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Thin-Film Trick Makes Gallium Arsenide Devices Cheap

Rubber-stamping makes creating solar cells, transistors, and infrared detectors easy

3 min read

19 May 2010—Researchers led by John Rogers at the University of Illinois at Urbana-Champaign have invented a cheaper way to build devices—including solar cells and infrared cameras—using highly efficient but notoriously pricey compound semiconductors. Their method, reported in the journal Nature, involves growing stacks of thin films of semiconductor, peeling off the films one by one, and printing them onto cheaper substrates, such as silicon or glass.

Silicon is the stuff of computer chips, but if you want to build the fastest transistor or the most efficient LED, compound semiconductors—such as gallium arsenide (GaAs) or gallium nitride—are your best bet. In solar cells, for instance, ”gallium arsenide is more efficient than anything known to man,” says Rogers, a materials engineer. Some GaAs solar cells can convert about 40 percent of the sun’s energy into electricity, while silicon cells max out at about 20 percent efficiency.

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The Transistor at 75

The past, present, and future of the modern world’s most important invention

2 min read
A photo of a birthday cake with 75 written on it.
Lisa Sheehan
LightGreen

Seventy-five years is a long time. It’s so long that most of us don’t remember a time before the transistor, and long enough for many engineers to have devoted entire careers to its use and development. In honor of this most important of technological achievements, this issue’s package of articles explores the transistor’s historical journey and potential future.

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