Surface preparation and post thermal treatment effects on interface properties of thin Al2O3 films deposited by ALD

Chang, Yung-Yuan; Ducroquet, F.; Gautier, Éric; Renault, O.; Legrand, J. F.; Damlencourt, J.-F.; Martín, F.

doi:10.1016/j.mee.2004.01.012

Cited by 28 publications

(24 citation statements)

References 19 publications

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“…However, Al 2 O 3 in MOS devices is usually deposited via atomic layer deposition, which results in an amorphous phase with electronic properties differing considerably from those of crystalline phases. [21][22][23][24] Furthermore, the experimental characterization of defect states in a-Al 2 O 3 has led to conflicting interpretations. The oxygen vacancy has been invoked as an electron trap in oxygen-deficient a-Al 2 O 3 films on the basis of electron energy loss, photoluminescence, and capacitance measurements, and this suggestion has received support from theoretical studies based on density-functional-theory calculations.…”

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confidence: 99%

Oxygen defects in amorphous Al2O3: A hybrid functional study

Guo

Ambrosio

Pasquarello

2016

Applied Physics Letters

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The electronic properties of the oxygen vacancy and interstitial in amorphous Al 2 O 3 are studied via ab initio molecular dynamics simulations and hybrid functional calculations. Our results indicate that these defects do not occur in amorphous Al 2 O 3 , due to structural rearrangements which assimilate the defect structure and cause a delocalization of the associated defect levels. The imbalance of oxygen leads to a nonstoichiometric compound in which the oxygen occurs in the form of O 2− ions. Intrinsic oxygen defects are found to be unable to trap excess electrons. For low Fermi energies, the formation of peroxy linkages is found to be favored leading to the capture of holes. The relative +2/0 defect levels occurs at 2.5 eV from the valence band. in MOS devices is usually deposited via atomic layer deposition, which results in an amorphous phase with electronic properties differing considerably from those of crystalline phases. [21][22][23][24] Furthermore, the experimental characterization of defect states in a-Al 2 O 3 has led to conflicting interpretations. The oxygen vacancy has been invoked as an electron trap in oxygen-deficient a-Al 2 O 3 films on the basis of electron energy loss, photoluminescence, and capacitance measurements, and this suggestion has received support from theoretical studies based on density-functional-theory calculations. 6,21 At variance,Århammar et al. 7 synthesized a-Al 2 O 3 via physical vapour deposition and investigated the defect states in the gap using X-ray absorption and resonant inelastic scattering techniques. Supplementing their experimental results with computational studies, they assigned the observed defect states to peroxy linkages between two oxygen atoms (O-O) rather than to oxygen vacancies.In order to elucidate the nature of oxygen-related defects in a-Al 2 O 3 , we here investigate the structural and electronic properties of oxygen vacancies (V O ) and interstitials (O i ) in a-Al 2 O 3 through ab initio molecular dynamics (MD) simulations and hybrid functional calculations. We find that structural rearrangements in the amorphous can assimilate oxygen vacancies in the +2 charge state and oxygen interstitials in the −2 charge state removing any electronic state from the band gap. While excess electrons cannot be trapped by intrinsic oxygen defects, the presence of excess holes results in the formation of peroxy linkages, with defect states in the band gap at 2.5 eV from the valence band.All the calculations are carried out with the freely available CP2K suite of codes, 25 which is based on the use of atomic a) Electronic mail: zhendong.guo@epfl.ch basis sets and of a plane-wave expansion for the electron density. Analytical Goedecker-Teter-Hutter pseudopotentials 26 are used to account for core-valence interactions. We use a triple-ζ correlation-consistent polarized basis set 27 for O atoms, and the shorter range molecularly optimized doublezeta basis set with one polarization function 28 for Al atoms. For the plane-waves, a cutoff of 500 Ry is employed. The ...

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confidence: 99%

Oxygen defects in amorphous Al2O3: A hybrid functional study

Guo

Ambrosio

Pasquarello

2016

Applied Physics Letters

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“…After forming gas 400 1C annealing for 5 min, the electrical characteristics showed little improvements. It has been reported by several groups that for ALD direct growth of high-k materials on H-terminated silicon, retardation in nucleation on the clean Si surface in the first few cycles led to poor interface and rough film surfaces [3][4][5][6]. The island growth results in electrically leaky films.…”

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confidence: 99%

A novel approach of using a MBE template for ALD growth of high-κ dielectrics

Lee

Huang

et al. 2007

Journal of Crystal Growth

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“…Therefore, influences of radiation on the electrical characteristics of MOS devices are complicated in nature [5]. Various dielectric materials such as Al 2 O 3 [6], HfO 2 [7,8], TiO 2 [9,10], La 2 O 3 [11] and ZrO 2 [12] have been studied for MOS-based technology to substitute conventional SiO 2 layer. However, there is not enough knowledge in the literature about their radiation responses.…”

Section: Introductionmentioning

confidence: 99%