Abstract
Development of renewable energy for environmental protection is the most critical issue in recent years, and solar energy is one of the key technologies for the possible solution. In order to reduce costs and improve efficiency of silicon based solar cells, surface texture is implemented to reduce the reflectivity of incident light to enhance the efficiency of light absorption. Recently, M. A. Green has demonstrated the efficiency as high as 25% in PERL solar cell module which has been textured only one side to be pyramid structure. The standard industrial process for the surface texture in single crystalline silicon based solar cell is alkaline immersion wet etching method. This process creates double-sided pyramid structure in silicon wafer which may give rise to a fragmentation problem caused by the stress due to immersion technique. As compared to the silicon wafer with two-sided pyramid structure, single-sided pyramid structure has advantage in the manufacturing process of the back surface field. Flat structure in BSF side could improve the uniformity in thickness of BSF layer and so that avoid electronic tunnel effect at the thinner BSF layer. Furthermore, the performance of passivation layer can also be benefited from the improvement in the flat structure and uniformity in BSF layer. In this thesis, we develop the spray etching method to texture single-sided pyramid structure in silicon wafer. This process is a simple and low cost method; it only takes one hour to fabricate the single-sided pyramid structure which has as low reflectivity as that from the traditional immersion process.