Determining the charge states and capture mechanisms of defects in silicon through accurate recombination analyses: A review

Abstract

A key strategy for further reducing the cost of solar electricity is through the development and production of very-high efficiency silicon solar cells (> 25%). The challenge in achieving this goal lies in overcoming limitations imposed by the electronic quality of the silicon wafers themselves. To overcome this challenge, it is necessary to understand the defects limiting the electronic quality of silicon wafers. In this review, we critically assess recent progress in understanding the recombination properties of defects in silicon and provide a nuanced and detailed picture of what constitutes accurate recombination parameters for such defects. Here we show that lifetime spectroscopy and capacitance spectroscopy analyses contain significant limitations, namely disregard of multivalent defect recombination in lifetime spectroscopy analyses, lack of exciton capture mechanisms in some deep level capacitance spectroscopy measurements and limitations in using detailed balance to extract capture parameters in capacitance spectroscopy. We demonstrate that combining multiple analyses leads to a more robust determination of recombination parameters. We use such combined analyses to review recombination pathways and parameters for technology relevant defects with the goal of enabling robust simulation of the lifetime in silicon for solar cell applications.