Gettering in multicrystalline silicon-a design-of-experiments approach

Statistical methods were used to design and analyze the results of a gettering experiment on four industrial multicrystalline silicon solar cell materials. The experiment studied the effects of temperature and time in the POCl/sub 3/ diffusion process and the aluminum alloy process using simple diagnostic devices. The time and temperature ranges were restricted to maintain compatibility with commercial fabrication sequences. The design was capable of picking up second order interactions between the various processing factors. Statistically significant gettering effects were detected in only two of the four materials. The results for one of these materials were further tested using full solar cells. Strengths and weaknesses of this approach to gettering studies have become apparent in the present work and are discussed.