Browsing by Author "Wang, Jyh-Liang"

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Characteristics of low-temperature pulse-laser-deposited (Pb,Sr)TiO3 films in metal/ferroelectric/silicon structure
(2007-01-07)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Lee, Trent Gwo-Yann
;
Chiou, Bi-Shiou
;
Tsai, Chun-Chien
In this study, pulsed- laser deposited ( Pb, Sr) TiO3 ( PSrT) films on p- type Si were studied at low substrate temperatures ranging from 300 to 450 degrees C for metal/ ferroelectric/ semiconductor applications. The substrate temperature strongly enhances film crystallinity without significant inter- diffusion at the PSrT/ Si interface and affects the electrical properties. As the substrate temperature increases, the films have smaller leakage currents, fewer trap states at the electrode interfaces, clockwise capacitance versus applied field hysteresis loops and larger memory windows correlated with superior crystallinity. Conversely, 300 degrees C- deposited films exhibit a small and counterclockwise loop with a positive shift of the flatband voltage, attributed to more negative trap charges within the films. However, the high substrate temperature ( 450 degrees C) may produce serious Pb - O volatilization, incurring more defects and leakage degradation. The analyses of fixed charge density and flatband voltage shift reveal the trap status and agree well with the leakage characteristic. An electron band model of the Pt/ PSrT/ Si electronic structure is proposed to explain the electrical behaviour. The excellent fatigue endurance with a small variation of memory windows (< 11%) after 1010 switching is also demonstrated.
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.
Effect of Oxygen Annealing on the Ultraviolet Photoresponse of p-NiO-Nanoflower/n-ZnO-Nanowire Heterostructures
(2011-07-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Tsai, Wei-Chih
;
Wang, Shui-Jinn
;
Lin, Jia-Chuan
A transparent ultraviolet (UV) sensor using nanoheterojunctions (NHJs) composed of p-type NiO nanoflowers (NFs) and n-type ZnO nanowires (NWs) was prepared through a sequential low-temperature hydrothermal-growth process. The devices that were annealed in an oxygen (O(2)) ambient exhibited better rectification behavior (l(forward)/l(reverse) = 427), a lower forward threshold voltage (V(th) = 0.98 V), a lower leakage current (1.68 x 10(-5) A/cm(2)), and superior sensitivity (l(UV)/l(dark) = 57.8; l(visible)/l(dark) = 1.25) to UV light (lambda = 325 nm) than the unannealed devices. The remarkably improved device performances and optoelectronic characteristics of the annealed p-NiO-NF/n-ZnO-NW NHJs can be associated with their fewer structural defects, fewer interfacial defects, and better crystallinity. A stable and repeatable operation of dynamic photoresponse was also observed in the annealed devices. The excellent sensitivity and repeatable photoresponse to UV light of the hydrothermally grown p-NiO-NF/n-ZnO-NW NHJs annealed in a suitable O(2) ambient indicate that they can be applied to nano-integrated optoelectronic devices.
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.
Fabrication and characterization of excimer laser crystallized double-gate low-temperature poly-silicon thin film transistors
(2007)
Tsai, Chun-Chien
;
Wei, Kai-Fang
;
Lee, Yao-Jen
;
Lee, I-Che
;
Chen, Hsu-Hsin
In this letter, high-performance low-temperature poly-Silicon (LTPS) thin film transistors (TFTs) with double-gate (DG) structure and lateral silicon grains have been demonstrated by excimer laser crystallization (ELC). Therefore, the proposeed ELC DG TFTs exhibited better current-voltage characteristics as compared with the conventional solid-phase crystallized (SPC) poly-Si double-gate TFTs or conventional ELC top-gate (TG) TFTs.
Ferroelectricity and negative temperature coefficient of resistance in pulsed-laser-deposited (Pb, Sr) TiO(3) films
(2008-04-21)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Liou, Sz-Chian
;
Tsai, Chun-Chien
;
Chiou, Bi-Shiou
(Pb, Sr)TiO(3) films deposited on Pt/SiO(2)/Si substrates by pulsed-laser deposition (PLD) at 400 degrees C with oxygen pressures ranging from 50 to 200 mTorr have been investigated. The paraelectricity-to-ferroelectricity transition of films depends on the oxygen pressure during deposition. Films deposited at 200 mTorr exhibit paraelectric-like nature, whereas films deposited at lower pressures present the ferroelectric characteristic. The (Pb, Sr) TiO(3) film is found to exhibit a negative temperature coefficient of resistance (NTCR) at the measurement temperature ranging from 30 to 390 degrees C. This work demonstrates that the ferroelectricity/paraelectricity and the temperature coefficient of resistance of (Pb, Sr) TiO(3) films could be controlled by oxygen pressures during PLD.
