Browsing by Author "Liao, Chan-Yu"

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Densification effects of the carbon nanotube pillar array on field-emission properties
(2016-06)
Wang, Kuang-Yu
;
Chou, Chia-Hsin
;
Liao, Chan-Yu
;
Li, Yu-Ren
;
Cheng, Huang-Chung
In this study, a simple densification method for carbon nanotube (CNT) pillars is proposed to achieve high-performance field emission characteristics and stable emission. Through capillary force during solution evaporation, the CNT density in each pillar can be increased by about six times without causing damage to the crystallinity of CNTs. The densified CNT pillars exhibit lower series resistance, sharper pillars, better contacts, higher thermal conductivity, and better mechanical stiffness than as-grown ones. Therefore, the threshold field of the field emitter with such CNT pillars of 50 mu m height can be reduced to 1.98 V/mu m, as compared with 2.2V/mu m for the undensified ones. Moreover, the fluctuation of field-emission current decreases from 15.5 to 9.4% after the stress tests at a field of 2V/mu m for 1800 s. These findings imply that the densified CNT pillars are promising for the field-emission applications. (C) 2016 The Japan Society of Applied Physics
Densification effects of the carbon nanotube pillar array on field-emission properties
(2016-06-01)
Wang, Kuang-Yu
;
Chou, Chia-Hsin
;
Liao, Chan-Yu
;
Li, Yu-Ren
;
Cheng, Huang-Chung
In this study, a simple densification method for carbon nanotube (CNT) pillars is proposed to achieve high-performance field emission characteristics and stable emission. Through capillary force during solution evaporation, the CNT density in each pillar can be increased by about six times without causing damage to the crystallinity of CNTs. The densified CNT pillars exhibit lower series resistance, sharper pillars, better contacts, higher thermal conductivity, and better mechanical stiffness than as-grown ones. Therefore, the threshold field of the field emitter with such CNT pillars of 50 mu m height can be reduced to 1.98 V/mu m, as compared with 2.2V/mu m for the undensified ones. Moreover, the fluctuation of field-emission current decreases from 15.5 to 9.4% after the stress tests at a field of 2V/mu m for 1800 s. These findings imply that the densified CNT pillars are promising for the field-emission applications. (C) 2016 The Japan Society of Applied Physics
Effect of oxygen plasma treatment on horizontally aligned carbon nanotube thin film as pH-sensing membrane of extended-gate field-effect transistor
(2015-04-01)
Wang, Kuang-Yu
;
Tsai, Wan-Lin
;
Yang, Po-Yu
;
Chou, Chia-Hsin
;
Li, Yu-Ren
The high-performance pH-sensing membrane of extended-gate field-effect transistors (EGFET) composed of high-conductivity horizontally aligned carbon nanotube thin films (HACNTFs) after oxygen plasma treatment is successfully demonstrated. The 10-mu m-wide catalytic metal lines with 60 mu m interspace produced CNT vertical plates, and the plates were mechanically pulled down and densified to form HACNTFs. A large amount of oxygen-containing functional groups are decorated on the CNTs after the oxygen plasma treatment. These functional groups act as the sensing sites and respond to the H+ or OH- ions in solutions with different pH values. Therefore, these functionalized HACNTFs as pH-EGFET-sensing membranes can achieve a high voltage sensitivity of 40 mV/pH and high current sensitivity of 0.78 mu A(1/2)/pH. Moreover, large linearity of 0.998 is measured in a wide sensing range from pH 1 to 13. These results reveal that the oxygen plasma treatment is an effective way to improve the CNT-sensing characteristics in pH-EGFET sensors. (C) 2015 The Japan Society of Applied Physics
Effects of a capping oxide layer on polycrystalline-silicon thin-film transistors fabricated by continuous-wave laser crystallization
(2018-06-01)
Li, Yi-Shao
;
Wu, Chun-Yi
;
Chou, Chia-Hsin
;
Liao, Chan-Yu
;
Chuang, Kai-Chi
A tetraethyl-orthosilicate (TEOS) capping oxide was deposited by low-pressure chemical vapor deposition (LPCVD) on a 200-nm-thick amorphous Si (a-Si) film as a heat reservoir to improve the crystallinity and surface roughness of polycrystalline silicon (poly-Si) formed by continuous-wave laser crystallization (CLC). The effects of four thicknesses of the capping oxide layer to satisfy an antireflection condition, namely, 90, 270, 450, and 630 nm, were investigated. The largest poly-Si grain size of 2.5 x 20 mu m(2) could be achieved using a capping oxide layer with an optimal thickness of 450 nm. Moreover, poly-Si nanorod (NR) thin-film transistors (TFTs) fabricated using the aforementioned technique exhibited a superior electron field-effect mobility of 1093.3 cm(2) V-1 s(-1) and an on/off current ratio of 2.53 x 10(9). (c) 2018 The Japan Society of Applied Physics
