title: Stability and segregation of B and P dopants in Si/SiO2 core-shell nanowires.
abstract: Using molecular dynamics simulations, we generate realistic atomic models for oxidized Si nanowires which consist of a crystalline Si core and an amorphous SiO(2) shell. The amorphous characteristics of SiO(2) are well reproduced, as compared to those for bulk amorphous silica. Based on first-principles density functional calculations, we investigate the stability and segregation of B and P dopants near the radial interface between Si and SiO(2). Although substitutional B atoms are more stable in the core than in the oxide, B dopants can segregate to the oxide with the aid of Si self-interstitials which are generated during thermal oxidation. The segregation of B dopants occurs in the form of B interstitials in the oxide, leaving the self-interstitials in the Si core. In the case of P dopants, dopant segregation to the oxide is unfavorable even in the presence of self-interstitials. Instead, we find that P dopants tend to aggregate in the Si region near the interface and may form nearest-neighbor donor pairs, which are energetically more stable than isolated P dopants.
authors.affiliation: Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors.forename: Sunghyun
authors.initials: S
authors.lastname: Kim
authors.forename: Ji-Sang
authors.initials: JS
authors.lastname: Park
authors.forename: K J
authors.initials: KJ
authors.lastname: Chang