500GHz Si-based Chip

A research team from IBM and the Georgia Institute of Technology has demonstrated the first silicon-germanium transistor able to operate at frequencies above 500 GHz. This is more than 100 times faster than the fastest PC chips sold today, and about 250 times faster than the typical mobile phone chip. That speed could be achieved when researchers cooled the transistor to minus 451 degrees Fahrenheit. However, the device still ran at 300GHz at room temperature.

Most improvements in chip speeds over the years have come from shrinking the size of transistors. Recently IBM initiated an approach to tweak the silicon at the atomic level. This allows designing transistors from the ground up with very specific applications in mind.

Until now, only integrated circuits fabricated from more costly III-V compound semiconductor materials have achieved such extreme levels of transistor performance. Achieving such extreme speeds in silicon-based technology – which can be manufactured using conventional low-cost techniques – could provide a pathway to high-volume applications.

IBM forecasts that the advances would show up in real products within a couple years, probably in chips to power super-fast wireless networks capable of moving a DVD-quality movie in as little as 5 seconds. Also, ultra-high-frequency silicon-germanium circuits may find potential applications in many communications systems, defense systems, space electronics platforms, and remote sensing systems.

Millenium Prize to Nakamura

Prof. Shuji Nakamura (photo courtsey: Univ. California, Santa Barbara)

Finland's Millenium Prize Foundation said Thursday that its one-million-euro technology prize had been awarded to Shuji Nakamura, a professor at the University of California at Santa Barbara and inventor of the high-brightness gallium nitride light-emitting diode (LED) and a blue laser. In 1993, Prof. Nakamura stunned the optoelectronic community with the announcement of very-bright blue GaN-based light emitting diodes (LEDs). In rapid succession, he then announced a green GaN-based LED, a blue laser diode, and a white LED. All these developments were things that other researchers in the semiconductor field had spent decades trying to do.

LED lights consume much less energy than incandescent lamps and are well-suited to operation with solar power systems and therefore ideal for use in developing countries. A significant future application of Prof Nakamura's invention is the sterilisation of drinking water, for the use of ultraviolet LEDs makes the purification process cheaper and more efficient, improving the lives and health of millions. Further, data storage and transfer using light from blue lasers enables a 5-fold increase in the amount of data stored on compact or digital versatile discs.

Photo: Time Square lit by LED

Prof Nakamuri is to receive the Millenium Technology Prize at a ceremony to be held in Helsinki on 8 November. The biennial prize is awarded for an innovation judged to improve the quality of human life and well-being. In 2004, the first prize was awarded to Tim Berners-Lee, the inventor of the world wide web.

Biography: Born in 1954 in Japan on the island called Shikoku, Prof. Nakamura received his master’s degree in 1979 at the University of Tokushima. He started his scientific and technological career working as an engineer at Nichia Chemical, a small phosphor company in the countryside. At Nichia Chemical’s laboratory, with only a limited budget and modest support from company management, Nakamura developed a highly-original two-flow growth system which led to the successful epitaxial growth of gallium nitride (GaN) in 1989. In 1992 he managed to produce p-type GaN, a fundamental breakthrough in III-V nitride research. Since the beginning of research into GaN almost three decades earlier, no-one had been able to create this particular compound. In 1993 Nakamura demonstrated bright-blue LEDs. Two years later he announced a green GaN-based LED, a blue laser diode, and a white LED. In 1994, Nakamura received his doctorate in engineering at the University of Tokushima. Five years later he left Japan and joined the engineering faculty of the University of California, Santa Barbara (UCSB). At UCSB he has built up a significant research programme in new areas of nitride research.

Seagate's New Drives

Today has been a great day for Seagate Technology as it announced three new 2.5-inch mobile hard drives built on perpendicular recording technology with up to 160GB capacities. The first of the new laptop hard drives (Momentus 5400 PSD) combined flash memory and magnetic storage to reduce power consumption and increase performance, which Microsoft's upcoming Vista operating system will utilize with certain technologies. Seagate's new notebook disc drives will be able to take advantage of breakthrough features in Windows Vista that will benefit customers by delivering faster boot times and longer battery life.