Effects of Crystallinity on the Electrical Characteristics of Counter-Doped Polycrystalline Germanium Thin-Film Transistor via Continuous-Wave Laser Crystallization
(2019-01-01)
Li, Yi-Shao
;
Wu, Chun-Yi
;
Liao, Chan-Yu
;
Luo, Jun-Dao
;
Chuang, Kai-Chi
The crystallinity of polycrystalline germanium (poly-Ge) films were demonstrated through continuous-wave laser crystallization (CLC) with Gaussian-distribution beam profile. The different grain sizes of CLC poly-Ge were observed in their three crystallization regions, which were 2 mu m, 680 nm, and 90 nm for the central, transition, and edge regions, respectively. Furthermore, the relation between crystallinity and carrier types in these three regions of counter-doped CLC poly-Ge films were investigated. In the central and transition regions, the CLC poly-Ge films with relatively low hole concentration were easily converted to n-type poly-Ge films through a counter-doping process. In contrast, the edge region with poor crystallinity exhibited p-type behavior due to high defect-generated hole concentration. According to these material properties of counter-doped CLC poly-Ge films, the corresponding transfer characteristics of p-channel poly-Ge thin-film transistor for three crystallization regions were further investigated. Subsequently, high-performance p-channel poly-Ge thin-film transistors in the central region exhibited a superior field-effect mobility of 792.2 cm(2)/V-s.
Field-Emission Characteristics of the Densified Carbon Nanotube Pillars Array
(2016)
Wang, Kang-Yu
;
Liao, Chan-Yu
;
Cheng, Huang-Chung
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this study, the densification effects of carbon nanotube (CNT) pillar array have been proved to significantly increase the field emission characteristics. Without damage to the crystallinity of CNTs, the CNT density of each densified pillar can be increased about 6.25 times as compared to the as-grown ones. Consequently, the densified CNT pillars exhibit higher electrical conductivity, better contacts, and more emission sites, which are favorable to the field emission properties. What\'s more, the optimum field emission characteristics occur at the condition of R/H = 2 with H = 30 mu m for both of the as-grown and densified samples because of the minimum screening effect and the proper aspect ratio. Therefore, the field emitter with densified CNT pillars of 30-mu m in height and 60-mu m in interspacing possesses the lowest turn on and threshold fields of 0.73 and 1.29 V/mu m, respectively. It implies that the densified CNT pillars are promising for the field-emission applications. (C) The Author(s) 2016. Published by ECS. All rights reserved.
Flexible Atmospheric-Pressure Gas Ionization Sensors with Horizontally Aligned Carbon Nanotube Electrodes
(2016-12)
Wang, Kuang-Yu
;
Tsai, Wan-Lin
;
Yang, Po-Yu
;
Chou, Chia-Hsin
;
Liao, Chan-Yu
A flexible atmospheric-pressure gas ionization sensor (GIS) with the horizontally aligned carbon nanotube (HACNT) electrodes in the planar structure has been demonstrated for the first time via the proposed rolling-down technique of CNTs. The gap between the electrodes of high-density and uniform HACNTs could be therefore precisely controlled via adjusting the length of the CNTs and the interspacing between the patterned catalysts. High-performance sensing characteristics to various gases Ar, N-2, air, and O-2 at atmospheric pressure with the breakdown voltages as low as 160, 193, 205, and 233, respectively, have been achieved with the electrode gap of 20 mu m. It is attributed to the field enhancement from the small gap and the double-side nanostructures. The superior flexibility of the proposed GIS with different bending tests has also been obtained. It reflects that the HACNTs possess excellent material properties, including great mechanical strength and good electrical conductivity. Such a simple, low-cost, and flexible GIS is promising for its applications in portable and wearable personal monitoring devices.
