EAPSI: Improving the Production of Solar Cells

Pogue Vanessa A, Atlanta GA

Investigators

Abstract

Solar energy, as a renewable energy source, has become a large part of reducing carbon pollution in order to begin to slow the effects of climate change and leave behind a more stable environment for future generations worldwide. Silicon (Si) is used in over 90 percent of solar cells and is the most important material for solar cell production today. To produce solar cells, silicon must be manufactured into thin wafers of approximately 200 micron thickness. As silicon is a very brittle material, breakage during processing is a significant issue leading to lower production yields and is attributable to a large proportion of the overall solar cell manufacturing cost. This research aims to study Silicon wafer microstructure as a result of the typical industry manufacturing processes and by doing so, better understand the process variables and mechanical properties that lead to increased fracture. Equipment at the Facility for Analysis, Characterization, Testing, and Simulation of Nanyang Technological University at Singapore will be employed for this study, in collaboration with Dr. David Butler, whose expertise is in the areas of surface characterization and abrasive mechanical processes. Specifically, focus will be placed on understanding the manufacturing induced microstructure mechanisms that are hypothesized to produce regions of very high residual stress. Raman spectroscopy and X-ray diffraction will be used to study surface stresses at grain boundaries as well as at regions of high dislocations. Samples from industry will be used to compare the effects of mono-crystalline vs. multi-crystalline grown Si wafers as well as the effects of fixed abrasive diamond wire sawing vs. loose abrasive slurry wire sawing used in the wafering process. NSF EAPSI award is funded in collaboration with the National Research Foundation of Singapore.