Magazine – June 2009
III-V industry stocks reach bottom?
The NASDAQ stock exchange has lost 40% of its value in the last 12 months, and the shares of most III-V players have fared worse. Well chosen acquisitions and manufacturing efficiency separate the winners and losers, finds Andy Extance.
China's LED production begins to fulfill domestic demands
As recent as 2002, China imported all of its LED chips. It is now meeting half of this demand with domestic production and making the transition from incandescents to solid-state lighting. Richard Stevenson catches up with progress.
Unsettled outlook hangs over CPV
Typically based on III-V solar cells, concentrated photovoltaics has the potential to be a fantastic source of renewable energy. But in a world where private finance has all but disappeared, Michael Hatcher wonders whether this fledgling industry has a future.
Epistar's chips plug and play
Conventional LEDs that are used for solid-state lighting have to be connected to an AC-to-DC converter. But this bulky power supply impacts efficiency and reliability, and can be discarded by turning to Epistar's AC-LEDs that feature on-chip rectification circuits, says Carson Hsieh.
Novel grating boosts brightness
Alfalight's top-emitting laser produces far higher output powers than edge-emitters thanks to a curved grating that runs along the underside of the chip. This radical design allows beam-focusing with simple optics and is ideal for pumping fiber lasers, say Manoj Kanskar and François Brunet.
SiC foundations assist AlN growth
Although AlN substrates have some great characteristics for UV-LED fabrication, it is very difficult to make this material. However, a fast sublimation growth process that deposits AlN onto SiC is producing very encouraging results, including incredibly low defect densities, say Mikael Syväjärvi, Reza Yazdi and Rositza Yakimova from Linköping University.
Dots speed datacom VCSELs
Transmitters operating well beyond 10 Gbit/s are needed for emerging communication standards. Quantum-dot VCSELs can operate at four times this, and even higher rates are promised with a design incorporating a modulator in the top mirror, says VI Systems' Nikolai Ledentsov.
Research Review
Nitrogen radicals repair InN epilayers…HfO2 dielectric layer increase output power…Native platform extends emitter life.