Optimization of oxidation processes to improve crystalline silicon solar cell emitters

Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 Omega/square performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 Omega/square that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 x 10(20) cm(-3) and 7.78 x 10(20) cm(-3) and with junction depths between 0.46 mu m and 0.55 mu m possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%(abs) compared to conventional emitters with 50 Omega/square sheet resistance. (C) 2014 Author( s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.