15 February 2011
Suniva, Inc. and Varian Semiconductor Equipment Associates are collaborating on ion implantation of boron in the manufacture of solar cells, which will enable Suniva to use fewer processing steps in the mass production of its next generation n-type cell product, ARTisun Star.
ARTisun Star is scheduled for production in the first quarter of 2012 with targeted cell efficiencies that will approach 20%.
Based on years of development collaboration with Varian Semiconductor, Suniva announced last week that it is using ion implantation of phosphorous on p-type wafers to achieve 19% efficiency on its second generation ARTisun Select cells. Suniva and Varian expanded their development partnership in February 2010 to focus on the utilization of n-type wafers and boron implantation. The use of n-type wafers in the third generation ARTisun Star cells completely eliminates Light Induced Degradation (LID) and provides a higher lifetime material, which is consistent with Suniva's objective to be the leader in high-efficiency, low-cost cell manufacturing.
Leveraging both boron and phosphorous implantation, Suniva has already produced 19.1% efficient n-type solar cells on 156 mm production wafers, which have been certified by Fraunhoffer. In addition, the National Renewable Energy Laboratory has certified 20+ percent efficiencies on several laboratory-scale cells that utilize Suniva’s advanced designs for ARTisun Star.
“Suniva’s ability to already achieve verified conversion efficiencies of over 19% on 156 mm size n-type production wafers using low-cost techniques, such as conventional screen printing of metal contacts and use of an ion implanted uniform emitter and back-surface field, is unrivaled; it is a testament to the company’s commitment to solar cell research and development,” said Dr. Ajeet Rohatgi, Suniva founder and CTO. “I fully expect Suniva will have even higher solar cell efficiencies verified in the near future as we execute on our clear development roadmap to eventually achieve 22% conversion efficiency.”
“Ion implantation is an enabling technology for advancing the solar industry roadmap towards grid parity. Precise single-sided doping control, species flexibility and process simplification are key requirements for cost-effective, high-efficiency cell designs,” said Jim Mullin, VP/GM of the Solar Business Unit at Varian.
Suniva believes it is the only manufacturer of high-efficiency silicon solar cells that has achieved certified conversion efficiencies of more than 19% on 156 mm n-type wafers using low-cost techniques, including conventional screen printing and ion implantation of both a boron homogeneous emitter and a phosphorus back-surface field. This efficiency milestone was made possible through processes and intellectual property initiated by Dr. Rohatgi and chief scientist Dr. Dan Meier, and further developed in the company’s R&D lab. Suniva’s collaboration with Varian Semiconductor on ion implantation equipment will continue to contribute to this success and to the success of Suniva’s mission to develop and manufacture cells and modules that are sensibly balanced between low-cost and high-efficiency – eventually approaching the cost of electricity produced by fossil fuels.
“Our broad and deep partnership with Suniva, extending over multiple years, has yielded a process and equipment solution for volume manufacturing of high-efficiency n-type cells with low-cost, high-yield and exceptional binning,” said Dr. Paul Sullivan, VP of business development at Varian. “The combination of boron implantation and precise patterned doping are critical steps in advancing the solar roadmap.”