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Washington State University researchers used light to write a highly conducting electric path in a crystal. This opens up the possibility of transparent, three-dimensional electronics that, like an Etch-A-Sketch, can be erased and reconfigured. On the left, a photograph of a sample with four metal contacts. On the right, an illustration of a laser drawing a conductive path between two contacts.
Credit: Washington State University

Transparent, 3D electronics can be configured and erased like an Etch A Sketch. It serves as a proof of concept for a phenomenon that WSU researchers first discovered by accident 4 years ago. At the time, a doctoral student found a 400-fold increase in the electrical conductivity of a crystal simply by leaving it exposed to light...

Artist’s rendition of optically-defined quantum circuits in a topological insulator. Credit: Peter Allen

In contrast to using advanced nanofabrication facilities based on chemical processing of materials, this flexible technique allows for rewritable ‘optical fabrication’ of devices. The electrons in topological insulators have unique quantum properties useful for developing low-power spin-based electronics and quantum computers. However, making even the simplest experimental circuits with these materials has proved difficult because traditional semiconductor engineering techniques tend to destroy their fragile quantum properties. Even a brief exposure to air can reduce their quality.

The researchers report the discovery of an optical effect that allows them to “tune” the energy of electro...