Browsing by Author "Lee, I-Che"

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A Novel pH Sensor of Extended-Gate Field-Effect Transistors With Laser-Irradiated Carbon-Nanotube Network
(2012-11-01)
Chien, Yun-Shan
;
Tsai, Wan-Lin
;
Lee, I-Che
;
Chou, Jung-Chuan
;
Cheng, Huang-Chung
The extended-gate field-effect transistors (EGFETs) with only the carbon-nanotube (CNT) thin film as both the sensing membrane and the contact electrode have been demonstrated for the first time to exhibit superior pH sensing characteristics. The continuous-wave laser was necessary to improve the pH sensitivity to be 50.9 mV/pH and the linearity values to be 0.9978 for pH = 3 to pH = 13 wide sensing range, respectively. It implied that the laser energy would unzip the chemically modified multiwalled CNTs (MWCNTs) into numerous graphite slices, resulting in the elevated sensing sites and the improved electrical and sensing properties. Therefore, the laser-irradiated MWCNT network is promising for the applications in the flexible and transparent pH-EGFETs.
A Novel Scheme for Fabricating CMOS Inverters With Poly-Si Nanowire Channels
(2012-06-01)
Kuo, Chia-Hao
;
Lin, Horng-Chih
;
Lee, I-Che
;
Cheng, Huang-Chung
;
Huang, Tiao-Yuan
A novel complementary metal-oxide-semiconductor inverter with poly-Si nanowire channels is proposed and demonstrated in this letter. The scheme employs a clever tilted-angle implant process in the fabrication; therefore, the formation of the source and drain of both p-channel and n-channel devices requires only one lithographic step. The fabricated n-channel and p-channel field-effect transistors in the inverters show a high ON/OFF current ratio, an acceptable subthreshold swing, and a symmetric driving current, thus enabling the realization of excellent characteristics of the inverters.
A Novel SONOS Memory With Recessed-Channel Poly-Si TFT via Excimer Laser Crystallization
(2012-04-01)
Lee, I-Che
;
Tsai, Chun-Chien
;
Kuo, Hsu-Hang
;
Yang, Po-Yu
;
Wang, Chao-Lung
A silicon-oxide-nitride-oxide-silicon memory with recessed-channel (RC) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) via excimer-laser crystallization (ELC) has been demonstrated to achieve a high mobility of similar to 400 cm(2)/V . s and a large ON/OFF current ratio of similar to 10(8). Such a high performance is because the RC poly-Si TFTs possess only one perpendicular grain boundary (GB) in the channel and the corresponding protrusion at this GB. In addition, the proposed devices also exhibited the largest memory window of 2.63 V in 10 ms with respect to 2.37 and 1.31 V for the conventional-ELC and solid-phase-crystallized ones, respectively. Since the silicon grain growth could be artificially controlled, the device-to-device uniformity could be significantly improved. Therefore, such a simple scheme is promising for applications of low-temperature poly-Si TFTs in 3-D ICs and system on panel.
Dimension dependent immunity of X-ray irradiation on low-temperature polycrystalline-silicon TFTs
(2017-06-01)
Wei, Yin-Chang
;
Li, Yi-Chieh
;
Lee, I-Che
;
Cheng, Huang-Chung
;
電子工程學系及電子研究所
Typically, each element in a large-area flat-panel X-ray image sensor consists of a photodetector and amorphous silicon (a-Si) thin-film transistor (TFT) switches. In order to reduce noise, increase sensor dynamic range, and increase carrying capacity, the low-temperature polycrystalline-silicon (LTPS) TFTs have been proposed as a candidate to replace the a-Si TFTs. However, there are concerns regarding the impact of X-ray radiation in LTPS-TFTs, and several studies have been conducted to inquire into the same. In this paper, we show that LTPS TFTs with small channel length (<2 mu m) are almost immune to X-ray radiation. (C) 2017 The Japan Society of Applied Physics
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 crystallization mechanism on the electrical characteristics of green continuous-wave-laser-crystallized polycrystalline silicon thin film transistors
(2013-07-29)
Chou, Chia-Hsin
;
Lee, I-Che
;
Yang, Po-Yu
;
Hu, Ming-Jhe
;
Wang, Chao-Lung
Thin film transistors (TFTs) with amorphous silicon films crystallized via continuous-wave green laser at a wavelength of 532 nm exhibit very different electrical characteristics in various crystallization regions, corresponding to the Gaussian energy density distribution of the laser beam. In the center region subjected to the highest energy density, the full melting scheme led to the best crystallinity of the polycrystalline silicon film, resulting in the highest field-effect mobility of 500 cm(2) V-1 s(-1). In contrast, the edge region that resulted in solid phase crystallization exhibited the worst mobility of 48 cm 2 V-1 s(-1) for the polycrystalline silicon TFTs. (C) 2013 AIP Publishing LLC.