Formation and characterization of high-performance silicon thin-film transistors with and without location-controlled grain boundary
(2017-10-01)
Liao, Chan-Yu
;
Lin, Hsiao-Chun
;
Wang, Chao-Lung
;
Lee, I-Che
;
Chou, Chia-Hsin
This paper reports the demonstration of structural effects on excimer laser crystallization (ELC) for the Si strip with a recessed-channel structure on the silicon nitride under-layer (RCS-ULN). We revealed that a single location-controlled grain boundary (GB) oriented normal to the Si strip in the middle site without any other GB in the recessed region can be attained via ELC for the RCS-ULN structures with a short recessed region between neighboring long thick regions in a narrow Si strip. This can be attributed to the effective production of a significant 2D lateral thermal gradient in the recessed region and neighboring thick regions. Consequently, the RCS-ULN TFTs fabricated at the position one-half of such an optimal recessed region can achieve a superior field-effect mobility of 670 cm(2) V-1 . s(-1) with minor performance variations since the single-crystal-like Si channel has been adopted.
High-Performance Germanium Thin-Film Transistors With Single-Crystal-Like Channel via Continuous-Wave Laser Crystallization
(2018-12-01)
Li, Yi-Shao
;
Wu, Chun-Yi
;
Liao, Chan-Yu
;
Huang, Wen-Hsien
;
Shieh, Jia-Min
This letter reports of the fabrication of high-performance p-channel polycrystalline germanium (poly-Ge) thin-film transistors (TFTs) using continuous-wave laser crystallization (CLC). During the CLC process, the direction of crystallization matches the direction of laser scanning due to a strong temperature gradient in the melting region. This makes it possible to fabricate high-quality poly-Ge thin films with 1-D longitudinal grains as large as 2 mu m x 20 mu m. We fabricated the proposed p-channel CLC Ge TFTs with channel width of 0.7 mu m and a channel length each of 0.7 mu m. Consequently, the proposed p-channel CLC Ge TFTs with single-crystal-like channel fabricated on a longitudinal grain with biaxial tensile strain achieved a superior field-effect mobility of 1014.9 cm(2/)V-s.
High-performance p-channel polycrystalline-germanium thin-film transistors via excimer laser crystallization and counter doping
(2016-04-01)
Liao, Chan-Yu
;
Huang, Ching-Yu
;
Huang, Ming-Hui
;
Chou, Chia-Hsin
;
Cheng, Huang-Chung
High-quality polycrystalline-germanium (poly-Ge) thin films have been successfully fabricated by excimer laser crystallization (ELC). Grains as large as 1 mu m were achieved by ELC at 300 mJ/cm(2). Meanwhile, the defect-generated hole concentrations in Ge thin films were significantly reduced. Furthermore, the majority carriers could then be converted to n-type by counter doping (CD) with a suitable dose. Then, high-performance p-channel Ge thin-film transistors (TFTs) with a high on/off current ratio of up to 1.7 x 10(3) and a high field-effect mobility of up to 208 cm(2) V-1 s(-1) were demonstrated for a channel width and length both of 0.5 mu m. It was revealed that ELC combined with CD is effective for attaining highp-erformance p-channel poly-Ge TFTs. (C) 2016 The Japan Society of Applied Physics
High-performance p-channel polycrystalline-germanium thin-film transistors via excimer laser crystallization and counter doping
(2016-04)
Liao, Chan-Yu
;
Huang, Ching-Yu
;
Huang, Ming-Hui
;
Chou, Chia-Hsin
;
Cheng, Huang-Chung
