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Semiconductor Stacks

A new method for growing large pieces of GaAs could boost the material’s use in electronic devices

by Bethany Halford
May 24, 2010 | A version of this story appeared in Volume 88, Issue 21

Credit: John Rogers
A photovoltaic module (4 mm) containing an array of GaAs solar cells on a plastic sheet.
Credit: John Rogers
A photovoltaic module (4 mm) containing an array of GaAs solar cells on a plastic sheet.

A new method for growing large, high-quality pieces of compound semiconductors such as gallium arsenide could help boost the use of these materials in photovoltaic and optoelectronic devices (Nature 2010, 465, 329). Compound semiconductors easily outperform silicon semiconductors, thanks to their direct band gaps and high electron mobilities. But growing large, high-quality wafers of GaAs and related materials has proven costly. To address this problem, a team led by John A. Rogers of the University of Illinois, Urbana-Champaign; Ungyu Paik of Hanyang University, in South Korea; and Matthew Meitl of photovoltaics developer Semprius, in Durham, N.C., developed a fabrication method in which multiple layers of GaAs or AlGaAs are grown via metal organic chemical vapor deposition in between separating layers of AlAs. Immersing this stack in hydrofluoric acid dissolves the AlAs, releasing pieces of the semiconductor material in sizes that range from micrometers to centimeters and in thicknesses that range from nanometers to micrometers. To show the capabilities of the method, the researchers used it to create GaAs-based field-effect transistors and logic gates on glass plates, near-infrared imaging devices on silicon wafers, and photovoltaic modules on plastic sheets.


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