Field-Emission Characteristics of Al-Doped ZnO Nanostructures Hydrothermally Synthesized at Low Temperature
(2011-07-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Tsai, Wei-Chih
;
Wang, Shui-Jinn
;
Lin, Jia-Chuan
The aluminum-doped ZnO (AZO) nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at a temperature as low as 85 degrees C. The morphologies, crystallinity, optical emission properties, and chemical bonding states of AZO nanostructures show evident dependence on the aluminum dosage. The morphologies of AZO nanostructures were changed from vertically aligned nanowires (NWs), and NWs coexisted with nanosheets (NSs), to complete NSs in respect of the Al-dosages of 0 similar to 3 at.%, 5 at.%, and 7 at.%, correspondingly. The undoped ZnO and lightly Al-doped AZO (<= 3 at.%) NWs are single-crystalline wurtzite structure. In contrast, heavily Al-doped AZO sample is polycrystalline. The AZO nanostructure with 3 at.% Al-dosages reveals the optimal crystallinity and less structural defects, reflecting the longest carrier lifetime and highest conductivity. Consequently, the field-emission characteristics of such an AZO emitter can exhibit the higher current density, larger field-enhancement factor (beta) of 3131, lower turn-on field of 2.17 V/mu m, and lower threshold field of 3.43 V/mu m.
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%).
High Field-Emission Stability of Offset-Thin-Film Transistor-Controlled Al-Doped Zinc Oxide Nanowires
(2011-04-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Tsai, Wei-Chih
;
Wang, Shui-Jinn
;
Lin, Jia-Chuan
Aluminum-doped zinc oxide (AZO) nanowire (NW) arrays incorporating an offset thin-film transistor (offset-TFT) have been proposed to achieve high field-emission (FE) stability. The AZO NW field emission arrays (FEAs) were hydrothermally grown at a low temperature of 85 degrees C. The uncontrolled AZO NW FEAs demonstrated superior FE characteristics (i.e., turn-on field of similar to 2.17 V/mu m and threshold field of similar to 3.43 V/mu m) compared with those of the conventional CNT FEAs grown at a temperature below 600 degrees C. However, uncontrolled AZO NW FEAs show a larger current fluctuation of 15.6%. Therefore, the offset-TFTs were used to control the AZO NW FEAs. Consequently, the fluctuation of AZO NW FEAs could be significantly reduced to less than 2%. This novel field emission device exhibits good emission stability, low-voltage controllability, low-temperature processing, and structural simplicity, making it promising for applications in flat panel displays. (C) 2011 The Japan Society of Applied Physics
High-Performance Bottom-Gate Poly-Si Polysilicon-Oxide-Nitride-Oxide-Silicon Thin Film Transistors Crystallized by Excimer Laser Irradiation for Two-Bit Nonvolatile Memory Applications
(2012-07-01)
Lee, I-Che
;
Kuo, Hsu-Hang
;
Tsai, Chun-Chien
;
Wang, Chao-Lung
;
Yang, Po-Yu
High-performance bottom-gate (BG) poly-Si polysilicon-oxide-nitride-oxide-silicon (SONOS) TFTs with single grain boundary perpendicular to the channel direction have been demonstrated via simple excimer-laser-crystallization (ELC) method. Under an appropriate laser irradiation energy density, the silicon grain growth started from the thicker sidewalls intrinsically caused by the bottom-gate structure and impinged in the center of the channel. Therefore, the proposed ELC BG SONOS TFTs exhibited superior transistor characteristics than the conventional solid-phase-crystallized ones, such as higher field effect mobility of 393 cm(2)/V-s and steeper subthreshold swing of 0.296 V/dec. Due to the high field effect mobility, the electron velocity, impact ionization, and conduction current density could be enhanced effectively, thus improving the memory performance. Based on this mobility-enhanced scheme, the proposed ELC BG SONOS TFTs exhibited better performance in terms of relatively large memory window, high program/erase speed, long retention time, and 2-bit operation. Such an ELC BG SONOS TFT with single-grain boundary in the channel is compatible with the conventional a-Si TFT process and therefore very promising for the embedded memory in the system-on-panel applications.
