Abstract
Ordered arrays of colloidal submicrometer-sized silica particles deposited onto silicon wafers were irradiated with MeV Si ions. The spherical silica particles turned into oblate particles as a result of the increase of the particle dimension perpendicular to the ion beam direction and the decrease in the parallel direction. Pulsed laser photoacoustic spectroscopy was used to study the structural changes of the silica particles after the ion-induced shape deformation. Our purpose is to correlate the mechanical vibrations generated by the pulsed laser as a function of the Si irradiation parameters: ion energy and fluence. Fast Fourier transform analysis of the photoacoustic signal was carried out in order to obtain the normal vibration modes of the system. The size, size distribution and shape of the silica particles were determined by scanning electron microscopy. Our results revealed significant structural differences between the spherical and the deformed silica particles.
Highlights
Periodic arrays of colloidal silica particles are very attractive because of their potential applications in coating technology, optoelectronic/plasmonics devices, and nanolithography [1,2]
The as-prepared samples consisted of ~520 nm diameter colloidal silica particles deposited onto a Si(100) substrate, arranged in a continuous and homogeneous monolayer, forming a 2-D hexagonally-ordered structure
One can observe that the spherical silica particles experimented extreme deformations under exposure to MeV Si ions at room temperature, and turned into oblate ellipsoids as a result of the increase of the particle dimension perpendicular to the ion beam and the decrease in the direction parallel to the ion beam [6,7]
Summary
Periodic arrays of colloidal silica particles are very attractive because of their potential applications in coating technology, optoelectronic/plasmonics devices, and nanolithography [1,2]. The properties of these arrays of SiO2 particles depend on their shape, size and spatial distribution, which in turn determine the different roles they can play as electronic substrates, thin film substrates, electrical and thermal insulators, photonic band gap crystals, masks for lithographic patterning, etc. The mechanical or elastic properties of these structures are poorly studied It seems that the mechanical characteristics of these deformed silica particles are size-dependent, and shape dependent. One of the aims of the present work is to study the structural changes induced by the ion irradiation on these silica particles as a function of the irradiation parameters (ion energy and fluence)
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