Investigation On The Sprayed Phosphoric Acid As An Dopant Source And Ceramic Roller Type Diffusion

In the production process of solar cells,the quality of diffusion directly affect the electrical performance of solar cells.Conventional phosphorus emitters are achieved by a thermal diffusion process which is called by tube diffusion(TD)process.The process includes pre-deposition to obtained desired amount of phosphorus and drive-in during subsequent furnace steps,can form both of the surface concentration and the depth of the emitter in one thermal step requiring a high thermal budget for an extended period of time about 1.5 hours.Alternately,a low-cost in line diffusion using phosphoric acid as a dopant source with a shorter process times can be used.But there are several research groups has been investigated this process and thought that the lower-grade chemical precursors,open-end furnace and metal conveyor belts have adverse impacts on the solar cell efficiency.In this thesis introduces the basic theory of crystalline silicon solar cell technology and related testing techniques.A higher sheet resistance is an adequate approach to achieve higher results in efficiency.PC1 D simulation results are shown that the cell efficiency increases rapidly with higher sheet resistance,while slightly increased with junction depth.In our work,we use Al2O3 ceramic roller instead of stainless steel mesh belt metal to avoid metal contamination.After the diffusion,KOH etching for c-Si wafers or acid etching for multi crystalline silicon wafer are used.Finally reported is a CRTD cell on a CZ substrate of 19.9% efficiency,it is equal to the efficiency of conventional solar cells.