1,720,965 research outputs found
Oxygen vacancy-assisted recovery process for increasing electron mobility in n-type BaSnO3 epitaxial thin films
Get PDFThe scattering of charge carriers by line defects, i.e., threading dislocations (TDs), severely limits electron mobility in epitaxial semiconductor films grown on dissimilar substrates. The density of TDs needs to be decreased to further enhance electron mobility in lattice-mismatched epitaxial films and heterostructures for application in high-performance electronic devices. Here, we report a strategy for the post-treatment of epitaxial La-doped BaSnO3 (LBSO) films by delicately controlling the oxygen partial pressure p(O-2), which achieved a significant increase in the room temperature (RT) electron mobility (mu(e)) to mu(e) = 122 cm(2) V-1 s(-1) at a carrier concentration of 1.1 x 10(20) cm(-3). This mobility enhancement is mostly attributed to an oxygen vacancy-assisted recovery process that reduces the density of TDs by accelerating the movement of dislocations in ionic crystals under a p(O-2)-controlled treatment despite an increase in the density of charged point defects. Our finding suggests that accurate control of the interactions between point defects and line defects can reduce dominant carrier scattering by charged dislocations in epitaxial oxide semiconductors that have dissimilar substrates. This method provides alternative approaches to achieving perovskite oxide heterostructures that have high RT mu(e) values.11Ysciescopu
Oxygen-Vacancy-Assisted Recovery Process to Enhance Electron Mobility in N-Type BaSnO3 Epitaxial Thin Films.
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High-throughput Roll-to-Roll Fabrication of Flexible Thermochromic Coatings for Smart Windows with VO2 Nanoparticles
No full textVO2-based ‘nanothermochromics’ that utilizes the dispersion of VO2 nanoparticles in passive host matrix has been evaluated as a economic strategy of energy-saving “smart” windows to reduce energy consumption for heating and air conditioning in building. Here, we demonstrate a high-throughput roll-to-roll fabrication of thermochromic coatings for smart windows that can adapt their optical properties in accordance with external temperature. A large quantity (250 g) of VO2 nanoparticles (NPs) was synthesized at a time by controlled thermal treatment of bead-milled V2O5 NPs as a fast and inexpensive method. The amorphous nature of bead-milled V2O5 NPs combined with nanometer size kinetically facilitates uniform synthesis of high-quality VO2 NPs even under the less-reducing condition than that used to obtain bulk VO2. This mass production of VO2 NPs could be used to fabricate the largest VO2/PVP composites thermochromic coatings (12 cm × 600 cm) yet produced with excellent infrared modulation ability (~ 45%). This scalable and continuous production of large coating with thermochromic NPs will accelerate the commercialization of thermochromic coatings for smart windows,
which will contribute to a large reduction in energy consumption to heat or cool buildings.1
Oxygen-vacancy-assisted recovery process for increasing electron mobility in n-type BaSnO3 epitaxial thin lms
No full textNew transparent oxide semiconductors (TOSs) have received extensive interests and demands for the application of current optoelectronic devices. In particular, La-doped BaSnO3 (LBSO) have recently attracted much attention due to the excellent room-temperature (RT) electron mobility ( 320 cm2V1s1 at n = 8.0 1019 cm3 in a single crystal) and the excellent thermal stability [1]. Despite the great potential of LBSO for transparent electronics, epitaxial LBSO lms were reported to show much lower electron mobility than single crystals, which has been ascribed into the high density of line defects, i.e., dislocations, which are generated by lattice mismatch between substrate and lm [2]. In this research, we demonstrate the signicant increase in the room-temperature electron mobility of LBSO by delicately modulating the oxygen vacancy (VO) concentration by post-growth treatment. Through the accurate adjustment of oxygen partial pressure (pO2) under annealing, the roomtemperature mobility of LBSO lms on STO substrates could increase up to 115 cm2V1s1 at a carrier concentration of 1.2 1020 cm3, which results in simultaneous increase of carrier density and mobility [3]. The electrical, optical and structural eects of VO formed during annealing were systematically investigated, and especially, signicant reduction of threading dislocations was directly observed by bright-eld and dark-eld image of transmission electron microscopy and reciprocal space mapping of x-ray diraction. Thus, the enhancement of RT electron mobility by adjusting pO2 was attributed to the annihilation of threading dislocation by high-temperature recovery process, i.e., the dislocation annihilation through oxygen-vacancy-induced climb. Our nding suggests that the interaction between point defects and line defects can be exploited to boost carrier density and mobility in transparent oxide semiconductors.1
Enhanced electron mobility of Sn-excess BaSnO3 epitaxial films induced by surface chemical reconstruction at high temperature
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High-throughput roll-to-roll fabrication of flexible thermochromic coatings for smart windows with V02 nanoparticles
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High-throughput roll-to-roll fabrication of flexible thermochromic coatings for smart windows with VO2 nanoparticles
No full textVO2-based ‘nanothermochromics’ that utilize the dispersion of VO2 nanoparticles in a passive host matrix have been evaluated as an economic strategy of “smart” windows to reduce energy consumption for heating and air conditioning in buildings. Here, we demonstrate a high-throughput roll-to-roll fabrication of thermochromic coatings for smart windows that can adapt their optical properties in accordance with external temperature. A large quantity (250 g) of VO2 nanoparticles (NPs) was synthesized at one time by controlled thermal treatment of bead-milled V2O5 NPs as a fast and inexpensive method. The amorphous nature of bead-milled V2O5 NPs combined with their nanometer size kinetically facilitates uniform synthesis of high-quality VO2 NPs even under less-reducing conditions than those used to obtain bulk VO2. This mass production of VO2 NPs could be used to fabricate the largest thermochromic coatings with VO2/PVP composites (12 cm × 600 cm) yet produced with excellent infrared modulation ability (∼45%). This scalable and continuous production of large coatings with thermochromic NPs will accelerate the commercialization of thermochromic coatings for smart windows, which will contribute to a large reduction in energy consumption to heat or cool buildings.112Nsciescopu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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