Suntech’s chief technology officer, Stuart Wenham, says his company got the idea for the technology from old patent applications by an inventor named Fred Schmid. The patents were about to expire, so Suntech researchers set about figuring out how to make the ideas work, Wenham says. Schmid had developed a method for growing large crystals of sapphire and founded a company called Crystal Systems to commercialize the technology in the 1970s. He worked to apply the technology to making monocrystalline silicon but wasn’t successful.
BP’s technology also had roots in Schmid’s ideas. In 2005, a researcher named Nathan Stoddard, who had just finished graduate school, joined BP Solar’s team in Frederick, Maryland. He learned about Schmid’s work from a former employee at Crystal Systems, and quickly found a way to make it work with silicon. “Within six months of my starting at BP, the process was working in production-scale furnaces,” Stoddard says.
Suntech’s approach still produces some multicrystalline silicon along the sides of the cube—it can still be used, but is lower efficiency than the monocrystalline. Clark says ALD’s approach could yet be competitive because it does not produce multicrystalline silicon.