U. ILLINOIS (US)—A novel manufacturing method that uses gallium arsenide (GaAs) instead of silicon to create semiconductor chips could greatly improve the efficiency and lower the cost of solar energy devices.

Using a compound semiconductor like gallium arsenide (GaAs) in applications such as photovoltaics and optoelectronics has several advantages over silicon—if manufacturing obstacles including the high cost of using GaAs can be overcome.

John Rogers, professor of materials science and engineering and of chemistry, and Xiuling Li, professor of electrical and computer engineering, have done just that at the University of Illinois by developing a method that uses multi-layers of GaAs to create chips that they integrated into solar energy devices and other applications.

The standard method for creating GaAs chips is to deposit a single layer of the compound semiconductor on a wafer. The new process uses films of GaAs, known as AIGaAs, that are grown in thick, multi-layer epitaxial assemblies, and then separated and printed on foreign substrates.

The method “yields large quantities of high quality semiconductor material capable of device integration in large area formats, in a manner that also allows the wafer to be reused for additional growths.”

Details of the research appear in the journal Nature.

The advantage of GaAs compound semiconductors is that they have direct bandgaps and high electron mobilities. Lower manufacturing costs and better integration are possible compared to other technologies, the researchers say. The method, for example, offers nearly twice the efficiency of silicon used in solar devices.

The researchers were able to demonstrate the capabilities of GaAs multi-layered chips in light sensors, high-speed transistors, and solar cells.

“By doing this we can generate much more material more rapidly and more cost effectively,” Rogers says. “We’re creating bulk quantities of material, as opposed to just the thin single-layer manner in which it is typically grown.

“If you can reduce substantially the cost of gallium arsenide and other compound semiconductors, then you could expand their range of applications.”

More news from the University of Illinois: www.beckman.illinois.edu/