Light-trapping properties of patch textures created using laser assisted texturing

For crystalline silicon solar cells, the efficient collection of light at wavelengths in the infrared is a challenge because of long absorption lengths. Especially for thinner wafers, an efficient light-trapping scheme, such as the patch texture, is required for high short-circuit current densities. We have measured the light-trapping properties of patch textures produced by laser assisted texturing (LAST) on polished h100i silicon wafers, and compared them with ray-tracing simulations. Single-sided random pyramid textures are created for comparison. Excellent agreement between simulations and measurements is achieved by employing diffuse scattering with a narrow angular distribution in the simulations, confirming the successful implementation of the process. We use our optical measurements of the textures for simulations of textures with rear reflectors, where we also investigate the influence on light-trapping properties when varying geometry and reflectance properties. The results from the optical simulations are imported into the solar cell simulation program PC1D. For a 50 mu m-thick solar cell, we simulate an improvement in J(sc) of up to 0.4 mA/cm(2) when going from single-sided random pyramid textures to patch textures, even when the performance of the texture is limited by process inaccuracies. Removing the physical inaccuracies of the laser system, the potential gain in Jsc on a 50 mu m-thick cell with a patch texture covering the complete wafer surface is 0.8 mA/cm(2). We therefore conclude that the LAST method for creating patch textures is suitable to achieve an improved J(sc) in thin monocrystalline silicon solar cells. Copyright (C) 2013 John Wiley & Sons, Ltd.