Gettering improvements of minority-carrier lifetimes in solar grade silicon

• Published in: Solar energy materials and solar cells 2012-06, Vol.101, p.123-130
• Main Authors: Osinniy, V., Nylandsted Larsen, A., Hvidsten Dahl, E., Enebakk, E., Søiland, A.-K., Tronstad, R., Safir, Y.
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Exact sciences and technology; Internal gettering; Minority-carrier lifetime; Natural energy; Phosphorus gettering; Photoelectric conversion; Photovoltaic conversion; Release/diffusion model; Segregation model; Solar cells. Photoelectrochemical cells; Solar energy; Solar grade silicon
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2012.02.027

The minority-carrier lifetime in p-type solar-grade silicon (SoG-Si) produced by Elkem Solar was investigated after different types of heat treatment. Two groups of samples differing by the as-grown lifetimes were exposed to internal and phosphorus gettering using constant and variable temperature processes. Optimal heat-treatment parameters for each group of samples were then identified which improved the minority-carrier lifetimes to values higher than the minimum value needed for solar cells. Phosphorus gettering using a variable temperature process enhanced in particular the lifetime within each group, increasing in certain cases the lifetime from 3 up to 81μs. ► Internal and phosphorus gettering considerably enhances the lifetime in Elkem SoG-Si. ► Variable-temperature processes are more effective than constant-temperature ones. ► Lifetime may be increased by a factor of 20 after variable-temperature P-gettering. ► Optimal temperature for constant-temperature processes varies between 800 and 930°C. ► Maximum temperature for variable-temperature processes is between 1100 and 1200°C.