Silicon carbide synthesis

#manufacturing #semiconductors

Semiconducting materials are the driving force behind IT and electronics industry. Silicon carbide is one of the oldest known semiconducting materials around. Silicon carbide's synthesis is quite easy in theory. All you need to do is heat up silica and carbon to very high temperatures. Because both silica and carbon are abundant materials and people have been synthesizing silicon carbide since 1800's. Infact the first led was made out of silicon carbide.

Making a semiconductor grade single crystal out of silicon carbide is challenging. Both from the perspective of energy required as well as the time it takes to grow the crystal. The most widely used technique today vaporizes the silicon and carbon containing constituents and have them deposit layer by layer on the growth surface,usually a silicon wafer.

For those interested in learning about manufacturing semiconductor grade silicon carbide heres a book which covers not only the synthesis of crystals but also gives information on the design of furnaces required for the growth , the kind of defects that can appear on the growth stage and how they can be minimized.

https://www.researchgate.net/publication/236156491_Silicon_Carbide_Epitaxy

However if you are short on time you may prefer to go through this presentation instead that takes a slightly different route of directly vaporizing a silicon carbide powder instead of constituents and creating a bulk sic crystal in the process.

http://www.mif.pg.gda.pl/homepages/tomek/ISSCG15/Wellman_lecture_ISSCG-15.pdf

Because SIC synthesis needs high temperatures – usually in excess of 1500C it is an ideal candidate for fabrication in a concentrated solar furnace.

https://www.linkedin.com/pulse/can-concentrated-solar-energy-used-materials-how-akshat-jiwan-sharma-5ufrc

We'll need to start with a carbon substrate and fuse sand on top of it. As temperatures increase functional groups will be driven out of the substrate and a SiO2/C composite will be formed. Further heating will cause reaction between SiO2 and C leading to formation of SIC and expulsion of CO2 gas. While not exactly semiconductor grade such sic materials can be used as structural components.

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Notes by Akshat Jiwan Sharma

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