Browsing by Author "Le, Phuoc Huu"

Now showing 1 - 3 of 3

Superconductivity in textured Bi clusters/Bi2Te3 films
(2014-09-01)
Le, Phuoc Huu
;
Tzeng, Wen-Yen
;
Chen, Hsueh-Ju
;
Luo, Chih Wei
;
Lin, Jiunn-Yuan
We report superconductivity at an onset critical temperature below 3.1 K in topological insulator similar to 200-nm-thick Bi2Te3 thin films grown by pulsed laser deposition. Using energy-dispersive X-ray spectroscopy elemental mapping and Auger electron spectroscopy elemental depth profiling, we clearly identified bismuth (Bi) precipitation and Bi cluster signatures. Superconductivity in the Bi2Te3 films was attributed to the proximity effect of Bi clusters precipitated on the surface of the Bi2Te3 films. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
The optical properties of Ag2Te crystals from THz to UV
(2017-11-25)
Yeh, Tien-Tien
;
Lin, Wen Hao
;
Tzeng, Wen-Yen
;
Le, Phuoc Huu
;
Luo, Chih-Wei
The optical properties of monoclinic Ag2Te crystals are studied in a wide range (3.7 meV-6.2 eV) of photon energies. The measured reflectivity spectra from THz to UV allow unambiguous a photon energy-dependent complex dielectric function, complex refractive index and absorption coefficient to be obtained. The spectral structure in these optical parameters further indicates the coexistence of an indirect transition with a bandgap energy of about 10 meV and a direct transition with a bandgap energy of about 1.84 eV. (C) 2017 Elsevier B. V. All rights reserved.
Ultrafast dynamics of coherent optical phonon in a thin film of Bi3Se2Te
(2018-08-17)
Ko, Ying-Kuan
;
Huang, Yan-Hao
;
Le, Phuoc Huu
;
Luo, Chih-Wei
;
Gospodinov, Marin Mirtchev
We have performed ultrafast time-resolved spectroscopy of transient absorption for a thin film of Bi3Se2Te, in which recent study result implies the existence of topological surface state. The observed relaxation signal was attributed to the band filling and Auger recombination processes based on the pump power dependence of the signal. After the band filling, bulk-to-surface scattering is thought to proceed being mediated by phonon emission. The dynamics of the phonon was observed from the dumped oscillation appeared on the relaxation curve of the observed signal. The phase of the oscillation indicates that the phonon mode has the period of 519 +/- 3 fs in the electronic excited state. (C) 2018 Elsevier B.V. All rights reserved.