Precise control of configuration, size and density of self-assembled Au nanostructures on 4H-SiC (0001) by systematic variation of deposition amount, annealing temperature and duration

Li, Mingyu; Sui, Mao; Pandey, Puran; Zhang, Quanzhen; Kunwar, Sundar; Salamo, Gregory J.; Lee, Jihoon

doi:10.1039/c5ce02439k

Cited by 20 publications

(11 citation statements)

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“…With the elevating temperature, D S × N Cu can be much more dominantly anabatic than the T , resulting in the truncation of isolated Cu NSs due to the enhanced surface diffusion of Cu adatoms by the anabatic J Cu as depicted in Figure e. Meanwhile, the metallic NSs had a tendency to reduce the surface energy by the formation of isotropic shape, which thereby resulted in the aggregation of the convex nanodroplets with the increasing temperatures as shown in Figure b–d. As a result, the size distribution gradually shrunk when the annealing temperatures increased, and the average diameter ( D Ave ) correspondingly decreased from 101.9 ± 8.5 to 63.7 ± 3.2 nm.…”

Section: Resultsmentioning

confidence: 98%

“…Generally, the Cu NSs underwent an obvious configuration transition from the irregular capillary nanomounds to convex nanodroplets with the increasing temperatures. Providing with higher thermal energy supply, more Cu atoms can be activated to escape from continuous thin films, leading to an increased amount of diffusing Cu adatoms within unit area ( N Cu ) based on the solid‐state dewetting theory . Thus, the diffusion flux of Cu adatoms ( J Cu ) can be given with

J_{Cu} = - \frac{D_{normalS} γ_{Cu} Ω N_{Cu}}{k T} \times \nabla κ

where ∇κ is the surface gradient of the Cu film curvature, γ Cu is surface energy of Cu, Ω is atomic volume, k is Boltzmann constant, and T is ambient temperature (annealing temperature).…”

Section: Resultsmentioning

confidence: 99%

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Ultrahigh Responsivity UV Photodetector Based on Cu Nanostructure/ZnO QD Hybrid Architectures

et al. 2019

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Strong near‐surface electromagnetic field formed by collective oscillation of electrons on Cu nanostructure a shows a strong dependence on geometry, offering a promising approach to boost the light absorption of ZnO photoactive layers with enhanced plasmon scattering. Here, a facile way to fabricate UV photodetectors with tunable configuration of the self‐assembled Cu nanostructures on ZnO thin films is reported. The incident lights are effectively confined in ZnO photoactive layers with the existence of the uplayer Cu nanostructures, and the interdiffusion of Cu atoms during fabrication of the Cu nanostructures can improve the carrier transfer in ZnO thin films. The optical properties of the hybrid architectures are successfully tailored over a control of the geometric evolution of the Cu nanostructures, resulting in significantly enhanced photocurrent and responsivity of 2.26 mA and 234 A W−1 under a UV light illumination of 0.62 mW cm−2 at 10 V, respectively. The photodetectors also exhibit excellent reproducibility, stability, and UV–visible rejection ratio (R370 nm/R500 nm) of ≈370, offering an approach of high‐performance UV photodetectors for practical applications.

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Section: Resultsmentioning

confidence: 98%

J_{Cu} = - \frac{D_{normalS} γ_{Cu} Ω N_{Cu}}{k T} \times \nabla κ

where ∇κ is the surface gradient of the Cu film curvature, γ Cu is surface energy of Cu, Ω is atomic volume, k is Boltzmann constant, and T is ambient temperature (annealing temperature).…”

Section: Resultsmentioning

confidence: 99%

Ultrahigh Responsivity UV Photodetector Based on Cu Nanostructure/ZnO QD Hybrid Architectures

et al. 2019

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“…The surface morphological evolution can be discussed with the thermodynamic diffusion mechanism. In a thermodynamic system, the diffusion distance of an adatom ( L D ) is given by

L_{D} = \sqrt{D_{S} t}

[25], where t is the residence time of adatoms at the substrate. D S is the surface diffusion coefficient and is given by

D_{s} = D_{0} e^{\frac{- E}{k T}}

, where D 0 and E (the diffusion barrier) are the certain values under an identical growth condition, k is the Boltzmann constant, and T is the substrate temperature (deposition temperature) [26].…”

Section: Resultsmentioning

confidence: 99%

“…For the thin films deposited at 650 °C, the grains distributed with a relatively wider size variation of between 22 and 30 nm due to the unfavorable surface diffusion of adatoms, as shown in Figure 3a,a-2. With the increased temperatures between 700 and 750 °C, the crystallite grains gradually became denser with the decreased grain size resulting from the enhanced nucleation [25,26], as shown in Figure 3b,c,b-2,c-2. Consequently, the average grain size noticeably decreased by 48% to ~14 nm with the increased deposition temperatures, and the corresponding average density increased from 1.0 × 1011 to 2.1 × 1011 cm−2, as shown in Figure 3d,e.…”

