Fabrication of Photonic Crystals Using Metal Clusters as Nuclei for Self-formation of Etching Masks
- PDF / 735,274 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 8 Downloads / 231 Views
Fabrication of Photonic Crystals Using Metal Clusters as Nuclei for Self-formation of Etching Masks Tetsuya Tada,Vladimir V. Poborchii1, and Toshihiko Kanayama Joint Research Center for Atom Technology (JRCAT), National Institute for Advanced Interdisciplinary Research, Tsukuba 305-8562, Japan 1 JRCAT-Angstrom Technology Partnership (ATP), Tsukuba, 305-0046, Japan
ABSTRACT We developed a fabrication process of regular arrays of Si nanopillars using self-formation of etching masks with metal clusters as formation nuclei. When Si substrates deposited with metal clusters are subjected to electron cyclotron plasma etching with SF6 at around -130 oC, reaction products in the plasma, SxFy, condense preferentially at the clusters, leading to the self-formation of nanoscale etching masks. As a result, Si pillars, about 10 nm in diameter and 100 nm tall, are formed with remarkably narrow size-distributions when Au clusters of 1-3 nm diameter are used. This method can be easily combined with electron beam lithography technique, which enables us to define pillar positions. Using this process, we have fabricated 2 dimensional photonic crystals (square and triangular lattices of Si nanopillars) with photonic band gaps in the visible and near infrared regions. We measured reflection spectra of the photonic crystals and observed polarization-dependent reflection bands in the wavelength range consistent with theoretical calculations. INTRODUCTION There has been a growing interest in photonic crystals recently. A photonic crystal is an optical analogue of a crystal, where the periodic potential is due to a lattice of dielectric media instead of atoms. Photonic crystals exhibit photonic band gaps (PBGs) in which the propagation of light is forbidden [1], making themselves attractive for the fabrication of numerous optical devices. For example, line defects introduced in photonic crystals confine light propagation through the defects, and work as waveguides capable of lossless bending around sharp corners. The fabrication of two-dimensional (2D) photonic crystals whose PBGs are in the microwave and infrared regions has been reported [2,3]. Since PBGs appear around a wavelength of ~2a (where a is the period of the photonic crystal), the period should be reduced to a few hundred nanometers to obtain photonic crystals with PBGs in the visible region. Recently, we developed a fabrication process of nanostructures using metal clusters as formation nuclei of etching masks; this process enables us to easily fabricate high-aspect-ratio Si nanopillars [4-6]. Using this process, we succeeded in fabricating 2D photonic crystals (square and triangular lattice) with PBGs in the visible and near infrared regions by periodically arranging Si nanopillars [7,8]. In this paper, we present details of the fabrication process and discuss the spectral response of the fabricated photonic crystals. FABRICATION METHOD
D9.43.1
ECR etching with SF6
SZF[
(a)
Si Pillars
SiZF[
Condensates (SxF y etc.)
-130 oC Si substrate
Q P
(b)
Ag Clusters
Fig
Data Loading...
