NGK Insulators, Ltd. claims has to have developed gallium nitride (GaN) wafers that double luminous efficiency of a LED light source compared to conventional materials. NGK says that its GaN wafers created with its original liquid phase epitaxial growth technology, have low defect density and colorless transparency over the whole wafer surface. NGK says a research institute outside tested the LED fabricated on its GaN wafer. According to NGK the test showed an internal quantum efficiency of 90% and an injection current of 200mA. The company says that LEDs now on the market range from 30 to 40 percent quantum efficiency. Specifically the internal quantum efficiency is the ratio of the number of electrons (current) injected into the LED to the number of photons emitted as light. NGK claims that 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.
This month, NGK established a new department named "Wafer Project", aimed 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). In addition to using the wafers for high brightness LED the company is aiming at the market for 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.
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