title: Silica-sol-based spin-coating barrier layer against phosphorous diffusion for crystalline silicon solar cells.
abstract: The phosphorus barrier layers at the doping procedure of silicon wafers were fabricated using a spin-coating method with a mixture of silica-sol and tetramethylammonium hydroxide, which can be formed at the rear surface prior to the front phosphorus spin-on-demand (SOD) diffusion and directly annealed simultaneously with the front phosphorus layer. The optimization of coating thickness was obtained by changing the applied spin-coating speed; from 2,000 to 8,000 rpm. The CZ-Si p-type silicon solar cells were fabricated with/without using the rear silica-sol layer after taking the sheet resistance measurements, SIMS analysis, and SEM measurements of the silica-sol material evaluations into consideration. For the fabrication of solar cells, a spin-coating phosphorus source was used to form the n(+) emitter and was then diffused at 930°C for 35 min. The out-gas diffusion of phosphorus could be completely prevented by spin-coated silica-sol film placed on the rear side of the wafers coated prior to the diffusion process. A roughly 2% improvement in the conversion efficiency was observed when silica-sol was utilized during the phosphorus diffusion step. These results can suggest that the silica-sol material can be an attractive candidate for low-cost and easily applicable spin-coating barrier for any masking purpose involving phosphorus diffusion.
authors.affiliation: Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Uzum
authors.affiliation: Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Fukatsu
authors.affiliation: Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanda
authors.affiliation: Specialty Materials Research Laboratory, Nissan Chemical Industries, Ltd., 11-1 Kitasode, Sodegaurashi, Chiba 299-0266, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kimura
authors.affiliation: Specialty Materials Research Laboratory, Nissan Chemical Industries, Ltd., 11-1 Kitasode, Sodegaurashi, Chiba 299-0266, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tanimoto
authors.affiliation: Graduate School of Materials Science Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Yoshinaga
authors.affiliation: Graduate School of Materials Science Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Yunjian
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Graduate School of Materials Science Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Graduate School of Materials Science Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Yukiharu
authors.initials: Y
authors.lastname: Uraoka
authors.affiliation: Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Ito
keywords: CZ-Si; Phosphorus barrier; Silica nanoparticle; Sol-gel; Spin-coating