Morphology and photonic band structure modification of polystyrene particle layers by reactive ion etching

Abstract

Morphology of self-assembled polystyrene particle layers has been modified by reactive ion etching. The etched layers have two-dimensional periodic structures in submicron scale, the period of which is determined by the initial size of the particles, and the shape of the etched particles has been gradually changed to a thinner ellipsoid depending on the etching time. Resonant phenomenon between incident light and electromagnetic eigenmodes of the photonic band of the etched layers has been observed in transmission measurement. The resonant frequencies have gradually shifted according to the etching time, i.e., the photonic band structure of the layers has been successfully modified. Various kinds of applications can be expected due to the electromagnetic resonant phenomenon and the characteristic surface structure of the layers.

Band-gap properties of two-dimensional low-index photonic crystals

“…These results can naturally be compared with the bandgap spectra of the two-dimensional structures created by circular holes (see below). In a full agreement with the previous studies [13] and recent fabricated devices [14], we observe that for the case of dielectric rods in air a deviation of the cylinders from a circular symmetry produces a reduction of the relative size of the bandgaps. The similar effect is produced by the rod rotation, so that larger values of the photonic band gap are observed for the ellipses with smaller or no rotation (dotted curve in Fig.…”

Modification of photonic band structure in an ordered polystyrene particle layer by controlling interparticle light-mode interaction

“…In this experiment, the initial LATEX diameter D before etching is 527 nm, and therefore, the interparticle distance d is fixed at 527 nm.In order to modify the diameter of the particles, the LATEX layer has been etched by oxygen RIE method as reported in Ref. [4]. The etching time increased by every 30 s and the maximum time is 150 s, where the particle size is reduced to about 70% of the non-etched sample measured from the top view of the SEM image.…”

“…Recently, we have studied optical properties of self-assembled, hexagonally close-packed monolayers of polystyrene particles (LATEX) with diameter similar to the visible wavelength and found quasi-two-dimensional PB structures formed by ''Mie resonance modes'' in these materials [3]. In our previous work, when the particle size is reduced without changing the interparticle distance by reactive ion etching method (RIE), the PB structures have been found to be strongly modified [4]. In this paper, we report more precise correlation between the PB structures and the ratio of the particle diameter to the interparticle distance and discuss about the validity of the tight binding model.…”

Unconventional methods for forming nanopatterns

“…In a representative application of NSL, RIE was used to reduce the dimensions of the nanospheres, yielding hole arrays with the same pitch, but different effective diameters depending upon the etch time [138,[697][698][699]. The pitch or period of the resulting array is determined by the initial diameter of the PS bead used.…”