In typical solar cell manufacturing, the surface of the cell is doped in a process that involves heating the entire silicon wafer to a temperature in the range of 800 to 900°C. The process can damage the silicon, and wastes considerable energy. Laser doping works by firing a focused laser beam on the wafer. A small amount of dopant is initially sitting on the surface. The laser beam actually melts the silicon, which then re-solidifies, usually in less than one microsecond. The microsecond, however, is enough time to accomplish the doping.
Because the laser delivers energy to a very localized area, it would heat only that portion of the wafer that needs to be heated and can lead to more efficient solar cells. Furthermore, a laser would reduce the amount of energy required to produce solar cells, because it would no longer be necessary to heat the whole cell and the furnace around it.
Natcore’s black silicon technology has also been tested to prove that its use could reduce silicon solar cell production costs by up to 23.5%. Black silicon can eliminate the plasma enhanced chemical vapour deposition (PECVD) of silicon nitride currently in solar cell production lines.
“For Natcore, adding laser processing to our repertoire has important implications,” said Dr David Levy, Natcore’s director of research & technology. “First, it gets us in on the ground floor with a technology that we feel will represent the next generation of high-efficiency/low-cost solar cells. Second, it’s an excellent fit with our black silicon technology.”
“We are reinventing the way that solar cells are made,” said Chuck Provini, Natcore’s president and CEO. “We are streamlining the process by removing costly steps and by eliminating dangerous and expensive chemicals, like silane and phosphorous oxychloride. We are making it a low-temperature process. Although we can’t quantify it yet, we believe the result will be lower cost, higher efficiency and better quality.”