Cheap, abundant silicon, the stuff computer chips are made of, is also the material of choice for solar cells, devices that transform sunlight into electricity. Silicon, however, converts at most only about 25 percent of the sunlight that hits it; increasing that percentage would go a long way toward making solar cells more competitive with other sources of power. Thanks to a happy accident, a group of Harvard physicists may have found a way to do just that.
About two years ago, Tsing-Hua Her, Eric Mazur, and Claudia Wu were using a laser to try to make pieces of silicon react with various types of gases inside a chamber. The physicists were hoping to find better ways to etch circuit patterns onto computer chips. But they discovered that their process created rows of perfect spikes on the surface of the silicon. "It's really amazing," says Her, "The spikes are very ...
