The structure of the ZnSe(100)<i>c</i>(2×2) surface

Farrell, H. H.

doi:10.1116/1.584982

Cited by 51 publications

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“…The selenium-rich surface exhibits a 2×1 reconstruction consisting of Se-dimers, very similar to the Te-terminated BeTe(001) surface, see below. The Zn-rich counterpart was under intense investigation for a long time since competing structural models were suggested for this surface [1][2][3][4][5][6]. Only recently a c(2×2) Zn-vacancy model could be confirmed for this surface [7].…”

Section: Introductionmentioning

confidence: 99%

Surface reconstructions of II‐VI compound semiconductor surfaces

Kumpf

Weigand

Müller

et al. 2007

Phys. Status Solidi (c)

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The surface structures of two model systems in the field of II-VI semiconductors -the ZnSe(001)-c(2×2) and the BeTe(001)-2×1 surface -are derived from spot-profile analysis low-energy electron diffraction and surface X-ray diffraction (SXRD). For the first, a Zn-vacancy model could be unambiguously confirmed by the comparison of our SXRD data with density functional theory calculations. The BeTe surface consists of [110]-oriented Te dimers inducing a large amount of surface strain. This causes pronounced vertical and lateral atomic displacements in the underlying BeTe bilayers which effectively relieve the surface strain. The experimentally derived atomic geometry is in very good agreement with the results of density functional theory calculations.

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Section: Introductionmentioning

confidence: 99%

Surface reconstructions of II‐VI compound semiconductor surfaces

Kumpf

Weigand

Müller

et al. 2007

Phys. Status Solidi (c)

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“…This reconstruction is also observed dur- ing ZnSe MBE in Zn-rich growth conditions, and is believed to correspond to a surface terminated by half a monolayer of Zn atoms on a complete ML of Se, i.e., to an ordered array of Zn vacancies within the outermost layer of Zn atoms. [9][10][11] The shoulder on the low kinetic-energy side of the main bulk-related Zn 3d feature, in particular, is believed to be associated with such Zn surface atoms. 9 Recent total-energy calculations have shown the c(2 ϫ2) and 2ϫ1 reconstructions to be the lowest energy configurations among those examined for Zn-rich and Se-rich surfaces, respectively.…”

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confidence: 99%

Al/ZnSe(100) Schottky-barrier height versus initial ZnSe surface reconstruction

et al. 1998

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Al/ZnSe͑100͒ Schottky barriers fabricated on c(2ϫ2), 2ϫ1, and 1ϫ1 reconstructed surfaces were studied by means of photoemission spectroscopy and first-principles calculations. Relatively similar values of the Schottky barriers were found for interfaces fabricated on Zn-stabilized c(2ϫ2) and Se-dimerized 2ϫ1surfaces, while substantially lower values of the p-type barriers were predicted theoretically and observed experimentally for junctions grown on the Se-rich 1ϫ1 surface. ͓S0163-1829͑98͒51716-X͔The possibility of tuning the Schottky-barrier height has been attracting attention since the inception of the study of metal/semiconductor junctions. 1 Recently, renewed interest has been stimulated by the contact problems that plague wide-band-gap semiconductors such as ZnSe and GaN. [2][3][4][5][6][7] We report experimental and theoretical studies of the Schottky barrier at Al/ZnSe͑100͒ interfaces showing that the barrier height is strongly dependent on the initial composition of the semiconductor surface. The observed experimental trend is that while the c(2ϫ2) and 2ϫ1 surface terminations correspond to similar barrier heights, a 0.25Ϯ0.05 decrease in the p-type barrier is found when the junction is fabricated on the Se-rich 1ϫ1 surface termination. The theoretical trend in the barrier is compellingly similar, i.e., junctions corresponding to the c(2ϫ2) and 2ϫ1 terminations are predicted to have relatively similar barrier heights ͑within 0.05 eV͒, while those obtained for the Se-rich 1ϫ1 surface are expected to have a lower p-type barrier, and specifically lower by 0.45Ϯ0.20 eV for the measured excess Se coverage of 0.41Ϯ0.18 ML of the 1ϫ1 relative to the 2 ϫ1 reconstruction. Our first-principles calculations for model interface configurations explain our experimental results in terms of a variable Se-induced local interface dipole.ZnSe epilayers ͑500 nm thick͒ were grown by molecularbeam epitaxy ͑MBE͒ on GaAs͑100͒. 8 All epilayers were Cl doped (nϳ1 -3ϫ10 18 cm Ϫ3 ). A thick Se cap layer was used to protect the samples during transfer in air to the photoelectron spectrometer. The Se cap layer was thermally desorbed in situ, and different surface reconstructions-as determined by reflection high-energy electron diffraction ͑RHEED͒-were obtained by varying the annealing conditions. Al overlayers 2-3 nm thick were evaporated in situ on ZnSe substrates kept at room temperature, with thickness determined using a quartz thickness monitor. Surfaces and interfaces were examined after quenching to room temperature by monochromatic x-ray photoemission spectroscopy ͑XPS͒ using Al K␣ radiation ͑1486.6 eV͒, an overall energy resolution ͑electron plus photons͒ of ϳ0.8 eV, and an effective photoelectron escape depth of ϳ1.5 nm, or by soft-x-ray synchrotron radiation photoemission spectroscopy ͑SRPES͒ at the Synchrotron Radiation Center of the University of Wisconsin-Madison, with an energy resolution of 0.2 eV.In Fig. 1 we show SRPES results for the Se 3d and Zn 3d core-level emission at a photon energy of 120 eV from surfaces exhi...

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“…This procedure would shift the rebonded Ga atom to the left and one As dimer to the right. A close inspection shows that this reconstruction is analogous to GaAs͑001͒a͑2 3 4͒ [33] and has been denominated ͑114͒a͑2 3 1͒ [24]. Therefore we call our structure ͑114͒a2͑2 3 1͒ and mention that it is the analog to InAs͑001͒a2͑2 3 4͒ [34].…”

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confidence: 83%

Atomic Structure of the Stoichiometric GaAs(114) Surface

et al. 2001

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The stoichiometric GaAs(114) surface has been prepared using molecular beam epitaxy followed by annealing in ultrahigh vacuum. Based on in situ scanning tunneling microscopy measurements and first-principles electronic-structure calculations, we determine the surface reconstruction which we call alpha2(2x1). Contrary to what is expected for a high-index surface, it is surprisingly elementary. The (2x1) unit cell contains two As dimers and two rebonded Ga atoms. The surface energy is calculated as 53 meV/Å(2), which falls well within the range of low-index GaAs surface energies.

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The structure of the ZnSe(100)c(2×2) surface

Cited by 51 publications

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Surface reconstructions of II‐VI compound semiconductor surfaces

Surface reconstructions of II‐VI compound semiconductor surfaces

Al/ZnSe(100) Schottky-barrier height versus initial ZnSe surface reconstruction

Atomic Structure of the Stoichiometric GaAs(114) Surface

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