June 7, 2010
Shannon Combs, a residential photovoltaics advisor from the US recently contacted CHANGING BEHAVIOUR and sent us this interesting article:
College of Illinois Experts Provide Us Little Known Approaches to Produce More Economical PV panelsEven if silicon is actually the industry normal semiconductor in the majority of electronic devices, which includes the PV cells that photovoltaic panels use to convert sunshine into power, it is hardly the most cost-efficient product on the market. For instance, the semiconductor gallium arsenide and associated compound semiconductors give practically twice the effectiveness as silicon in solar units, but they are rarely employed in utility-scale applications because of their excessive manufacturing value.
University of Illinois (http://illinois.edu/) teachers J. Rogers and X. Li explored lower-cost techniques to produce thin films of gallium arsenide which also allowed adaptability in the sorts of units they could be integrated into.
If you can lower significantly the expense of gallium arsenide and other compound semiconductors, then you can expand their own variety of applications.
Usually, gallium arsenide is transferred in a single thin layer on a small wafer. Either the preferred unit is produced directly on the wafer, or the semiconductor-coated wafer is break up into chips of the ideal size. The Illinois team considered to deposit multiple layers of the material on a single wafer, making a layered, “pancake” stack of gallium arsenide thin films.
If you increase 10 layers in one growth, you simply have to load the wafer one time. If you do this in 10 growths, loading and unloading with heat range ramp-up and ramp-down take a lot of time. If you take into account exactly what is necessary for each growth – the equipment, the procedure, the time, the people – the overhead saving this method presents is a considerable cost reduction.
Next the experts separately peel off the layers and transfer them. To accomplish this, the stacks alternate levels of aluminum arsenide with the gallium arsenide. Bathing the stacks in a solution of acid and an oxidizing agent dissolves the layers of aluminum arsenide, freeing the individual small sheets of gallium arsenide. A soft stamp-like device selects up the layers, 1 at a time from the top down, for move to one other substrate – glass, plastic or silicon, based on the application. After that the wafer can be reused for another growth.
By performing this it's possible to generate significantly more material a lot more rapidly and much more price efficiently. This process could produce bulk amounts of material, as compared to merely the thin single-layer manner in which it is usually grown.
Freeing the material from the wafer additionally opens the possibility of flexible, thin-film electronics produced with gallium arsenide or other high-speed semiconductors. To make products which may conform but still keep high efficiency, which is significant.
In a document shared on-line May 20 in Nature (http://www.nature.com/), the group describes its methods and displays three types of units making use of gallium arsenide chips made in multilayer stacks: light products, high-speed transistors and photovoltaic cells. The authors also offer a detailed cost comparison.
One more advantage associated with the multilayer method is the release from area constraints, particularly crucial for photo voltaic cells. As the levels are taken away from the stack, they could be laid out side-by-side on one more substrate to make a significantly bigger surface area, whereas the standard single-layer method restricts area to the dimension of the wafer. For photovoltaics, you need big area coverage to catch as much sunshine as achievable. In an extreme case we may increase enough levels to have ten times the area of the traditional.
Next, the team programs to explore more prospective unit applications and other semiconductor materials that might adapt to multilayer growth.
About the Article writer
Shannon Combs gives advice for the residential solar power cost website, her personal hobby website based on points to help home owners to save energy with sun power.
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