High-quality polycrystalline-germanium (poly-Ge) thin films have been successfully fabricated by excimer laser crystallization (ELC). Grains as large as 1 mu m were achieved by ELC at 300 mJ/cm(2). Meanwhile, the defect-generated hole concentrations in Ge thin films were significantly reduced. Furthermore, the majority carriers could then be converted to n-type by counter doping (CD) with a suitable dose. Then, high-performance p-channel Ge thin-film transistors (TFTs) with a high on/off current ratio of up to 1.7 x 10(3) and a high field-effect mobility of up to 208 cm(2) V-1 s(-1) were demonstrated for a channel width and length both of 0.5 mu m. It was revealed that ELC combined with CD is effective for attaining highp-erformance p-channel poly-Ge TFTs. (C) 2016 The Japan Society of Applied Physics
High-performance p-channel thin-film transistors with lightly doped n-type excimer-laser-crystallized germanium films
(2017-06-01)
Liao, Chan-Yu
;
Huang, Ching-Yu
;
Huang, Ming-Hui
;
Huang, Wen-Hsien
;
Shen, Chang-Hong
High-performance polycrystalline-germanium (poly-Ge) thin-film transistors (TFTs) fabricated with lightly doped Ge thin films by excimer laser crystallization (ELC) and counter doping (CD) have been demonstrated. High-quality n-type Ge thin films with a grain size as large as 1 mu m were fabricated by ELC in the super lateral-growth regime and CD at a dose of 1 x 10(13) cm(-2) or higher. Consequently, a superior field-effect mobility of 271cm(2)V(-1)s(-1) and a high on/off current ratio of 2.7 x 10(3) have been obtained for p-channel Ge TFTs with the channel width and length of both 0.5 mu m fabricated by ELC at 300mJ/cm(2) and CD at a dose of 1 x 10(13)cm(-2). The effects of ELC conditions and CD dose on the electrical characteristics of p-channel Ge TFTs were also investigated. (C) 2017 The Japan Society of Applied Physics.
High-Performance Polycrystalline Silicon Thin-Film Transistors with Two-Dimensional Location Control of the Grain Boundary via Excimer Laser Crystallization
(2012-07-01)
Wang, Chao-Lung
;
Lee, I-Che
;
Wu, Chun-Yu
;
Liao, Chan-Yu
;
Cheng, Yu-Ting
High-performance low-temperature polycrystalline silicon (Poly-Si) thin-film transistors (TFTs) have been fabricated with two-dimensional (2-D) location-controlled grain boundaries using excimer laser crystallization (ELC). By locally increased thickness of the amorphous silicon (a-Si) film that was served as the seed crystals with a partial-melting crystallization scheme, the cross-shaped grain boundary structures were produced between the thicker a-Si grids. The Poly-Si TFTs with one parallel and one perpendicular grain boundary along the channel direction could therefore be fabricated to reach excellent field-effect mobility of 530 cm(2)/V-s while the conventional ones exhibited field-effect mobility of 198 cm(2)/V-s. Furthermore, the proposed TFTs achieved not only superior electric properties but also improved uniformity as compared with the conventional ones owing to the artificially controlled locations of grain boundaries.
High-Performance Recessed-Channel Germanium Thin-Film Transistors via Excimer Laser Crystallization
(2018-03-01)
Liao, Chan-Yu
;
Chen, Shih-Hung
;
Huang, Wen-Hsien
;
Shen, Chang-Hong
;
Shieh, Jia-Min
This letter demonstrates the excimer laser crystallization (ELC) of germanium (Ge) thin films with the recessed-channel (RC) structure for high-performance p-channel Ge thin-film transistors (TFTs). Using ELC, large longitudinal grainswith a single perpendicular grain boundary (GB) in the center of the recessed region were formed. This can be attributed to the lateral grain growth from unmelted Ge solid seeds in the thick region toward the complete melting recessed region during ELC. Consequently, the proposed p-channel RC-ELC Ge TFTs possessing large longitudinal grains without the perpendicular GB in the channel region exhibited a superior field-effect holemobility of 447 cm(2)V(-1)s(-1) with minor performance deviation.
