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February 15, 2006...Ever since news came to our attention that Nichia is putting their original 404 blue LED patent out to pasture, questions have started to stir around the compound semi (CS) and solid state lighting (SSL) communities asking "Why?" The obvious and logical answer is that Nichia has perfected more efficient formulas now and they simply no longer need it. But the news of Nichia's retreat from that linchpin gallium nitride (GaN) on sapphire technology that led to bitter IP related disputes (ref: our Feb. 13 coverage) has moved to even higher levels of speculation among knowledgeable crystal growers that Nichia might also be moving ahead more quickly into the production of their own bulk GaN than many may be aware. Nichia just filed for two more international patents that involve the perfection of very low defect bulk GaN crystals, created in conjunction with a team of Polish GaN developers that have been working with Nichia since 1999.

The two newest patent applications are on top of quite a few WIPO and USPTO patent applications (and other international registries) related to bulk GaN. To date, sources who have done patent searches on Nichia's bulk GaN work with the Polish team have reported to me that they've found over 18 international patents and 8 USA patents. The first Polish patent application was June of 2001. By outside calculations, estimates are that Nichia has been spending about $1 million per year for the last five or six years on the work, securing the necessary IP to fortify their blue spectrum LED and LD production efforts with bulk GaN. By closely reading the two new WIPO patent applications, it looks like Nichia has produced 1 inch very low defect GaN wafers (out of 3 inch by 1 inch wide boules producing 6 mm of material.)

GaN epi on very low defect bulk GaN crystals (or just plain good GaN crystals) for light emitting, lasing, and electronic devices has long been the true goal of GaN researchers and device manufacturers. A number of small companies are working on the next level of GaN substrates, but it's the "ammonothermal" technique of growing GaN crystals in alkaline solutions that's causing the stir.

The real potential of the amonothermal process is, unlike HVPE, you can eventually put hundreds of templates or seeds and grow simultaneously. That's the approach Nichia is taking and it seems that's what the heaviest hitters feel will best replace HVPE GaN which is the method that leading USA true bulk GaN makers, such as Cree and TDI use, which experts conjecture will tide everyone over until the ammonothermal technique becomes manufacturable. (The estimated timeframe for getting ammonothermal growth method into commercially-viable shape, providing the right R&D money is thrown at the effort, is anywhere between 5-20 years. If Nichia puts enough money into it and is willing to sell it to the outside market, the estimate is that they could sell limited quantities of 2 inch wafers to the market in three years. If anyone is to compete with them, now is the time to get rolling.Right now, Sumitomo Electric (SEI) probably remains the leading supplier of GaN, but that's still not the pure stuff.

If you haven't heard much about the ammonothermal growth technique of bulk GaN wafers, it's also known sometimes as "growth by high pressure ammonia," according to my experts. A good description of the approach can be found in the January issue of Elsevier's Jan '06 Journal of Crystal Growth with lead authors being Buguo Wang, M.J Callahan, et al. The paper is titled: Ammonothermal growth of GaN crystals in alkaline solutions pages 376-380. Here's the link to the abstract. The full text is available by subscription only... or you can call or email me and I'll zap you over a pdf of it.

Although he hasn't publicly made a big deal of it yet, this is reputed to be the basic growth method used by Shuji Nakamura's group at UC Santa Barbara. It's also being researched by General Electric at their research facilities in Schenectady, New York under the direction of Mark D'evely and considerable progress has been made within the USA's DoD by Michael Callahan at the Air Force Research Labs (AFRL) Sensors Directorate, Electromagnetics Technology Division at Hanscome AFB near Boston, Massachusetts (a stones throw from Lincoln Labs). GE's process differs some in that it uses acidic ammonia at higher pressures and temperatures, i.e. the same technique with slightly different chemistry. These researchers are the usual tight knit international community, from which Nichia and their Polish colleagues have been absent. So all we really know is what we can find from the Nichia-related patents. The search names used are Nichia and the Polish group, which calls itself AMMONO Sp. z o.o. The lead inventor from Poland is Robert Dwilinski and for Nichia, it's Yasuo Kanbara. The WIPO patent application is number: WO 2005/121415 A1 titled "Bulk Mono-crystalline gallium-containing nitride and its applications".

Those who know this journalist know that my strong suit is not technical prowess, so I heartily encourage all you material scientists and bulk GaN groupies to read the posted patent information carefully for yourselves. The litany of Nichia-related bulk GaN patents can be found by clicking this link and simply typing in the name "Dwilinski" in the query box. It's a pretty cool read. The US Patent & Trademark Office (USPTO) yield is similar, and perhaps an easier read. Simply click on this link to find it. Again, it was accessed by simply putting in Dwilinski in the refined search on www.uspto.gov (how many "Dwilinski's could there be working on bulk GaN?) These patent resource sites have all become very refined in a relatively short period of time. For example, if one looks at the examples on page 19-23 on the Nichia patent application ending in “232” you can see they have already produced very low defect 1” substrates. And if you look at all their patents applications, they've also already made HEMTs and laser diodes on ammono GaN substrates. If you want to compare this with what GE is doing, simply click on this link.

So what's the goal of those who don't want to see the entire bulk GaN production business centered in Japan? The USA's Department of Defense, for one, would need a good reliable USA-based supply in the queue (shades of Title III). Shuji Nakamura's group is heavily funded by Japanese entities, thus that end product is more than likely to also be produced in Japan... unless a company like Cree can convince him otherwise. GE is one probable USA contender, and if Cree did something exciting like augmenting the bulk GaN expertise and capability they inherited from ATMI with George Brandes' group with what the Air Force Labs is producing, plus weave in some of the terrific small home-grown GaN substrate suppliers (Kyma, Cermet, Crystal IS, etc.) or... if a sapphire producer like Rubicon in Chicago decided to branch out and ramp into bulk GaN by going in league with AFRL and one or more of the above small companies, the USA would have a shot at staying ahead of the curve.

No matter who elects to get into the bulk GaN game, it's going to take quite a bit of high risk bankroll to compete with Nichia... if that's where Nichia is headed. And it certainly looks like they are. Right now, the key researchers in competition with Nichia and their Polish team are simply learning what they can about the Nichia process and, as usual, trying to figure out how to design their methods around Nichia's fast-growing store of bulk GaN IP.

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