Browsing by Author "Shye, Der-Chi"

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Dependence of ferroelectric characteristics on the deposition temperature of (Pb,Sr)TiO3 films
(2007-10-01)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Shye, Der-Chi
;
Chou, Chen-Chia
;
Chiou, Bi-Shiou
The pulsed laser deposition (PLD) of (Pb,Sr)TiO3 (PSrT) films on Pt/SiO2/Si at low substrate temperatures (T-s, ranging from 300 to 450 degrees C, has been investigated. The PLD PSrT films prepared at low Ts exhibit ferroelectric proper-ties, good crystallinity, and no significant interdiffusion between the PSrT film and the Pt bottom electrode. The conduction mechanism is identified as Schottky emission at low electric fields and as Poole-Frenkel emission at high electric fields. PSrT films grown at appropriate T, yield fewer interface states and fewer trapping states, leading to a smaller leakage current. The enhanced (100) preferred orientation of PSrT films deposited at T-s= 350-400 degrees C exhibits optimum ferroelectricity. In addition, the dielectric constant and ferroelectricity are associated with the preferred orientation. This shows that the electrical characteristics strongly rely on the preferred orientation and trapping states, which could be controlled by varying the substrate temperature (T, <= 450 degrees C during PLD.
Effects of accumulated laser pulses on (Pb,Sr)TiO(3) films post-excimer laser annealed at low temperatures
(2007-08-01)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Chiou, Bi-Shiou
;
Shye, Der-Chi
;
Hwang, Chuan-Chou
In this article, we report the effect of excimer laser annealing (ELA) on the characteristics of (Pb,Sr)TiO(3) (PSrT) films. The unirradiated and irradiated films are characterized by atomic force microscope (AFM), X-ray photoelectron spectroscopy, X-ray diffractometer (XRD), transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). It is found that the crystallinity is improved and the oxygen content is increased by ELA. Besides, the surface morphology becomes rough after ELA. Moreover, PSrT films irradiated by ELA are found to increase the grain size near the surface. The material properties of unirradiated and irradiated films, as well as the characteristics of PSrT films irradiated with various laser pulses, will be explored in this study. (c) 2007 Elsevier B.V. All rights reserved.
Effects of accumulated laser pulses on (Pb,Sr)TiO3 films post-excimer laser annealed at low temperatures
(2007-08-01)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Chiou, Bi-Shiou
;
Shye, Der-Chi
;
Hwang, Chuan-Chou
In this article, we report the effect of excimer laser annealing (ELA) on the characteristics of (Pb,Sr)TiO3 (PSrT) films. The unirradiated and irradiated films are characterized by atomic force microscope (AFM), X-ray photoelectron spectroscopy, X-ray diffractometer (XRD), transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). It is found that the crystallinity is improved and the oxygen content is increased by ELA. Besides, the surface morphology becomes rough after ELA. Moreover, PSrT films irradiated by ELA are found to increase the grain size near the surface. The material properties of unirradiated and irradiated films, as well as the characteristics of PSrT films irradiated with various laser pulses, will be explored in this study. (c) 2007 Elsevier B.V. All rights reserved.
Field-Emission Stability of Hydrothermally Synthesized Aluminum-Doped Zinc Oxide Nanostructures
(2012-07-01)
Hsieh, Tsang-Yen
;
Wang, Jyh-Liang
;
Yang, Po-Yu
;
Hwang, Chuan-Chou
;
Shye, Der-Chi
The Al-doped ZnO (AZO) nanostructures field-emission arrays (FEAs) were hydrothermally synthesized on AZO/glass substrate. The samples with Al-dosage of 3 at.% show the morphology as nanowires vertically grown on the substrates and a structure of c-axis elongated single-crystalline wurtzite. The good field-emission (i.e., the large anode current and low fluctuation of 15.9%) can be found by AZO nanostructure FEAs with well-designed Al-dosage (i.e., 3 at.%) because of the vertical nanowires with the less structural defects and superior crystallinity. Moreover, the Full width at half maximum (FWHM) of near band-edge emission (NBE) decreased as the increase of annealing temperature, representing the compensated structural defects during oxygen ambient annealing. After the oxygen annealing at 500 degrees C, the hydrothermal AZO nanostructure FEAs revealed the excellent electrical characteristics (i.e., the larger anode current and uniform distribution of induced fluorescence) and enhanced field-emission stability (i.e., the lowest current fluctuation of 5.97%).
