Ultra-short pulsed laser ablation of highly oriented pyrolytic graphite

Highly oriented pyrolytic graphite (HOPG) targets were irradiated by use of an ultra-short pulsed (pico to femtosecond) Ti:Sapphire laser operating at 825-nm wavelength. The morphology and quality of laser ablated surfaces we re characterized by stylus profilometry, scanning electron microscopy (SEM) , atomic force microscopy (AFM), and Raman spectroscopy. The results were a lso compared with those obtained in nanosecond pulsed excimer laser ablatio n. The ablation rates expressed in depth per pulse were substantially highe r for ultra-short pulsed lasers, and were in close agreement with the theor etical model predictions of laser-solid interactions in the short-pulse reg ime. Post-analysis of laser irradiated regions revealed a reduction in ther mal effects and a decrease in the formation of diamond-like carbon as the p ulse width was shortened. This work demonstrates the clean and precise mach ining capabilities of ultra-short pulsed lasers for HOPG that could be appl ied in the areas of thin-film deposition, nanotube synthesis, and dust-free machining. (C) 2001 Elsevier Science Ltd. All rights reserved.