New deposition process makes LEDs brighter

Researchers at North Carolina State University (NCSU) say they have developed a new gallium nitride (GaN) deposition process that purifies high-energy semiconductor materials and reduces defect concentrations by a factor of 1000 relative to typical levels. They predict that LEDs, power transistors and other devices made from GaN process will be able to double their outputs with the new process.

The process, co-invented by electrical engineering professor Salah Bedair and materials science professor Nadia El-Masry, intentionally introduces voids into the GaN layer near its interface with a sapphire substrate. This causes thousands of defects typically present in the semiconductor material to be sucked into the voids.

The GaN film in the tests was around two microns thick with ellipsoidal voids around 0.25 micron in diameter, surrounded by a film with 1000 times fewer defects. Instead of degrading the performance of the film, the voids apparently enabled it to nearly double its output.

According to Bedair, the voids act as sinks for defects and dislocations near the interface, as well as acting as expansion joints for lattice mismatches. Bedair discovered the technique by chance when his graduate student, Pavel Frajtag, complained that nanowires had formed in bulk-grown GaN films formed using a maskless inductively coupled plasma/reactive ion etching technique. Bedair asked to try to eliminate the nanowires by using epitaxial overgrowth, which resulted in the void formation and dislocation trapping effect.

Currently the researchers are working on further characterisation of the material, as well as using the process to fabricate LEDs and other devices order to test its ability to boost the output of GaN devices.


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New ZigBee RF4CE chips launched

GreenPeak Technologies have launched three new chips designed to facilitate the development of robust, low cost ZigBee RF4CE remote control applications for television sets and set-top boxes. All three devices have full RF4CE functionality with embedded ZRC and are targeted at specific applications. The GP520 is a front-panel controller for set-top boxes with SPI/TWI interface, the GP530 is a front-panel controller for television sets with UART interface, and the GP540 is a complete, low-cost remote control on a chip, including an embedded keyboard scanner and full IR functionality.


All devices are optimised for low cost, easy integration, and simple configuration. GreenPeak’s unique ultra low power and synchronisation for remote controls enables operation from a single coin cell battery for ten years or more. It also enables advanced thin remote control designs not requiring a battery lid, and it implements find-me and push functionality.


GreenPeak additionally takes Wi-Fi coexistence a step further. Thanks to superior radio design with antenna diversity, GreenPeak RF4CE chips offer an extra 30 dB of interference immunity for Wi-Fi, Bluetooth and other RF signals. This patented technology uses two separate antennas to avoid typical indoor wave cancellation, which is becoming essential as more and more television sets and set-top boxes are being equipped with wireless network ports.


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Wind-up charger boosts battery life for Android phones

element14, a collaborative social community and electronics store for design engineers and electronics enthusiasts, and modding guru Benjamin J. Heckendorn, a.k.a. Ben Heck, present an action-packed episode of

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Nanotape may oust solder pads

Solder pads in IC packages could soon be made obsolete by a new nanotape material developed by researchers at the Semiconductor Research Corporation (SRC) and Stanford University. Using a sandwich of thermally conductive carbon nanotubes between thin metal foils, the nanotape transfers heat away from chips better than solder, and according to the researchers it is a lightweight, flexible material that is cheaper and more compliant.

Externally, a nanotape pad looks like a conventional solder pad because both the top and bottom are metallic, but internally it harbours the superior thermal conductivity of carbon nanotubes, with heat transfer characteristics similar to those of copper.


Professor Ken Goodson, lead researcher for SRC at Stanford University, said that solder joints are usually made very thick to provide mechanical compliance, but the new nanotape allows solder pads to be replaced by a thin, lightweight material that improves thermal energy management. The tape has a core composed of a vertically aligned carbon nanotube forest, with carefully chosen alloys on the top and bottom that wet the carbon nanotubes and provide thermal contact with the heat sink and the chip.

Initially the material will be fabricated as a direct replacement for solder pads, according to SRC, but its foam-like flexible compliance, which allows it expand and contract together with semiconductor materials in a manner impossible with solder, could form the basis for entirely new semiconductor packaging methods. The researchers predict that early adopters will begin using the nanotape by the end of next year, with mainstream benefits to end users starting around 2014. The SRC-funded nanotape material will be made available to all SRC members.


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Obama gets ‘Sputnik Moment’ wrong by four years

In his State of the Union address, U.S. President Barack Obama called for more federal government investment in R&D, education and transportation at what he dubbed is a "Sputnik moment". Obama is keen to bolster federal R&D spending in "biomedical, IT and especially clean technology" in his 2011 budget to come in a few weeks. Bolstered spending on energy R&D will come from "eliminating the billions we currently give to oil companies," he said.


The President called for putting a million electric vehicles on the road by 2015. Looking farther ahead he challenged the U.S. to get 80 percent of its energy by 2035 from renewable sources including clean coal, wind, solar, nuclear sources.


Obama compared the technological challenges now ahead of his fellow Americans (and the rest of the world) with the late 1950s when the US felt acutely challenged by a softly beeping USSR satellite, calling today

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Digital Photo Keychain: Be smaller, be better, the marvelous keychain phot...

Digital Photo Keychain: Be smaller, be better, the marvelous keychain phot...: "by Sakurako KitsaWhen it comes to electronic gadgets, it seems to be the smaller, the better. Now just make a comparison, small or mini ele..."

ARM releases development environment for Linux platforms

the complete end-to-end software development tool suite for ARM-powered Linux and Android platforms’, ARM Developer Studio 5 (DS-5) features an application and kernel space debugger with trace, a system-wide profiler and performance analyzer, a real-time system simulator, and a compiler, all packaged in a tailored, powerful and user-friendly Eclipse based IDE. According to ARM, the tool suite makes it easy to develop and optimise Linux-based systems for ARM-powered systems, shortens development and testing cycles, and helps engineers create resource-efficient software.


New features in the DS-5 debugger include Linux boot code, kernel and driver debuging with process/thread awareness and module listing. In the Streamline tool, software profiling and performance analysis has been extended to support SMP configurations, native Android applications and libraries, and the additional ARM cores. The configuration database provides out-of-the-box debug support for additional devices and development boards, and the package includes new example software for the BeagleBoard.


DS-5 provides access to coprocessor registers and enables the use of hardware breakpoints and data access watchpoints. It also supports instruction tracing for localising timing-related software bugs and analysing performance-critical code. For debugging kernel-space code, DS-5 provides information on kernel threads, processes and loadable modules. This is complemented by a display of memory-mapped peripheral registers as they appear in the ASSP documentation, eliminating the need to consult device datasheets during driver development.


AMR DS-5 is available in two versions. The DS-5 Application Edition targets application development with a low-cost Ethernet or USB connection to the target, while the DS-5 Linux Edition adds support for platform bring-up, kernel and driver development, with the debug connection to the target provided by a DSTREAM debug and trace unit. Currently supported platforms include Atmel, Freescale, Marvell, NXP, ST, and TI catalogue devices. More devices will be added in future DS-5 releases.
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