Browsing by Author "Lin, CW"

Now showing 1 - 20 of 28

A high-performance thin-film transistor with a vertical offset structure
(1996-12-01)
Chang, CY
;
Lin, CW
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
In this study, we propose a novel device structure combined with conventional hydrogenated amorphous silicon (a-Si:H) for the source and drain regions and microcrystalline silicon (mu c-Si:H) for the channel region to obtain a high-performance thin-film transistor (TFT), This is a vertical a-Si:H offset structure used to suppress OFF-state current to a small value which is comparable to the conventional a-Si:H TFT's with a much higher drivability. The fabrication process is simple, low temperature (less than or equal to 300 degrees C), and low cost, with a potential for high reliability.
A high-performance thin-film transistor with a vertical offset structure
(1996-12-01)
Chang, CY
;
Lin, CW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this study, we propose a novel device structure combined with conventional hydrogenated amorphous silicon (a-Si:H) for the source and drain regions and microcrystalline silicon (mu c-Si:H) for the channel region to obtain a high-performance thin-film transistor (TFT), This is a vertical a-Si:H offset structure used to suppress OFF-state current to a small value which is comparable to the conventional a-Si:H TFT's with a much higher drivability. The fabrication process is simple, low temperature (less than or equal to 300 degrees C), and low cost, with a potential for high reliability.
A novel device structure for low-temperature polysilicon TFTs with controlled grain growth in channel regions
(2000)
Cheng, LJ
;
Lu, YL
;
Lin, CW
;
Chang, TK
;
Cheng, HC
In this paper, we demonstrate a novel device structure of low-temperature polysilicon thin-film transistors (LTPS TFTs) for AMLCD applications with using excimer-laser crystallization (ELC). The device structure consists of a thin channel and a thick source/drain. This structure has its merit in the process of ELC and is capable of improving TFTs' electrical characteristics. During excimer laser irradiation, this kind of recessed structure is able to build up localized lateral thermal gradients in the regions near the steps and entice crystallization from the chiller thick source/drain regions toward the hotter thin channels. Because of the development of crystallization process, the average field-effect mobility of the devices can be increased to about 350 cm(2)/V.s, and the on/off current ratios exceed eight orders. In addition to improvement of device performance, the process window of ELC is broadened with the recessed structure.
A novel germanium doping method for fabrication of high-performance p-channel poly-Si1-xGex TFT by excimer laser crystallization
(2003-04-01)
Chang, TK
;
Chu, FT
;
Lin, CW
;
Tseng, CH
;
Cheng, HC
In this letter, a novel process for fabricating p-channel poly-Si1-xGex thin-film transistors (TFTs) with high-hole mobility was demonstrated. Germanium (Ge) atoms were incorporated into poly-Si by excimer laser irradiation of a-Si1-xGex/poly-Si double layer. For small size TFTs, especially when channel width/length (W/L) was less than 2 mum/2 mum, the hole mobility of poly-Si1-xGex TFTs was superior to that of poly-Si TFTs. It was inferred that the degree of mobility enhancement by Ge incorporation was beyond that of mobility degradation by defect trap generation when TFT size was shrunk to 2 mum/2 mum. The poly-Si0.91Ge0.09 TFT exhibited a high-hole mobility of 112 cm(2)/V-s, while the hole mobility of the poly-Si counterpart was 73 cm(2)/V-s.
A novel laser-processed self-aligned gate-overlapped LDD poly-Si TFT
(2002-03-01)
Lin, CW
;
Tseng, CH
;
Chang, TK
;
Lin, CW
;
Wang, WT
A novel process for fabricating self-aligned gate-overlapped LDD (SAGOLDD) poly-Si thin film transistors (TFTs) was demonstrated. Laser Irradiation for dopant activation was performed from the backside of the quartz wafer. The graded LDD structure was naturally formed under the gate edges due to the lateral diffusion of the dapants during the laser activation. In comparison with the conventional laser-processed self-aligned poly-Si TFTs, the SAGOLDD poly-Si TFTs exhibited lower leakage current, suppressed kink effect, and higher reliability. Moreover, the proposed process was simple and very suitable for low-temperature process.
A novel thin-film transistor with vertical offset structure
(1997-04-01)
Lin, CW
;
Chang, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel device structure consisting of conventional hydrogenated amorphous silicon (a-Si:H) for the source and drain and of hydrogenated microcrystalline soilicon (mu c-Si:H) for the channel region which can improve the performance of thin-film transistors (TFTs) has been proposed and fabricated. Undoped a-Si:H serves as a blocking layer to suppress the OFF-state current in the drain region which is comparable to that of conventional a-Si:H TFT with a much higher drivability. The fabrication process is simple and inexpensive e with the possibility of high reliability.
