Air Annealing Effect on Oxygen Vacancy Defects in Al-doped ZnO Films Grown by High-Speed Atmospheric Atomic Layer Deposition

Hsu, Chia-Hsun; Geng, Xin-Peng; Wu, Wan-Yu; Zhao, Ming-Jie; Zhang, Xiaoying; Huang, Pao-Hsun; Lien, Shui−Yang

doi:10.3390/molecules25215043

Cited by 27 publications

(13 citation statements)

References 49 publications

(49 reference statements)

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“…Distorted hexagonal islands occurred on the surfaces of the annealed film at 700 • C, as shown in Figure 1d, similar to the reported island nucleation of ε-Ga 2 O 3 in epitaxial growth on a c-plane sapphire substrate by metalorganic chemical vapor deposition at 650 • C [12,24,25]. It was considered that agglomeration, rather than the merging into large crystals, began to occur at 800 • C in a part of the film, and discontinuities and voids were observed [26]. Uniform, dense, compact, and well-defined grains with clear boundaries were observed in the annealed films at 900 • C; the grain size gradually increased with an increase in the annealing temperature from 500 to 900 • C.…”

Section: Resultssupporting

confidence: 84%

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

Pech

Kim

2022

Coatings

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Gallium oxide (Ga2O3) is a semiconductor with a wide bandgap of ~5.0 eV and large breakdown voltages (>8 MV·cm−1). Among the crystal phases of Ga2O3, the monoclinic β-Ga2O3 is well known to be suitable for many device applications because of its chemical and thermal stability. The crystalline quality of polycrystalline β-Ga2O3 films on c-plane sapphire substrates was studied by rapid thermal annealing (RTA) following magnetron sputtering deposition at room temperature. Polycrystalline β-Ga2O3 films are relatively simple to prepare; however, their crystalline quality needs enhancement. The β-phase was achieved at 900 °C with a crystallite size and d-spacing of 26.02 and 0.2350 nm, respectively, when a mixture of ε- and β-phases was observed at temperatures up to 800 °C. The strain was released in the annealed Ga2O3 films at 900 °C; however, the clear and uniform orientation was not perfect because of the increased oxygen vacancy in the film at that temperature. The improved polycrystalline β-Ga2O3 films with dominant (−402)-oriented crystals were obtained at 900 °C for 45 min under a N2 gas atmosphere.

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Section: Resultssupporting

confidence: 84%

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

Pech

Kim

2022

Coatings

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“…This is attributable to the development of the lattice strain in the ZnO crystal due to deposition of CDs at its surface. In general, the lattice strain tends to create structural defects in the ZnO lattice, such as oxygen vacancy (V o ), zinc vacancy (V zn ), zinc interstitial (Zn i ), oxygen interstitial (O i ), and so forth . Compared to pristine ZnO, the PL intensity corresponding to the defect state emission was more for ZnO/CD NCs, which indicates a higher concentration of defect states in ZnO/CD NCs as compared to ZnO NPs. , Interestingly, a new emission peak was observed at 371 nm in ZnO/CD NCs, which is attributable to the emission of a CD component of ZnO/CD.…”

Section: Resultsmentioning

confidence: 97%

Sunlight-Driven Photocatalytic Degradation of Ciprofloxacin by Carbon Dots Embedded in ZnO Nanostructures

Mukherjee

Cilamkoti

Dutta

2021

ACS Appl. Nano Mater.

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Surface modification of ZnO nanoparticles (NPs) is considered as a key for enhanced sustained generation of reactive oxygen species (ROS) in the reaction medium for improving the photocatalytic degradation phenomenon. Here, we present a simple chemical method of synthesizing carbon dots (CDs) embedded on the surface of ZnO NPs denoted as ZnO/CD nanocomposites (NCs) as a photocatalyst for efficient sunlight-driven degradation of ciprofloxacin (CIP). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirmed the formation of needle-shaped clusters of ZnO/CD NCs. The band gaps of ZnO/CD NCs and pristine ZnO are determined from Tauc's plot. Under optimized conditions, the batch of CIP at pH 6.3 ± 0.1 treated with 0.6 g L −1 of ZnO/CD NCs revealed 98% photocatalytic degradation of CIP in 110 min by harnessing longer UV and the visible components of sunlight. The rate of photocatalytic degradation was 0.30 min −1 , which was 3 times higher than that of the pristine ZnO NPs. The enhanced rate of degradation by ZnO/CD NCs is attributed to the improved mobility of charge carriers and the generation of enhanced ROS. This is confirmed by the scavenging studies of hydroxyl radicals and superoxide radicals. The higher ROS generation is attributed to the inhibition of charge carrier recombination facilitated by the CDs embedded on the surface of ZnO NPs. The applicability of ZnO/CD NCs as a photocatalyst is demonstrated from five cycles of repeatability studies. After five cycles of operation, the structure and surface morphology of the used ZnO/CD NCs were stable, confirmed by XRD, TEM, and Fourier transform infrared studies. It is concluded that ZnO/CD NCs are efficient sunlight-driven photocatalysts for improved photocatalytic degradation of CIP, a model emerging contaminant.

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“…The second part was 530.2 eV, which was attributed to oxygen vacancies (O v ; Figure S2a, Supporting Information). , The oxygen vacancies disappeared at higher temperatures. , At temperatures from 500 to 1000 °C, the oxygen vacancies disappeared (Figure S2b–f, Supporting Information). Furthermore, in the EPR spectra, a corresponding g-factor around 2.002 indicated the existence of oxygen vacancies in the composite at different temperatures (Figure e) .…”

Section: Resultsmentioning

confidence: 99%

Flexoelectric Catalysts Based on Hierarchical Wrinkling Surface of Centrosymmetric High-Entropy Oxide

Lin

et al. 2023

ACS Nano

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A high-entropy oxide nanocomposite with Ag(CuZn)(AlCr)2O4 and CuO phases is fabricated to form an abundantly hierarchical wrinkled surface. Application of a mechanical force to the nanocomposite resulted in a nonhomogeneous strain gradient at the interface between the Ag(CuZn)(AlCr)2O4 and CuO phases, changing the local charge distribution and creating flexoelectric polarization that delayed electron/hole recombination. Transmission electron microscopy energy-dispersive X-ray spectroscopy mapping revealed that the Ag, Cu, Zn, Al, Cr, and O elements were highly distributed throughout the nanocomposite. The nanocomposite produced 2116 μmol·g–1 h–1 of H2 without external light irradiation, which is 980% higher than the H2 produced by the same nanocomposite under the photocatalytic process. A strong electrical field is observed at the interface between the Ag(CuZn)(AlCr)2O4 and CuO phases, demonstrating that a flexoelectric potential (flexopotential) is established at the structural boundaries because the strain gradient is localized at these interfaces. The nanocomposite is a promising approach for environmentally friendly energy production.

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Air Annealing Effect on Oxygen Vacancy Defects in Al-doped ZnO Films Grown by High-Speed Atmospheric Atomic Layer Deposition

Cited by 27 publications

References 49 publications

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

Sunlight-Driven Photocatalytic Degradation of Ciprofloxacin by Carbon Dots Embedded in ZnO Nanostructures

Flexoelectric Catalysts Based on Hierarchical Wrinkling Surface of Centrosymmetric High-Entropy Oxide

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