Electronic structure and properties of magnesium oxide

Pantelides, Sokrates T.; Mickish, Daniel J.; Kunz, A. Barry

doi:10.1103/physrevb.10.5203

Cited by 106 publications

(40 citation statements)

References 40 publications

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“…where φ 0 = 1 eV represents the estimated maximum total band bending, ε 0 = 12 is the average static dielectric constant of SnO2 [23] and ρ = e ND = 10 16 cm -3 is the average charge carrier density, which is assumed to be of the same order of magnitude of the estimated bulk carrier concentration. A value for d of about 100 nm is found.…”

Section: Resultsmentioning

confidence: 99%

Morphological, structural and optical study of quasi‐1D SnO₂ nanowires and nanobelts

Calestani¹,

Lazzarini

Salviati

et al. 2005

Cryst. Res. Technol.

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0.1-0.3 mm thick entanglements of quasi-one-dimensional semiconducting Tin dioxide nanocrystals, in form of nanowires and nanobelts, are successfully grown by low cost Chemical Vapour Deposition directly on large area (100 mm 2 ) Al2O3, SiO2 and Si substrates. Their lateral size ranges from 50 to 700 nm and their length can achieve several hundreds of micrometers. Transmission Electron Microscopy reveals either the nanowires and the nanobelts grow in the tetragonal Rutile structure. Diffraction contrast analyses and selected area diffraction investigations show the nanowires are single crystals without defects while the nanobelts sometimes present twins inside. An almost cylindrical shape and an average diameter of about 30-50 nm for the smallest nanowires is reported. X-ray diffraction investigations exclude the presence of spurious phases. A broad band structured in two emissions peaked at about 450 nm and 560 nm is revealed by large area Cathotoluminescence, while single nanocrystal spectroscopy shows that the reduction of the lateral dimension of the nanobelts from 1000 nm to 50 nm blue-shifts the main emission band at 560 nm of about 40 nm (at room temperature). These preliminary results suggest a possible role of oxygen vacancies and of the surface/volume ratio on the origin and the blue shift of Cathodoluminescence spectra. The near band edge emission, typical of bulk tin dioxide (~320 nm), is not found in nanobelts narrower than 1000 nm.

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Section: Resultsmentioning

confidence: 99%

Morphological, structural and optical study of quasi‐1D SnO₂ nanowires and nanobelts

Calestani¹,

Lazzarini

Salviati

et al. 2005

Cryst. Res. Technol.

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“…This energy is very close to that obtained in previous studies. 18 Alternatively, it can be estimated as a difference of the total energies of the system with N, Nϩ1, and NϪ1 electrons 19 E g ͑ theor͒ϭE͑per,Ϫ1 ͒ϩE͑ per,ϩ1 ͒Ϫ2•E͑ per,0͒. ͑1͒…”

Section: Methodsmentioning

confidence: 99%

Structure and electrical levels of point defects in monoclinic zirconia

et al. 2001

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We performed plane wave density functional theory ͑DFT͒ calculations of formation energies, relaxed structures, and electrical levels of oxygen vacancies and interstitial oxygen atoms in monoclinic zirconia. The atomic structures of positively and negatively charged vacancies and interstitial oxygen atoms are also investigated. The ionization energies and electron affinities of interstitial oxygen atoms and oxygen vacancies in different charge states are calculated with respect to the bottom of the zirconia conduction band. Using the experimental band offset values at the interface of ZrO 2 films grown on silicon, we have found the positions of defect levels with respect to the bottom of silicon conduction band. The results demonstrate that interstitial oxygen atoms and positively charged oxygen vacancies can trap electrons from the bottom of the zirconia conduction band and from silicon. Neutral oxygen vacancy serves as a shallow hole trap for electrons injected from the silicon valence band. The calculations predict negative U for the O Ϫ center and stability of V ϩ centers with respect to disproportionation into V 2ϩ and V 0 in monoclinic zirconia.

