Seminar: Nathan Stoddard

Nathan Stoddard
Silicon Crystallization Scientist
SolarWorld USA 

How to Freeze Silicon: A Many-Splendored Problem

October 10, 2012 | 4:00pm | Elings 1605

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Abstract
Since the first use of silicon in electronic devices, the crystallization of silicon into useful forms for device processing has been a constant subject of both fundamental research and commercial development. To make suitable substrates for ever-smaller devices, companies have perfected the Czochralski crystal growth process for sizes up to 450 mm in diameter, with ingots up to 300 kg in weight. For use in photovoltaic applications, up to six different crystallization methods have been in production at different companies at the same time. The requirements for use in solar panels covering ever larger areas of the planet are quite different. For the past decade, the most prevalent technology has been multicrystalline ingot formation, which results in ingots up to 1,000 kg in weight but with considerably lower crystal quality. Neither technique has been able to take a truly dominant position in the solar industry.

What is it about silicon that makes it such an interesting material to solidify? What are the most outlandish methods used to make substrates? What happens when things go wrong? Could a new technique still break out and take over from the incumbents? Come and find out.

Biography
Nathan Stoddard is a senior member of the research and development team at SolarWorld Industries America, the leading manufacturer of silicon-based solar panels in the US. Nathan graduated summa cum laude from Villanova University with a BS in Honors and Physics and minors in math and French. He worked for Lockheed Martin and Made4Me.com before going to North Carolina State University for a PhD in Materials Science and Engineering, working on fundamental properties of point defects and light element impurities in silicon. Dr. Stoddard then took a job in R&D at BP Solar where he invented and subsequently implemented in production a new technique for crystallizing silicon, called Mono^{2 TM}, which is currently spreading throughout the solar industry. He holds three patents on the technology, with 16 other patent applications still pending.