Detailed XPS and UPS studies of the band structure of zinc oxide

Leontiev, S. A.; Кощеев, С. В.; Devyatov, V. G.; Черкашин, А. Е.; Mikheeva, E. P.

doi:10.1007/bf02763884

Cited by 28 publications

(17 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Accordingly, straight lines with slope +3 in the Wagner plot correspond to atoms with the same initial states. We have to point out that although this simplified picture is valid for core levels, in the case of ZnO, the participation of 3d states in the Auger transition could be ambiguous, as it hybridizes with about a 10% of the valence band . Due to this restricted hybridization we are confident that the previous equations for the Wagner plot are valid for the interpretation of the ZnO/graphene/Cu system.…”

Section: Resultsmentioning

confidence: 88%

Study of the Interface of the Early Stages of Growth under Quasi‐Equilibrium Conditions of ZnO on Graphene/Cu and Graphite

Morales

Black

Urbanos

et al. 2018

Adv Materials Inter

View full text Add to dashboard Cite

The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi‐equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.

show abstract

Section: Resultsmentioning

confidence: 88%

Study of the Interface of the Early Stages of Growth under Quasi‐Equilibrium Conditions of ZnO on Graphene/Cu and Graphite

Morales

Black

Urbanos

et al. 2018

Adv Materials Inter

View full text Add to dashboard Cite

show abstract

“…6,d) contain two components. The first one (O1) at 530.2 eV corresponds to the lattice oxygen in the ZnO phase, while the high-energy component (O2) at 531.2 eV is assigned to the different oxygen-containing species on the zinc oxide surface, which include hydroxy groups and different forms of chemisorbed oxygen [25–28]. No changes were detected in the Zn 2p XPS spectrum of ZnO/SiC nanocomposites compared with the similar spectrum of ZnO.…”

Section: Resultsmentioning

confidence: 99%

High-temperature resistive gas sensors based on ZnO/SiC nanocomposites

Platonov¹,

Rumyantseva²,

Frolov³

et al. 2019

Beilstein J. Nanotechnol.

View full text Add to dashboard Cite

Increasing requirements for environmental protection have led to the need for the development of control systems for exhaust gases monitored directly at high temperatures in the range of 300–800 °C. The development of high-temperature gas sensors requires the creation of new materials that are stable under these conditions. The stability of nanostructured semiconductor oxides at high temperature can be enhanced by creating composites with highly dispersed silicon carbide (SiC). In this work, ZnO and SiC nanofibers were synthesized by electrospinning of polymer solutions followed by heat treatment, which is necessary for polymer removal and crystallization of semiconductor materials. ZnO/SiC nanocomposites (15–45 mol % SiC) were obtained by mixing the components in a single homogeneous paste with subsequent thermal annealing. The composition and microstructure of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The electrophysical and gas sensing properties of the materials were investigated by in situ conductivity measurements in the presence of the reducing gases CO and NH3 (20 ppm), in dry conditions (relative humidity at 25 °C RH25 = 0) and in humid air (RH25 = 30%) in the temperature range 400–550 °C. The ZnO/SiC nanocomposites were characterized by a higher concentration of chemisorbed oxygen, higher activation energy of conductivity, and higher sensor response towards CO and NH3 as compared with ZnO nanofibers. The obtained experimental results were interpreted in terms of the formation of an n–n heterojunction at the ZnO/SiC interface.

show abstract

“…20,21 From x-ray photoelectron spectra the admixture of Zn 3d states in the O 2p band has been determined to be about 9% indicating a small covalent contribution to bonding. 22 The band dispersion has been investigated via angle-resolved photoelectron spectroscopy along a few highsymmetry directions. 23,24 The measurements reveal a strong dispersion of the upper valence bands and a smaller dispersion of the Zn 3d levels.…”

Section: Band Structure Of Zinc Oxidementioning

confidence: 99%

“…This effect is further enhanced in ZnO due to the underestimation of the repulsion between the Zn 3d and conduction band levels, 21 which leads to a significant hybridization of the O 2p and Zn 3d levels 21 and eventually to an overestimation of covalency. 25 Schröer et al have performed an analysis of the wave functions obtained from self-consistent pseudopotential calculations and determined a contribution of 20%-30% of the Zn 3d orbitals to the levels in the upper valence band 26 ͑to be compared with the experimental estimate of 9% covalency cited above 22 ͒. For zinc oxide the band gap calculated with LDA or GGA is about 0.7-0.9 eV, which is just about 25% of the experimental value ͑3.4 eV͒.…”

Section: Band Structure Of Zinc Oxidementioning

confidence: 99%

First-principles study of intrinsic point defects in ZnO: Role of band structure, volume relaxation, and finite-size effects

2006

View full text Add to dashboard Cite

Density-functional theory ͑DFT͒ calculations of intrinsic point defect properties in zinc oxide were performed in order to remedy the influence of finite-size effects and the improper description of the band structure. The generalized gradient approximation ͑GGA͒ with empirical self-interaction corrections ͑GGA+ U͒ was applied to correct for the overestimation of covalency intrinsic to GGA-DFT calculations. Elastic as well as electrostatic image interactions were accounted for by application of extensive finite-size scaling and compensating charge corrections. Size-corrected formation enthalpies and volumes as well as their charge state dependence have been deduced. Our results partly confirm earlier calculations but reveal a larger number of transition levels: ͑1͒ For both the zinc interstitial as well as the oxygen vacancy, transition levels are close to the conduction band minimum. ͑2͒ The zinc vacancy shows a transition rather close to the valence band maximum and another one near the middle of the calculated band gap. ͑3͒ For the oxygen interstitials, transition levels occur both near the valence band maximum and the conduction band minimum.

show abstract

Detailed XPS and UPS studies of the band structure of zinc oxide

Cited by 28 publications

References 18 publications

Study of the Interface of the Early Stages of Growth under Quasi‐Equilibrium Conditions of ZnO on Graphene/Cu and Graphite

Study of the Interface of the Early Stages of Growth under Quasi‐Equilibrium Conditions of ZnO on Graphene/Cu and Graphite

High-temperature resistive gas sensors based on ZnO/SiC nanocomposites

First-principles study of intrinsic point defects in ZnO: Role of band structure, volume relaxation, and finite-size effects

Contact Info

Product

Resources

About