Fabrication and characterization of aluminum nanostructures using femtosecond ablation technique

Abstract

In this paper we report the fabrication of nanostructures through the interaction of ultrashort laser pulses (*40 fs) with bulk Aluminum immersed in various liquid media of different polarity (chloroform which is polar, carbon tet-rachloride which is non-polar, and water which is polar) using femtosecond laser ablation. Except water medium other two media showed yellow coloration after ablation indicating the formation of nanoparticles in the solution. The coloration of the laser exposed portion in the Al substrate was golden yellow and its closer view depicted micro-grating and nano-ripple (period 330 nm) formation. The investigation of polarization dependence on the ablation was performed for the liquid media. Depending on the focal position we observed sub-micron structures and nano-ripples on the surface. As the rate of ablation depends on the position of the focus on the Al substrate and beam waist and other laser parameters, we have studied the liquid level dependence of ablation with different water levels on the Al substrate and we compared these patterns when focus was beyond the sample and on the sample. Size distribution of the generated nanoparticles in the liquid in which ablation took place and surface morphology of the substrates were investigated using SEM technique.