Despite the fact that silicon is the industry normal semiconductor in many electronic devices, which includes the pv cells that photo voltaic panels use to transform sunshine into energy, it is hardly the most efficient material on the market. For instance, the semiconductor gallium arsenide and similar ingredient semiconductors give practically double the performance as silicon in solar units, however they are rarely utilized in utility-scale applications because of their high manufacturing value.
U. of Illinois teachers J. Rogers and X. Li discovered lower-cost methods to manufacture thin films of gallium arsenide that also made possible flexibility in the kinds of units they could be included into.
If you may minimize considerably the price of gallium arsenide and some other compound semiconductors, then you could increase their variety of applications.
Generally, gallium arsenide is deposited in a single thin layer on a small wafer. Either the wanted unit is made specifically on the wafer, or the semiconductor-coated wafer is break up into chips of the ideal dimension. The Illinois group chose to put in numerous levels of the material on a simple wafer, producing a layered, “pancake” stack of gallium arsenide thin films.
If you increase 10 levels in one 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 each growth – the machine, the planning, the period, the workers – the overhead saving this method offers is a significant price decrease.
After that the scientists independently peel off the levels and transport them. To achieve 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 thin sheets of gallium arsenide. A soft stamp-like system picks up the layers, just one at a time from the top down, for move to one more substrate – glass, plastic or silicon, based on the application. Then the wafer may be reused for an additional growth.
By executing this it's possible to generate considerably more material more fast and much more cost efficiently. This process could take mass amounts of material, as compared to just the thin single-layer method in which it is generally grown.
Freeing the material from the wafer also opens the chance of flexible, thin-film electronics made with gallium arsenide or other high-speed semiconductors. To make units that may conform but still keep high efficiency, which is significant.
In a paper shared on-line May 20th in the journal Nature (http://www.nature.com/), the team details its procedures and displays three types of devices using gallium arsenide chips manufactured in multilayer stacks: light devices, high-speed transistors and photo voltaic cells. The authors additionally supply a detailed price comparability.
An additional benefit of the multilayer method is the release from area constraints, particularly essential for solar cells. As the layers are taken out from the stack, they can be laid out side-by-side on another substrate to produce a significantly greater surface area, whereas the standard single-layer process restricts area to the size of the wafer.
For solar panels, you need large area coverage to catch as much sunshine as possible. In an extreme situation we may increase adequate layers to have ten times the area of the conventional.
Up coming, the group plans to explore more potential product applications and other semiconductor materials which could adapt to multilayer growth.
About the Writer - Shannon Combs is currently writing for the residential solar power manufacturers web site, her personal hobby blog focused on guidelines to aid home owners to conserve energy with sun power.