A novel thin-film transistor with vertical offset structure
(1997-04-01)
Lin, CW
;
Chang, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel device structure consisting of conventional hydrogenated amorphous silicon (a-Si:H) for the source and drain and of hydrogenated microcrystalline soilicon (mu c-Si:H) for the channel region which can improve the performance of thin-film transistors (TFTs) has been proposed and fabricated. Undoped a-Si:H serves as a blocking layer to suppress the OFF-state current in the drain region which is comparable to that of conventional a-Si:H TFT with a much higher drivability. The fabrication process is simple and inexpensive e with the possibility of high reliability.
A production inventory model which considers the dependence of production rate on demand and inventory level
(2001-01-01)
Su, CT
;
Lin, CW
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study presents a production inventory model for deteriorating products in which the production rate at any instant depends on the demand and the inventory level. While the demand rate is assumed to decrease exponentially, shortages are allowed and excess demand is backlogged as well. Optimal expressions are obtained for the production scheduling period, maximum inventory level, unfilled order backlog and the total average cost. Some cases of the model are briefly discussed. A numerical example illustrates the practicality of the model. The sensitivity of these solutions to changes in underlying parameter values is also discussed.
An investigation of bias temperature instability in hydrogenated low-temperature polycrystalline silicon thin film transistors
(2002-09-01)
Lin, CW
;
Tseng, CH
;
Chang, TK
;
Chang, YH
;
Chu, FT
The instability mechanisms of the hydrogenated n-channel low-temperature polycrystalline silicon thin film transistors under on-state stress were investigated with various bias stress conditions and device channel widths. It was found that hot carrier degradation which originated from a high drain electric field and self-heating during high current operation were the two dominant mechanisms responsible for device degradation. An electrically reversible depassivation/passivation phenomenon was also found in devices under high current stress. but not in those under hot carrier stress. It was inferred that the self-heating effect would accelerate the bond breakage and diffusion of hydrogen ions, thus enhancing the rate of depassivation/passivation. Moreover. when the Current in the hot carrier stress mode was sufficiently high. self-heating became the dominant degradation mechanism and hot carrier degradation phenomenon was also suppressed for devices with large channel width, Meanwhile, the electrically reversible depassivation/passivation phenomenon also occurred in this case.
Chemical vapor deposition of epitaxial zinc oxide thin films on gallium nitride/sapphire substrates
(2004)
Hou, WC
;
Lin, BW
;
Chang, L
;
Lin, TS
;
Lin, CW
High-quality ZnO thin films were formed on (0002) oriented GaN/sapphire substrates by chemical vapor deposition (CVD) of Zinc acetylacetonate (Zn(C5H7O2)(2)) and oxygen. The surface morphology and crystallinity of the deposited ZnO thin films have been investigated using atomic force microscopy and X-ray diffraction. Low temperature photoluminescence spectra show that there is a sharp band edge emission positioned at 3.37 eV and the deep level emission is hardly seen. High-resolution transmission electron microscopy in cross section shows that ZnO is directly grown on GaN in epitaxy without any interlayer, and the ZnO/GaN interface remains atomically flat. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.
Chemical vapor deposition of zinc oxide thin films on Y2O3/Si substrates
(2004)
Lin, CW
;
Cheng, TY
;
Chang, L
;
Juang, JY
;
材料科學與工程學系
Highly-oriented ZnO films were deposited on Y2O3/Si(111) and Y2O3/Si(100) substrates by atmospheric pressure metal-organic chemical vapor deposition (MOCVD) using zinc acetylacetonate (Zn(C5H7O2)(2)) and oxygen as sources. The substrate temperature and O-2 gas temperature were all kept at 500 degreesC. Y2O3, thermodynamically more stable than SiO2 and epitaxially formed on Si, is used as buffer layer. Epitaxial Y2O3 of 200 nm thickness were first grown by pulsed laser deposition on Si(111) and Si(100) substrates at 800 degreesC for 30 min. X-ray diffraction patterns of the samples only show sharp diffraction peaks of Y2O3{222} and ZnO{0002}. The photoluminescence spectra of ZnO show strong peaks of near the band edge and very weak peaks of deep-level emission at 7 K and room temperature. Cross-sectional transmission electron microscopy shows that the highly-oriented ZnO films has columnar structure with a grain size distribution of 600-850 Angstrom. Most of ZnO grains exhibit orientation relationship with Y2O3 as {0002}(ZnO)//{222}(Y2O3), <0110>(ZnO)//(112)(Y2O3), and <1120>(ZnO)//<110>(Y2O3). (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.
