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S U S T A I N A B I L I T Y
R E S E A R C H @ H K U S
opment of GaN-based LEDs at the early
stage, improving the efficiency, stability,
as well as packaging designs, benefitting
LED performance and consumer per-
ceptions on the capabilities of LEDs as a
lighting source.
Lighting takesup to15%of the total power
consumption globally, according to the
enlighten initiative.
*
Demand for lighting
will only increase in future years.
Light-emitting diodes, or LEDs, offer
an energy-efficient solution to lighting.
Compared to the legacy
incandescent and fluo-
rescent lights, LEDs con-
sume significantly less
power and also enjoy a
much longer lifetime,
upward of 50,000 hours.
Unlike fluorescent lights,
they are non-hazardous
as they do not use
mercury. Given all these
benefits, LEDs are in-
creasingly being used in
general indoor and out-
door lighting, following
successful applications
such as backlighting LCD televisions,
headlights for automobiles, and large-
area billboards.
Today, global LED adoption in general
lighting is still relatively small mainly be-
cause LED lights are expensive in terms of
the initial cost compared to incandescent
and fluorescent lights. Up to now that
cost factor appears to have played a more
significant role in decision-making than
benefits to the environment, said Prof Kei
May Lau, Chair Professor of Electronic
and Computer Engineering. Reliability
issues of products on the market made by
manufacturers cutting corners for lower
cost at the expense of good design are
another factor.
An expert in semiconductor materials
and devices, Prof Lau set up the Univer-
sity’s Photonics Technology Center in
2001 to advance LED research. She also
coined the term “ecotronics” to describe
the economically affordable and environ-
mentally friendly electronic technologies,
such as LEDs, that she and her colleagues
have been developing. Her work is based
around compound semiconductors (GaN,
GaAs, InP) and optimization of optoelec-
tronic technologies to assist the devel-
and her research team developed inno-
vative device design to make the actual
LED system more user-friendly. This
involved “a delicate balance of optical
science, materials science, thermal
science and electronics,” explained Prof
Lau, who was recently
awarded a large-scale
Theme-based Research
Scheme project, sup-
ported by Hong Kong
Research Grants Council,
to further advance LED-
based lighting tech-
nologies.
The licensed tech-
nologies developed by
Prof Lau’s team will
likely open up new
applications, improve
reliability and lower man-
ufacturing costs through
integration of LEDs on silicon wafers.
Among novel applications, the first LEDoS
(GaN-LED on silicon) active micro-displays
were successfully demonstrated in 2013,
namelya0.19inch,1,700pixelperinchpas-
sivematrix LEDoSmicro-display and a high
resolution 400 x 240 active-matrix micro-
display. Applications include projectors
and head-up displays, which allow users
to read data without moving their head
as required in vehicles today. Advantages
include visibility under bright day-
light, power efficiency, thermal stability,
longer lifespan and robustness under
harsh conditions.
PROF KEI MAY LAU
Fang Professor of Engineering
A BRIGHTER FUTURE
Light emitting diode on silicon (LEDoS) micro-displays
IEEE/OSA Journal of Display Technology, Vol.9, Issue 8, 2013
* United Nations Environment Programme
(UNEP)-Global Environment Facility (GEF),
One watt saved is more than
one watt created
The HKUST research team is one
of the leading groups worldwide in its
focus on integrating ICs and LEDs. Using
silicon integrated circuit technologies in
conjunction with LED lighting, Prof Lau
