Browsing by Author "Chen, Y. T."

Now showing 1 - 9 of 9

Conduction control at ferroic domain walls via external stimuli
(2014)
Yang, J. C.
;
Yeh, C. H.
;
Chen, Y. T.
;
Liao, S. C.
;
Huang, R.
Intriguing functionalities at nano-sized domain walls have recently spawned a new paradigmfor developing novel nanoelectronics due to versatile characteristics. In this study, we explore a new scenario to modulate the local conduction of ferroic domain walls. Three controlling parameters, i.e., external electrical field, magnetic field and light, are introduced to the 90 degrees domain walls (90 degrees DWs) of BiFeO3. Electrical modulation is realized by electrical transport, where the mobility of 90 degrees DWs can be altered by gating voltage. We further use the ferromagnetic/antiferromagnetic coupling to reveal the inherent magnetism at the DWs. With an established magnetic nature, magneto-transport has been conducted to introduce magnetic controlling parameter, where a giant positive magnetoresistance change can be observed up to 200%. In addition, light modulated conduction, a core factor for multifunctional applications, is successfully demonstrated (current enhancement by a factor of 2 with 11 W white lamp). These results offer new insights to discover the tunability of domain wall nanoelectronics.
Crosstalk Measurement Investigation of Glasses Type Stereoscopic Displays
(2011)
Chen, Y. T.
;
Pong, B. J.
;
Lai, Y. Y.
;
Tsai, T. C.
;
Wen, B. J.
There are three 3D televisions (TVs) used for 3D crosstalk evaluation, including TV1 (PDP with shutter glasses), TV2 (LCD with passive glasses) and TV3 (LCD with shutter glasses). Four 3D crosstalk formulas are investigated, one is black to white (B to W) method of crosstalk evaluation, and the rest of them are dealing gray to gray (G to G) method of crosstalk evaluation. The crosstalk are determined by the four formulas and then compared with each other. In the noticeable crosstalk region, the determined results of four gray to gray crosstalk methods are consistent to illustrate the worse one which is the left channel of TV3. The calculated crosstalk, by these formulas, seems not able to fully quantize the crosstalk effect of 3D TVs. For example, in the left channel of TV3, the result is 2746.9% by using the gray to gray crosstalk method which is proposed by AUO. On the other hand, the result of black to white crosstalk method, 18.24%, is quite different in comparison with AUO proposed method. In this circumstance, the human factor experiments will be performed to verify consistency of the formulas with the human perception.
Direct observation of ferroelectric polarization-modulated band bending at oxide interfaces
(2012-03-19)
Huang, B. C.
;
Chen, Y. T.
;
Chiu, Y. P.
;
Huang, Y. C.
;
Yang, J. C.
This study presents a direct visualization of the influences of ferroelectric polarization on the electronic properties of the Schottky contact at the Nb-SrTiO3/BiFeO3 hetero-interface using scanning tunneling microscopy and spectroscopy (STM/S). The evolution of the local density of states across the Nb-SrTiO3/BiFeO3 interface reveals the interfacial band alignment and the characteristic quantities of the metal/ferroelectric contact. The unique combination of STM and STS in this study delivers an approach to obtain critical information on the interfacial electronic configurations of ferroelectric oxide interfaces and also their variation with ferroelectric polarization switching. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3691615]
Marked enhancement of Neel temperature in strained YMnO(3) thin films probed by femtosecond spectroscopy
(2011-04-01)
Wu, K. H.
;
Chen, H-J
;
Chen, Y. T.
;
Hsieh, C. C.
;
Luo, C. W.
In this paper, the (001)-oriented hexagonal YMnO(3) (h-YMO) thin films with various nominal strain states were deposited on MgO(100), MgO(111) and YSZ(111) substrates by pulsed laser deposition. The ultrafast dynamics probed by wavelength-tunable femtosecond pump-probe spectroscopy was performed to disclose the effects of the epitaxial strain on the electronic structure and associated magnetism. Analyses based on the measured transient-reflectivity-change (Delta R/R) curves revealed that while the magnitude of the on-site Mn d-d transition energy E(dd)(T) changes only slightly with the variation of the lattice constant ratio c/a, a marked shift in the antiferromagnetic (AFM) Neel temperature T(N) was observed and the direction of shift was dependent on the type of strain. The possible mechanism for the observed strain effect on the AFM ordering is discussed. Copyright (C) EPLA, 2011
Marked enhancement of Neel temperature in strained YMnO3 thin films probed by femtosecond spectroscopy
(2011-04-01)
Wu, K. H.
