title: Paired gap states in a semiconducting carbon nanotube: deep and shallow levels.
abstract: Several paired, localized gap states were observed in semiconducting single-wall carbon nanotubes using spatially resolved scanning tunneling spectroscopy. A pair of gap states is found far from the band edges, forming deep levels, while the other pair is located near the band edges, forming shallow levels. With the help of a first-principles study, the former is explained by a vacancy-adatom complex while the latter is explained by a pentagon-heptagon structure. Our experimental observation indicates that the presence of the gap states provides a means to perform local band-gap engineering as well as doping without impurity substitution.
authors.affiliation: School of Physics, Seoul National University, Korea.
authors.forename: Sungjun
authors.initials: S
authors.lastname: Lee
authors.forename: Gunn
authors.initials: G
authors.lastname: Kim
authors.forename: Hajin
authors.initials: H
authors.lastname: Kim
authors.forename: Byoung-Young
authors.initials: BY
authors.lastname: Choi
authors.forename: Jhinhwan
authors.initials: J
authors.lastname: Lee
authors.forename: Byoung Wook
authors.initials: BW
authors.lastname: Jeong
authors.forename: Jisoon
authors.initials: J
authors.lastname: Ihm
authors.forename: Young
authors.initials: Y
authors.lastname: Kuk
authors.forename: Se-Jong
authors.initials: SJ
authors.lastname: Kahng