title: Electronic Band Structure and Sub-band-gap Absorption of Nitrogen Hyperdoped Silicon.
abstract: We investigated the atomic geometry, electronic band structure, and optical absorption of nitrogen hyperdoped silicon based on first-principles calculations. The results show that all the paired nitrogen defects we studied do not introduce intermediate band, while most of single nitrogen defects can introduce intermediate band in the gap. Considering the stability of the single defects and the rapid resolidification following the laser melting process in our sample preparation method, we conclude that the substitutional nitrogen defect, whose fraction was tiny and could be neglected before, should have considerable fraction in the hyperdoped silicon and results in the visible sub-band-gap absorption as observed in the experiment. Furthermore, our calculations show that the substitutional nitrogen defect has good stability, which could be one of the reasons why the sub-band-gap absorptance remains almost unchanged after annealing.
authors.affiliation: Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Hezhu
authors.initials: H
authors.lastname: Shao
authors.affiliation: Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Bo-Yuan
authors.initials: BY
authors.lastname: Ning
authors.affiliation: Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433, China.
authors.forename: Xi-Jing
authors.initials: XJ
authors.lastname: Ning
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhuang