Internal stress induced natural self-chemisorption of ZnO nanostructured films

Chi, Po‐Wei; Su, Chih-Wei; Wei, Da‐Hua

doi:10.1038/srep43281

Cited by 25 publications

(11 citation statements)

References 59 publications

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“…The hydrophobic or hydrophilic materials are usually prepared by modifying their surface with varied surface energy for tunable surface wetting characteristics. The surface characteristics for other oxide materials have also been claimed in our previous work 45 , 46 . In addition, this kind of surface nanostructures could not only be used for self-cleaning 47 – 49 , drug delivery 50 – 54 and biological interactions 55 , but also could be used for other potential surface engineering such as oil-water separation 56 – 58 , self-dustproof surfaces 59 and anti-fogging 60 .…”

Section: Resultssupporting

confidence: 71%

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Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition

Tong

Chi

Kung

et al. 2018

Sci Rep

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Stress variation induced bandgap tuning and surface wettability switching of spinel nickel ferrite (NiFe2O4, NFO) films were demonstrated and directly driven by phase transition via a post-annealing process. Firstly, the as-deposited NFO films showed hydrophilic surface with water contact angle (CA) value of 80 ± 1°. After post-annealing with designed temperatures ranged from 400 to 700 °C in air ambience for 1 hour, we observed that the crystal structure was clearly improved from amorphous-like/ nanocrystalline to polycrystalline with increasing post-annealing temperature and this phenomenon is attributed to the improved crystallinity combined with relaxation of internal stress. Moreover, super-hydrophilic surface (CA = 14 ± 1°) was occurred due to the remarkable grain structure transition. The surface wettability could be adjusted from hydrophilicity to super-hydrophilicity by controlling grain morphology of NFO films. Simultaneously, the saturation magnetization (Ms) values of NFO films at room temperature increased up to 273 emu/cm3 accompanied with transitions of the phase and grain structure. We also observed an exceptionally tunable bandgap of NFO in the range between 1.78 and 2.72 eV under phase transition driving. Meanwhile, our work demonstrates that direct grain morphology combined with the stress tuning can strongly modulate the optical, surface and magnetic characteristics in multifunctional NFO films.

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Section: Resultssupporting

confidence: 71%

“…Chi et al . observed the bandgap shift of ZnO nanostructured films accompanied by changing in size variation combined with internal stress effect 46 . Figure 6 shows a plot of grain band gap E (gap, grain) versus the grain size of NFO.…”

Section: Resultsmentioning

confidence: 97%

Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition

Tong

Chi

Kung

et al. 2018

Sci Rep

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“…This phenomenon could be attributed to an air pocket forming and existing between the grains and against the grain boundaries. In other words, air pockets play an important role in supporting the water droplets in the case of the penetration, and they lead to higher water-contact angles [ 57 , 58 , 59 , 60 , 61 ], hence the similar, corresponding tendency of the SEM images with calculated average grain sizes performed via histograms, as shown in Figure 2 a. Moreover, the histograms of the calculated average grain sizes show the same tendency, with the gradually increasing values of the water-contact angles.…”

Section: Resultsmentioning

confidence: 99%

Tuning Surface Plasmonic Resonance and Surface Wettability of Au/CrN Films Using Nitrogen-Containing Gas

Wei

Tong²,

Chen

et al. 2022

Nanomaterials

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The surface plasmonic resonance, surface wettability, and related mechanical nanohardness and of face-centered-cubic (fcc) chromium nitride (CrN) films have been successfully manipulated via the simple method of tuning nitrogen-containing gas with different nitrogen-to-argon ratios, varying from 3.5 (N35), to 4.0 (N40), to 4.5 (N45), which is directly proportional to argon. All of the obtained CrN films showed that the surface wettability was due to hydrophilicity. All of the characteristics were mainly confirmed and explained by using X-ray diffraction (XRD) patterns, including plan-view and cross-section SEM images, with calculations of the average grain size performed via histograms accompanied by different preferred grain orientations. In the present work, not only the surface plasmonic resonance, but also the surface wettability and the related mechanical nanohardness of CrN films were found to be tunable via a simple method of introducing adjustable nitrogen-reactive-containing gas during the deposition process, while the authors suggest that the crystal orientation transition from the (111) to the (200) crystalline plane changed significantly with the nitrogen-containing gas. So the transition of the preferred orientation of CrN’s cubic close-packed from (111) to (200) varied at this composite, caused and found by the nitrogen-containing gas, which can be tuned by the nitrogen-to-argon ratio. The surface plasmonic resonance and photoluminescence quenching effects were coupled photon and electron oscillations, which could be observed, and which existed at the interface between the CrN and Au metals in the designed heterostructures.

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“…At higher fluences (ie, >1 × 10 13 ions cm −2 ), the increase of stress could possibly be due to ion irradiation induced disordering in the matrix. We also calculated the stress of ZnO layer from Raman shift ( σ Raman ) using the relation:

σ_{Raman} = 450 \times ε_{cc},

and the obtained values of σ Raman with ion fluence are also plotted along with the stress of NiO obtained from XRD for comparison (Figure ). Stresses of both the layers follow similar variation with ion fluence.…”

Section: Resultsmentioning

confidence: 99%

Effect of 120 MeV Au⁹⁺ ion irradiation on the structure and surface morphology of ZnO/NiO heterojunction

Das

Biswal

Choudhary

et al. 2018

Surface & Interface Analysis

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ZnO/NiO thin films, each of thickness 100 nm, were deposited on Si(100) substrate by pulsed laser deposition method. The resulting heterojunction, ZnO/NiO/Si, was irradiated by 120 MeV Au 9+ ions and characterized by grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, and atomic force microscopy (AFM). The GIXRD confirmed the presence of both NiO and ZnO in the samples. Ion irradiation induced suppression of crystalline nature, and the recrystallization of the same occurred at the fluence of 1 × 10 13 ions cm −2 . The occurrence of most intense band at 302 cm −1 in Raman spectra corresponds to the symmetric stretching vibration of ZnO. The linear shift of stretching mode of ZnO with ion fluence could be associated with the effect of compressive stress in the material. AFM analysis of the films indicated that the rms roughness increased when the film is irradiated at a fluence of 1 × 10 12 ions cm −2 .Beyond this fluence, the value of roughness decreased up to fluence of 1 × 10 13 ions cm −2 and increased thereafter. To see the effect of the stress of buffer layer on the surface layer, we calculated the stress for NiO layer with ion fluence form the lattice parameter. Comparing the stress of buffer layer with roughness of surface layer at the given fluence, we can say that the compressive stress in the buffer layer could possibly control the roughness of the surface layer. KEYWORDS atomic force microscope, heterostructure, ion irradiation, stress 1 | INTRODUCTION Heterojunction devices, formed by combining semiconductors with different band gap and closely matching lattice parameters, have attracted much attention in optoelectronics. 1 ZnO is a wide-band gap (3.37 eV) semiconductor of the II-VI group. 2 It exhibits intrinsic n-type semiconducting property due to oxygen vacancies and zinc interstitials. It exhibits several properties like large exciton binding energy, 3 good transparency, 4 high electron mobility, 5 high thermal conductivity, 6 and strong room-temperature luminescence 7 for various device applications like liquid crystal displays, transparent conducting electrodes in solar cells, light emitting diodes, thin film transistors, gas sensors, and spintronic applications. 8 NiO is another wide band gap semiconductor that shows p-type behaviour due to the vacancy at Ni 2+ sites. NiO is widely used for applications such as transparent conductive films, 9 anode material, 10 and electrochromic devices. 11 Heterojunctions formed out of two layers (n-type ZnO and p-type NiO) can exhibit the potential of both the materials, in addition to the junction characteristics. In 2003, Ohta et al., 12 first reported the preparation of transparent NiO/ZnO heterojunction by pulsed laser deposition (PLD) combined with a solid-phase-epitaxy technique. Since then, many developments have been reported on the preparation and application of this heterojunction. These include methods like sol-gel spin coating, 13 chemical bath deposition, 4 hydrothermal method, 14and PLD. 15 On the application front, use of the hete...

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Internal stress induced natural self-chemisorption of ZnO nanostructured films

Cited by 25 publications

References 59 publications

Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition

Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition

Tuning Surface Plasmonic Resonance and Surface Wettability of Au/CrN Films Using Nitrogen-Containing Gas

Effect of 120 MeV Au⁹⁺ ion irradiation on the structure and surface morphology of ZnO/NiO heterojunction

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Internal stress induced natural self-chemisorption of ZnO nanostructured films

Cited by 25 publications

References 59 publications

Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition

Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition

Tuning Surface Plasmonic Resonance and Surface Wettability of Au/CrN Films Using Nitrogen-Containing Gas

Effect of 120 MeV Au9+ ion irradiation on the structure and surface morphology of ZnO/NiO heterojunction

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Effect of 120 MeV Au⁹⁺ ion irradiation on the structure and surface morphology of ZnO/NiO heterojunction