Ab initio theoretical studies of atomic and electronic structures of III-nitride (110) surfaces

Alves, H. W. Leite; Alves, J.L.A.; Nogueira, R. A.; Leite, J. R.

doi:10.1590/s0103-97331999000400044

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…The obtained results for the calculated structural parameters are depicted in Table 1, compared with GaN and InN(110) surfaces [14]. First, we note that, in both cases, the uppermost layer (the GaN or InN monolayer) moves inward the surface, but it still respect the fact that the cation relaxes inward and the anion outward.…”

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confidence: 93%

Adsorption of Ga, In and N over GaAs(110) Surfaces

Paiva

Alves

2002

phys. stat. sol. (c)

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PACS : 68.35.Bs; 68.43.Bc We present, in this work, our preliminary results of a systematic theoretical study of the adsorption of Ga, In and N over GaAs(110) surfaces. We analyze the changes in the bond lengths and in the bond angles before and after deposition, as well as the total energy behaviour with the adsorbate position variation. Our results show that both the InN and GaN growth over GaAs(110) are possible. Also, based on our results, we speculate the arsenic mediated growth for GaN over GaAs substrates which shows a surfactant effect.Introduction The group III-nitrides (AlN, GaN, InN) and the corresponding alloys have attracted great interest due to their successful applications in the electronic and optoelectronic device technology [1]. However, their growth in the zinc-blende structure has been a hard task to the experimentalists, once the most stable structure for these compounds is the wurtzite one.A lot of substrates has been proposed for the III-nitride growth in the cubic modification, and the nitridation of the GaAs surfaces seems to be the most efficient technique for such growth [2][3][4]. Here, the (110) or the (100) GaAs surfaces are exposed to a nitrogen plasma, once that nitrogen molecules do not dissociate on these surfaces due to their large binding energy. In the plasma process, since the cross section is much larger for the dissociation than for ionization of N 2 molecules, N atoms may be produced by electron impact. So, the nitridation proceeds simply via an anion exchange reaction over the GaAs substrate [3,4].Despite the experimental advances on the III-nitride growth by nitridation techniques, however, the amount of theoretical calculations on this subject is rather scarce, to our knowledge. In order to supply the missing theoretical understanding of this new growth process for III-nitrides over GaAs substrate, we present, in this work, our preliminary results of a systematic theoretical study of the adsorption of Ga, In and N over GaAs(110) surfaces.By using the slab supercell model, our results were obtained by two types of calculations: the first based on accurate, parameter-free, self-consistent total energy and force calculations using the density functional theory [5], the local-spin-density approximation for the exchange-correlation term [6], and the plane-wave pseudopotential method with the Hartwigsen-Goedecker-Hutter pseudo-potentials [7]. (The Abinit code is a common project of the Université Catholique de Louvain, Corning Incorporated, and other contributors [8]). The second is based on the semi-empirical Extended Hü ckel method (EHT) in the crystalline orbital theory (Bicon-Cedit code [9]). We have used, in both calculations, supercells build up of 7 atomic layers and a vacuum region equivalent of

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confidence: 93%

Adsorption of Ga, In and N over GaAs(110) Surfaces

Paiva

Alves

2002

phys. stat. sol. (c)

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“…Electronic structure calculations [36] are essential for studying the microscopic quantum mechanical properties of solids, molecules and some nanoscale materials. PDOS provide an insight into the interactions between the adsorbates and the adsorbents.…”

Section: Electronic Structure Analysismentioning

confidence: 99%

First-principles study of carbon chemisorption on γ-Fe(111) surface

Jiang¹,

Liu²,

Chen³

2010

Braz. J. Phys.

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In order to study the interaction between γ-Fe and carbon, the geometry structures, surface relaxations, adsorption energies and electronic structures for carbon chemisorption at four different adsorption sites on γ-Fe(111) surface at a monolayer coverage of 1 were studied using density functional theory. The electronic structures were compared with the chemisorption of carbon on nickel (111) at the fcc hollow site. Based on the computational adsorption energies, the relative stabilities were described as follows: hcp hollow ≈ fcc hollow > top-on site, whereas the atomic carbon can not occupy the bridge sites stably. The partial density of states indicated the strong C(2p)-Fe(3d, 4s+p) and the wide C(2s+p)-Fe(3d) ionic bonds, which largely confined the electrons of the surface iron. Accordingly, the number of orbitals at the Fermi level for the iron in the surface is obviously less than that in the subsurface. Moreover, comparing the carbon chemisorptions on γ-Fe and nickel surface at the fcc hollow site, one could see that the number of orbitals at the Fermi level for carbon adsorbed on γ-Fe(111) is less than on Ni(111) surface. This could imply the weaker catalysis of γ-Fe than nickel for carbon atom.

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