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TOPIC-1 |
GaN Nanostructures Growth for Optoelectronic
Applications
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SPEAKER |
Mr.
Wee Qixun
(PhD student), Singapore-MIT
Alliance SMA and COE, ECE, NUS. |
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DATE |
14 July 2009 (Tuesday) |
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TIME |
2 : 00 pm to 2 : 30 pm |
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VENUE |
Executive Seminar Room E5-02-32 |
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SYNOPSIS |
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GaN and its compounds are revolutionary
materials for blue (and white) LEDs because of
their remarkable physical and chemical
properties. On top of that, no other
semiconductor is capable of producing short
wavelength light, while being commercially
viable.
However, GaN are plagued with dislocations,
together with poor light extraction. These are
due to the lack of suitable substrate and its
relatively high refractive index.
If nanorod array with high periodicity is
successfully fabricated, then the photonic
crystal effect could be derived and improve the
light extraction efficiency of an LED.
One of the nanorod array fabrication methods
which using porous anodized aluminum oxide (AAO)
as a template will be discussed. And the method
to increase the performance will also be
discussed.
In this seminar, the main focus will be
implementing nanostrutures/array and introduce
them into this current technology of making LEDs.
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BIOGRAPHY
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Mr.
Wee Qixun
received his B.Eng. in Bioengineering from
the Nanyang Technological University (NTU) in
2007 and M.Eng. in Materials Science and
Engineering from Massachusetts Institute of
Technology (MIT) in 2008. He is currently
pursuing his Ph.D. in SMA, under Advanced
Materials for Micro- and Nano-Systems (AMMNS)
program.
His research interest is mainly on
low-dimensional structures of compound
Semiconductors for optoelectronic applications.
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TOPIC-2 |
ZnO nanotube arrays by atomic layer deposition
towards solid-state lighting |
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SPEAKER |
Ms
Wang Miao
(PhD student), Singapore-MIT
Alliance SMA and COE, ECE, NUS. |
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DATE |
14 July 2009 (Tuesday) |
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TIME |
2:30 pm to 3:15 pm |
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VENUE |
Executive Seminar Room E5-02-32 |
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SYNOPSIS |
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ZnO is an attractive compound semiconductor with
a direct energy band gap of 3.37 eV and exciton
bonding energy of 60 meV. Among various
approaches to synthesize ZnO nano-structures ,
Atomic layer deposition (ALD) is a self-limiting
gas-phase thin film deposition method enabling
growth of uniform thin films or nanostructures
with precisely thickness control to atomic
level.
In this seminar, ZnO nanotube arrays which
successfully deposited by ALD on Si substrates
using anodic aluminum oxide (AAO) as templates
using the zinc precursor diethylzinc (DEZ) and
the oxygen precursor (H2O) are pulsed
alternately into the deposition chamber using
nitrogen as a carrier gas. Each cycle is
separated by nitrogen gas purges will be
reported.
The photoluminescence emission intensity of ZnO
nanotubes was enhanced by 30 times comparing to
that of ZnO films and this 1D nanostructure is
very promising in the application of solid-state
lighting because of its surface area increase
and quantum confinement effect.
The morphology, optical properties and
crystallinity of the nanotubes were analyzed and
will be presented.
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BIOGRAPHY
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Ms Wang Miao obtained her Bachelor and Master
degree in the
School
of
Mechanical Engineering
from Tianjin University, Tianjin, China in the
year of 1999 and 2002, respectively. After
working with Motorola electronic Ltd Co, China.
as an engineer for 3 years, she joined
Singapore-MIT Alliance to pursue her PhD degree
in Advanced Materials for Micro-and Nano-
System. Her current research interest is on ZnO
nanostructure fabrication and characterization.
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