title: Insight into insulator-to-metal transition of sulfur-doped silicon by DFT calculations.
abstract: Using density functional theory calculations, the mechanism of insulator-to-metal transition of S-doped Si has been systematically investigated. The calculated crystal structure indicates that the gentle lattice distortion is caused by sulfur doping, and this doping effect is gradually weakened with the increase of sulfur concentration. Two distinct impurity energy levels in the band gap are induced by sulfur doping, and their position and width are linearly varying along with the increase of sulfur concentration. Owing to the overlap and dispersion of these impurity energy levels, the insulator-to-metal transition occurs at the sulfur concentration of 2.095 × 10(20) cm(-3), which is consistent with the experimental measurement. Moreover, the defect states related with sulfur doping show delocalization features and are more outstanding at the higher sulfur concentration. The calculated results suggest that S-hyperdoped Si is a suitable candidate for intermediate band solar cells.
authors.affiliation: Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, People's Republic of China. zzy@kmust.edu.cn.
authors.forename: Zong-Yan
authors.initials: ZY
authors.lastname: Zhao
authors.forename: Pei-Zhi
authors.initials: PZ
authors.lastname: Yang