NEC and NEC Electronics Develop High Threshold Voltage Control Gallium Nitride (GaN) Power Transistor on a Silicon (Si) Substrate

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NEC and NEC Electronics Develop High Threshold Voltage Control
Gallium Nitride (GaN) Power Transistor on a Silicon (Si) Substrate


New Delhi, December 11, 2009:

NEC Corporation (NEC) and NEC Electronics

Corporation (NECEL)
today announced the development of a nitride semiconductor (*1) power transistor on a silicon
(Si) substrate that

has improved the control and suppression of electrical currents
when

electrical

power is turned off (normally
-
off characteristics (*2)),

a necessary feature for
the safe operation of consumer electronics and IT devices. The transistor features a new
structure for the layer

beneath the gate electrode, which improves the controllabilit
y
of

threshold voltage that intercepts electrical currents and enables the realization of low
-
power
losses, high speed switching and high

temperature operations.

Power transistors that use silicon semiconductors occupy an

important role in the advancement

of energy conserving machines, as

they convert electrical power and serve as a controlling
element for a

wide range of applications, from consumer electronics to industrial

machinery.
Future expectati ons are high for the implementation of

Nitride semicond
uctor transistors,
which demonstrate lower
-
level

losses, higher speeds and higher temperature operations when
compared to current silicon transistors. However, it is important to suppress

variations of
threshold voltage and improve reproducibility of their

normally
-
off characteristics.

Current transistors are composed of a two
-
layer structure that

consists of an AlGaN electron
supply layer and GaN channel layer. A

great deal of variation in threshold voltage occurs due to
differences in the thickness of the

AlGaN electron supply layer under the gate,

which is etched
down to a few nm from 20
-
30 nm to achieve normally
-
off

characteristics. A high precision
etching process is specifically

required in order to reduce the variation of threshold voltage
and

stabili
ze normally
-
off characteristics.

A five layer structure makes it possible for these new transistors to control threshold voltage
with a high degree of precision by reducing the threshold voltage's dependence on the
thickness of the electron

supply layer. T
his is accomplished by introducing an electric charge
neutralization layer, the "piezo" neutralization layer, within the

electron supply layer, while at
the same time i ntroducing a buffer

layer, located beneath the channel layer, with the same
composition
as

the piezo neutralization layer. This structure enables uniform

manufacturing of
nitride semiconductor power transistors that realize normally
-
off characteristics at a low cost.
These transistors also

exhibit excellent performance such as low power loss
and
high

breakdown voltage.


Looking forward, NEC and NEC Electronics aim to accelerate research

and development
towards the design, evaluation and implementation of


nitri de semiconductor power
transistors.

NEC will present transistor results at the Intern
ational Electron

Devices Meeting (IEDM) held in
Baltimore from December 7, 2009

(announcement on December 7).

(*1) Nitride Semiconductor: Semiconductors composed of Gallium nitride (GaN)/aluminum
nitride gallium (AlGaN) that have bandgaps larger than 3.4eV
. These promising devices feature
high breakdown field strength and high electron mobility, as well as components that

produce
high power output and resist high temperatures and

voltage. Th ese semiconductors are widely
used by Blue LED

materials that capi
talize on large bandgaps.

(*2) Normally
-
Off Characteristics: Characteristics that block

electrical currents when voltage is
not applied to a transistor. This is necessary for the safe operation of machinery and tools.

About NEC Corporation

NEC Corporati
on is one of the world's leading providers of Internet, broadband network and enterprise
business solutions dedicated to meeting the specialized needs of a diversified global base of customers.
NEC delivers tailored solutions in the key fields of computer,

networking and electron devices, by
integrating its technical strengths in IT and Networks, and by providing advanced semiconductor
solutions through

NEC Electronics Corporation. The NEC Group employs more than 140,000

people
worldwide. For additional inf
ormation, please visit the NEC

website at:
http://www.nec.com
.

About NEC Electronics

NEC Electronics Corporation (TSE: 6723) specializes in semiconductor

products encompassing advanced
technology solutions for the high
-
en
d

computing and broadband networking markets; system solutions
for the

mobile handset, PC peripheral, automotive and digital consumer markets; and multi
-
market
solutions for a wide range of customer

applications. NEC Electronics Corporation has subsidiarie
s
worldwide

including NEC Electronics America, Inc. and NEC Electronics (Europe)

GmbH. More information
about NEC Electronics worldwide can be found at
www.necel.com
.

NEC is a registered trademark of NEC Corporation.
NEC Electronics is a

registered trademark or trademark of NEC Electronics
Corporation in Japan and/or other countries. All Rights Reserved. Other product or

service marks mentioned herein are the
trademarks of their respective owners. ©2009 NEC Corporation

.
Press Contacts:

Swati Srivastava

Perfect Relations

Tel : 9810616405

swatis@perfectrelations.com