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Abstract: |
We overview our work in controlled patterned
nanostructure formation and dependence MOCVD growth parameters.
Our patterned quantum dot (PQDs) are formed atop the (001) apex
of a GaAs pyramidal buffer to achieve sufficiently small growth
platform for quantized carrier confinement and to separate the
recombination region from the processed interface. The GaAs
pyramids are characterized by well-defined equilibrium crystal
shapes (ECS) defined by three crystal plane families including
{11n}, {10n} and (001). Subsequent patterned QD (PQD)
nucleation on the GaAs pyramidal facets is highly preferential
towards the (11n) planes due to superior energy minimization and
the shape of the QDs on the (11n) planes is also highly
predictable and uniform. The GaAs pyramid formation strongly
correlates to the pyramidal shape and to the subsequent PQD PL
characteristics. The wavelength of the patterned In(Ga)As QDs
can be controlled and ranges from 950 nm to as long as 1.6 μm.
Several aspects to be discussed are the effects of
crystallographic structure measured using photoluminescence and
SEM. By controlling crystal faceting, we are able to form
coupled quantum clusters along with truly isolated QDs. This
initial work correlates the basic PQD characteristics to the
GaAs pyramidal buffer formation. Our ongoing studies include
time resolved photoluminescence and photo-excitation
luminescence studies to further elucidate band-structure.
Planarization and overgrowth for room temperature light emitting
diodes will also be described. |
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Bio: |
Professor Diana Huffaker
received her Ph.D. in Electrical Engineering from the University
of Texas at Austin with dissertation studies focused on vertical
cavity microlasers and other quantum dot devices.
Prior to joining the University of California at
Los Angeles, she was Associate Professor of Electrical
Engineering at the Univeresity of New Mexico at the Center for
High Technology Materials. She has also served as Senior
Research Scientist at Picolight Incorporated in Boulder, CO. Her
research interests include directed and self-assembled
nanostructure solid-state epitaxy, optoelectronic devices for
energy and biosensing applications with special emphasis in
III-V/Si photonics. Professor Huffaker has co-authored over 120
refereed journal publications, 2 awarded patents with 8
disclosures pending, 2 book chapters and has reported her work
through many invited presentations. She has been awarded the
2002 Compound Semiconductor International Symposium Young
Scientist Award for developments in novel quantum dot and
selectively oxidized optoelectronic materials and devices
including the first oxide-confined VCSEL and the first 1.3 mm
self-organized quantum dot laser. She recently received the
2004 Alexander von Humboldt research fellowship to study (In)GaN
quantum dot light emitters at Technical University Berlin. She
is an active participant in the technical community with
appointments in IEEE/LEOS, SPIE, WISE, MRS, OSA and TMS. She is
an elected member of the IEEE/LEOS Board of Governors and IEEE
WIE Region 6 chairman. |