The second drive uses encryption technology to provide on the fly hardware-level security. The Momentus 5400 FDE, or Full Disk Encryption, drive is a 2.5-inch notebook drive which packs in a hardware encryption algorithm for on-the-fly protection of data without any user intervention during the reading and writing process. The drive is packaged and ready to allow the user to enter a password ( or up to 5, if used by multiple users) which allows access to the disk in a laptop. The user will only need to enter the password once during the boot process to "open" the disk's contents.

Rounding out the trio of new drives is the second lineup of 7200RPM models for super-speedy laptops, bringing capacities to 160GB.

Momentus 5400 PSD, Momentus 5400.2 FDE and Momentus 7200.2 are scheduled to ship in the first half of calendar 2007. Seagate's newest notebook hard drives will be available in 40GB to 160GB capacities.

Toshiba 200GB 2.5 inch Hard Drive

Today Japanese electronics giant Toshiba Corporation released a new hard drive that can store 200GB using the recently developed perpendicular magnetic recording technology. In April hard drive manufacturer Seagate caused a stir announcing a new perpendicular drive technology that enabled the production and release of a 750GB hard drive. The new technology enables bits of data to be stored in a perpendicular format rather than longitudinally and, thus enables the magnetic disc to store significantly more data in the same space. Hitachi followed up with the release of its own perpendicular drives in May.

But Toshiba is claiming to have set a storage density record with its 2.5 inch drive system containing only two platters able to store 277.1 megabits per square millimeter, or 178.8 gigabits per square inch, a world record that surpasses the current record, which Toshiba also holds, at 133 gigabits per square inch.

Toshiba plans to start mass production of the hard drive in August 2006. The new technology may play a role in Toshiba's planned digital audio player to be developed in conjunction with Microsoft and Japan's NTT DoCoMo for the Japanese market.

Glowing Nanowires

Photo: Gallium nitride wires growing on a silicon substrate (credit: Lorelle Mansfield/NIST )

Scientists at National Institute of Standards and Technology (NIST) has grown a variety of nanowires and extensively characterized their structural and optical properties and studied defects, strains or impurities, which resulted in high light output compared to the bulk material. NIST is one of few laboratories capable of growing semiconductor nanowires without using metal catalysts. This approach is believed to enhance luminescence and flexibility in crystal design.

A group of researchers at NIST are engaged in growing nanowires made of gallium nitride alloys under high vacuum by depositing atoms layer by layer on a silicon crystal. The wires are generally between 30 and 500 nanometers (nm) in diameter and up to 12 micrometers long. When excited with a laser or electric current, the wires emit an intense glow in the ultraviolet or visible parts of the spectrum, depending on the alloy composition.

A paper in the May 22 issue of Applied Physics Letters reports that individual nanowires grown at NIST produce sufficiently intense light to enable reliable room-temperature measurements of their important characteristics. This will have significant imapct in the world of nanotechnology. Such nanowires can be used to make prototype lasers and light-emitting diodes with emission apertures roughly 100 nm in diameter—about 50 times narrower than conventional counterparts. Nanolight sources may have many applications, including “lab on a chip” devices for identifying chemicals and biological agents, scanning-probe microscope tips for imaging objects smaller than is currently possible, or ultra-precise tools (like sensors and nanoscale mechanical resonators) for laser surgery and electronics manufacturing.

For further details, you may go through the paper we are talking about: J.B. Schlager, N.A. Sanford, K.A. Bertness, J.M. Barker, A. Roshko and P.T. Blanchard. 2006. Polarization-resolved photoluminescence study of individual GaN nanowires grown by catalyst-free MBE. Applied Physics Letters. May 22.