Enhanced efficiency of the dye-sensitized solar cells by excimer laser irradiated carbon nanotube network counter electrode
(2014-02-03)
Chien, Yun-San
;
Yang, Po-Yu
;
Lee, I-Che
;
Chu, Chih-Chieh
;
Chou, Chia-Hsin
The carbon nanotube network decorated with Pt nanoparticles (PtCNT) irradiated by excimer laser as counter electrode (CE) of dye-sensitized solar cells (DSSCs) has been systematically demonstrated. The conversion efficiency would be improved from 7.12% to 9.28% with respect to conventional Pt-film one. It was attributed to the enhanced catalytic surface from Pt nanoparticles and the improved conductivity due to the adjoining phenomenon of PtCNTs irradiated by laser. Moreover, the laser annealing could also promote the interface contact between CE and conductive glass. Therefore, such a simple laser-irradiated PtCNT network is promising for the future flexible DSSCs applications. (C) 2014 AIP Publishing LLC.
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.
Field Emission Properties of Carbon Nanotube Arrays on the Thickness-Controlled Flexible Substrate by the Pattern Transfer Process
(2012-07-01)
Chang, Chia-Tsung
;
Juan, Chuan-Ping
;
Lin, Yi-Chan
;
Li, Yu-Ren
;
Tsai, Wan-Lin
A technigal with the polydimethylsiloxane (PDMS) solution infiltrated into the SiOx-coated CNTAs has been utilized to directly transfer the CNTAs away from the silicon substrate. The oxide coating layer was utilized to protect the morpholgy of as-grown patterned vertical aligmed carbon nanotube (CNTs) arrays. The high density plasma reactive ions etching (HDP-RIE) system was used to make the CNTs emerge from the surface of the flexible substrate and modify the crystallines of CNTs. After the protecting oxide was HDP-RIE-processed for 8 min, the emission current properties were enhanced to be 1.03 V/mu m and 1.43 V/mu m, respectively, for the turn-on field and the threshold field, as compared with 1.25 V/mu m and 1.59 V/mu m for the as-grown CNTs, accordingly. The Field Emission (FE) enhancement after dry etching could be attributed to the open-ended structures and better crystalline.
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.
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 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 Excimer-Laser-Crystallized Polycrystalline Silicon Thin-Film Transistors with the Pre-Patterned Recessed Channel
(2012-06-01)
Wang, Chao-Lung
;
Cheng, Huang-Chung
;
Lee, I-Che
;
Wu, Chun-Yu
;
Cheng, Yu-Ting
High-performance polycrystalline silicon (poly-Si) thin-film transistors (TFTs) have been achieved using an excimer laser crystallization method on a prepatterned recessed channel (RC). Such a prepatterned RC TFT exhibited an excellent field-effect mobility of 412 cm(2) V-1 s(-1) and an on/off current ratio higher than 1:1 x 10(8) as compared with 125 cm(2) V-1 s(-1) and 2:2 x 10(7) for the conventional ones, respectively. This is attributed to the two-dimensional control of the grain boundary location and the resultant cross-shaped grain boundary structures within the recessed regions. Therefore, the prepatterned RC TFTs with only one grain boundary parallel to the channel direction as the TFTs could be fabricated to avoid the perpendicular grain boundary. This technology is thus promising for the future applications of poly-Si TFTs in the system-on-panel (SOP) and three-dimensional integrated circuits (3D-ICs). (C) 2012 The Japan Society of Applied Physics
High-performance polycrystalline silicon thin-film transistors prepared via the laser crystallization of the prepatterned channel layer on the bottom-gate structure
(2013-02-01)
Wang, Chao-Lung
;
Lee, I-Che
;
Wu, Chun-Yu
;
Cheng, Yu-Ting
;
Yang, Po-Yu
High-performance polycrystalline silicon thin-film transistors (TFTs) using an excimer laser crystallization of the prepatterned channel layer on the bottom-gate (BG) structure were fabricated to exhibit a field-effect mobility as high as 339 cm(2)/V s and an on/off current ratio of 9.5x10(7) with respect to 102 cm(2)/V s and 1.5x10(7) for the conventional top-gate (TG) TFTs, respectively. Such a superior performance is attributed to the cross-shaped grain boundary structure formed in the channel region owing to the two-dimensional location control of grain boundaries. Moreover, the prepatterned BG TFTs show better device-to-device uniformity than the conventional TG ones due to the manipulated grain boundaries. This technology is thus promising for the future applications of system-on-panel and three-dimension integrated circuits. (C) 2012 Elsevier B.V. All rights reserved.
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 Polycrystalline-Silicon Nanowire Thin-Film Transistors With Location-Controlled Grain Boundary via Excimer Laser Crystallization
(2012-11-01)
Wang, Chao-Lung
;
Lee, I-Che
;
Wu, Chun-Yu
;
Chou, Chia-Hsin
;
Yang, Po-Yu
High-performance polycrystalline-silicon (poly-Si) nanowire (NW) thin-film transistors (TFTs) are demonstrated using excimer laser crystallization to control the locations of grain boundaries two-dimensionally. Via the locally increased thickness of the amorphous-silicon (a-Si) film as the seeds, the cross-shaped grain boundary structures were produced among these thicker a-Si grids. The NW TFTs with one primary grain boundary perpendicular to the channel direction could be therefore fabricated to achieve an excellent field-effect mobility of 346 cm(2)/V . s and an on/off current ratio of 3 x 10(9). Furthermore, the grain-boundary-location-controlled NW TFTs also exhibited better reliability due to the control of grain boundary locations. This technology is thus promising for applications of low-temperature poly-Si TFTs in system-on-panel and 3-D integrated circuits.
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 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).
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.