Novel Low Cost Processes for Production of Crystalline Silicon Wafers for Photovoltaic Industry

¿Clean energy¿ is attracting more and more interest, which in turn exerts cost pressure on photovoltaic (PV) manufacturers for more efficient solar panel production. This project will develop a cost-effective technology to produce PV-grade silicon wafers. In Phase I, a non-oxide-based reuseable crucible was developed for the production of high purity, low oxygen content crystalline silicon ingots. The approach was based on a reusable thermal-expansion-coefficient-matched graphite crucible and a high purity, multilayered release coating. The crucible was used to develop a rapid, single-crystal growth technique for photovoltaic-grade silicon. Silicon ingots grown with this technique resulted in better yield and higher throughput. Phase II will: (1) scale-up the reusable crucible to grow 270 kg ingots, using a state-of-the-art directional solidification system; (2) optimize the rapid crystal growth process using the reusable crucible; and (3) develop a high-throughput, continuous, in-line, silicon brick casting system using the reusable crucible. Commercial Applications and other Benefits as described by the awardee: The new silicon wafer production technique should reduce the cost of solar wafers, which is the bottleneck for the healthy growth of the photovoltaic industry. The new technology should have significant advantages over existing techniques ¿ reduced energy costs, much lower cost of solar wafers, higher cell efficiency.