Panasonic claims GaN substrate LED breakthrough
Panasonic, the Japanese company better known for its televisions and washing machines, claims to have developed the first commercial white power LEDs to be manufactured on GaN substrates.
According to the Osaka-based electronics company, InGaN-based LEDs grown on the native host material have an efficiency that is more than 50 percent higher than conventional LEDs fabricated on sapphire substrates.
The company has issued few details about the exact nature of the material system and the deposition method that it uses, but, if the company has indeed developed single-crystal GaN suitable for commercial LED production it would represent a significant breakthrough for the industry.
Makers of GaN-based transistors, LEDs and lasers have always known that the same material would make the ideal host substrate, but producing high-quality single-crystal GaN at a large enough diameter and a low enough price to support volume wafer manufacturing has proved impossible thus far (see related magazine feature articles).
The Panasonic development is not something that is restricted to the laboratory, either. It is set to begin sampling three different white LED products within weeks.
According to the company s own research, the power LEDs also have the highest output in the industry:
Performance details quoted by Panasonic say that the 460 nm-emitting blue chips produce a total radiative flux of 355 mW when driven at a forward current of 350 mA. This translates to an external quantum efficiency of 38 percent.
Those figures compare well with similar devices that have been developed by Philips Lumileds. In an Applied Physics Letters paper published last year, Lumileds researchers showed that their new thin-film flip-chip InGaN LEDs also had an external quantum efficiency of 38 percent (see link to this research paper).
Emitting at the slightly shorter wavelength of 440-445 nm, the Lumileds LEDs also deliver around 350 mW of radiative flux when driven at 350 mA, increasing to nearly 900 mW at a drive current of 1 A.
Panasonic s three products include a 3 W power device for lighting applications, a reflector design that is suited to camera flashes, and a point source for use in compact lighting fixtures.
Samples of the products are available at ¥500 ($4.30) per unit.
