X-ray-absorption near-edge structure of transition-metal zinc-blende semiconductors: Calculation versus experimental data and the pre-edge feature (original) (raw)
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Physical Review B, 1989
X-ray near-edge absorption structure for Zn Te, CdTe, and Hg Te has been studied with the use of synchrotron radiation. The Ll, L2, and L3 edges have been analyzed for Cd and Te in CdTe, as well as the Ll and L3 edges for Te in ZnTe and HgTe and the K edge of Zn in ZnTe. The experimental results are compared with absorption spectra which have been calculated on the basis of conduction-band state densities obtained from self-consistent linear muffin-tin-orbital calculations. A comparison of the experimental and theoretical results yields in most cases a good quantitative agreement, in particular for all Ll and K edges analyzed. Due to deficiencies of the theoretical model, not quite so satisfactory results have been obtained for Cd L2 and L3 edges. In general, the results substantiate the opinion that the near-edge x-ray absorption for semiconductors can be satisfactorily described within the one-electron approximation, although for L2 and L3 edges the preedge region seems to be influenced by excitonic many-body eft'ects, and that the combination of xray-absorption spectroscopy (XAS) and band-structure calculations constitutes a powerful tool for investigations of the empty states of these materials.
ELECTRONIC STRUCTURE FROM X-RAY K-EDGES IN ZnS:Fe AND CuFeS 2
Le Journal de Physique Colloques, 1986
RESUME Les structures des seuils K de Zn, Fe, Cu et S dans la blende (ZnS:Fe) et dans la chalcopyrite apportent des informations sur leur structure electronique. Une Bnergie de reference commune a ete determinee pour tous les seuils. La relation XANES distance-bnergie est applicable aux differents elements a partir de cette Bnergie de reference. La comparaison avec les calculs de structure de bande de CuFeS2 est satisfaisante. ABSTRACT Information about the electronic structures of natural ZnS:Fe (zinc-blende) and CuFeS2 (chalcopyrite) has been obtained from K-edge absorption structure of Zn, Fe, Cu and S. The features in the edges of the different atoms have been used to place these spectra on a common energy scale. The inverse distance-energy relationship is consistent with the positions of shape resonances in the metal cation spectra, referenced to the same zero energy. A good agreement has been found with band structure calculations for CuFeS;?.
Physical Review B - Condensed Matter and Materials Physics, 2008
The valence band density of states ͑VB-DOS͒ of zinc-blende InN͑001͒ is investigated using a combination of high-resolution x-ray photoemission spectroscopy and quasiparticle corrected density functional theory. The zinc-blende VB-DOS can be characterized by three main regions: a plateau region after the initial rise in the DOS, followed by a shoulder on this region and a second narrow but intense peak, similar to other III-V and II-VI semiconductor compounds. Good general agreement was observed between the experimental and theoretical results. Tentative evidence for an s-d coupling due to the interaction between valence-like N 2s states and semicore-like In 4d states is also identified. Measurements and calculations for wurtzite InN͑1120͒ are shown to yield a VB-DOS similar to that of zinc-blende InN, although the nonzero crystal field and different Brillouin zone shape in this case lead to a more complicated band structure which modifies the DOS. In adlayers terminating the InN͑1120͒ surface are also evident in the experimental VB-DOS, and these are discussed.
Absorption-edge anisotropy of Cu< sub> 2 ZnSiQ< sub> 4(Q= S, Se) quaternary compound semiconductors
Journal of Alloys and Compounds, 2011
Polarization-dependent absorption characterization of Cu 2 ZnSiQ 4 (Q = S, Se) quaternary single crystal compound semiconductors were carried out in the temperature range of 10-300 K. The absorption measurements were performed on the as grown basal plane with the normal along [2 1 0] and the axis c parallel to the long edge of the crystal platelet. A significant shift towards lower energy was observed in the absorption spectra of E⊥c polarization with respect to those corresponding to E c polarization. A comprehensive analysis of the absorption spectra revealed that the absorption edges of the studied crystals are indirect allowed transitions. A schematic representation of the plausible assignments for the observed near band edge optical transitions for Cu 2 ZnSiQ 4 was proposed. The variation of the indirect transition energies with temperature were analyzed by Varshni and Bose-Einstein expressions. The parameters that describe the temperature dependence of the indirect transition energies with different polarizations were evaluated and discussed.
X-ray absorption spectroscopy of the cubic and hexagonal polytypes of zinc sulfide
Physical Review B, 2002
We investigate the sensitivity of x-ray absorption spectroscopy to cubic-hexagonal polytypism in which nearest-neighbor positions are virtually unchanged. Experimental spectra and multiple-scattering calculations are reported at the major absorption edges in the zinc-blende and wurtzite modifications of ZnS. We demonstrate that d-like unoccupied bands are preferentially affected, as only L-edge absorption is sensitive to this structural transition. The results allow
Chemical shift at the X-ray K-absorption edge of Zn in some Zn compounds
Madridge J Anal Sci Instrum, 2017
It is known that the X-ray absorption edge of metal ion may change to different extent depending upon the chemical environment viz. effective charge, nature of ligands, coordination numbers, electronegativity of anions, covalent character of the bonds, surrounded the metal ion, even at the same oxidation state. This change in the absorption energy of the metal ion in its compound from the pure metallic state (zero oxidation state) is known as the chemical shift ΔE (eV) of the metallic ion. In the present study by means of synchrotron based X-ray absorption spectroscopy study we have calculated the chemical shift and their corresponding effective charge on the Zn atoms in different Zn compounds where the Zn is present in the 2+ oxidation state.
Absorption-edge anisotropy of Cu 2ZnSiQ 4 (Q = S, Se) quaternary compound semiconductors
Journal of Alloys and Compounds, 2011
Polarization-dependent absorption characterization of Cu2ZnSiQ4 (Q = S, Se) quaternary single crystal compound semiconductors were carried out in the temperature range of 10–300 K. The absorption measurements were performed on the as grown basal plane with the normal along [2 1 0] and the axis c parallel to the long edge of the crystal platelet. A significant shift towards lower energy was observed in the absorption spectra of E⊥c polarization with respect to those corresponding to E∥c polarization. A comprehensive analysis of the absorption spectra revealed that the absorption edges of the studied crystals are indirect allowed transitions. A schematic representation of the plausible assignments for the observed near band edge optical transitions for Cu2ZnSiQ4 was proposed. The variation of the indirect transition energies with temperature were analyzed by Varshni and Bose–Einstein expressions. The parameters that describe the temperature dependence of the indirect transition energies with different polarizations were evaluated and discussed.► The polarization-dependent absorption characterization of Cu2ZnSiQ4 (Q = S, Se) quaternary single crystals were carried out. ► A significant shift towards lower energy was observed in the absorption spectrum of E⊥c polarization with respect to that corresponding to E∥c polarization. ► Analysis of the absorption spectra revealed that the absorption edges of the studied crystals are indirect allowed transitions. ► A schematic representation of the plausible assignments for the observed near band edge optical transitions for Cu2ZnSiQ4 was presented.