;
Chen, H-J
;
Chen, Y. T.
;
Hsieh, C. C.
;
Luo, C. W.
In this paper, the (001)-oriented hexagonal YMnO3 (h-YMO) thin films with various nominal strain states were deposited on MgO(100), MgO(111) and YSZ(111) substrates by pulsed laser deposition. The ultrafast dynamics probed by wavelength-tunable femtosecond pump-probe spectroscopy was performed to disclose the effects of the epitaxial strain on the electronic structure and associated magnetism. Analyses based on the measured transient-reflectivity-change (Delta R/R) curves revealed that while the magnitude of the on-site Mn d-d transition energy E-dd(T) changes only slightly with the variation of the lattice constant ratio c/a, a marked shift in the antiferromagnetic (AFM) Neel temperature T-N was observed and the direction of shift was dependent on the type of strain. The possible mechanism for the observed strain effect on the AFM ordering is discussed. Copyright (C) EPLA, 2011
Optical fine structures of highly quantized InGaAs/GaAs self-assembled quantum dots
(2010-06-30)
Ramirez, H. Y.
;
Lin, C. H.
;
Chao, C. C.
;
Hsu, Y.
;
You, W. T.
A theoretical model for the electron-hole exchange interaction in three-dimensionally (3D) confining semiconductor nanostructures is presented to explain the observed decreasing tendency of the fine-structure splittings (FSSs) of small InGaAs/GaAs self-assembled quantum dots (QDs) with increasing the emission energies. The experimentally revealed FSS reduction is shown to be highly associated with the significant 3D spreading of electronic orbitals and reduced overlap of electron and hole wave functions in small and/or Ga-diffused QDs. The combination of quantum size and Ga-diffusion effects substantially reduces the averaged e-h exchange interaction and leads to the reduced FSSs in the regime of high emission energy.
Self-mode-locked Nd:GdVO(4) laser with multi-GHz oscillations: manifestation of third-order nonlinearity
(2009-10-01)
Liang, H. C.
;
Chang, H. L.
;
Huang, W. C.
;
Su, K. W.
;
Chen, Y. F.
The large third-order nonlinearity of GdVO(4) crystals is employed to realize the compact efficient continuous-wave self-mode locking in the range of several GHz in a Nd:GdVO(4) laser with a simple linear cavity without the need of any additional components. With a pump power of 2.5 W, the compact laser cavity produces average output powers greater than 0.7 W with a pulse width as short as 23 ps in the range of 2-6 GHz.
Self-mode-locked Nd:GdVO4 laser with multi-GHz oscillations: manifestation of third-order nonlinearity
(2009-10-01)
Liang, H. C.
;
Chang, H. L.
;
Huang, W. C.
;
Su, K. W.
;
Chen, Y. F.
The large third-order nonlinearity of GdVO4 crystals is employed to realize the compact efficient continuous-wave self-mode locking in the range of several GHz in a Nd:GdVO4 laser with a simple linear cavity without the need of any additional components. With a pump power of 2.5 W, the compact laser cavity produces average output powers greater than 0.7 W with a pulse width as short as 23 ps in the range of 2-6 GHz.
Singlet-triplet transitions in highly correlated nanowire quantum dots
(2010-02-01)
Chen, Y. T.
;
Chao, C. C.
;
Huang, S. Y.
;
Tang, C. S.
;
Cheng, S. J.
We consider a quantum dot embedded in a three-dimensional nanowire with tunable aspect ratio a. A configuration interaction theory is developed to calculate the energy spectra of the finite ID quantum dot systems charged with two electrons in the presence of magnetic fields B along the wire axis. Fruitful singlet-triplet transition behaviors are revealed and explained in terms of the competing exchange interaction, correlation interaction, and spin-Zeeman energy. In the high aspect ratio regime, the singlet-triplet transitions are shown designable by tuning the parameters a and B. The transition also manifest the highly correlated nature of long nanowire quantum dots. (C) 2009 Elsevier B.V. All rights reserved.