Electronic and Structural Properties of the (101̅0) and (112̅0) ZnO Surfaces

The photoluminescence (PL) emission from zinc sulfide (ZnS) synthesized by the microwave-assisted solvothermal method in the presence/absence of a capping agent was examined to understand the key role of its PL activity. In addition, we also investigated the electronic structure using a first-principle calculation based on density functional theory (DFT) applied to periodic models at BÁLYP level. Two models were selected to simulate the effects of structural deformation on the electronic structure; the ordered o-ZnS model and the disordered d-ZnS model, dislocating the Zn atom, 0.1 Å , in the z-direction. The PLemission in the visible region showed different peak positions and intensities in capped and uncapped ZnS. The PL emission was linked to distinct distortions in lattices and the emission of two colors, green in the capped and blue in the uncapped, was also examined in the light of favorable structural and electronic conditions. The computational simulations indicate that the electronic behavior can be associated with the new electronic levels above the valence band.

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“…[27][28][29][30] The atomic centers have been described by an all electron basis set, Zn_86-411d31 G, 31 for Zn and S_86-311 G* S, 32 atoms.…”

Section: Theoretical Studiesmentioning

confidence: 99%

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

Santana

Raubach

Ferrer

et al. 2011

Journal of Applied Physics

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“…This can be avoided using non-polar growth directions, where out-of-plane electric fields and spontaneous polarization effects are absent. The physical properties of non-polar ZnO surfaces were investigated theoretically [4][5][6][7] and experimentally by low energy electron diffraction (LEED), [8][9][10] scanning tunneling microscopy (STM) and/or spectroscopy (STS), [11][12][13] and other surface sensitive techniques. [14][15][16][17] It is generally accepted that non-polar ð11 20Þ and ð10 10Þ ZnO surfaces exhibit a 1 Â 1 surface unit cell, where the surface oxygen atom relaxes slightly outward, while the surface zinc atom becomes more sp 2 hybridized.…”

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confidence: 99%

“…This relaxation is combined with a charge transfer from Zn to O, but the resulting electronic properties are strongly debated: Some calculations predict that the intrinsic surface states are outside of the fundamental bulk bandgap, 4,5 while a newer calculation suggests intrinsic surface states within the fundamental bandgap, at least for the ð10 10Þ surface. 7 In STS spectra, the apparent surface bandgaps range from $2.0 eV (Ref. 11) down to 1.0 eV.…”

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confidence: 99%

Intrinsic bandgap of cleaved ZnO(112¯) surfaces

Sabitova

Ebert

Lenz

et al. 2013

Applied Physics Letters

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The existence of intrinsic surface states, the position of the Fermi level, and the size of the surface bandgap of the non-polar ZnO(112¯0) cleavage surfaces were investigated by scanning tunneling microscopy and spectroscopy. The comparison of spectroscopic measurements performed on atomically flat and stepped surfaces reveals the absence of intrinsic surface states within the fundamental bulk bandgap, but shows the occurrence of step-induced gap states. These states lead to a pinning of the Fermi level at the surface within the bandgap and generate a significant defect-related tunnel current, narrowing the measured apparent bandgap.

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“…The unit cell has two external lattice parameters: the basal plane (a) and uniaxial plane (c) and an internal parameter u, which describes the cation and anion positions relative to the z axis (Jaffe and Hess, 1993;Marana et al, 2008). The ZnO wurtzite structure belongs to the space group P63mc with a Bravais lattice (a = 3.250 Å and c = 5.207 Å and internal coordinate u = 0.382) (Decremps et al, 2003) and can be depicted as a zinc atom surrounded by four oxygen atoms with sp 3 -hybridization in a tetrahedron configuration along the caxis.…”

Section: Resultsmentioning

confidence: 99%

Optical and Structure Analysis of ZnO:Al Film

Trindade¹,

Chaves²,

Bortoleto³

et al. 2017

American Journal of Engineering and Applied Sciences

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ZnO and ZnO:Al are wide-bandgap semiconductors which have many applications, mainly as transparent conducting films. Thin films of these compounds were deposited onto glass and silicon substrates by RF magnetron sputtering for the investigation of structural and optical characteristics. The XRD results show that the films present wurtzite structure. The formation of a polycrystalline film having a preferential crystallographic orientation in the plane (002) is observed in the doped samples. The Al incorporated films exhibited optical transmittance above 80% in the visible spectrum and a clear absorption band in the infrared due to free carriers. Additionally, the optical band gap around 3.48 eV is significantly above the values for the intrinsic ZnO (3.25 eV). Photoluminescence (PL) measurements showed a broad emission band in the visible region. In addition, PL emission lines at 3.32 and 3.37 eV showed up in Al incorporated films, and were related to excitonic emissions. The results show that the Burstein-Moss effect plays a central role in determining the optical characteristics of the doped material.

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Electronic and Structural Properties of the (101̅0) and (112̅0) ZnO Surfaces

Cited by 84 publications

References 54 publications

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

Intrinsic bandgap of cleaved ZnO(112¯) surfaces

Optical and Structure Analysis of ZnO:Al Film

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