Better solar cells, faster chips


Researchers at Stanford University have invented a new manufacturing process that could dramatically reduce the cost of Gallium Arsenide (GaAs)  electronic devices, opening prospects of use in solar cell applications.

Computer chips, solar cells and devices for photovoltaic applications have traditionally used silicon semiconductor material owing to its unique electronic properties and low cost of manufacturing. Other semiconductor materials like GaAs, albeit possessing superior technical properties have limited utility because of its high cost. The new technology seeks to make GaAs solar cells more practical on earth, hence not limiting its use to exotic applications such as satellites where the niche application justifies the cost of manufacturing 1000 times more expensive GaAs films in comparison to silicon.

“Solar cells that use Gallium Arsenide hold the record when it comes to the efficiency at which they convert sunlight into electricity,” said Bruce Clemens, the professor of materials science and engineering who led this work.

While it takes about $5000 to make a GaAs wafer of 8 inches diameter compared to $5 to prepare a silicon wafer of same dimensions according to Aneesh Nainani, the new Stanford process seeks to lessen this 1,000-1 cost differential by reusing that $5,000 wafer.

Nainani estimates that this reuse could create gallium arsenide devices that would be 50 to 100 times more expensive than silicon circuits – still a big differential but much less than what exists today.

“The Stanford process could rekindle interest in gallium arsenide electronics.Silicon is inexpensive today because, over time, the electronics industry has focused all of its ingenuity on making silicon cheaper. Silicon wafers are $5 today because manufacturers compete to satisfy the world’s ever-increasing appetite for silicon wafers and, over the course of decades, that competition has driven prices down.It all boils down to economies of scale,”Clemens said.

“Once it becomes possible to make gallium arsenide more cost-effectively, other people will jump in to improve other parts of the process,” Clemens added.”And with each advance, more uses will open up, especially in solar energy generation where gallium arsenide has clear efficiency advantages.”