Small polaron formation in dangling-bond wires on the Si(001) surface

Abstract

From electronic structure calculations, we find that carriers injected into dangling-bond atomic wires on the Si(001) surface will self-trap to form localised polaron states. The self-trapping distortion takes the form of a local suppression of the buckling of the dimers in the wire, and is qualitatively different for the electron and hole polarons. This result points to the importance of polaronic effects in understanding electronic motion in such nanostructures.Comment: LaTeX with APS RevTeX macros; 14 pages including 4 figures in EPS forma

Soliton effects in dangling-bond wires on Si(001)

“…These show that the gap states are strongly localized on the defect atoms, and have almost no contributions from neighboring atoms. The overall structures of the defects are similar to that of the polaron seen in the same system, 11,12 and indicates that the soliton is similarly weakly coupled to the bulk. The overall behavior and form of the soliton in the DB wire are very different from the conjugated polymer system.…”

“…We also note that the value of the gap is in good agreement with our previous calculations on the system. 11 A soliton is generally associated with a midgap state, which is seen here in the change of the valence and conduction bands. These effects can be understood in terms of the hybridization of the silicon making up the surface: in ideal, bulk positions the atoms are sp 3 hybridized, but reconstruction into dimers at the surface pulls the atoms away from this state.…”

Interaction of atomic hydrogen with the β-SiC(100) 3×2 surface and subsurface

“…33,57,58 Indeed, such a mode could also be identified in similar IRAS experiments performed on hydrogen atoms covering the Si-terminated ␤-SiC͑100͒ c͑4 ϫ 2͒ surface reconstruction 58 where the topmost Si plane is located just above the first carbon plane. [10][11][12][13][14][15][16][17] 33,58 Turning to the metallization process, the above Si 2p results indicate that it is likely to result from two origins: ͑i͒ An effective charge transfer from H atoms terminating each topmost Si dangling bond belonging to the first Si atomic plane and ͑ii͒ an attack in the third Si plane leading to an additional asymmetric charge transfer.…”

“…2,5,7 Molecular hydrogen has been shown to interact with the Si-terminated ␤-SiC͑100͒ c͑4 ϫ 2͒ surface at sticking probabilities eight orders of magnitude higher than on silicon surfaces and efficient molecular dissociation leading to have H atoms also decorating the top-surface Si dangling bonds. [13][14][15][16][17] Silicon carbide ͑SiC͒ is a IV-IV compound wide-bandgap semiconductor having a strong interest in high power, high temperature, high frequency, and high voltage microelectronic devices and sensors. 8 This very selective interaction of hydrogen molecules with these two very different surface reconstructions has been explained in terms of interdimer versus intradimer adsorption sites.…”

Energetics and stability of dangling-bond silicon wires on H passivated Si(100)

“…We can observe that two bands appear in the bulk energy gap, and they mainly come from the DB-silicons. The gap is reduced with respect to the completely passivated surface, but we still obtain 0.66 eV for the direct band gap, and 0.50 eV x: [110] (a) y: [110] x: [1][2][3][4][5][6][7][8][9][10] y: [110] 0.14 Å 0.78 Å (c) (b)…”