Revealing the Bonding Environment of Zn in ALD Zn(O,S) Buffer Layers through X-ray Absorption Spectroscopy

Abstract

Zn(O,S) buffer layer electronic configuration is determined by its composition and thickness, tunable through atomic layer deposition. The Zn K and L-edges in the X-ray absorption near edge structure verify ionicity and covalency changes with S content. A high intensity shoulder in the Zn K-edge indicates strong Zn 4s hybridized states and a preferred c-axis orientation. 2–3 nm thick films with low S content show a subdued shoulder showing less contribution from Zn 4s hybridization. A lower energy shift with film thickness suggests a decreasing bandgap. Further, ZnSO4 forms at substrate interfaces, which may be detrimental for device performance.

Atomic Layer Deposition ZnO Over-Coated Cu/SiO2 Catalysts for Methanol Synthesis from CO2 Hydrogenation

“…Compared to the spectrum of ZnO, the peaks at 9663.8 and 9668.4 eV assigned to 1s-4sp and 1s-4p transitions, were merged to one peak at 9667.5 eV in the spectra of the catalysts. The peaks at 9679.3 and 9683.4 eV were smoothed and became a shoulder (9681.1 eV), which was assigned to multiple scattering (midrange order and short-range order) [31]. This peak was only shown in the spectrum of 5Cu-5CyZn-5s instead of the catalysts with one cycle of ZnO deposition, since there was a single layer of ZnO appearance with an uncoated area on the catalyst 5Cu-1CyZn-5s and a relatively uniform ZnO layer on the catalyst 5Cu-1CyZn-30s.…”

High Energy Resolution-X-ray Absorption Near Edge Structure Spectroscopy Reveals Zn Ligation in Whole Cell Bacteria

“…The identity and number of the atoms in the first coordination shell for the Zn standards in Figure 1 is reflected in the edge position (μ′) and spectral features of the HR-XANES, which arise from Zn 1s to Zn 4sp or Zn 4p transitions as well as multiple scattering. 30 The energy of the absorption edge of a XANES spectrum is typically affected most dramatically by the oxidation state of the target element. However, at a fixed oxidation state, as is the case for Zn(II) in this study, the edge energy is also influenced by the electronegativity and number of coordinating atoms, bond angles, nearest-neighbor interatomic distances, and higher coordination spheres.…”

Synergistic ultraviolet and visible light photo-activation enables intensified low-temperature methanol synthesis over copper/zinc oxide/alumina

“…15) on samples post reaction under differing irradiation conditions. Surprisingly, no sign of Cu oxide was detected and the X-ray absorption near edge structure (XANES) region of the X-ray absorption spectra exhibited identical spectroscopic features in all treated samples similar to that of the reference Cu foil, with a shoulder on the main edge (Feature A at 8981 eV) and a main absorption peak (Feature B at 8993 eV) 41 , which appears to contradict the XPS observations. This could be explained by the difference of detection depth of the two characterization techniques, where XAS is a bulk characterisation technique giving average information for the whole sample and XPS is sensitive to the outermost surface atoms (<10 nm).…”

“…The Zn K-edge XANES spectra indicate that the overall oxidation state of ZnO in the reduced and spent catalysts did not change compared to the commercial ZnO reference, as there is no relative shift in the adsorption edge. The Zn K-edge spectrum is characterized by a main absorption peak (B, 1s → Zn 4p-O 2p hybridized states) located at 9669 K eV, a low-energy shoulder (A, 1s → Zn 4sp-O 2p hybridized states) at 9663 eV 41 . When subtracted with respect to the reduced CZA catalyst (inset of Fig.…”