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Vanadium dioxide (VO2) has attracted extensive attention due to the specific metal-insulator phase transition as well as the wide device applications. The practical performance of VO2-based device strongly depends on the quality of VO2, since the higher quality of VO2 film always shows much more pronounced phase transition behavior. Thus, the preparation of high quality VO2 film is essential and highly desirable. In this work, we have prepared high-quality VO2 film on SiC substrate by water vapor oxidation with graphene (G) buffer layer, which showed excellent phase transformation properties. Compared with the VO2/SiC sample without G buffer layer, the VO2/G/SiC films show the resistance changes up to four-orders of magnitude across the phase transition boundary and superior optoelectronic properties, which indicates the significant role of G layer in the film growth process. The current study not only provides an economical and feasible method for VO2/G/SiC thin film preparation with high quality, but also supply some clues for the application of G-based VO2 devices in the future.

ZrO2 as a wide-bandgap semiconductor with high dielectric constant and ferroelectric properties has been extensively studied. To explore the impact of chemical doping on the structure and optical performance of ZrO2, HfxZr1−xO2 (x = 0, 0.25, 0.5, 0.75, 1) thin films were prepared through pulsed laser deposition. X-ray diffraction reveals that the orthorhombic phase (o) (111) gradually transforms into the monoclinic phase (m) (−111) with the increase in Hf content from 0 to 1. Furthermore, optical property analysis demonstrates an increase in the optical bandgap from 5.17 to 5.68 eV with the increase in Hf doping content. Density functional theory calculations and x-ray photoelectron spectroscopy suggest that the widening of the bandgap in HZO films is associated with the hybridization of Zr 4d and Hf 5d orbitals. [ABSTRACT FROM AUTHOR]

In this study, La- and V-doped SrSnO3 epitaxial films were fabricated via pulsed laser deposition, and the effects of doping on the structure and physical properties of films were systematically investigated. Detailed x-ray diffraction characterization demonstrates that the lattice parameters of V-doped SrSnO3 (SrSn1−xVxO3, x = 0–1, SSVO) films decrease gradually as the V content increases. The optical bandgap first increases from 4.43 to 4.56 eV and then decreases to 3.31 eV with the increasing V content. Density functional theory calculations indicate that the strong hybridization between Sn 5s and V 3d orbitals causes an initial expansion of the bandgap. Doping SSVO films with 5% La greatly improves the electrical conductivity. Hall-effect measurements show that the (La0.05Sr0.95)VO3 film has the lowest room-temperature resistivity of 0.05 mΩ cm and correspondingly the largest carrier density of 1.79 × 1022 cm−3. Ferromagnetism in SrSn1−xVxO3 films is highly dependent on V concentration at room-temperature, and the origin of ferromagnetism may be explained by the bound magnetic polaron model. [ABSTRACT FROM AUTHOR]

Epitaxial Cd2SnO4 films were fabricated on MgO(00l) single crystalline substrates by pulsed laser deposition technique at various substrate temperatures and growth oxygen pressures. The microstructure, transport, and optical properties of the films were studied in detail. High‐resolution X‐ray diffraction and high‐resolution transmission electron microscopy results demonstrate that all the Cd2SnO4 films are grown epitaxially on MgO(00l) substrates. Atomic force microscope images indicate that the films have smooth surface morphologies. Hall‐effect measurements reveal that the epitaxial film grown at 680°C and 40 Pa presents the minimum resistivity value of 0.61 mΩcm and maximal Hall mobility of 32.87 cm2 V−1 s−1. The metal–semiconductor transitions of Cd2SnO4 films were observed and explained by competitive effects of two conductive mechanisms. The optical transmittance of the Cd2SnO4 films is higher than 75% in the visible and near‐infrared range, and the optical bandgap was determined to be about 3.09 eV for the film grown at optimal condition. The band structure and density of states of the Cd2SnO4 were calculated by the density functional theory. [ABSTRACT FROM AUTHOR]