Tabula Rasaforn-Cz silicon-based photovoltaics
Author(s)LaSalvia, Vincenzo; Youssef, Amanda; Jensen, Mallory Ann; Looney, Erin E.; Nemeth, William; Page, Matthew; Nam, Wooseok; Buonassisi, Anthony; Stradins, Paul; ... Show more Show less
MetadataShow full item record
High-temperature annealing, known as Tabula Rasa (TR), proves to be an effective method for dissolving oxygen precipitate nuclei in n-Cz silicon and makes this material resistant to temperature-induced and process-induced lifetime degradation. Tabula Rasa is especially effective in n-Cz wafers with oxygen concentration >15 ppma. Vacancies, self-interstitials, and their aggregates result from TR as a metastable side effect. Temperature-dependent lifetime spectroscopy reveals that these metastable defects have shallow energy levels ~0.12 eV. Their concentrations strongly depend on the ambient gases during TR because of an offset of the thermal equilibrium between vacancies and self-interstitials. However, these metastable defects anneal out at typical cell processing temperatures ≥850°C and have little effect on the bulk lifetime of the processed cell structures. Without dissolving built-in oxygen precipitate nuclei, high-temperature solar cell processing severely degrades the minority carrier lifetimes to below 0.1 millisecond, while TR-treated n-Cz wafers after the cell processing steps exhibit carrier lifetimes above 2.2 milliseconds.
DepartmentMassachusetts Institute of Technology. Department of Mechanical Engineering
Progress in Photovoltaics: Research and Applications
LaSalvia, Vincenzo et al. "Tabula Rasaforn-Cz silicon-based photovoltaics." Progress in Photovoltaics: Research and Applications 27, 2 (August 2018): 136-143 © 2018 John Wiley & Sons
Author's final manuscript