ChemInform Abstract: Controlled Growth of TaN, Ta3N5, and TaOxNy Thin Films by Atomic Layer Deposition.

Ritala, Mikko; Kalsi, Pia; Riihelae, Diana; Kukli, Kaupo; Leskelae, Markku; Jokinen, Jukka

doi:10.1002/chin.199938034

Cited by 2 publications

(4 citation statements)

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“…Its calculated absorption response shows an absorption edge at 414 nm (Figure a). Note that our DOS calculated with PBE gave much smaller band gap energy of 1.9 eV (Figure S4 in Supporting Information), in agreement with the previous theoretical works. ,, Our predicted band gaps with HSE06 for TaO 0.90 N 1.06 (2.7 eV) and TaO 0.81 N 1.12 (2.5 eV) match the experimental data reported on TaON powders. − This result indicates that the experimentally prepared tantalum oxynitride materials might not be fully stoichiometric but slightly enriched in N, closer to TaO 0.81 N 1.12 rather than TaON (see Supporting Information S5 and S6). In contrast, our formation energy calculations of TaO 0.90 N 1.06 and TaO 0.81 N 1.12 revealed metastable compounds with respect to TaON with higher formation energies of 0.30 and 0.58 eV than that obtained for TaON.…”

Section: Resultssupporting

confidence: 90%

“…Transition metal oxynitrides have been invoked in the literature as active photocatalysts for H 2 or O 2 evolution in the presence of appropriate sacrificial reagents. , In particular, TaON has received particular attention for its suitable band gap energy estimated at 2.5 eV. − TaON powders were obtained from high-temperature ammonolysis of Ta 2 O 5 under various heating and nitridation regimes. − The obtained samples were analyzed by the neutron powder diffraction technique which revealed a monoclinic crystal structure (known as β-phase) . Nevertheless, overall water splitting using TaON has not yet been achieved.…”

Section: Introductionmentioning

confidence: 99%

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First-Principles Investigation of Optoelectronic and Redox Properties of (Ta_1–xNb_x)ON Compounds for Photocatalysis

Harb

2015

J. Phys. Chem. C

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We investigate essential fundamental properties of monoclinic (Ta 1-x Nb x )ON (x = 0.0625, 0.125, 0.25, and 0.5) solid solution semiconductor materials for water splitting using first-principles computations on the basis of density functional theory (DFT) and density functional perturbation theory (DFPT) using the PBE and HSE06 functionals. The formation energies, band gaps, UVvisible optical absorption coefficients, dielectric constants, charge carrier effective masses and band edge energy positions of these compounds are evaluated. Similarly to TaON, our calculations reveal strongly 3D delocalized characters of the band edge electronic states through the crystal lattices, high dielectric constants, small hole effective masses along [001] direction and small electron effective masses along [100] direction. This leads to good exciton dissociation ability into free charge carriers, good hole mobility along [001] direction and good electron mobility along [100] direction. The main difference, however, is related to their band edge positions with respect to water redox potentials. TaON with a calculated bandgap energy of 3.0eV is predicted as a good candidate for water oxidation and O 2 evolution while the (Ta 1-x Nb x )ON materials (for 0.25 ≤ x ≤ 0.5) with calculated bandgap energies between 2.8 and 2.9 eV reveal suitable band edge positions for water oxidation and H + reduction. These results offer a grand opportunity for these compounds to be properly synthesized and tested for solar-driven overall water-splitting reactions. KeywordsNb-modified TaON, dielectric constant, charge carrier transport, band edge energy positions.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta_1–xNb_x)ON Compounds for Photocatalysis

Harb

2015

J. Phys. Chem. C

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“…This is in contrast to the Ta–N system, which shows a dielectric N‐rich Ta 3 N 5 phase . The formation of Ta 3 N 5 has often been reported in the wide range of thin film deposition methods, such as physical vapor deposition, chemical vapor deposition (CVD), and atomic layer deposition (ALD) . In particular, Ta 3 N 5 is reported routinely in CVD and ALD systems using a range of Ta precursors and reactants.…”

Section: Introductionmentioning

confidence: 99%

“…ALD is a viable option because it involves a self‐limited film growth mode through surface‐saturated reactions, which enables atomic‐scale control of the film thickness and composition with excellent step coverage . In contrast to the extensive studies of Ta‐based nitrides ALD, there are few reports on TaC x ALD process . Plasma‐enhanced ALD (PEALD) Ta‐rich TaC x films with a growth rate of ~1 Å per cycle were deposited using an inorganic precursor and a carbon‐containing gas, but the process details were not reported .…”

Section: Introductionmentioning

confidence: 99%

TaC_x Thin Films Prepared by Atomic Layer Deposition as Diffusion Barriers for Cu Metallization

et al. 2013

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TaCx films were deposited by atomic layer deposition (ALD) using tris (neopentyl) tantalum dichloride, (Ta[CH2C(CH3)3]3Cl2) and H2 plasma as the precursor and reactant, respectively, at substrate temperatures ranging from 200°C to 400°C. The ALD–TaCx films with the formation of nanocrystalline structures and a rock‐salt phase were confirmed by X‐ray and electron diffraction. The ALD temperature window was found to be 225°C–300°C with a growth rate of ~0.11 nm per cycle. The resistivity of the ALD–TaCx films was dependent on the microstructural features, such as the grain size and crystallinity, as well as their composition (C/Ta ratio), and the presence of impurities in the films, which could be controlled by varying the deposition parameters, such as the deposition temperature and reactant pulse conditions. With increasing deposition temperature and reactant pulse time, Ta‐rich films with a low Cl impurity concentration and larger grain size were obtained. The film with a resistivity less than 400 μΩ cm was obtained at 300°C, which was within the ALD temperature window, by optimizing the H2 plasma pulse time. The step coverage of the film deposited at 300°C was approximately 100% over the trench structure (top opening width of 25 nm) with an aspect ratio of ~4.5. The performance of the ALD–TaCx films deposited under the optimized conditions was evaluated as a diffusion barrier for the Cu interconnects. The structure of Cu (100 nm)/ALD–TaCx (5 nm)/ Si was stable without the formation of copper silicide after annealing at 600°C for 30 min.

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ChemInform Abstract: Controlled Growth of TaN, Ta₃N₅, and TaO_xN_y Thin Films by Atomic Layer Deposition.

Cited by 2 publications

References 1 publication

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta_1–xNb_x)ON Compounds for Photocatalysis

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta_1–xNb_x)ON Compounds for Photocatalysis

TaC_x Thin Films Prepared by Atomic Layer Deposition as Diffusion Barriers for Cu Metallization

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ChemInform Abstract: Controlled Growth of TaN, Ta3N5, and TaOxNy Thin Films by Atomic Layer Deposition.

Cited by 2 publications

References 1 publication

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta1–xNbx)ON Compounds for Photocatalysis

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta1–xNbx)ON Compounds for Photocatalysis

TaCx Thin Films Prepared by Atomic Layer Deposition as Diffusion Barriers for Cu Metallization

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ChemInform Abstract: Controlled Growth of TaN, Ta₃N₅, and TaO_xN_y Thin Films by Atomic Layer Deposition.

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta_1–xNb_x)ON Compounds for Photocatalysis

First-Principles Investigation of Optoelectronic and Redox Properties of (Ta_1–xNb_x)ON Compounds for Photocatalysis

TaC_x Thin Films Prepared by Atomic Layer Deposition as Diffusion Barriers for Cu Metallization