Two stage oxidation in epitaxial Ni (111)/GaN (0001) thin films

Kang, Hee-Cheol; Seo, S. H.; Jang, Ho Won; Kim, D. H.; Noh, Do Young

doi:10.1063/1.1610248

Cited by 18 publications

(4 citation statements)

References 11 publications

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“…For this 600 °C Ni nanoparticle oxidation, we think the "critical thickness" can be approximated by the above h(S1 end ) of the large Ni. This value is higher than the retraction of 3.5 nm reported for a Ni film oxidization at 300 °C, 50 consistent with the temperature effect on nucleation and oxide nuclei size. 49 Thus, since the radii of small Ni nanoparticles are smaller than the critical thickness under our oxidation condition, their oxidation did not proceed into the subsequent NiO thickening process (i.e., no Kirkendall voids were observed).…”

Section: Resultssupporting

confidence: 88%

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening

Sainju

Rathnayake

et al. 2022

ACS Nano

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High-temperature oxidation mechanisms of metallic nanoparticles have been extensively investigated; however, it is challenging to determine whether the kinetic modeling is applicable at the nanoscale and how the differences in nanoparticle size influence the oxidation mechanisms. In this work, we study thermal oxidation of pristine Ni nanoparticles ranging from 4 to 50 nm in 1 bar 1%O2/N2 at 600 °C using in situ gas-cell environmental transmission electron microscopy. Real-space in situ oxidation videos revealed an unexpected nanoparticle surface refacetting before oxidation and a strong Ni nanoparticle size dependence, leading to distinct structural development during the oxidation and different final NiO morphology. By quantifying the NiO thickness/volume change in real space, individual nanoparticle-level oxidation kinetics was established and directly correlated with nanoparticle microstructural evolution with specified fast and slow oxidation directions. Thus, for the size-dependent Ni nanoparticle oxidation, we propose a unified oxidation theory with a two-stage oxidation process: stage 1: dominated by the early NiO nucleation (Avrami–Erofeev model) and stage 2: the Wagner diffusion-balanced NiO shell thickening (Wanger model). In particular, to what extent the oxidation would proceed into stage 2 dictates the final NiO morphology, which depends on the Ni starting radius with respect to the critical thickness under given oxidation conditions. The overall oxidation duration is controlled by both the diffusivity of Ni2+ in NiO and the Ni in Ni self-diffusion. We also compare the single-particle kinetic curve with the collective one and discuss the effects of nanoparticle size differences on kinetic model analysis.

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Section: Resultssupporting

confidence: 88%

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening

Sainju

Rathnayake

et al. 2022

ACS Nano

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“…8 Recently, NiO formed by thermal oxidation of Ni films has been proposed as the gate insulator in AlGaN/GaN HEMTs. 9 However, the thermal oxidation of Ni films can proceed through different stages 10,11 and can result into the formation of voids in the oxide layer. 10 This latter severely compromise the devices reliability and a uniform and epitaxial layer would certainly be preferred.…”

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confidence: 99%

Epitaxial NiO gate dielectric on AlGaN/GaN heterostructures

Roccaforte

Greco

Fiorenza

et al. 2012

Applied Physics Letters

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This letter reports on epitaxial nickel oxide (NiO) films grown by metal-organic chemichal vapor deposition on AlGaN/GaN heterostructures. The grown material was epitaxial, free from voids and exhibited a permittivity of 11.7, close to bulk NiO. This approach is advantageous with respect other methods such as the thermal oxidation of Ni films due to a better reproducibility and film quality. A reduction of the leakage current in Schottky diodes with an interfacial NiO layer has been observed and described using the metal-insulator-semiconductor Schottky model. The results indicate that these films are promising as gate dielectric for AlGaN/GaN transistors technology.

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“…Composite Interfaces 129 contact relaxes the Fermi-level pinning and suppresses the trap-assisted tunneling current. [11] Kang et al [12] reported that a NiO layer is easily formed when Ni is oxidized at temperature 300°C. NiO is also reported to behave as a p-type semiconductor with nickel vacancies and/or oxygen interstitials.…”

Section: Methodsmentioning

confidence: 98%

Ni/Ag Schottky contacts on Al_0.11Ga_0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE

Yusoff

Hassan

et al. 2015

Composite Interfaces

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Al 0.11 Ga 0.89 N/GaN samples are grown by plasma-assisted molecular beam epitaxy method on (1 1 1) silicon substrates. High purity gallium (7N) and aluminum (6N5) were used to grow Al 0.11 Ga 0.89 N, GaN, and AlN, respectively. The surface morphology, structural and optical properties of the sample has been investigated by scanning electron microscope (SEM), and high-resolution X-ray diffraction (HR-XRD), respectively. HR-XRD measurement showed that the sample has a typical diffraction pattern of hexagonal Al 0.11 Ga 0.89 N/GaN heterostructures. Ni/Ag bilayers are deposited on Al 0.11 Ga 0.89 N as the Schottky contacts. The effect of annealing in oxygen ambient on the electrical properties of Ni/Ag/Al 0.11 Ga 0.89 N is studied by currentvoltage measurement. The annealing at a temperature of 700°C for 10 min results in an increase in the ideality factor from 1.033 to 1.042 and an increase in the Schottky barrier height from 0.708 to 0.811 eV. Furthermore, the annealing in oxygen ambient also leads to an increase in the surface roughness of the contacts from 0.0098 to 0.1360 μm which is in agreement with the SEM results.

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Two stage oxidation in epitaxial Ni (111)/GaN (0001) thin films

Cited by 18 publications

References 11 publications

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening

Epitaxial NiO gate dielectric on AlGaN/GaN heterostructures

Ni/Ag Schottky contacts on Al_0.11Ga_0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE

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Two stage oxidation in epitaxial Ni (111)/GaN (0001) thin films

Cited by 18 publications

References 11 publications

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening

In Situ Studies of Single-Nanoparticle-Level Nickel Thermal Oxidation: From Early Oxide Nucleation to Diffusion-Balanced Oxide Thickening

Epitaxial NiO gate dielectric on AlGaN/GaN heterostructures

Ni/Ag Schottky contacts on Al0.11Ga0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE

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Product

Resources

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Ni/Ag Schottky contacts on Al_0.11Ga_0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE