Porous and nanocrystalline silicon exhibit strong

Interest Group: Australian Optical Society/ Condensed Matter Physics
Silicon Nanocrystal Photonics: Luminescence, Waveguides and Microcavities
Robert. G. ELLIMAN, Nat. SMITH, Marc SPOONER and Tim WALSH
Department of Electronic Materials Engineering, Research School of Physical Sciences and
Engineering, Australian National University, Canberra, ACT 0200, Australia
Presenting Author
Telephone: (02) 6125 0521
Facsimile: (02) 6125 0511
Email: Rob.Elliman@anu.edu.au
Presntation: Poster
Porous and nanocrystalline silicon exhibit strong room-temperature luminescence as a
consequence of quantum and spatial confinement effects. This paper reports on the
optical properties of silicon nanocrystals embedded in SiO2 thin films, and on the
properties of novel structures that exploit this effect, including optical microcavities
and waveguides.
Nanocrystals were formed within SiO2 layers by the precipitation of excess silicon,
which was introduced into the SiO2 either by ion-implantation or during deposition of
thin layers SiO2 layers by plasma-enhanced chemical vapour deposition (PECVD).
Precipitation was achieved by annealing at 1100oC for 1 hr which produced
nanocrystals with an average diameter of ~3nm. The resulting high refractive index
(n ~ 0.3) layer is shown to act as an effective low-loss waveguide, making it suitable
for the fabrication of planar waveguide devices, such as optical amplifiers. The effect
of a microcavity structure on the nanocrystal emission is also reported. Microcavities
were constructed by enclosing the nanocrystal-containing layer between Bragg
mirrors made by PECVD of alternate low (SiO2) and high (Si3N4 or Si-rich SiO2)
refractive index layers. Results show that this is a very effective way of tuning the
nanocrystal emission.