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. |