Harvard physicists, led by Eric Mazur, have stumbled on a new material, called black silicon that could have a major impact on digital photography, night vision and solar cells.
The researchers shone an exceptionally powerful laser light on a silicon wafer and also applied sulfur hexafluoride, a gas used by the semiconductor industry to make etchings for circuits. As a result, the silicon wafer looked black to the naked eye. But when the material was examined with an electron microscope, the surface appeared covered with a forest of ultra-tiny spikes.
At first, the researchers had no idea what they had stumbled onto but black silicon has since been found to have extreme sensitivity to light – 100 to 500 times as sensitivity to light as conventional silicon detectors. The material has the ability to detect infrared light that is invisible to the current generation of silicon detectors.
Black silicon was discovered because Dr. Mazur, who had been financed by the Army Research Organization to explore catalytic reactions on metallic surfaces, became concerned in the late 1990s that his funding would dry up. So he wrote in a new direction for research, got his funding but didn’t pursue the new line of research until recently.
The new material has a tremendous cost advantage because it is compatible with current semiconductor manufacturing plants.
The low cost and higher sensitivity of black silicon make it attractive for the multibillion-dollar digital camera and video markets as well as for solar cells, but the first application is likely to be in night vision equipment.