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To: slacker711 who wrote (2402)	3/12/2000 8:09:00 PM
From: slacker711	Respond to of 10714

Here is the second article....gallium nitride substrates? Blue-violet laser gains credibility Sumitomo Electric grows first commercially viable gallium-nitride substrate Sumitomo Electric developed a technique to grow gallium-nitride substrates. Sumitomo Electric Industries Ltd. has scored an industry first with the development of a monocrystalline gallium-nitride substrate measuring a commercially viable 2 inches in diameter, company officials said. Gallium-nitride substrates have the potential to offer numerous advantages when used for blue-violet lasers for the next generation of high-capacity digital-versatile-disc (DVD) recording and playback devices. Blue-violet laser samples have begun to appear on the market. However, attempts to grow gallium nitride on sapphire, which is used for the laser substrate, have so far commonly resulted in defects and poor yields because of the structural differences between the two substances. Sumitomo Electric has established its own method for producing monocrystalline gallium-nitride substrates partly by applying thermodynamics theory at the suggestion of Tokyo University of Agriculture and Technology. It has also developed a new surface-processing technology that allows it to successfully grow gallium-nitride substrates. The new substrates can be used to create chips half the size of those produced from sapphire substrates at a significantly lower cost, according to company officials. Blue-violet lasers produced with the substrates also offer better performance and longer operating life. Previous attempts at production of monocrystalline gallium-nitride substrates were mainly carried out under ultrahigh temperature and pressure. But that method had many problems as gallium nitride grows slowly and production costs end up being substantial. Sumitomo Electric plans to mass-produce the new substrates and begin sales to laser manufacturers by 2001. Currently, red lasers with a 650 nanometer wavelength are used for DVDs, which can store up to 4.7 gigabytes of data. Blue-violet lasers have a wavelength of 400 nanometers, shorter than the 650 nanometers for red lasers, and can be used for large-capacity DVDs with more than 25 gigabytes memory capacity. Thus fierce competition to develop the technology has emerged among companies including Nichia Chemical Industries Ltd., Sony Corp., Toshiba Corp., Pioneer Corp.and Matshushita Electric Industrial Co.