He he, calm down Chuca.
First, CREE.
I know way more about SiC than you do and I picked CREE last year when it was at 9 or so on fundamentals. Ask Sting Ray 57, he will verify that we have had a number of public conversations about CREE long before it took off.
Since I work in that field, I have been watching them since 1989 and know a number of people that work there. A good company, overall, that understands how to balance actual bricks and mortar with attracting investment capital. Right now, I think they are overbought, but they do seem to keep going up. I'm not sure which post you are referring to, but basically I like CREE.
Now lets look the Rhombic press release
Rhombic Corporation Accepts University of Missouri Proposal Business Editors, Computer & Education Writers VANCOUVER, British Columbia--(BUSINESS WIRE)--June 21, 1999-- Rhombic Corporation (OTC BB:NUKE) announces that the company has accepted a proposal from the University of Missouri to use its laboratory facilities, technical equipment, and personnel, to develop selected projects using the company's "Forced Diffusion" technology. The question here is what are the terms? I can get into a university lab for (lowest) 5K and typically 30K per year (1/2 time for 1 grad student and 1/8 time for the advisor).
Purification of silicon carbide and gallium nitride wafer materials will begin July 1, 1999 under the supervision of Dr. Mark Prelas. I have looked at Prelas previously, he seems OK, though I don't know him.
The wafers will be bought from U.S. manufacturers in two and three inch crystal sizes, and treated with the patented "Forced Diffusion" process. There is no such thing as a GaN bulk wafer at any size. Silicon carbide is available from CREE and others in two and three inch diameters. I assume that the reference to GaN is for GaN/SiC epitaxial wafers, but this sentence is not precise. The forced diffusion process also looks plausible. The manufacture of Li-drifted Si X-ray detectors is very similar and has been used since the early '60s.
The University proposal is to use the Rhombic technology "to purify the gallium nitride of the unintentional oxygen and silicon impurities incorporated into the structure, and to purify the silicon carbide wafers of the pollutants boron, nitrogen and oxygen. This is, of course, proposed - unless you an point me to some data. SIMS, AUGER, DLTS, and PL are some methods that would indicate if the forced diffusion process is effective in moving impurities from the surface to the bulk of the wafer (by the way, that is what they want to do, you only need the top few microns of a wafer to make a MESFET or a MOSFET or a JFET). Also, pollutants is not an accepted technical term - it should be "unintentional impurity incorporation"
The gallium nitride wafer is a blue laser generator, (Yes, see what Nichia has achieved, they are the leaders in this area) and silicon carbide is a major factor in high temperature, high speed electronics (Yes, but there are problems - micropipes, oxide trapping states, and deep doping levels (not contamination - look it up) have held these devices back from the theoretical values).
Both materials are light emitting diodes (True, but SiC is really dim compared to GaN - these are no longer on the market) that can be modified to produce photovoltaic cells that assist in the conversion of ultra violet light to electricity. Also true, technically. However, there are some real issues here. Basically, there is not and never will be a market for UV photovoltaic cells - I stand by this statement categorically.
It would take a long time to explain this, but basically, there is too little energy content in the solar flux for high-bandgap PV devices. Even if they were free, the BOS trade-off would wipe them out compared to silicon (which in comparison to SiC, is nearly free).
For a single junction device, the optimum bandgap is near GaAs and InP ~ 1.4 eV. This is calculated by integrating the solar insolation with the spectral response of the device to get the photogenerated current and then calculating the voltage and resulting IV curve of the PV cell.
Materials like SiC and GaN have too high of a bandgap to generate a useful amount of current and the theoretical efficiency is less than 5%. Silicon solar cells dominate the terrestrial market due to cost reasons and GaAs solar cells are starting to dominate the space market.
Whoever wrote this sentence (and the following one does not know what he/she is talking about.
Reducing the impurities in the wafers would give them an improved effectiveness with a longer life span, and simplify the construction of photovoltaic cells. As mentioned above, this is laughable. (1) it would not simplify the construction of PV cells - which are non-viable due to the high bandgap anyway. (2) In general, impurities have nothing to do with lifespan - it is the metallurgy and the thermal stress history that counts. The improved effectiveness is arguable, although vague. The problems with these materials are more related to crystal defects and doping depth and passivation issues than in impurity issues. In fact, the progress that has been made in the past few years is due in a large part to the successful control of impurities
According to the 1999 Industry Report, "Silicon will remain the dominant material for substrates and wafers for the foreseeable future with demand exceeding $7 billion in 1999. True, I haven't checked the number, but it seems about right. However, what does this have to do with SiC and GaN? These have very different markets and should be compared to the laser diode and LED industry (which also have huge numbers, but not as high as 7 billion).
The push for ever greater performance at lower prices has brought new wafer technologies into the market." False. A 3" SiC wafer is about $4,000, an 8" silicon wafer is about $150 - 300. The real market for these devices is nichey and costs are high and delivery is a problem (except for blue LEDs which are getting pretty common).
Rhombic's patented "Forced Diffusion" process can be used to add to or to take out impurities from diamond, silicon carbide, gallium nitride, and other special materials to modify the optical, chemical, electrical, and mechanical properties of those materials. OK, lets see the data
Rhombic Corporation will announce soon that, beginning in September, 1999, its "Forced Diffusion" technology will be used to develop a second project at the University Of Missouri's facilities. For details on Rhombic Corporation, call the company's public relations office at 1-888-821-6607 and 604-421-5543, or visit the Rhombic website www.rhombic.com. --30--jam/clv*
I'm going to ignore the rest of your post for now since it is clear that you don't understand what you are talking about. However, I do like SOI and also know a lot about that subject if you are interested (it has nothing to do with NUKE though).
I am also going to ask Zeev to look at this post. He understands these technologies quite well and can tell you if I am wrong in any particular. |
