Accidental Discovery of Black Silicon Holds Practical Applications

A treatment accidentally discovered in the laboratory of physics professor Eric Mazur has the potential to vastly increase the effectiveness of silicon.

The newly discovered “black silicon” is created through a laser treatment inside a chamber filled with sulfur gases—a procedure that allows silicon to absorb a larger fraction of the solar spectrum, according to Meng-Ju Sher, a physics research assistant.

Unlike regular silicon, black silicon can absorb the infrared region of the light spectrum as well absorb visible light much more efficiently.

Black silicon has practical applications, such as cameras and night vision goggles, but Kenneth C. Hammond ’12—who works in Mazur’s lab—hopes to create more efficient solar cells with the new substance.

Though regular silicon does “a fairly good job” of absorbing the solar spectrum, black silicon is able to absorb a much greater percentage, and Hammond said researchers hypothesize that black silicon could create a more efficient solar cell.

“When you’re building a solar cell, you want to look for a substance that can absorb most of what the sun gives you,” Hammond said.

Mazur’s team is currently seeking to expand silicon’s absorption range even further—a task that requires a better understanding of how the sulfur gases affect the silicon and transform it into black silicon.

The researchers are also exploring the capabilities and limitations of black silicon, while Mazur’s company SiOnyx is working on prototypes of practical applications of the material.

The Harvard researchers had discovered black silicon by accident while Mazur was researching the properties of platinum and semi-conductors. Mazur had arbitrarily chosen silicon to study—a random vial of sulfur later, black silicon was born.

“I think it shows that serendipity has a role in science,” Mazur said. “If you experiment, you’re bound to discover surprises that nature has in store for us.”

“Some people think of science as a straight paved road to a goal but that’s not the case,” he added. “Often it’s the most expected things that give the biggest surprises.”