Fabrication of periodical surface structures by picosecond laser irradiation of carbon thin films: transformation of amorphous carbon in nanographite

• Published in: Applied surface science 2016-12, Vol.390, p.236-243
• Main Authors: Popescu, C., Dorcioman, G., Bita, B., Besleaga, C., Zgura, I., Himcinschi, C., Popescu, A.C.
• Format: Article
• Language: English
• Subjects: Carbon; Diamond-like carbon; Irradiation; Laser induced periodic surface structures; Lasers; Nanostructure; Picosecond laser irradiation; Pulsed laser deposition; Surface structure; Thin films; Transformations; Tuning
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.08.029

•Ripples obtained on carbon films after irradiation with visible ps laser pulses.•Amorphous carbon was transformed in nanographite following irradiation.•Ripples had a complex morphology, being made of islands of smaller ripples.•Hydrophilic carbon films became hydrophobic after surface structuring. Thin films of carbon were synthesized by ns pulsed laser deposition in vacuum on silicon substrates, starting from graphite targets. Further on, the films were irradiated with a picosecond laser source emitting in visible at 532nm. After tuning of laser parameters, we obtained a film surface covered by laser induced periodical surface structures (LIPSS). They were investigated by optical, scanning electron and atomic force microscopy. It was observed that changing the irradiation angle influences the LIPSS covered area. At high magnification it was revealed that the LIPSS pattern was quite complex, being composed of other small LIPSS islands, interconnected by bridges of nanoparticles. Raman spectra for the non-irradiated carbon films were typical for a-C type of diamond-like carbon, while the LIPSS spectra were characteristic to nano-graphite. The pristine carbon film was hydrophilic, while the LIPSS covered film surface was hydrophobic.