News & Events
Nanostructured thin films using oblique angle deposition: synthesis, optical properties and applications
Dr. Andrew Sarangan, University of Dayton
Thursday, February 14, 2013
3:30 p.m.4:30 p.m.
Sloan Auditorium
Abstract:
Oblique angle deposition
(OAD) is an inexpensive and scalable method for fabricating nanostructured thin
films. In this technique the vapor atoms are made to condense and nucleate on
the substrate at a glancing angle. The self-shadowing effect of each nucleated site
results in the evolution of a columnar morphology with 5-10nm diameters. A
variety of metals and dielectrics have been grown using this method, and have
shown significantly different optical and electrical properties than their bulk
counterpart, such as SiO2 films with ultra-low refractive indices. Due
to the growing interest in nano-plasmonic and SERS sensing applications,
Silver, Copper, and Gold nanostructures have been of even greater interest.
Unfortunately, these soft metals have been difficult to sculpt using the OAD
technique, partly due to the increased surface mobility of these atoms on
common substrate like silicon or glass. We have recently developed a technique
for growing soft metal nanostructures with extremely high aspect ratios. This
is based on cryogenically cooling the substrate during the growth to reduce the
surface mobility. The SERS signal from these films has also been found to be
significantly higher than comparable silver-enhanced substrates. In this talk,
I will describe the basic principles of OAD film fabrication, their optical
dispersion and polarization properties, and their applications in sensing
platforms.
Bio:
Andrew Sarangan is a
Professor and Associate Director of the Electro-Optics Graduate Program at the
University of Dayton, Ohio. He received his BASc and PhD degrees from the
University of Waterloo in Canada in 1991 and 1997 respectively. His research areas
are in infrared photodetector technologies, polarimetric imaging,
nanofabrication, nano-structured thin films and computational electromagnetics.
At Dayton he founded the nano-fabrication laboratory for optical thin films, interference
lithography and semiconductor processing. He has developed optical computational
tools including BPM, FDTD and integrated optical waveguide simulation. He regularly
teaches a short course on nanophotonics at the OSA Frontiers in Optics
conference.
Previously, Andrew was a research faculty at the
University of New Mexico. He also spent several years as a Research Scientist
at Nortel Networks where he developed a novel architecture for multi-wavelength
DFB lasers.