Fabrication and characterization of single crystalline silicon solar cells

Es, Fırat
The electricity generation using photovoltaic (PV) solar cells is the most viable and promising alternative to the fossil-fuel based technologies which are threatening world’s climate. PV cells directly convert solar energy into electrical power through an absorption process that takes place in a solid state device which is commonly fabricated using semiconductors. These devices can be employed for many years with almost no degradation and maintenance. PV technologies have been diversified in different directions in recent years. Many technologies with different advantages have been developed. However, with more than %85 percent market share, Si wafer based solar cells have been the most widely used solar cell type. This is partly due to the fact that Si technology is well known from the microelectronic industry. This thesis is concerned with the production of single crystalline silicon solar cells and optimization of process parameters through the characterization of each processing step. Process steps of solar cell fabrications, namely, the light trapping by texturing, cleaning, solid state diffusion, lithography, annealing, anti reflective coating, edge isolation have all been studied with a systematic approach. Each sample set has been characterized by measuring I-V characteristics, quantum efficiencies and reflectance characteristics. The best efficiency that we reached during this study is 10.37% under AM1.5G illumination. This is below the efficiency values of the commercially available solar cells. The most apparent reason for the low efficiency value is the series resistance caused by the thin metal contacts. It is observed that the efficiency upon the reduction of series resistance effect is reduced. We have shown that the texturing and anti-reflective coating have a critically important effect for light management for better efficiency values. Finally we have investigated the fabrication of metal nanoparticles on the Si wafer for possible utilization of plasmonic oscillation in them for light trapping. The self assembly formation of gold nanoparticles on silicon surface has been successfully demonstrated. The optical properties of the nanoparticles have been studied; however, further and more detailed analysis is required.
Citation Formats
F. Es, “Fabrication and characterization of single crystalline silicon solar cells,” M.S. - Master of Science, Middle East Technical University, 2010.