Comparison of poly-Si films deposited by UHVCVD and LPCVD and its application for thin film transistors
(2002-09-26)
Peng, DZ
;
Zan, HW
;
Shih, PS
;
Chang, TC
;
Lin, CW
The ultra-high vacuum chemical vapor deposition (UHVCVD) system can deposit poly-Si film without any laser or furnace annealing. The uniformity of threshold voltage and mobility is superior to that deposited by low-pressure chemical vapor deposition (LPCVD) system. However, due to the deposition in polycrystalline phase for UHVCVD, the film surface is rough and results in low field effect mobility compared to that obtained by LPCVD using disilane (Si2H6) in amorphous phase followed by solid phase crystallization (SPC). The on-off current ratio for UHVCVD deposited poly-Si thin film transistors (TFTs) is approximately one order smaller, however, the leakage current for LPCVD SPC TFTs is higher. In this experiment, NH3 was introduced to both of the two samples to improve the device performance. It can be shown that improvements on device characteristics are more significant for UHVCVD deposited poly-Si TFTs, e.g. threshold voltage decreased dramatically and the on-off current ratio improved by two orders of magnitude. (C) 2002 Elsevier Science Ltd. All rights reserved.
Cooling atoms below 100 mu K
(2000-04-01)
Tung, SK
;
Chen, YC
;
Lin, CW
;
Hsu, L
;
Yu, IA
We capture Rb-87 atoms from room-temperature background vapor with a magneto-optical trap (MOT). The temperature of the atoms in the MOT is 320 mu K as the result of Doppler cooling. We further employ polarization gradient cooling to lower atom temperature. The factors that can affect the performance of polarization gradient cooling have been systematically studied. An atom temperature of 75 mu K has been reached with the optimized conditions. Temperatures are measured by the release and recapture method and the time of flight method. Such cold atoms are ready for the evaporative cooling which will finally realize the Bose-Einstein condensation.
Crack-free GaN/AlN distributed Bragg reflectors incorporated with GaN/AlN superlattices grown by metalorganic chemical vapor deposition
(2006-02-06)
Huang, GS
;
Lu, TC
;
Yao, HH
;
Kuo, HC
;
Wang, SC
A crack-free GaN/AlN distributed Bragg reflector (DBR) incorporated with GaN/AlN superlattice (SL) layers was grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition. Three sets of half-wave layers consisting of 5.5 periods of GaN/AlN SL layers and GaN layer were inserted in every five pairs of the 20 pair GaN/AlN DBR structure to suppress the crack generation. The grown GaN/AlN DBRs with SL insertion layers showed no observable cracks in the structure and achieved high peak reflectivity of 97% at 399 nm with a stop band width of 14 nm. Based on the x-ray analysis, the reduction in the in-plane tensile stress in the DBR structure with insertion of SL layers could be responsible for the suppression of crack formation and achievement of high reflectivity. (c) 2006 American Institute of Physics.
Degradation of passivated and non-passivated N-channel low-temperature polycrystalline silicon TFTs prepared by excimer laser processing
(2002-08-01)
Teng, TH
;
Huang, CY
;
Chang, TK
;
Lin, CW
;
Cheng, LJ
The instability mechanisms of passivated and non-passivated low-temperature polycrystalline silicon thin film transistors (LTPS TFTs) under various bias stress conditions have been investigated. Irrespective of plasma treatment, the degradation was more severe under negative gate bias stress than that under positive gate bias stress. This could be due to Fowler-Nordheim tunneling electron induced impact ionization. For hot carrier stress, TFTs with NH3 plasma treatment degraded more severely than those without plasma treatment. This might be attributed to collapsing of weak Si-H bonds in NH3-plasma passivated devices. For the high current stress, it showed the opposite results against hot carrier stress. (C) 2002 Elsevier Science Ltd. All rights reserved.
