitable for multi-crystalline Silicon due to grains of random crystallographic orientation. The aim of this study is to employ laser texturing which is an anisotropic texturing process as an alternative method for texturing multi-c solar cells. The approach utilizes a laser to create pits on the surface of multi-crystalline silicon wafers. The laser processing parameters are justified by performing series of experiments for different values of processing parameters. In order to determine the effectiveness of the process, the reflectance and Scanning Electron Microscopy (SEM) images of produced textures are taken into account. As a result, proper parameters for laser and laser motor is founded. The SEM images show that textures are deep enough to trap light inside and the reflection measurements indicate that samples have a low reflection.