The origins of pressure-induced phase transformations during the surface texturing of silicon using femtosecond laser irradiation

Abstract:

Surface texturing of silicon using femtosecond (fs) laser irradiation can reduce the surface reflectivity to less than 5%, enables control over the resulting surface morphology, and uses little material. The laser-induced damage that occurs in parallel with surface texturing, however, can result in increased recombination currents that inhibit device performance. In this work, we investigate the light- material interaction during the texturing of silicon by directly correlating the formation of pressure-induced silicon polymorphs, fs-laser irradiation conditions, and the resulting morphology and microstructure using scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. We identify resolidification-induced stresses as the mechanism responsible for driving sub- surface phase transformations during the surface texturing of silicon, the understanding of which is an important first step towards reducing laser-induced damage during the texturing of silicon with fs-laser irradiation.