Electronic, optical, and structural properties of some wurtzite crystals

Xu, Yong‐Nian; Ching, W. Y.

doi:10.1103/physrevb.48.4335

Cited by 696 publications

(366 citation statements)

References 102 publications

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“…Another way consists of attaching an atom, usually hydrogen, to the dangling bonds (the so-called passivation), which displaces the energies of the surface states far from the band gap. [26][27][28] However, the determination of the hydrogen pseudopotentials is not a trivial task, and it can depend on the material and on the surface orientation. The simplest way is to model the passivant pseudopotential by an analytical function, such as a Gaussian.…”

Section: Surface States and Passivationmentioning

confidence: 99%

Semiempirical pseudopotential approach for nitride-based nanostructures andab initiobased passivation of free surfaces

2012

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We present a semiempirical pseudopotential method based on screened atomic pseudopotentials and derived from ab initio calculations. This approach is motivated by the demand for pseudopotentials able to address nanostructures, where ab initio methods are both too costly and insufficiently accurate at the level of the local density approximation, while mesoscopic effective-mass approaches are inapplicable due to the small size of the structures along, at least, one dimension. In this work, we improve the traditional pseudopotential method by a two-step process: First, we invert a set of self-consistently determined screened ab initio potentials in wurtzite GaN for a range of unit-cell volumes, thus determining spherically symmetric and structurally averaged atomic potentials. Second, we adjust the potentials to reproduce observed excitation energies. We find that the adjustment represents a reasonably small perturbation over the potential, so that the ensuing potential still reproduces the original wave functions, while the excitation energies are significantly improved. We furthermore deal with the passivation of the dangling bonds of free surfaces which is relevant for the study of nanowires and colloidal nanoparticles. We present a methodology to derive passivant pseudopotentials from ab initio calculations. We apply our pseudopotential approach to the exploration of the confinement effects on the electronic structure of GaN nanowires.

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Section: Surface States and Passivationmentioning

confidence: 99%

Semiempirical pseudopotential approach for nitride-based nanostructures andab initiobased passivation of free surfaces

2012

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“…Density-functional theory (DFT) 16 in the local-density approximation (LDA) 17 has also been used to calculate optical spectra for ZnO-w 18 and ZnS-w 18 by linear combination of atomic orbitals, and for ZnS-z 19 and ZnSe-z 19 by self-consistent linear combination of Gaussian orbitals. The optical spectra of ZnO (including excitons) has been investigated 20 by solving the Bethe-Salpeter equation.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure and optical properties ofZnX(X=O,S, Se, Te): A density functional study

et al. 2007

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Electronic band structure and optical properties of zinc monochalcogenides with zinc-blende-and wurtzite-type structures were studied using the ab initio density functional method within the LDA, GGA, and LDA+U approaches. Calculations of the optical spectra have been performed for the energy range 0-20 eV, with and without including spin-orbit coupling. Reflectivity, absorption and extinction coefficients, and refractive index have been computed from the imaginary part of the dielectric function using the Kramers-Kronig transformations. A rigid shift of the calculated optical spectra is found to provide a good first approximation to reproduce experimental observations for almost all the zinc monochalcogenide phases considered. By inspection of the calculated and experimentally determined band-gap values for the zinc monochalcogenide series, the band gap of ZnO with zinc-blende structure has been estimated.

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“…[31] The calculated band gap is 1.13 eV within LSDA, which is consistent with the reported results. [32,33] Our calculations predicted magnetism in carbon doped ZnO and revealed that it results from carbon substitution for oxygen. The estimated formation energy of the C O defect is 5.3 eV.…”

mentioning

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Room-Temperature Ferromagnetism in Carbon-Doped ZnO

et al. 2007

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We report magnetism in carbon doped ZnO. Our first-principles calculations based on density functional theory predicted that carbon substitution for oxygen in ZnO results in a magnetic moment of 1.78 µ B per carbon. The theoretical prediction was confirmed experimentally. Cdoped ZnO films deposited by pulsed laser deposition with various carbon concentrations showed ferromagnetism with Curie temperatures higher than 400 K, and the measured magnetic moment based on the content of carbide in the films (1.5 − 3.0µ B per carbon) is in agreement with the theoretical prediction. The magnetism is due to bonding coupling between Zn ions and doped C atoms. Results of magneto-resistance and abnormal Hall effect show that the doped films are ntype semiconductors with intrinsic ferromagnetism. The carbon doped ZnO could be a promising room temperature dilute magnetic semiconductor (DMS) and our work demonstrates possiblity of produing DMS with non-metal doping.

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Electronic, optical, and structural properties of some wurtzite crystals

Cited by 696 publications

References 102 publications

Semiempirical pseudopotential approach for nitride-based nanostructures andab initiobased passivation of free surfaces

Semiempirical pseudopotential approach for nitride-based nanostructures andab initiobased passivation of free surfaces

Electronic structure and optical properties ofZnX(X=O,S, Se, Te): A density functional study

Room-Temperature Ferromagnetism in Carbon-Doped ZnO

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