Dislocation density reduction in multicrystalline silicon via cyclic annealing

作者：Choi Kwangmin; Castellanos Sergio; Powell Douglas Michael; Buonassisi Tonio; Choi Hyunjoo^*

来源：Physica Status Solidi A-Applications and Materials Science, 2015, 212(10): 2315-2321.

DOI：10.1002/pssa.201532233

• cyclic annealing
• dislocation density
• multicrystalline silicon
• pair-wise annihilation

Manufacturing processes to reduce dislocation densities in multicrystalline silicon (mc-Si) solar cells could reduce the cost of photovoltaics by increasing cell efficiency with minimum additional process complexity. The present work investigates how cyclically varying temperature (stress) in mc-Si blocks can lead to dislocation-density reduction. Cyclic annealing is found to be more effective at activating immobile dislocations than isothermal annealing. Once immobile dislocations are activated, however, they are hypothesized to impede density reduction of mobile dislocations by accelerating multiplication of overall dislocations. Thus, a combined process of thermal cycling and isothermal annealing is found to provide a maximum dislocation density reduction of approximate to 70%, with 12h of static annealing followed by 12h of cyclic annealing. Dislocation etch-pit images of as-grown control and mc-Si sample after 12h cyclic annealing followed by 12h static annealing.

• 出版日期2015-10
• 单位MIT