New production techniques could allow gallium arsenide semiconductors to edge in on silicon's overwhelming territory. The flexible thin films hold hope for everything from integrated circuits to solar cells.  (Source: John Rogers/University of Illinois)
Could silicon's choke hold on the semiconductor universe be threatened?

Silicon isn't the best semiconductor in the world. But among the features keeping it nearly ubiquitous in electronic devices is the relative ease of construction of silicon-based chips in comparison to superior materials. As with just about any mass-produced product in the world, quality has long since taken the back seat to quantity.

One contender for semiconductor superiority is gallium arsenide. Unfortunately, as one might be led to believe, the vapor deposition method typically utilized to create gallium arsenide is more costly than its silicon counterpart. Fortunately for gallium arsenide, a group of DoE and NSF-funded professors, students and scientists based at the University of Illinois, has pioneered a new manufacturing process that will help even the field.

As the previously utilized methods of gallium arsenide semiconductor production involved deposition to create a thin film, devices either needed to be created directly on the substrate or in a more typical wafer design which could then be clipped out into multiple pieces much like a standard silicon wafer technique used for manufacturing computer processor cores. The cleverness of the UI team's take on the thin films isn't in a revolutionary deposition process, but in using the same process over and over on the same substrate. By utilizing the same substrate multiple times, stacking the thin films on top of each other, they save time, money and manpower involved in producing the same amount of film in single sheets.

In order to ensure the layers are easily disassembled, each layer of gallium arsenide is alternated with a layer of aluminum arsenide. Once the deposition process is complete, the finished multi-layer unit can be washed in a solvent and oxidizing agent to dissolve the layers of aluminum arsenide and free the sheets of gallium arsenide. A specialized piece of equipment then peels each layer off, one at a time, and transfers them to their new home substrate. In this manner, a single "wafer" can produce ten or more times the amount of semiconductor material of a single sheet deposition.

The group's initial work with the new semiconductor process has been with solar cells, where cost versus efficiency is the breaking point for any new material. A North Carolinian  company, Semprius Inc., has already begun using the process to manufacture new solar cells. They have also utilized the process to create light sensors and high-speed transistors. In the future they hope to find more devices that could benefit from the more cost-effective process, as well as other materials that may benefit from it.

"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson

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