Oxygen annealing effect on field-emission characteristics of hydrothermally synthesized Al-doped ZnO nanowires
(2013-09-01)
Wang, Jyh-Liang
;
Hsieh, Tsang-Yen
;
Yang, Po-Yu
;
Hwang, Chuan-Chou
;
Shye, Der-Chi
Al-doped ZnO (AZO) nanowires (NWs) were synthesized using low-temperature hydrothermal growth to investigate field emission (FE) characteristics. The intensity ratio of NBE peak to DLE peak (R = I-NBE/I-DLE) increases and the half-maximum of NBE peaks (FWHMNBE) decreases with the Al contents. Experimental results reveal the FE characteristics of AZO NWs are functions of Al content. Moreover, the larger R value and the smaller FWHMNBE are found as the oxygen annealing temperature increases. The hydrothermal AZO NWs annealed in oxygen ambience with an appropriate temperature (i.e. 300-500 degrees C) can demonstrate the further improved FE properties (i.e. the turn-on field of 1.70 V/mu m (at 1 mu A/cm(2)), threshold field of 2.92 V/mu m (at 1 mA/cm(2)), and beta of 4547). (C) 2012 Elsevier B.V. All rights reserved.
Polarization degradation and breakdown of pulse-laser-deposited (Pb,Sr)TiO3 films at low temperatures
(2007-01-01)
Wang, Jyh-Liang
;
Shye, Der-Chi
;
Lai, Yi-Sheng
;
Tseng, Huai-Yuan
;
Juan, Chuan-Ping
(Pb,Sr)TiO3 (PST) films were deposited on Pt/SiO2/Si by pulsed laser deposition at low substrate temperatures (T-s) ranging from 300 to 450 degrees C. The loss in remnant polarization (P-r) and coercive field (E-c) is found to be less than 17% after 10(10) switching cycles when T-s is higher than 350 degrees C. It is also suggested that the leakage current is reduced when T-s increases up to a temperature of 400 degrees C. However, PST films deposited at 450 degrees C may produce serious Pb-O volatilization, resulting in the deterioration of the crystallinity and high leakage currents. As a result, the 400 degrees C-deposited PST film reveals the lowest leakage current, nearly fatigued-free J-E characteristics after 10(10) switching cycles, and the best breakdown property, attributed to the enhanced crystallinity and low concentration of defects.
The effects of oxygen annealing on the electrical characteristics of hydrothermally grown zinc oxide thin-film transistors
(2012-11-01)
Wang, Jyh-Liang
;
Yang, Po-Yu
;
Hsieh, Tsang-Yen
;
Hwang, Chuan-Chou
;
Shye, Der-Chi
High-performance transparent zinc oxide (ZnO) thin-film transistors (TFTs) with location-controlled lateral-grain growth were fabricated by hydrothermal method. The ZnO active channel was laterally grown with aluminum-doped ZnO (AZO) seed layer underneath the Ti/Pt film. Compare to the unannealed ZnO TFTs, the annealed devices reveal the high-quality ZnO layer with the compensated structural defects in the channel region after oxygen ambient annealing at 400 degrees C. Therefore, the superior device performances (i.e. the excellent filed-effect mobility of 9.07 cm(2)/V s, positive threshold voltage of 2.25 V. high on/off current ratio of similar to 10(6), and low gate leakage current of <1 nA) of hydrothermally grown ZnO TFTs can be achieved with oxygen ambient annealing. (c) 2012 Elsevier Ltd. All rights reserved.