High-performance short-channel double-gate low-temperature polysilicon thin-film transistors using excimer laser crystallization
(2007-11-01)
Tsai, Chun-Chien
;
Wei, Kai-Fang
;
Lee, Yao-Jen
;
Chen, Hsu-Hsin
;
Wang, Jyh-Liang
In this letter, high-performance low-temperature polysilicon thin-film transistors (TFTs) with double-gate (DG) structure and controlled lateral grain growth have been demonstrated by excimer laser crystallization. Via a proper excimer laser condition, along with the a-Si step height beside the bottom gate, a superlateral growth of Si was formed in the channel length plateau. Therefore, the DG TFTs with lateral silicon grains in the channel regions exhibited better current-voltage characteristics, as compared with the conventional top-gate ones. The proposed DG TFTs (W/L = 1/1 mu m) had the field-effect mobility exceeding 550 cm(2)/V . s, an ON/OFF current ratio that is higher than 10(8), superior short-channel characteristics, and higher current drivability. In addition, the device-to-device uniformity could be improved since grain growth could be artificially controlled by the spatial plateau structure.
High-performance top and bottom double-gate low-temperature poly-silicon thin film transistors fabricated by excimer laser crystallization
(2008-03-01)
Tsai, Chun-Chien
;
Lee, Yao-Jen
;
Wang, Jyh-Liang
;
Wei, Kai-Fang
;
Lee, I-Che
In this work, high-performance low-temperature poly-silicon (LTPS) thin film transistors (TFTs) with double-gate (DG) structure and lateral grain growth have been demonstrated by excimer laser crystallization (ELC). Therefore, the DG TFTs with lateral silicon grains in the channel regions exhibited better current-voltage characteristics as compared with the conventional solid-phase crystallized (SPC) poly-Si double-gate TFTs or conventional ELC top-gate (TG) TFTs. The proposed ELC DG TFTs (W/L = 1.5/1.5 mu m) had the field-effect-mobility exceeding 400 cm(2)/V s, on/off current ratio higher than 10(8), superior short-channel characteristics and higher current drivability. (c) 2007 Elsevier Ltd. All rights reserved.
High-Performance ZnO Thin-Film Transistors with Location-Controlled Crystal Grains Fabricated by Low-Temperature Hydrothermal Method
(2012-07-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Tsai, Wei-Chih
;
Chang, Yu-Cheng
;
Wang, Shui-Jinn
In this paper, high-performance bottom-gate (BG) thin-film transistors (TFTs) with zinc oxide (ZnO) artificially location-controlled lateral grain growth have been prepared via low-temperature hydrothermal method. For the proper design of source/drain structure of ZnO/Ti/Pt thin films, the grains can be laterally grown from the under-cut ZnO beneath the Ti/Pt layer. Consequently, the single one vertical grain boundary perpendicular to the current flow will be produced in the channel region as the grown grains from the source/drain both sides are impinged. As compared with the conventional sputtered ZnO BG-TFTs, the proposed location-controlled hydrothermal ZnO BG-TFTs (W/L = 250 mu m/10 mu m) demonstrated the higher field-effect mobility of 6.09 cm(2)/V.s, lower threshold voltage of 3.67 V, higher on/off current ratio above 10(6), and superior current drivability, reflecting the high-quality ZnO thin films with less grain boundary effect in the channel region.
Ionic pH and glucose sensors fabricated using hydrothermal ZnO nanostructures
(2016-01)
Wang, Jyh-Liang
;
Yang, Po-Yu
;
Hsieh, Tsang-Yen
;
Juan, Pi-Chun
;
電子工程學系及電子研究所
Hydrothermally synthesized aluminum-doped ZnO (AZO) nanostructures have been adopted in extended-gate field-effect transistor (EGFET) sensors to demonstrate the sensitive and stable pH and glucose sensing characteristics of AZO-nanostructured EGFET sensors. The AZO-nanostructured EGFET sensors exhibited the following superior pH sensing characteristics: a high current sensitivity of 0.96 mu A(1/2)/pH, a high linearity of 0.9999, less distortion of output waveforms, a small hysteresis width of 4.83 mV, good long-term repeatability, and a wide sensing range from pHs 1 to 13. The glucose sensing characteristics of AZO-nanostructured biosensors exhibited the desired sensitivity of 60.5 mu A.cm(-2).mM(-1) and a linearity of 0.9996 up to 13.9 mM. The attractive characteristics of high sensitivity, high linearity, and repeatability of using ionic AZO-nanostructured EGFET sensors indicate their potential use as electrochemical and disposable biosensors. (C) 2016 The Japan Society of Applied Physics
Ionic pH and glucose sensors fabricated using hydrothermal ZnO nanostructures
(2016-01-01)
Wang, Jyh-Liang
;
Yang, Po-Yu
;
Hsieh, Tsang-Yen
;
Juan, Pi-Chun
;
電子工程學系及電子研究所
Hydrothermally synthesized aluminum-doped ZnO (AZO) nanostructures have been adopted in extended-gate field-effect transistor (EGFET) sensors to demonstrate the sensitive and stable pH and glucose sensing characteristics of AZO-nanostructured EGFET sensors. The AZO-nanostructured EGFET sensors exhibited the following superior pH sensing characteristics: a high current sensitivity of 0.96 mu A(1/2)/pH, a high linearity of 0.9999, less distortion of output waveforms, a small hysteresis width of 4.83 mV, good long-term repeatability, and a wide sensing range from pHs 1 to 13. The glucose sensing characteristics of AZO-nanostructured biosensors exhibited the desired sensitivity of 60.5 mu A.cm(-2).mM(-1) and a linearity of 0.9996 up to 13.9 mM. The attractive characteristics of high sensitivity, high linearity, and repeatability of using ionic AZO-nanostructured EGFET sensors indicate their potential use as electrochemical and disposable biosensors. (C) 2016 The Japan Society of Applied Physics
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.