Section: Resultsmentioning

confidence: 99%

Ultra Uniform Pb0.865La0.09(Zr0.65Ti0.35)O3 Thin Films with Tunable Optical Properties Fabricated via Pulsed Laser Deposition

Jiang

Huang

et al. 2018

Materials

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Ferroelectric thin films have been utilized in a wide range of electronic and optical applications, in which their morphologies and properties can be inherently tuned by a qualitative control during growth. In this work, we demonstrate the evolution of the Pb0.865La0.09(Zr0.65Ti0.35)O3 (PLZT) thin films on MgO (200) with high uniformity and optimized optical property via the controls of the deposition temperatures and oxygen pressures. The perovskite phase can only be obtained at the deposition temperature above 700 °C and oxygen pressure over 50 Pa due to the improved crystallinity. Meanwhile, the surface morphologies gradually become smooth and compact owing to spontaneously increased nucleation sites with the elevated temperatures, and the crystallization of PLZT thin films also sensitively respond to the oxygen vacancies with the variation of oxygen pressures. Correspondingly, the refractive indices gradually develop with variations of the deposition temperatures and oxygen pressures resulted from the various slight loss, and the extinction coefficient for each sample is similarly near to zero due to the relatively smooth morphology. The resulting PLZT thin films exhibit the ferroelectricity, and the dielectric constant sensitively varies as a function of electric filed, which can be potentially applied in the electronic and optical applications.

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“…In addition, the electronic heterogeneity, site-specific response, and combinational effect of constituent metals are some interesting features of the alloy NPs, which could not be achieved with monometallic NPs. At the same time, the alloy NPs can provide additional flexibility for tuning optical [7,8], catalytic [9][10][11][12][13], electronic, and magnetic [14][15][16] properties by controlling shape, size, and density [17] as well as elemental composition. In particular, the localized surface plasmon resonance (LSPR) frequency of alloy NPs can be modulated through the composition variation, which potentially enables many applications in the plasmonic, energy, and biomedical fields.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Ternary AuAgPd Nanoparticles by the Control of Temperature, Thickness, and Tri-Layer

Kunwar

Pandey

Sui

et al. 2017

Metals

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Metallic alloy nanoparticles (NPs) possess great potential to enhance the optical, electronic, chemical, and magnetic properties for various applications by the control of morphology and elemental composition. This work presents the fabrication of ternary AuAgPd alloy nanostructures on sapphire (0001) via the solid-state dewetting of sputter-deposited tri-metallic layers. Based on the systematic control of temperature, thickness, and deposition order of tri-layers, the composite AuAgPd alloy nanoparticles (NPs) with various shape, size, and density are demonstrated. The metallic tri-layers exhibit various stages of dewetting based on the increasing growth temperatures between 400 and 900 • C at 15 nm tri-layer film thickness. Specifically, the nucleation of tiny voids and hillocks, void coalescence, the growth and isolated nanoparticle formation, and the shape transformation with Ag sublimation are observed. With the reduced film thickness (6 nm), tiny alloy NPs with improved structural uniformity and spatial arrangement are obtained due to enhanced dewetting. The growth trend of alloy NPs is drastically altered by changing the deposition order of metallic tri-layers. The overall evolution is governed by the surface diffusion and inter-mixing of metallic atoms, Rayleigh-like instability, surface and interface energy minimization, and equilibrium state of the system. The UV-VIS-NIR reflectance spectra reveal the formation of an absorption band and reflectance maxima at specific wavelengths based on the morphology and composition of AuAgPd alloy NPs. In addition, Raman spectra analysis shows the modulation of intensity and peak position of natural vibration modes of sapphire (0001).

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Precise control of configuration, size and density of self-assembled Au nanostructures on 4H-SiC (0001) by systematic variation of deposition amount, annealing temperature and duration

Abstract: Hexagonal Au nano-crystals, round dome-shaped droplets and irregular nano-mounds were fabricated on GaN (0001) based on the combinational effects of thermal dewetting and surface free energy minimization.

Cited by 20 publications

References 50 publications

Ultrahigh Responsivity UV Photodetector Based on Cu Nanostructure/ZnO QD Hybrid Architectures

Ultrahigh Responsivity UV Photodetector Based on Cu Nanostructure/ZnO QD Hybrid Architectures

Ultra Uniform Pb0.865La0.09(Zr0.65Ti0.35)O3 Thin Films with Tunable Optical Properties Fabricated via Pulsed Laser Deposition

Evolution of Ternary AuAgPd Nanoparticles by the Control of Temperature, Thickness, and Tri-Layer

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