One-Step Nanosecond-Laser Microstructuring, Sulfur-Hyperdoping, and Annealing of Silicon Surfaces in Liquid Carbon Disulfide

Abstract

We perform a single-shot IR nanosecond laser processing of commercial silicon wafers in ambient air and under a 2 mm thick carbon disulfide liquid layer. We characterize the surface spots modified in the liquid ambient and the spots ablated under the same conditions in air in terms of its surface topography, chemical composition, band-structure modification, and crystalline structure by means of SEM and EDX microscopy, as well as of FT-IR and Raman spectroscopy. These studies indicate that singlestep microstructuring and deep (up to 2–3% on the surface) hyperdoping of the crystalline silicon in its submicron surface layer, preserving via pulsed laser annealing its crystallinity and providing high (10⁴ cm⁻¹) spectrally flat near- and mid-IR absorption coefficients, can be obtained in this novel approach, which is very promising for thin-film silicon photovoltaic devices.