Growth of single-crystal silicon islands on bulk fused silica by CO2 laser annealing

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Abstract
A CO2 laser beam focused to 50 μm was used to heat bulk fused silica which had previously defined Si3N4 encapsulated chemical vapor deposited polycrystalline silicon islands (25×100 μm) on its surface. It was easily possible to melt the silicon and force recrystallization without damaging the fused silica substrate. The recrystallization process produces single-crystal islands under a wide variety of laser treatment parameters. Under certain conditions, the recrystallized islands exhibit a (100) plane parallel to the substrate. These results are the first demonstration of oriented single-crystal thin-film growth using island predefinition, which eliminates thermal stress induced microcracking resulting from the mismatch in expansion between silicon and bulk fused silica.