Transformation of Cl bonding structures on Si(100)-(2×1)

Cheng, Chih‐Chia; Gao, Quanyin; Choyke, W. J.; Yates, John T.

doi:10.1103/physrevb.46.12810

Cited by 42 publications

(26 citation statements)

References 33 publications

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“…This structural model is confirmed by photoemission measurements [8], Low-Energy Electron Energy-Loss Spectroscopy (LEELS) [73] and SEXAFS measurements [74]. This binding configuration is also favoured by measurements of the Electron-Stimulated-Desorption IonAngular-Distribution (ESDIAD) [75].…”

Section: Adsorption Of Group-vil Elements: C1 On Si(o01)supporting

confidence: 50%

Theory of adsorption: Ordered monolayers from Na to Cl on Si(001) and Ge(001)

Krüger

Pollmann

1994

Appl. Phys. A

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Abstract. First principles calculations of clean and adsorbate-covered surfaces of Si(001) and Ge(001) are reported. Chemical trends in the adsorption of ordered Na, K, Ge, As, Sb, S, Se and CI overlayers are discussed. The calculations are based on the local-density approximation and employ non-local, norm-conserving pseudopotentials together with Gaussian orbital basis sets. The semi-infinite geometry of the substrate is properly taken into account by employing our scattering theoretical method. From total-energy minimization calculations we obtain optimal surface reconstructions which show asymmetric dimers for Si(001), Ge(001) and Ge:Si(001). For As:Si(001), Sb:Si(001) and Sb:Ge(001), we find symmetric adatom dimers in the equilibrium geometries. S or Se adlayers are found to be adsorbed in bridge positions forming a (1 x 1) unit cell with a geometry very close to the configuration of a terminated bulk lattice. C1 atoms adsorb on top of the dangling bonds of symmetric Si dimers residing in the first substrate-surface layer. Our calculations for Na:Si(001) and K:Si(001) confirm valleybridge site adsorption for half monolayer coverage. For full monolayer alkali-metal coverage, adsorption in pedestal and valley-bridge positions is found to be energetically most favourable. The calculated optimal adsorption configurations are in excellent agreement with a whole body of recent experimental data on surface-structure determination. For these structural models, we obtain electronic surface band structures which agree very good with a wealth of data from angle-resolved photoemission spectroscopy investigations. The adsorption of adlayers at semiconductor surfaces has been under intensive study in recent years. These investigations are motivated by fundamental physical reasons and important technological applications. In basic research, semiconductors are interesting substrates for adsorption systems due to the unsaturated directional bonds at their surfaces. This allows the formation of chemical compounds which are neither stable as small, isolated molecules nor as extended solids. The technological interest ranges from homoand heteroepitaxy and growth, via surface passivation and doping to dry etching and photo-surface cleaning. For example, the quality of the heteroepitaxial growth of GaAs on Si is determined by the initial stage of this process which consists in formation of As adlayers. Furthermore, surface passivation may involve As, S or Se atoms. In the fabrication of electronic devices, dry etching and photo-surface cleaning is carried out by the reaction of C1 on Si. The adsorption of alkali metals in the range of monolayer coverage leads to a drastic reduction of the ionization energy. These systems have important applications as high-efficiency emitters. They are also widely discussed in the context of the Schottky-barrier problem [1].

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Section: Adsorption Of Group-vil Elements: C1 On Si(o01)supporting

confidence: 50%

Theory of adsorption: Ordered monolayers from Na to Cl on Si(001) and Ge(001)

Krüger

Pollmann

1994

Appl. Phys. A

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“…In particular, the adsorption of Cl 2 on Si(001) surfaces has been studied by a variety of experiments and theoretical calculations [2][3][4][5][6][7][8][9][10][11]. Experiments using electron stimulated desorption ion angular distribution (ESDIAD) and high resolution electron energy loss (HREELS) have demonstrated the existence of a stable adsorption site at the dangling bond and a metastable bridge-bonded state [6]. The structural properties and energetics of these two sites have been explained satisfactorily by density functional calculations [7][8].…”

Section: Introductionmentioning

confidence: 99%

First principles total energy calculations of the adsorption of single Cl₂ and Br₂ molecules on the Si(001)‐c(2 × 4) surface

Takeuchi¹

2003

Physica Status Solidi (b)

