Browsing by Author "Xiang, Ping-Hua"

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Proton-Mediated Phase Control in Flexible and Transparent Mott Transistors
(1970-01-01)
Deng, Xing
;
Zhao, Yi-Feng
;
Zhong, Ni
;
Yue, Fang-Yu
;
Huang, Rong
To meet the development of wearable and energy-efficient flexible electronics, multifunctional oxide film on soft substrate and its versatile phase control are in demand. Here, flexible VO2 film is directly deposited on mica via van der Waals epitaxy, exhibiting pronounced metal-insulator (MI) transition and infrared (IR) switching properties. Using a rubbery solid ionic gel as gate insulator, a fully flexible and transparent VO2-channel Mott transistor is successfully demonstrated. The prototype Mott transistor processes excellent mechanical flexibility and giant on/off current ratio of approximate to 10(5)% even at room temperature. Highly reversible suppression of MI transition is realized by applying small gate voltages and the nonvolatile phase modulation suggests an electrochemical reaction mechanism. X-ray diffraction and secondary-ion mass spectroscopy analyses, together with theoretical calculation, confirm that electrically controlled phase transformation is mainly caused by reversible and nonvolatile proton (H+) doping into VO2 lattices. Significant modulation of IR transmittance (>40%) is observed in the VO2 Mott transistor, which is attributed to electrically driven phase transition between insulating VO2 and metallic HxVO2 phases. The flexible and transparent Mott transistor provides a good platform for proton-mediated Mottronics and realizes novel electric control of optical characteristics, showing a promising application for flexible energy-saving smart windows.
Ultrafast Giant Photostriction of Epitaxial Strontium Iridate Film with Superior Endurance
(2018-12-01)
Yang, Jan-Chi
;
Liou, Yi-De
;
Tzeng, Wen-Yen
;
Liu, Heng-Jui
;
Chang, Yao-Wen
Photostriction, optical stimulus driven mechanical deformation in materials, provides a solution toward next-generation technology. Here, the giant photostriction (similar to 2% change of lattice) of epitaxial strontium iridate (SrIrO3) films under illumination at room temperature is revealed via power-dependent Raman scattering, which is significantly larger as compared to conventional inorganic materials. The time scale and mechanism of this giant photostriction in SrIrO3 are further studied through time-resolved transient reflectivity measurements. The main mechanism is determined to be the electron-phonon coupling. In addition, we find that such an exotic behavior happens within few picoseconds and remains up to 107 cyclic on/off operations. The observation of giant photostriction in SrIrO3 films with superior endurance promises the advance of shape responsive solids that are sensitive to environmental stimuli, which could be widely utilized for multifunctional optoelectronics and optomechanical devices.