A. Fleszar

Band structure of BeTe: A combined experimental and theoretical study

Using angle-resolved synchrotron-radiation photoemission spectroscopy we have determined the dispersion of the valence bands of BeTe(100) along

Formation of the ZnSe/(Te/)GaAs(1 0 0) heterojunction

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Energy level alignment at zinc blende Cd(Mn)Se/ZnTe/InAs(100) interfaces

, i.e. the [100] direction. The measurements are analyzed with the aid of a first-principles calculation of the BeTe bulk band structure as well as of the photoemission peaks as given by the momentum conserving bulk transitions. Taking the calculated unoccupied bands as final states of the photoemission process, we obtain an excellent agreement between experimental and calculated spectra and a clear interpretation of almost all measured bands. In contrast, the free electron approximation for the final states fails to describe the BeTe bulk band structure along

REELS measurements on a CdTe(1 0 0) surface

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Resonant inelastic soft x-ray scattering of CdS: A two-dimensional electronic structure map approach

properly.

ATOMIC AND ELECTRONIC STRUCTURE OF THE CDTE(001) SURFACE : LDA AND GW CALCULATIONS

We have investigated the underlying electronic and structural effects of the previously published influence of a Te substrate pretreatment on the heterovalent ZnSe/GaAs(1 0 0) interface [Appl. Phys. Lett. 78 (2001) 1867]. For this purpose, photoelectron spectroscopy and density functional theory calculations were employed. To determine the valence band maximum accurately, the choice of suitable photon energies to maximize the contribution from the Cpoint as well as a variation of the k-vector by measuring under selected angles is investigated. We discuss the resulting band offsets with respect to the atomic interface structure and to the broadening of core level line shapes. The theoretical investigations focus on the effect of replacing Se by Te atoms at the interface, particularly in view of the lattice structure and the band offsets. We find that Te helps to establish a group-VI-rich interface, thus lowering the valence band offset, while maintaining a good crystal quality by acting as a diffusion barrier for Se atoms. 2003 Elsevier Science B.V. All rights reserved.

Local-field effects and anisotropic plasmon dispersion in diamond

We have investigated the electronic interfacial structure of the heterovalent Cd(Mn)Se/ZnTe/InAs(100) system, which is a promising material for use in spintronic devices. By combining k-resolved valence- and core-level photoelectron spectroscopy at selected photon energies and a comparison to theoretical density of states with conduction band measurements using inverse photoemission, we find that the ZnTe interlayer leads to a stepwise alignment of the valence band offsets. The overall offset between CdSe and InAs is determined to be −0.86±0.15 eV. Furthermore, the ZnTe interlayer leads to a 1.1 eV potential barrier in the conduction band. Finally, the introduction of 12% Mn into the CdSe overlayer does not induce a significant change in the valence band discontinuity.

Resonant inelastic soft x-ray scattering of Be chalcogenides

The (1 0 0) surface of CdTe has been studied by reflection electron energy loss spectroscopy (REELS). The sample was prepared in situ in our UHV system and shows a c(2 x 2) reconstruction. The angle resolved REELS measurements for primary energies between 30 and 100eV show distinct losses between 2 and 15eV that are attributed to interband transitions, d-band transitions as well as surface and bulk plasmons. The experimental investigations are accompanied by ab initio calculations (LDA/RPA) for the bulk loss function - Im(l/e) of CdTe. From these calculations the surface loss function - Im(l/(e + 1)) is determined. The dominant loss feature at 8.7 eV in the experimental spectra is assigned to a surface plasmon. Its energetic position is ∼ 1 eV below the maximum of the calculated surface loss function and earlier measurements for the nonpolar CdTe(1 1 0) surface. This shift is attributed to the reconstruction of the CdTe(1 0 0) surface that leads to a reduced surface charge density.