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We have performed first principles total energy calculations to investigate the adsorption of Cl 2 and Br 2 molecules on the Si(001)-c(2 × 4) surface. First of all, our results indicate that the adsorption of Cl 2 and Br 2 as molecules is not energetically favorable. Instead, Cl 2 (Br 2 ) dissociates into two Cl (Br) subunits. The most stable geometry was achieved when each Cl (Br) subunit is bonded to a Si atom of the same Si dimer along the dangling bonds. Three other geometries were considered in our study: the first one corresponds to adsorption of the two subunits on Si dimer sites in adjacent silicon dimer rows. The second corresponds to adsorption of the two Cl (Br) subunits along dangling bonds of two consecutive dimers of the same Si dimer row, with the two Cl(Br) atoms in the same side of the Si dimer row. The third one is similar to the second, but the ad-atoms are now in a staggered arrangement, occupying sites in opposite sides of the Si dimer row. These are adsorption configurations that have been observed experimentally for Cl 2 on Si(001). Our results indicate that energetics and atomic geometries are similar for Cl 2 and Br 2 . We have also calculated energy barriers for the ad-atom to move along and across the Si dimer rows. It is found that the barriers for Br are smaller than the barriers for Cl. This result can explain the differences observed in the adsorption of Cl 2 and Br 2 molecules.

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“…The first ESDIAD studies on a covalent surface, Si(100), concerned the adsorption of fluorine [14]. More recently, -CI groups produced by Cl 2 chemisorption near 500 K on Si(100)-(2x1) have been investigated with ESDIAD [7,15]. A four-beam Cl+ pattern is observed at 120 K as shown in Figure 4b and 4c.…”

Section: B Chemisorption On a Semiconductor Surfacementioning

confidence: 99%

“…A four-beam Cl+ pattern is observed at 120 K as shown in Figure 4b and 4c. These CI+ beams originate from Si-Cl covalent bonds, which are inclined from the surface normal in four specific directions at an angle of 25 ± 4 from the surface normal [7]. These four directions correspond to the orthogonal Si-Si surface dimer bond directions exposed on alternate terraces of Si (100); the steps and terraces are caused by slight misalignment of the crystal, and a symmetric dimer site in one domain is shown in Figure 4a.…”

Section: B Chemisorption On a Semiconductor Surfacementioning

confidence: 99%

“…The measured angles of ejection of ions must be corrected for final state effects which include deflections by attractive image effects between the ion and the substrate from which the ion is escaping [6]. Also, angle and velocity dependent neutralization effects must be considered in correcting the measured ejection angles to determine the true bond directions [6,7]. In addition, in recent years it has been found that neutral metastable electronically excited particles are also produced in ESD, and in some cases these may be detected by the ESDIAD apparatus [8].…”

Section: I1 the Esdiad Phenomenonmentioning

confidence: 99%

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Electron Stimulated Desorption-Ion Angular Distribution (ESDIAD): A method for Imaging Chemical Bond Directions and Thermal Disorder in Adsorbed Species

Yates¹

1993

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Transformation of Cl bonding structures on Si(100)-(2×1)

Cited by 42 publications

References 33 publications

Theory of adsorption: Ordered monolayers from Na to Cl on Si(001) and Ge(001)

Theory of adsorption: Ordered monolayers from Na to Cl on Si(001) and Ge(001)

First principles total energy calculations of the adsorption of single Cl₂ and Br₂ molecules on the Si(001)‐c(2 × 4) surface

Electron Stimulated Desorption-Ion Angular Distribution (ESDIAD): A method for Imaging Chemical Bond Directions and Thermal Disorder in Adsorbed Species

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Transformation of Cl bonding structures on Si(100)-(2×1)

Cited by 42 publications

References 33 publications

Theory of adsorption: Ordered monolayers from Na to Cl on Si(001) and Ge(001)

Theory of adsorption: Ordered monolayers from Na to Cl on Si(001) and Ge(001)

First principles total energy calculations of the adsorption of single Cl2 and Br2 molecules on the Si(001)‐c(2 × 4) surface

Electron Stimulated Desorption-Ion Angular Distribution (ESDIAD): A method for Imaging Chemical Bond Directions and Thermal Disorder in Adsorbed Species

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First principles total energy calculations of the adsorption of single Cl₂ and Br₂ molecules on the Si(001)‐c(2 × 4) surface