Solar Energy Publication News

by Shannon Combs

Although silicon is the market common semiconductor in many electronic units, including the pv cells that sun panels use to transform sun rays into energy, it is not really the most cost-efficient product on the market. For instance, the semiconductor gallium arsenide and similar compound semiconductors provide practically two times the effectiveness as silicon in photo voltaic units, but they are rarely employed in utility-scale applications because of their high production value.

U. of Illinois. (http://illinois.edu/) professors J. Rogers and X. Li explored lower-cost techniques to produce thin films of gallium arsenide which also granted usefulness in the sorts of units they might be incorporated into.

If you can minimize significantly the price of gallium arsenide and some other compound semiconductors, then you could increase their variety of applications.

Generally, gallium arsenide is placed in a single thin layer on a smaller wafer. Either the ideal device is made right on the wafer, or the semiconductor-coated wafer is break up into chips of the desired dimension. The Illinois group decided to deposit numerous levels of the material on a individual wafer, creating a layered, “pancake” stack of gallium arsenide thin films.

If you increase 10 levels in 1 growth, you simply have to fill the wafer 1 time. If you do this in ten growths, loading and unloading with temperature ramp-up and ramp-down get a lot of time. If you consider what is needed for every growth – the equipment, the procedure, the period, the people – the overhead saving this solution gives is a significant cost decrease.

After that the researchers separately peel off the layers and shift them. To complete this, the stacks swap levels of aluminum arsenide with the gallium arsenide. Bathing the stacks in a formula of acid and an oxidizing agent dissolves the levels of aluminum arsenide, freeing the single thin sheets of gallium arsenide. A soft stamp-like system picks up the layers, 1 at a time from the top down, for exchange to another substrate – glass, plastic or silicon, based on the application. After that the wafer can be reused for another growth.

By doing this it’s possible to generate significantly more material much more quickly and more price efficiently. This process could generate mass amounts of material, as compared to just the thin single-layer method in which it is usually grown.

Freeing the material from the wafer additionally starts the possibility of flexible, thin-film electronics made with gallium arsenide or additional high-speed semiconductors. To make units that may conform but still keep higher efficiency, which is considerable.

In a paper published on-line May twenty in the magazine Nature (http://www.nature.com/), the team describes its procedures and demonstrates 3 kinds of units making use of gallium arsenide chips manufactured in multilayer stacks: light units, high-speed transistors and photo voltaic cells. The authors additionally offer a comprehensive price comparability.

Another advantage associated with the multilayer technique is the release from area constraints, particularly essential for solar cells. As the layers are eliminated from the stack, they could be laid out side-by-side on one more substrate in order to generate a much larger surface area, whereas the typical single-layer process limits area to the size of the wafer.

For photovoltaics, you want big area coverage to get as much sunshine as achievable. In an extreme case we may grow sufficient levels to have ten times the area of the traditional.

Next, the team plans to explore more potential product applications and additional semiconductor resources that could adapt to multilayer growth.

About the author: Shannon Combs gives advice for the residential solar power tax credits blog site, her personal hobby website based on guidelines to aid home owners to conserve energy with sun power.

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