22 - Development based of photonic crystals on nanoparticle assembly

Abstract

This chapter presents a method of developing photonic crystals based on nanoparticle assembly by using a micromanipulator under the observation of a scanning electron microscope (SEM). Photonic crystals are a new type of optical material, in which small dielectric cells with the size of optical wavelength from several 100 nm to several 10 μm are periodically arranged in two or three dimensions. These crystals are expected to contribute to the drastic improvement of the performances of lasers and to the miniaturization of integrated optical circuits. An actual nanoparticle assembly system is presented, which is comprised of a field-emission-type SEM coupled with a piezoelectric micromanipulator. The manipulator is maneuvered by an operator with joysticks while observing a real-time SEM image with a magnification from 5,000 to several tens of thousands, and micro objects are stuck to a tip of a probe (needle) and then transferred. The nanoparticle assembly technique under SEM observation is able to produce completely controlled precise three-dimensional structures and helps in the trial fabrication of new crystals for verifying theoretical predictions, for investigation of underlying physics based on systematic experiments, and for exploring a novel phenomenon. The fundamental principle of the nanoparticle assembly technique is the adhesion phenomenon between the nanoparticles and other particles, the probe, or the substrate. A bcc lattice made of silica and polystyrene spheres with a diameter of 1.18 μm is presented, which when exposed to oxygen plasma, decomposes the polystyrene spheres only.