27 research outputs found
Systematic control of persistent photoconductivity induced by oxygen vacancies in BaSnO3 epitaxial thin films
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Oxygen vacancy-assisted recovery process for increasing electron mobility in n-type BaSnO3 epitaxial thin films
No full textThe 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.
No full text1
Oxygen-vacancy-assisted recovery process for enhancing electron mobility in n-type BaSnO3 epitaxial thin films
No full text2
Ni metal nanoparticle exsolution on perovskite stannate support with high electrical conductivity
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Steep-slope NbO2-based threshold switch enabled by pulsed-laser-induced phase transformation
No full textThe correlated oxides, including NbO2, show promising potential for threshold switching device in that it prevents sneak current in 3D cross-point array architecture and overcomes a limitation of subthreshold swing (SS 573K) to observe voltage-induced insulator-to-metal transition (IMT), this high-temperature processing needs to be avoided due to degradation by unwanted layers and high energy consumption[3]. Moreover, due to the multivalency of Nb cation, there was very limited oxygen partial pressure (pO2) window to stabilized Nb4+ valence states during the NbO2 lm growth[3]. In contrast, pulsed laser annealing, which generates temperature eld at conned area, is powerful tool for rapid crystal growth and a reduction reaction is also possible by changing process environment. In this research, we report new strategy for fabricating high performance threshold switch with correlated oxides NbO2 using pulsed laser annealing, showing steep voltage-induced insulator-to-metal transition. As the number of pulses and process environment were accurately controlled during laser annealing, the as-grown Nb2O5 lms were transformed into NbO2 by forming stable Nb4+ valence states. The fabricated selector device using laser-annealed NbO2 lms shows low o-current (665 nA) and high Ion=Ioff ratio (>230) without high temperature process. A comprehensive study with transmission electron microscopy and synchrotron X-ray photoemission spectroscopy reveals that the crystallization combined with oxygen loss stimulates the formation of stable NbO2 crystallites in the lms during pulsed laser annealing. Our approach provides novel solution for facile fabrication of high-performance correlated oxide-based selector device with steep transition.1
Steep-slope NbO2-based threshold switch enabled by pulsed-laser-induced phase transformation
No full text1
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
