2006/11/15 by Hassan Raza · 2 citations
Engineering · Physics and Astronomy · #Quantum and electron transport phenomena #Semiconductor materials and devices #Surface and Thin Film Phenomena #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.76.045308
published as Phys. Rev. B 76, 045308 (2007) · 7 pages, 10 figure, 1 table
arxiv created 2006/11/15 · openalex publication_date 2007/07/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We theoretically study the electronic band structure of isolated unpaired and paired dangling bonds (DBs), DB wires, and DB clusters on H:Si(001)\text\ensuremath-(2\ifmmode×\else\texttimes\fi1) surface using extended H"uckel theory and report their effect on the Si band gap. We show that an isolated unpaired DB introduces a near-midgap state, whereas a paired DB leads to \ensuremathπ and \ensuremathπ* states, similar to those introduced by an unpassivated asymmetric dimer (AD) Si(001)\text\ensuremath-(2\ifmmode×\else\texttimes\fi1) surface. On the other hand, the surface state induced due to an unpaired DB wire in the direction along the dimer row (referred to as [110]) has a large dispersion due to the strong coupling between the adjacent DBs, being 3.84\phantom\rule0.3em0ex\mathrm\AA apart. However, in the direction perpendicular to the dimer row (referred to as [110]), the DBs are 7.68\phantom\rule0.3em0ex\mathrm\AA apart and there is a reduced coupling between them due to exponential dependence of the wave function, leading to a small dispersion. Moreover, a paired DB wire in the [110] direction introduces \ensuremathπ and \ensuremathπ* states similar to those of an AD surface, but with a large dispersion, and a paired DB wire in the [110] direction exhibits surface states with a smaller dispersion, as expected. Besides this, we report the electronic structure of different DB clusters, which exhibit states inside the band gap that can be interpreted as superpositions of states due to unpaired and paired DBs.