Influence of the target temperature on Si femtosecond laser surface structuring

• Effects of the target temperature on the formation of laser induced periodic surface structures on silicon. • Femtosecond laser surface structuring of silicon in air at variable target temperature. • How target temperature affects the fundamental processes involved in the laser surface structuring of silicon. • Influence of target temperature on debris back deposition and LIPSS. The laser surface structuring of an intrinsic (100) silicon target with femtosecond laser pulses (pulse width ≈180 fs; wavelength λ≈1030 nm) was investigated under static irradiation conditions at preset sample temperatures, T s , ranging from 23° C to 400 °C, in air. Scanning Electron Microscopy reveals a clear temperature dependent morphological evolution of the sample surface, characterized by a reduction in the subwavelength ripples and a progressive predominance of supra-wavelength grooves as T s increases. Moreover, the temperature dependence of the incubation factor ξ and fluence threshold F th have been also analyzed, observing that the former parameter remains almost independent on T s , whereas the latter one increases as a function of T s . The experimental findings are rationalized by assessing the influence of various mechanisms involved in the laser surface structuring of silicon at higher temperatures, including changes in absorption pathways, damping of the carrier oscillation and plume expansion. Our findings provide interesting qualitative insights on the influence of the sample temperature on the surface structures generated on Si in air by femtosecond laser irradiation, demonstrating the intriguing role of sample pre-heating in tailoring the surface structure formation processes.