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Subject:  Re: The future of Cree: Part III Date:  6/21/2000  10:42 PM
Author:  marimba Number:  2625 of 41734

Roughbeast writes:
Does anyone have any insight as to whether or not SiC has any optical properties? Any and all answers appreciated.

Are you speaking in the chemical sense of stereoisomers or do you mean suitable as a material for optics?

I poked around on the web to find some answers but was unable to find anything that directly answered either of those questions. From my readings, it appears that SiC as a crystal by itself has a tetrahedral or hexahedral symmetrical structure so chemically it would not be considered optical.

As far as physically optical, well, we know that SiC crystals can be cut into diamond surrogates (popularly called Moissanite). That means it's transparent and could conceivably be cut into lenses if anyone ever determined that this were the solution to any existing optical engineering problem (which I do not believe to be the case).

It's important to remember that SiC needs to be doped with other ions in order to have the commercially needed electrical properties. When we talk about CREE's products we are not actually talking about SiC crystals but crystals based on an SiC matrix. Some understanding of crystal-matrix doping provides valuable background toward understanding semiconductor function and fabrication.
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