12 June 2006 Formation of nanohills on the surface of 6H-SiC:N at an early stage of laser ablation
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Proceedings Volume 5946, Optical Materials and Applications; 59460C (2006) https://doi.org/10.1117/12.639155
Event: Optical Materials and Applications, 2005, Tartu, Estonia
Irradiating nitrogen doped 6H-SiC(000l) crystals with a focused beam of an N2 pulse laser, we could form discrete circularly placed nanohills on their surface. The necessary light intensities were close to the ablation threshold. The evidence was obtained by atomic force microscopy and photoluminescence. The measurements demonstrated that in the area acted upon, the surface morphology and the nitrogen concentration depended on the irradiation dose. Supplementary data was obtained from the numerical modeling of the temporal depth dependence of the temperature in SiC in response to an N2 laser pulse. The appearance of the nanohills is accounted for by a temperature-gradient gathering of nitrogen into the subsurface focal area and by a rapid surface vaporization. The former process leads, via the melting point decrease, to a local area melting, and the latter, via the surface temperature decrease, to the capping of the melt with a thin solid lid. The interplay between the pressures exerted by the light and the liquid ends in a lid-peripheral extrusion of a portion of the liquid and formation of the nanohills. The whole process proceeds in a clearly distinguishable and repeatable two-stage mode.
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Artur Medvid, Artur Medvid, Vitaly Malevich, Vitaly Malevich, Petro Lytvyn, Petro Lytvyn, } "Formation of nanohills on the surface of 6H-SiC:N at an early stage of laser ablation", Proc. SPIE 5946, Optical Materials and Applications, 59460C (12 June 2006); doi: 10.1117/12.639155; https://doi.org/10.1117/12.639155

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