Nanoscale Dots, Grids, Ripples, and Hierarchical Structures on PET by UV Laser Processing
Sprache des Titels:
Englisch
Original Kurzfassung:
Nanostructures can be produced on poly(ethylene terephthalate) (PET) foils by using a
krypton fluoride (KrF) excimer laser with a wavelength of 248 nm and a pulse duration of about 20 ns.
We show that surface nanoripples, nanodots, nanogrids, and hybrid patterns of ripples with dots or
finer ripples on top can be fabricated. The effects of a water layer in front of the PET foil and of cooling
during laser processing were investigated. For pattern formation, several irradiation parameters
(pulse number, pulse energy, and polarization) were varied systematically. The spatial periods of
the ripples were changed by adjusting the angle of incidence of the laser beam. All nanostructures
were characterized by scanning electron microscopy, and relevant morphological parameters, such as
peak-to-peak distances and spatial periods, were assessed. Shapes and heights of some structures
were characterized by using focused ion beam cuts to avoid the tip-sample convolution effects typical
of atomic force microscopy images. We further demonstrate nanoripple formation on PET foils as
thin as 12 ?m, 6 ?m, and 1.4 ?m. The remarkable variety of nanostructures on PET we present here
enables customized fabrication for a wide range of applications.