Dynamic scheduling for GSM data services
(1997-02-01)
Jeng, JY
;
Lin, CW
;
Lin, YB
;
交大名義發表
;
National Chiao Tung University
A new GSM data protocol called high speed circuit switched data (HSCSD) have been developed by European Telecommunications Standards Institute (ETSI) for high speed file transfer and mobile video applications. HSCSD increases data rate by using multiple TDMA time slots (up to 8) instead of one time slot in the current GSM implementation. The problem of multiple time slot assignment is that the blocking rate of the system will increase. This problem can be solved by flexible resource assignment where the service specifies the maximum and the minimum capacity. Based on the current available capacity of a base station, a user will be assigned any rate between the maximum and the minimum capacities. This article describes HSCSD protocol and presents four radio resource allocation strategies for HSCSD: always allocates maximum, always allocates minimum, allocates maximum unless available resources are not enough, and allocates resources according to the current blocking statistics of the base station. A simulation model is proposed to investigate the performance of these algorithms. The blocking probability, the call completion probability, and the quality of service are used to evaluate the effects of algorithms in different system behaviors.
Dynamic scheduling for GSM data services
(1997-02-01)
Jeng, JY
;
Lin, CW
;
Lin, YB
;
交大名義發表
;
National Chiao Tung University
A new GSM data protocol called high speed circuit switched data (HSCSD) have been developed by European Telecommunications Standards Institute (ETSI) for high speed file transfer and mobile video applications. HSCSD increases data rate by using multiple TDMA time slots (up to 8) instead of one time slot in the current GSM implementation. The problem of multiple time slot assignment is that the blocking rate of the system will increase. This problem can be solved by flexible resource assignment where the service specifies the maximum and the minimum capacity. Based on the current available capacity of a base station, a user will be assigned any rate between the maximum and the minimum capacities. This article describes HSCSD protocol and presents four radio resource allocation strategies for HSCSD: always allocates maximum, always allocates minimum, allocates maximum unless available resources are not enough, and allocates resources according to the current blocking statistics of the base station. A simulation model is proposed to investigate the performance of these algorithms. The blocking probability, the call completion probability, and the quality of service are used to evaluate the effects of algorithms in different system behaviors.
Effects of excimer laser dopant activation on low temperature polysilicon thin-film transistors with lightly doped drains
(2001-11-01)
Tseng, CH
;
Lin, CW
;
Chang, TK
;
Cheng, HC
;
Chin, A
Excimer laser annealing has been utilized to manufacture low temperature polycrystalline silicon thin-film transistors with lightly doped drain (LDD) structures. The excimer laser annealing can effectively reduce the thermal budget of source/drain dopant activation, namely, without substrate heating. With the advantages of LDD structure, high performance device characteristics with a low "off" state current of 4.38 x 10(-12) A/mum, high on/off current ratio of 1.6 x 10(7). and good field-effect mobility of 268 cm(2)/V s. can be achieved simultaneously. (C) 2001 The Electrochemical Society.
Fabrication of low-temperature poly-Si thin film transistors with self-aligned graded lightly doped drain structure
(2002-01-01)
Cheng, HC
;
Lin, CW
;
Cheng, LJ
;
Tseng, CH
;
Chang, TK
A novel approach for fabricating low-temperature poly-Si (LTPS) thin film transistors (TFTs) with self-aligned graded lightly doped drain (LDD) structure was demonstrated. The self-aligned graded LDD structure was formed by side-etching the Al gate under the photoresist followed by excimer laser irradiation for dopant activation and lateral diffusion. The graded LDD poly-Si TFTs exhibited low-leakage-current characteristics without significantly sacrificing driving capability due to the graded dopant distribution in the LDD regions, in which the drain electric field could be reduced. The leakage current of 1 mum graded LDD UPS TFTs at Vds = 5 V and Vgs = -10 V could reach below 1 pA/mum, and the on/off current ratio at Vds = 5 V exceeded 10(7). (C) 2001 The Electrochemical Society.
Growth and characterization of chemical-vapor-deposited zinc oxide nanorods
(2006-03-01)
Wu, CL
;
Chang, L
;
Chen, HG
;
Lin, CW
;
Chang, TF
ZnO nanorods were grown on Si substrates by metal-organic chemical vapor deposition (CVD). The ZnO nanorods were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction. It was found that highly oriented ZnO single-crystalline nanorods were formed only on the substrate coated with a gold film. Without the gold, ZnO was deposited as a continuous film. No Au was observed on top of the ZnO nanorods, implying that the Au plays no role as catalytic metal in vapor-liquid-solid mechanism for formation of ZnO nanorods. In CVD, oriented ZnO nanorods along the c-axis were grown as a result of < 111 > textured Au. High-resolution TEM shows that the gold layer and ZnO are in orientation relationship of Au 111 planes//ZnO (0002) basal planes. (c) 2005 Elsevier B.V. All rights reserved.