Plessey set to make HB-LEDs at UK facility
07 Feb 2012
Historic semiconductor firm acquires GaN-on-silicon technology with
buy-out of Cambridge start-up CamGaN.
GaN-on-silicon LED
Plessey, one of the few remaining semiconductor manufacturers in
the UK, is set to move into production of high-brightness LEDs
based on some highly regarded technology developed at the
University of Cambridge.
The company, which has a 6-inch wafer facility in Plymouth, has
just acquired the Cambridge start-up CamGaN. The deal sees Plessey
gain CamGaN’s intellectual property relating to GaN-on-silicon LED
epiwafer fabrication, while three employees from the start-up will
now work for Plessey.
Derek Rye, Plessey’s marketing manager, told optics.org that it had
been working with the Cambridge team for the past 18 months, and
that Sir Colin Humphreys - the Cambridge professor upon whose
research the GaN-on-silicon technology is based – will continue to
work as a consultant, alongside previous CEO Andrew Lynn.
At this stage, it is not clear exactly what Plessey will sell into
the highly competitive HB-LED market – with Rye saying that
processed wafers, bare die and LED components are all
possibilities.
What is clear is that Plessey is intending to
purchase a number of metal-organic chemical vapor deposition
(MOCVD) reactors to manufacture the epiwafers in significant
volumes at its own fab – rather than outsourcing this part of
the process to a third-party specialist.
Those purchases are being financed by private equity funding that
Plessey has already put in place,
while the company will
continue to use the MOCVD facilities at Cambridge to further
develop the technology in the meantime.
By the end of this year, Plessey is aiming to have produced
GaN-on-silicon LEDs with a white-light efficacy of 150 lumens per
watt – comparable with state-of-the-art performance with
conventional LEDs based on sapphire or silicon carbide substrates.
“It’s a challenging goal, but an achievable goal,” Rye said.
Competitive advantage?
Plessey is by no means the first company to pursue GaN-on-silicon
LEDs.
China's Lattice Power is regarded as the first to have
moved into commercial production with a flip-chipped version of the
technology, while last month Osram Opto Semiconductors said that it
had made some key breakthroughs that would enable it to start
selling silicon-based LEDs within two years, following a
long-standing development partnership with Azzurro
Semiconductors. Osram's white emitters had a quoted efficacy of
127 lm/W and a chip conversion efficiency of nearly 60%.
The competition is likely to get even tougher. At the recent
Photonics West conference, Alois Krost from Germany’s University of
Magdeburg - and head of the research group that spawned Azzurro –
applauded the Osram OS results as “very good”, while adding that
industry giants Philips and Samsung were actively pursuing the
silicon option through their respective Lumileds and LED
subsidiaries.
[update: Feb 8]: Another major HB-LED player, this time Taiwan's
Epistar, has ordered deposition equipment from Veeco to support the
commercial development of GaN-on-silicon epiwafers.
According to Rye, the key advantage of the approach developed at
Cambridge relates to the thickness of the semiconductor layers that
are used to overcome the natural lattice mismatch between the
silicon substrate and the active gallium nitride layers within the
chip structure.
Osram and Azzurro have overcome the mismatch problem through the
use of relatively thick buffer material, for example using multiple
layers of aluminum nitride. Rye says that the Cambridge team has
been able to produce high-quality structures with a much thinner
layer structure – meaning that it can be deposited more quickly and
at lower overall cost.
John Ellis, Plessey’s chief engineer, said: “To date, the biggest
technological challenge preventing the commercialization of
high-brightness LEDs grown on large-area silicon substrates has
been the large lattice mismatch between GaN and silicon.”
“Plessey’s new GaN-on-silicon process has overcome this challenge
and our expertise combined with the intrinsic cost savings of using
automated 6-inch processing equipment will position Plessey’s
HB-LED lighting products at the forefront of the industry.”
Cost curve
While some in the LED industry regard the switch to silicon
substrates as a necessary evolution of the technology in order to
enable the kind of low-cost, high-volume manufacturing of
high-performance devices needed for general lighting applications,
not everybody agrees.
Huge cost reductions have already been achieved through advances in
volume manufacturing on sapphire and SiC substrates, and leading
LED companies including Samsung, Cree, Osram OS and Philips
Lumileds are already in the process of migrating their production
to the 6-inch format.
Additionally, the emergence of several well-funded manufacturers in
first Korea and then China in recent years – initially to target
the market for LED-backlit LCD televisions – has flooded the market
with white emitters and pushed down the average selling price of
the devices across the board. The past year has been a particularly
tough one for western LED makers, who have seen their margins
slashed.
Even so, LED-based replacements for conventional bulbs remain an
expensive option. Commenting in a University of Cambridge statement
on the CamGaN/Plessey deal, Humphreys said: “LED light bulbs
currently cost as much as £40, but we expect to be able to reduce
that cost by a factor of five by growing on silicon.”
In fact, the cost of LED-based replacement bulbs is also falling
fast, meaning that Plessey will be faced with a similarly
fast-moving target to beat. Analyst firm IMS Research reported last
October that the global average retail price of a 60 W incandescent
replacement was $36 – although that figure masked a wide variation
in which prices in Germany were upwards of $70 but in Taiwan were
less than $20.
And the existing substrate technologies appear to have the headroom
for further significant cost reductions. Also speaking at Photonics
West, Lumileds’ R&D manager Jyoti Bhardwa told an industry
panel session that he expected white-light efficacies to double in
the next two years, while a similar level of cost reduction would
see LED replacements on sale for just $5.
One company to back up that theory is GT Advanced Technologies, one
of the key suppliers of equipment for sapphire boule manufacturing
– the raw material from which sapphire substrates are produced –
through its Crystal Systems subsidiary.
GT told optics.org that it believed the real battleground between
sapphire and silicon substrates for LED production would be fought
out when the industry transitions to 8-inch wafer sizes, and that
it was making good progress on sapphire at the larger size.
• One of the oldest names in the semiconductor industry, Plessey
Semiconductors was founded in 1957 – the same year that it produced
one of the earliest integrated circuits. During World War II, its
parent company began research at the influential Caswell campus in
central England, where Oclaro now manufactures semiconductor lasers
for optical telecommunications.
After several subsequent mergers and acquisitions, the Plessey name
all but disappeared – before a management buy-out in early 2010 saw
it re-emerge under the guise of the privately-owned Plessey
Semiconductors Ltd.
Aixtrons UK office ist ganz in der Nähe von Cambridge und ich
vermute man forscht in Cambridge mit AIX equipment. Die Chancen
dass man dann die MOCVD Reaktoren auch dort kauft sind m.E.
groß.
Lattice Power: Aixtron Kunde
Azurro der Partner von Osram (long-standing development partnership
with Azzurro Semiconductors) bei der GaN on Silicon ist ebenfalls
Aixtron Kunde.
Scheint mir so als ob Aixtron bei der Entwicklung dieses neuen LED
Herstellungverfahrens ganz weit vorne mitspielt.
Gruß
baggo-mh
