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Stanford researchers have invented a manufacturing process that could dramatically reduce the cost of making gallium arsenide electronic devices.
Gallium arsenide, as a semiconductor, outperforms silicon since electrons travel through its structure faster than they do silicon.
However, gallium arsenide is not widely adopted because of cost issues. Silicon semiconductor devices are roughly a thousand times cheaper to make.
As a result, gallium arsenide-based devices are only used in niche applications where their special capabilities justify their higher cost. Cellphones, for instance, typically rely on gallium arsenide chips to process the high-frequency radio signals that arrive faster than silicon can handle.
Gallium arsenide is also useful for extremely high efficiency solar panels, though again the cost factor means gallium arsenide based solar panels can only be found in specialty applications, such as satellite systems, where gallium arsenide panels pay for themselves by delivering high efficiency-to-weight ratios.
The new manufacturing process from Stanford seeks to allow gallium arsenide wafers to be reused, thus driving down costs. It can cost about $5,000 to make a wafer of gallium arsenide 8 inches in diameter, versus $5 for a silicon wafer, so a reuse strategy makes sense.
Manufacturers make the circuitry layer on top of the gallium arsenide wafer by flowing gaseous gallium arsenide and other materials across the wafer surface. This material condenses into thin layer of circuitry atop the wafer.
Since the wafer is only a backing, Stanford researchers covered the wafer with a layer of disposable material, then they used standard gas deposition processes to form a gallium arsenide circuit layer on top of the disposable layer.
Next, using a laser, they vaporized the disposable layer and lifted off the circuitry layer off the wafer. They then mounted the thin circuitry layer on a more solid backing and cleaned the costly gallium arsenide wafer to make the next batch of circuits.
The resulting gallium arsenide devices would still be 50 to 100 times more expensive than silicon circuits, but the lower costs will open up the material for use in many more applications, then the economies of scale for further developments in making the material cheaper.