pH Sensing Characteristics of Extended-Gate Field-Effect Transistor Based on Al-Doped ZnO Nanostructures Hydrothermally Synthesized at Low Temperatures
(2011-11-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Chiu, Po-Chun
;
Chou, Jung-Chuan
;
Chen, Cheng-Wei
The pH sensing properties of an extended-gate field-effect transistor (EGFET) with Al-doped ZnO (AZO) nanostructures are investigated. The AZO nanostructures with different Al dosages were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85 degrees C. The pH sensing characteristics of pH-EGFET sensors with an Al dosage of 1.98 at% can exhibit a higher voltage sensitivity of 57.95 mV/pH, a larger linearity of 0.9998, and a wide sensing range of pH 1-13, attributed to the well-aligned nanowire (NW) array, superior crystallinity, less structural defects, and better conductivity. Consequently, the hydrothermally grown AZO NWs demonstrate superior pH sensing characteristics and reveal the potentials for flexible and disposable biosensors.
pH-Sensing Characteristics of Hydrothermal Al-Doped ZnO Nanostructures
(2013)
Wang, Jyh-Liang
;
Yang, Po-Yu
;
Hsieh, Tsang-Yen
;
Hwang, Chuan-Chou
;
Juang, Miin-Horng
Highly sensitive and stable pH-sensing properties of an extended-gate field-effect transistor (EGFET) based on the aluminumdoped ZnO (AZO) nanostructures have been demonstrated. The AZO nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85 degrees C. The AZO sensing nanostructures were connected with the metal-oxide-semiconductor field-effect transistor (MOSFET). Afterwards, the current-voltage (I-V) characteristics and the sensing properties of the pH-EGFET sensors were obtained in different buffer solutions, respectively. As a result, the pH-sensing characteristics of AZO nanostructured pH-EGFET sensors with Al dosage of 3 at.% can exhibit the higher sensitivity of 57.95mV/pH, the larger linearity of 0.9998, the smaller deviation of 0.023 in linearity, the lower drift rate of 1.27mV/hour, and the lower threshold voltage of 1.32V with a wider sensing range (pH 1 similar to pH 13). Hence, the outstanding stability and durability of AZO nanostructured ionic EGFET sensors are attractive for the electrochemical application of flexible and disposable biosensor.
Photoresponse of hydrothermally grown lateral ZnO nanowires
(2010-10-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Tsai, Wei-Chih
;
Wang, Shui-Jinn
;
Lin, Jia-Chuan
In this paper, a simple self-assembled lateral growth of ZnO nanowires (NWs) photodetector has been synthesized by a hydrothermal method at a temperature as low as 85 degrees C. The ZnO NWs exhibit single-crystalline wurtzite with elongated c-axis and can be selectively lateral self-assembled around the edges of ZnO seeding layer. The current of ZnO NWs is sensitive to the variation of ambient pressures, i.e. 4.47 mu A was decreased to 1.48 mu A with 5 V-bias as 1.1 x 10(-6) Torr changed to 760 Torr. accordingly. Moreover, the current voltage characteristics of ZnO NWs photodetectors can be evidently distinguished by UV illumination (i.e. lambda = 325 nm). The photocurrent of ZnO NWs with UV illumination is twice larger than dark current while the voltage biased at 5 V. Consequently, this faster photoresponse convinces that the hydrothermally grown lateral ZnO NWs devices have a fairly good for the fabrication of UV photodetectors. (C) 2010 Elsevier B.V. All rights reserved.