| Nanoelectronics for
Innovation
Nanotechnology Making Dreams
Come True
ARINOBU Mutsuhiro
Expectations for Nanoelectronics
Technologies toward Ubiquitous Network Society
ISHIKAWA Masayuki / HIRAOKA Toshiro
Performance improvement along a road map is driving the development
of electronics technologies. However, it is predicted that the road
map of electronics technologies will encounter technological limits.
New developments in electronics technologies due to the limits of
the road map and the wide array of needs in the ubiquitous network
society are therefore expected. Electronics technologies will develop
in two directions in this context: toward surpassing the limits
of the road map on the one hand, and toward adding or changing the
value axis on the other. A wide diversity of innovations by revolutionary
nanotechnologies will appear due to these developments around 2010-2020.
New Batteries Using
Nanomaterial Electrodes
TAKAMI Norio / INAGAKI Hiroki / MORITA Tomokazu
Lithium-ion batteries have been developed to enhance capacity, power,
cycle life, and fast-charging performance for many applications
such as mobile devices, automobiles, and various industrial sectors.
New materials for lithium-ion batteries have been researched to
achieve the high performance required for new applications.
Toshiba has developed new types of lithium-ion batteries using nanomaterials
as the negative electrode. The use of nano silicon and carbon composites
as a high-capacity negative electrode resulted in double the discharge
capacity compared to conventional carbon electrodes and good cyclability,
indicating the possibility of realizing lithium-ion batteries with
higher capacity. For the development of fast-charging batteries,
a new negative electrode consisting of a nanoparticle material exhibited
the rapid insertion of lithium ions without decomposition of the
electrolyte. A prototype fast-charging battery demonstrated 60 times
faster charging than conventional lithium-ion batteries. This fast-charging
battery technology not only offers the advantage of rapid charging,
but also effective saving and reuse of energy.
MOSFETs Fabricated
on Ultrathin Silicon-on-Insulator Film
UCHIDA Ken / KOGA Junji
Metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated
on ultrathin silicon-on-insulator (SOI) films show promise as transistors
in future large-scale integrated circuits (LSIs).
Toshiba has successfully fabricated and operated ultrathin SOI MOSFETs
with an SOI film thickness of less than 1 nm, for the first time.
In addition, we have found that quantum mechanical effects have
a significant impact on transistor operations.
Ultrasmall Random
Number Generator
TANAMOTO Tetsufumi / OHBA Ryuji / FUJITA Shinobu
As the demand for information security becomes increasingly severe,
higher level random number generators, which are one of the fundamental
information technologies, are also required every year. Because
the unpredictability of a random number is closely relevant to the
basis of information security, significantly stricter statistical
tests of commercial random numbers have been adopted in recent years.
Toshiba has developed an ultrasmall random number generation circuit
that can generate high-quality and high-speed random numbers. This
was achieved by the development of nano-scale Si devices.
CPP Spin-Valve Films
with Current-Confined-Path Nano-oxide Layer
FUKUZAWA Hideaki / YUASA Hiromi / IWASAKI Hitoshi
Demand has recently arisen for new reader heads with high sensitivity
for use in hard disk drives (HDDs), in order to realize high-areal-density
recording. Since such high-density recording cannot be achieved
by improvement of the conventional technology, spin-valve films
with high sensitivity and new functionality are required.
Toshiba has successfully developed new spin-valve films having a
special nanostructure. A significant increase in sensitivity has
been achieved by inserting a nano-oxide layer (NOL) in the spin-valve
film, with the NOL being mainly composed of an insulator material
having nano-size current-confined paths that punch through the insulator
layer.
Nanopatterned Media
SAKURAI Masatoshi / KIMURA Kaori / HIEDA Hiroyuki
The areal recording density of hard disk drives (HDDs) has increased
over the years and reached a very high level today. In order to
maintain this high growth in recording density in the future, it
is necessary to overcome the media noise problem.
Toshiba has developed nanopatterned media with uniform magnetic
dot size, the areal recording density of which can exceed a terabit
(1012 bits) per square inch. All magnetic
dots in the nanopatterned media are accurately placed in position
by an artificially assisted self-assembly method.
RF-MEMS Devices
ITAYA Kazuhiko / KAWAKUBO Takashi
Wireless communication systems have undergone a remarkable evolution
to realize a comfortable ubiquitous society. With the constant demand
for higher communication speeds and seamless connection, however,
the increase of components in personal terminals, especially passive
devices, is becoming a serious problem. In this situation, radio-frequency
microelectromechanical systems (RF-MEMS) technology has recently
been attracting considerable attention.
Toshiba has developed a technology for atomic-order control of orientation
in thin-film piezoelectric materials, which has been adapted to
RF-MEMS devices such as filters and tunable capacitors. This process
technology is compatible with LSI processes, and both miniaturization
and high performance have been realized. This technology will make
possible the further miniaturization of next-generation wireless
terminals with, for example, passive devices and an LSI in one chip.
Semiconductor Nanotechnology
for Quantum Photonics
Andrew Shields
Toshiba is making progress toward developing a nanotechnology for
the generation and detection of quantum light states using self-assembled
semiconductor quantum dots. Previously we demonstrated that a single
quantum dot placed within a conventional semiconductor light-emitting
diode (LED) acts as a single photon source. It is shown here that
the quantum dot growth can be manipulated to achieve an emission
wavelength compatible with transmission over optical fiber. Incorporation
of a cavity into the LED structure leads to a tenfold increase in
the single photon generation efficiency, and electrical control
of the carrier dynamics has been used to achieve repetition rates
as high as 1 GHz. Quantum dot devices are also demonstrated to be
efficient detectors of single photons.
Nanoarchitectures
Based on Post-Silicon Devices
FUJITA Shinobu / NOMURA Kumiko / ABE Keiko
As silicon complementary metal-oxide semiconductor (Si-CMOS) technology
reaches its limits in the coming 10 years, it is expected to be
replaced by post-silicon devices such as transistors using carbon
nanotubes or nanowires. To continue increasing the performance of
integrated circuits, new architectures suitable for these post-silicon
devices are necessary. Such "nanoarchitectures" must be
constructed based on three-dimensional circuits, with both the device
resources and bandwidth increased by means of three-dimensional
stacking. Mechanical switching nanodevices are also a promising
candidate for three-dimensionally fabricated post-silicon devices.
Spin-Electronics Devices
and Magnetic Switching Technique
NAKAMURA Shiho / SAITO Yoshiaki / MORISE Hirofumi
Spin-electronics devices utilize the spin degree of freedom in addition
to the charge degree of freedom and the nonvolatile property of
magnetic materials.
To realize ultralow power consumption and new functions, Toshiba
has developed a current-induced magnetic switching technique as
a fundamental technique for such devices, and lowered the switching-current
density to 1 x 106 A/cm2
by introducing new device structures. This technique is expected
to lead to the realization of new devices including spin memories
and logic devices, which will form the basis of the advanced ubiquitous
society.
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