A team of engineers have joined forces to develop a better monocrystalline Si-growing process using a strong magnetic field produced by a novel type of superconducting crystal growth magnet (SC-CGM). The technology is being developed at Bruker Energy & Supercon Technologies (BEST), while PVA TePla will also be involved in the project with the integration of a crystal puller at PVA TePla’s Competence Center for Industrial Crystal Growth (CCIC) in Wettenberg, Germany. First results from the project are expected in the spring of 2011.
“The goal of our cooperation with PVA TePla is to demonstrate the increase in solar cell photovoltaic conversion efficiency, which has been predicted by computer simulations, along with achieving a stable yield of crystal production,” noted Dr. Detlef Krischel, the Managing Director at BEST responsible for the SC-CGM product line. “We believe the planned novel magnetic field characteristics will allow us to better control process parameters, which are key for a high productivity Si-growing process.”
Today, the efficiency of solar cells is often degraded by too high of an oxygen content in the crystal structure. The oxygen stems from the silicon-oxide that is used in the crucible wall of the growing furnace for the so-called Czochralski process.
The application of a magnetic field along with special process control is expected to dampen the melt flow and the transport of oxygen to the crystal. A problem for the Czochralski process is that high oxygen content can be transferred to the wafers, lowering cell efficiencies.