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“…35 A result was already predicted in the pioneering work on Pantelides, Mickish, and Kunz on the electronic structure of MgO including second-order contributions for the electronic correlation effects on the excitation energies. 36 However, it is important to stress the fact that these periodic approaches are unable to predict the existence of excitons; the exciton peak on the experimental spectra has to be removed in order to obtain agreement between experimental and calculated optical spectra. 36 From the discussion above, to assume that an excitation from the metal 2p core level to the conduction band produces a change in the character of this band with the appearance of a rather localized state appears to be necessary.…”

Section: Introductionmentioning

confidence: 99%

“…36 However, it is important to stress the fact that these periodic approaches are unable to predict the existence of excitons; the exciton peak on the experimental spectra has to be removed in order to obtain agreement between experimental and calculated optical spectra. 36 From the discussion above, to assume that an excitation from the metal 2p core level to the conduction band produces a change in the character of this band with the appearance of a rather localized state appears to be necessary. Theoretical work based on ab initio Hartree-Fock cluster model wave functions shows that the excitation from the orbitals that have mainly O(2p 6 ) character to the first empty orbital of a cluster model results in an orbital that extends considerably beyond the model independently of the cluster size.…”

Section: Introductionmentioning

confidence: 99%

Core exciton energies of bulk MgO,Al2O3,and
Sousa
¹
,
Graaf
²
,
Illas
³

2000
Phys. Rev. B
17
1
5
0
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Ab initio cluster model wave functions are used to predict the existence of localized excited states in MgO, Al 2 O 3 , and SiO 2 arising from metal 2p core-level excitations. Theoretical values obtained at different levels of theory result in a quantitative agreement with experiment, and the use of different models permits us to quantify the different contributions to the final excitation energy. The most important contribution is atomic in nature; a meaningful zero-order approximation is that in MgO and Al 2 O 3 the exciton can be assigned to a M (2p 6 )→M (2p 5 3s 1 )-like excitation, where M ϭMg or Al. For the atomic models, the singlet-triplet exchange in the excited configuration is in good agreement with experiment. In addition, the solid-state effects on this exchange energy predicted by experiment are well reproduced by the cluster models representing MgO and SiO 2 , whereas a less clear situation appears in Al 2 O 3 . The open-shell orbital in the final state has, however, important contributions from the ions near the atomic site where excitation occurs. Nevertheless, the final state appears to be localized in space without any a priori assumption, the localization following from the holeparticle interaction implicitly induced in the final-state wave function. The Madelung field reduces the excitation energy with respect to the atomic value; the effect of neighboring atoms, mainly Pauli repulsion, acts in the opposite way; and electronic correlation effects decrease it again. In agreement with the covalent nature of SiO 2 , the exciton cannot be simply understood as arising from a Si(2p 6 )→Si(2p 5 3s 1 ) in a fully oxidized Si cation.

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Electronic structure and properties of magnesium oxide

Cited by 106 publications

References 40 publications

Morphological, structural and optical study of quasi‐1D SnO₂ nanowires and nanobelts

Morphological, structural and optical study of quasi‐1D SnO₂ nanowires and nanobelts

Structure and electrical levels of point defects in monoclinic zirconia

Core exciton energies of bulk MgO,Al2O3,and
Sousa
¹
,
Graaf
²
,
Illas
³

2000
Phys. Rev. B
17
1
5
0
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Electronic structure and properties of magnesium oxide

Cited by 106 publications

References 40 publications

Morphological, structural and optical study of quasi‐1D SnO2 nanowires and nanobelts

Morphological, structural and optical study of quasi‐1D SnO2 nanowires and nanobelts

Structure and electrical levels of point defects in monoclinic zirconia

Core exciton energies of bulk MgO,Al2O3,andSousa1, Graaf2, Illas3 2000Phys. Rev. B17150View full textAdd to dashboardCite

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Morphological, structural and optical study of quasi‐1D SnO₂ nanowires and nanobelts

Morphological, structural and optical study of quasi‐1D SnO₂ nanowires and nanobelts

Core exciton energies of bulk MgO,Al2O3,and
Sousa
¹
,
Graaf
²
,
Illas
³

2000
Phys. Rev. B
17
1
5
0
View full text Add to dashboard Cite