Role of Scanning Speed in Morphological and Optical Properties of Nanosecond Laser Textured Silicon Surfaces

Abstract

Laser surface texturing (LST) is a rapid single-step method for surface functionalization. Different micro and nanoscale structures can be fabricated by controlling the laser parameters, ambient conditions, and material properties. In this work, we investigated the role of laser scanning speed in the morphological and optical properties of nanosecond laser textured silicon surfaces. Keeping the laser flounce just above the threshold, we controlled the laser scanning speed in the range 50-100 μm/s to monitor the morphological and optical changes. Morphological analysis shows various randomly arranged microstructures in the processed area, and the induced structures strongly depend on the scanning speed. The total reflection spectrum (specular+diffuse) from laser textured silicon shows that a significant reduction (≈60%) in reflectivity is possible with the decrease in scanning speed from 100 μm/s to 50 μm/s. These highly absorptive and large-area microstructures have numerous possibilities in photovoltaics, optoelectronic devices, and other material science applications.