Generation of microstructures and extreme sub-wavelength laser-induced periodic structures on the Si surface using N$_2$ nanosecond pulsed laser for the reduction of reflectance

摘要

A detailed study is done on the growth of microstructures and sub-wavelength laser-induced periodic surface structures (LIPSSs) on silicon (Si) surface using nitrogen (N2) nanosecond (ns) laser processing in air. The period of LIPSS is found to be as small as 37 nm which is close to λ/9 times the irradiated laser wavelength (337 nm). In the optimised condition the sums total of reflectance (specular reflectance + diffuse reflectance) was found to be as low as 10% for a broad wavelength range. The reflectance behaviour has been correlated with the morphology of the generated microstructures.