AVS 53rd International Symposium
    Nanometer-scale Science and Technology Monday Sessions
       Session NS-MoA

Paper NS-MoA7
Growth of Tungsten Nanoripples Induced by Linearly Polarized Femtosecond Laser

Monday, November 13, 2006, 4:00 pm, Room 2016

Session: Nanoscale Structures and Characterization I
Presenter: H. Zhang, The University of North Carolina at Charlotte
Authors: H. Zhang, The University of North Carolina at Charlotte
M. Tang, The University of North Carolina at Charlotte
J. McCoy, The University of North Carolina at Charlotte
T.H. Her, The University of North Carolina at Charlotte
Correspondent: Click to Email
Single-laser-beam induced nanoripples of tungsten is demonstrated in a laser-induced chemical vapor deposition (LCVD) system using tungsten hexacarbonyl as precursor and a linearly-polarized 400-nm femtosecond laser beam at 80MHz. The ripples have the shape of willow leaf with a long strip and two pointed ends, whose width is less than 100 nm and height on the order of 15 nm. The periodicity of the ripples is around 130 nm, which is about one third of the wavelength of the laser beam. The ripple orientation was found always parallel to the laser polarization, and hence can be controlled by changing the laser polarization direction. Different grating patterns were formed by scanning the laser beam along the substrate surface. Transverse pattern was formed when the scanning direction is perpendicular to the laser polarization, and longitudinal pattern was obtained when the scanning direction was parallel to the laser polarization. Effects of the laser power, exposure time, and scanning speed on the ripple formation were investigated. Different from the conventional laser-induced periodic surface structures (LIPSS)@footnote 1,2@ which can only occur by irradiating substrates near melting threshold, the tungsten nanoripples and gratings we report here can be heterogeneously deposited on a variety of substrates including insulators (glass, quartz, and sapphire etc.), wide band gap semiconductor (gallium nitride), and metals (gold, copper, and palladium etc.). Considering the simplicity of this process and material flexibility of CVD, our finding may provide a novel cost-effective patterning method to produce periodic subwavelength nanostructures of a wide range of materials. @FootnoteText@ @footnote 1@ Dieter Baüerle, Laser processing and chemistry, 3rd. ed. (Springer, Berlin, 2000).@footnote 2@ J. E. Sipe, J. F. Young, J. S. Preston, and H. M. van Driel, Phys. Rev. B 27, 1141-1154 (1982).