The research team saw the potential for creating durable patterns on the glass surface that could produce electricity when illuminated. Photo courtesy of EPFL / Lisa Ackermann.

A team of researchers may have discovered how to turn glass into a light-powered semiconductor using a femtosecond laser.

The team from the Galatea Lab at Ecole Polytechnique Federale de Lausanne (EPFL) and Tokyo Tech scientists sought to learn how tellurite glass would reorganize when exposed to fast pulses of high-energy femtosecond laser light. Tellurite glass is known for its optical and electrical properties, comprising tellurium dioxide and other oxides, such as sodium oxide.

During their research, the team discovered nanoscale tellurium and tellurium oxide crystals etched in the glass where it had been exposed to the laser light. The team saw the potential for creating durable patterns on the glass surface that could produce electricity when illuminated.

“Tellurium being semiconducting, based on this finding, we wondered if it would be possible to write durable patterns on the tellurite glass surface that could reliably induce electricity when exposed to light, and the answer is yes,” explains Yves Bellouard, who runs EPFL’s Galatea Laboratory. “An interesting twist to the technique is that no additional materials are needed. To make an active photoconductive material, you only need tellurite glass and a femtosecond laser.”

With the tellurite glass produced by members at Tokyo Tech, the EPFL team used femtosecond laser technology to modify the glass and analyze the effect of the laser. After exposing a simple line pattern on the surface of a tellurite glass one centimeter in diameter, they found that they could reliably generate a current when exposed to ultraviolet light and the visible spectrum for months.

“It’s fantastic, we’re locally turning glass into a semiconductor using light,” says Bellouard.  “We’re essentially transforming materials into something else.”

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