Optical absorption enhancement of thin-film amorphous silicon induced by femtosecond laser pulses for solar cell fabrication

In this paper, we present a new method for direct-write laser fabrication of thin-film amorphous silicon (a-Si) on crystalline silicon substrate induced by femtosecond laser irradiation. Using megahertz frequency femtosecond laser pulses makes it possible to control laser fluence in the amorphization range of silicon under ambient condition. Finally, a thin-film of amorphous silicon is generated on the silicon substrate. It was observed a significant drop in light reflectance of the irradiated area (a-Si) in the visible range. This method can lead to promising solutions for solar cell fabrication techniques based on amorphorized silicon. In comparison with previous methods, our approach is singlestep and both processing time and cost of fabrication are reduced. A Scanning Electron Microscope (SEM), a Micro-Raman, Energy Dispersive X-ray (EDX) spectroscopy and an optical spectrometer were used to investigate the properties of the amorphorized thin layer on Si-substrate.