Growth of Single-Crystalline ZnO Films on 18%-Lattice-Mismatched Sapphire Substrates Using Buffer Layers with Three-Dimensional Islands

Nakamura, Yuta; Yamashita, Naoto; Kamataki, Kunihiro; Okumura, Takamasa; Koga, Kazunori; Shiratani, Masaharu; Itagaki, Naho

doi:10.1021/acs.cgd.2c00145

Cited by 5 publications

(1 citation statement)

References 37 publications

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“…The immobilization of the ZnO nanostructures on suitable substrates also exhibit the emergence of new physical properties. For example, it has been observed that the heteroepitaxial growth of ZnO films on the c -plane of sapphire substrates leads to the observation of the inverted Stranski-Krastanov mode, which is of significance in elecronics and optoelectronics nanodevices . Therefore, it can be conceived that the variation in geometrical structures, exposed crystal facets, nature and concentration of the surface defects, possible charge separation, and orientation to hierarchical architectures can lead to tuning of the physicochemical characteristics.…”

Section: Crystallinity and Physical Propertiesmentioning

confidence: 99%

Growth of ZnO Polytypes: Multiple Facets of Diverse Applications

Debnath,

Sen,

Neog

et al. 2024

Crystal Growth & Design

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Zinc oxide has been considered as a specific and versatile bridging agent that bears an intrinsic relationship with the crystal structure−property application in physics, chemistry, materials, and biomedical sciences. Due to inherent polytypism through the abundance of crystal structures, the properties can interconnect from classical (bulk structures) to quantum (nanostructures) regimes that have been the subject of immense investigation using theoretical, experimental, and simulation perspectives. Prudent advances in the synthetic strategies have offered the opportunity to achieve diverse morphologies from ultrasmall to hierarchical superstructures employing chemical manipulation, and the possibility of maneuvering the crystal patterns has marked zinc oxide as an attractive recipe in the buffet of modern materials research. The interplay between the mere variation in the crystalline structures and spatial confinement of ZnO at the nanoscale dimension has become the epicenter of the emergence of unique physicochemical characteristics that can be exploited in a diverse range of niche multifarious applications. Moreover, the ease of syntheses which mostly follow green techniques, cost effectiveness, physical and chemical stability, and biocompatibility have made zinc oxide a semiconductor of great interest in the past three decades. An intrinsic n-type semiconductor with a wide band gap and large exciton binding energy have rendered ZnO as a fundamental material with a synergism of semiconducting, optoelectronic, piezoelectric, pyroelectric, photocatalytic, and biological properties with outstanding industrial and technological applications. The possibility to control the crystallinity through the manipulation of particle shape, size, exposed facets, composition, and doping imbues a diverse range of materials properties that can be tailored to pursue the preconceived applications. Althouth the onset of research with ZnO can be traced back to nearly a century ago, the renewed interest has been rekindled with the accessibility of high-quality single crystals, facile synthesis to various nanostructures, and the availability of p-type ZnO as the cornerstone. Based on these contexts at the backstage, it is now time to condense the large and voluminous work to assess the epicenter of the conceptive, to rationalize the perpectives between crystallographic and physical properties, and to design the objectives to explore the future technological applications in the realm of present major global challenges in the field of energy, environment, and biomedical applications.

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Section: Crystallinity and Physical Propertiesmentioning

confidence: 99%

Growth of ZnO Polytypes: Multiple Facets of Diverse Applications

Debnath,

Sen,

Neog

et al. 2024

Crystal Growth & Design

View full text Add to dashboard Cite

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Enhanced orbital magnetic moment of Co film grown on Fe3O4(001)

Zhang,

Lu,

et al. 2024

AIP Advances

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We investigate the magnetic and electronic properties of Co films on Fe3O4(001) achieved through epitaxial growth using magnetron sputtering. X-ray magnetic circularly dichroism measurements characterize the atomic magnetism. Compared to Co films on the MgO substrate, Co on Fe3O4 exhibits a 96% enhancement in orbital magnetic moment (from 0.25 to 0.49 µB/atom) and an increase in spin magnetic moment (from 1.37 to 1.53 µB/atom), resulting in an increased mratio(ml/ms) from 0.18 to 0.32. This enhancement of the orbital moment emerges as a consequence of the interface interaction between Co and Fe3O4. Density functional theory calculations attribute this heightened orbital magnetic moment to the robust electronic exchange interactions. Our findings not only offer insights into the modulation of magnetic and electronic characteristics in Co-based magnetic heterostructures but also provide valuable implications for the potential application of magnetic oxide/ferromagnetic heterostructures in future spintronic devices.

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Sputtering deposition of dense and low-resistive amorphous In2O3: Sn films under ZONE-T conditions of Thornton's structural diagram

Wada,

Magdy,

Takeda

et al. 2024

Applied Physics Letters

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We have fabricated smooth-surfaced amorphous In2O3:Sn (a-ITO) films at a high temperature of 550 °C, far above the typical crystallization threshold of 150 °C for ITO films. This achievement has been made possible by intentionally introducing N2 into the sputtering atmosphere, which maintains a low N atom incorporation of only a few atomic percent within the films. Positioned within ZONE-T of the Thornton diagram (higher-temperature region characterized by high film density), our method allows the preparation of films with superior film density about 6.96 g/cm3, substantially exceeding the density of 6.58 g/cm3 for conventional a-ITO films fabricated under ZONE-1 (low-temperature region) and approaching the bulk crystal density of In2O3 at 7.12 g/cm3. The films also feature a high carrier density of 5 × 1020 cm−3 and a remarkably low resistivity of 3.5 × 10−4 Ω cm, comparable to those of polycrystalline films. The analysis via vacuum-ultraviolet absorption spectroscopy on N and O atom densities in the plasma suggests that amorphization is primarily caused not by N atoms incorporated in the films but by those temporally adsorbed on the film surface, inhibiting crystal nucleation before eventually desorbing. Our findings will pave the way not only for broader applications of a-ITO films but also for the design of other amorphous materials at temperatures beyond their crystallization points.

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Growth of Single-Crystalline ZnO Films on 18%-Lattice-Mismatched Sapphire Substrates Using Buffer Layers with Three-Dimensional Islands

Cited by 5 publications

References 37 publications

Growth of ZnO Polytypes: Multiple Facets of Diverse Applications

Growth of ZnO Polytypes: Multiple Facets of Diverse Applications

Enhanced orbital magnetic moment of Co film grown on Fe3O4(001)

Sputtering deposition of dense and low-resistive amorphous In2O3: Sn films under ZONE-T conditions of Thornton's structural diagram

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