High-performance resistive switching characteristics of programmable metallization cell with oxidized Cu-Ti electrodes
(2013-09-30)
Huang, Yu-Chih
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Chou, Chia-Hsin
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Liao, Chan-Yu
;
Tsai, Wan-Lin
;
Cheng, Huang-Chung
Programmable metallization cell (PMC) memory devices with oxidized Cu-Ti alloy films as the bottom electrodes have been shown to exhibit a superior on/off state current ratio (memory window) of as high as 10(3) and endurance of 3000 cycles as compared to conventional pure copper and unoxidized Cu-Ti alloy electrodes. It was conjectured that the Cu-Ti alloy electrodes could obtain the appropriate amount of copper atoms to format and rupture the conductive filaments in the resistive switching layer. Furthermore, the oxidized Cu-Ti alloys could control the Cu cations from the Cu and Cu2O to the appropriate amountto achieve the most favorable PMC characteristics. (C) 2013 AIP Publishing LLC.
High-Performance Single-Crystal-Like Strained-Silicon Nanowire Thin-Film Transistors via Continuous-Wave Laser Crystallization
(2015-04-01)
Chou, Chia-Hsin
;
Chan, Wei-Sheng
;
Lee, I-Che
;
Wang, Chao-Lung
;
Wu, Chun-Yu
High-performance polycrystalline-silicon nanowire (NW) thin-film transistors (TFTs) have been demonstrated via continuous-wave laser crystallization (CLC) to exhibit the low subthreshold swing of 216 mV/decade and high ON/OFF ratio of 1.6x10(9). In addition, the thermal stress of similar to 800 MPa induced from the CLC process also contributed to the single-crystal-like silicon NW CLC TFTs to achieve an excellent field-effect mobility of up to 900 cm(2)V(-1)s(-1).
Improvement of ferroelectric properties in undoped hafnium oxide thin films using thermal atomic layer deposition
(2019-06-01)
Luo, Jun-Dao
;
Zhang, He-Xin
;
Wang, Zheng-Ying
;
Gu, Siang-Sheng
;
Yeh, Yun-Tien
Modulating the water pulse time during thermal atomic layer deposition is an effective approach to enhancing the ferroelectric properties of undoped HfO2 thin films. Through grazing incidence X-ray diffraction (GI-XRD), it was observed that a shorter water pulse time can inhibit formation of the monoclinic phase and thereby obtain good remanent polarization. Transmission electron microscopy (TEM) images and GIXRD analysis were used to reveal the crystallization conditions of the undoped HfO2 thin films. By modulating the water pulse time during deposition of all samples, no impurities were found in these films via X-ray photoelectron spectroscopy. Moreover, samples with shorter water pulse times revealed lower binding energy and higher leakage current. However, electric measurement results of samples with shorter water pulse times revealed a higher remanent polarization of approximately 9 mu C cm(-2) and a coercive field of similar to 1.95 MV cm(-1) compared with other samples. After endurance testing, the films lasted for more than 10(8) cycles at 2.25 V, so they are ideally suited to low-power ferroelectric CMOS devices and nonvolatile memory applications. (c) 2019 The Japan Society of Applied Physics
Location-Controlled Single-Crystal-Like Silicon Thin-Film Transistors by Excimer Laser Crystallization on Recessed-Channel Silicon Strip With Under-Layered Nitride
(2016-09)
Liao, Chan-Yu
;
Lin, Hsiao-Chun
;
Wang, Chao-Lung
;
Lee, I-Che
;
Chou, Chia-Hsin
High-performance Si thin-film transistors (TFTs) on the recessed-channel Si strips with the under-layered nitride film have been fabricated using excimer laser crystallization (ELC). A nitride film was added as a light absorption layer to suppress solidification along the edge of the Si strip. Thus, only one primary grain boundary perpendicular to the Si strip formed in the middle of the recessed region during ELC. The single-crystal-like Si TFTs fabricated on one-half of the recessed region are capable of excellent field-effect mobility of 640 cm(2)/V-s, with only minor deviation.