NGK Developed GaN Wafer for Ultra High Brightness LEDs
June 7, 2012
NGK Insulators, Ltd. (President: Taro Kato; Headquarters: Nagoya, Japan) has announced it has developed gallium nitride (GaN) wafers that double luminous efficiency of a LED light source compared to conventional materials.
Created with original liquid phase epitaxial growth technology, NGK's GaN wafer has low defect density and colorless transparency over the whole wafer surface.
With the assistance of a research institute outside the Company, a light emitting test was performed on a LED element using NGK's GaN wafer. The test showed a world top class internal quantum efficiency of 90% at an injection current of 200mA. The GaN wafer achieves a luminous efficiency of 200lm/W, which is twice as efficient as those on the market today. Under the same brightness, this reduces power consumption by 50%. Since the wafer reduces heat generation within LEDs, it lengthens lifetime of LEDs and enables downsizing of lighting equipment.
NGK established a new department named "Wafer Project" this month, aiming at prompt commercializing of wafer products. Within 2012 the Company will launch the shipment of sample products of 4-inch-diameter GaN wafer, which is the world's first 4-inch-diameter GaN wafer produced with the liquid phase epitaxial growth technology. NGK is accelerating the development of GaN wafers with lower defect density and of larger diameter (6 inches), aiming at the market for wafers to be used for power devices for hybrid cars, electric vehicles and power amplifiers for cellular base stations. The GaN wafer is optimum for such applications, taking advantage of its features including high breakdown voltage, high frequency operation, etc.
LED element under light emitting test Substrate size: 1cm square, Element size: 0.3mm square Injection current: approx. 200mA, Center wavelength: 450nm
GaN wafers (left: 2 inches, right: 4 inches)
* Internal quantum efficiency: Ratio of the number of electrons (current) injected into LED to the number of photons generated in the emission layer. The ratio is dependent on crystal defect density in the emission layer and the ideal ratio is 100%. The ratio of LED elements on the market today is 30 to 40 percent at the injection current of 200mA.