Fundamental research in crystalline silicon photovoltaic materials: program perspective

The directions and goals for future research in crystalline silicon materials for high-efficiency solar cells are identified. Currently, the substrates produced by technologies of commercial interest have lower chemical purity and crystal perfection than those of microelectronics-grade wafers. The material quality of these substrates can be improved by post-growth treatments that can be incorporated in the cell fabrication process schedule. Such treatments, applicable to low-cost single- and polycrystalline substrates, include impurity gettering, defect passivation, and defect annihilation. Development of these processes requires a better understanding of point-defect phenomena involving interactions of defects and impurities