Browsing by Author "Chen, C. H."

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A compact biological cell irradiation system with a Van de Graaff accelerator
(2013-11-15)
Cho, I. C.
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Niu, H.
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Chen, C. H.
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Chou, W. T.
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Yu, Y. C.
This report describes the development of a compact microcell irradiation system in the 3 MV MN Van de Graaff accelerator in the Accelerator Laboratory of National Tsing Hua University (NTHU). The main feature of this system is backscattering, a technique whereby a 100 nm gold scattering foil is placed in the center of a scattering chamber, instead of a 90 bending magnet. The incident particles produced by the accelerator bombard the scattering foil and scatter isotropically. A set of micro pinholes was installed above the scattering foil and directed the 90 scattering particles to irradiate the cell target. This innovation simplifies the system design and massively reduces the cost and space requirements for system construction. (C) 2013 Elsevier B.V. All rights reserved.
A dispatching rule for photolithography scheduling with an on-line rework strategy
(2006-07-01)
Sha, D. Y.
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Hsu, S. Y.
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Che, Z. H.
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Chen, C. H.
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工業工程與管理學系
Generally speaking, wafer fabrication factories define the photolithography area as the dispatching center of the entire factory. To establish a set of operative dispatching rules in the photolithography area while taking into consideration the rework of defective products would assist in coordinating and balancing the workload of the entire production line. Furthermore, it would help to enhance both the productivity and efficiency of the wafer fabrication, reduce the on-line WIP stock, shorten the production cycle time, and satisfy the requirements of customers regarding production due time and product quality. This research uses on-line rework as the basis for bringing the factor of reworking of a batch process into the dispatching rule for measurement. It then develops the dispatching rule (Rw-DR) which includes the rework strategy. In addition, this research focuses on the batch with high finished proportion in the photolithography area for finding a way to complete the manufacturing procedure faster, lighten the machine workload of the waiting line, and at the same time increase the output quantity. (c) 2006 Elsevier Ltd. All rights reserved.
A Novel Cell Irradiation System Using Backscattering Technique
(2009-01-01)
Cho, I. C.
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Chen, C. H.
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Weng, M. F.
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Chiang, S. Y.
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Chou, W. T.
In this paper, we report a novel cell irradiation system at the HVEE Van de Graaff accelerator at National Tsing Hua University. The significant change of system design is use the backscattering technique to replace the 900 magnet which was widely used to derive beam direction from horizontal to vertical. A silicon barrier detector was used to measure the scattered particle energy. Meanwhile, nuclear track detector CR-39 was also applying in this study to assess the particle distribution at beam nozzle. The preliminary experiment performed by using 2 MeV alpha particle to irradiate the HeLa cell. The result showed, this system can provide an efficiently vertical particle beam irradiation and a standard growth condition during the period of irradiation. Furthermore, it's more economical and easier to set up than others.
A Novel ReWritable One-Time-Programming OTP (RW-OTP) Realized by Dielectric-fuse RRAM Devices Featuring Ultra-High Reliable Retention and Good Endurance for Embedded Applications
(2018-01-01)
Cheng, H. W.
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Hsieh, E. R.
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Huang, Z. H.
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Chuang, C. H.
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Chen, C. H.
A novel concept of OTP has been demonstrated to create another feasibility to allow re-writable capability before storing the data. This OTP is named ReWritable One-time programming (RW-OTP) memory. With RW-OTP, users can do the test by modifying the contexts repeatedly before finalizing the stored data. To implement the memory cell, it consists of a gate-floated FinFET and an RRAM where a bilayer has been designed as a thicker dielectric layer with resistive-switching property on a thinner dielectric-fuse layer. Moreover, the process of RW-OTP is fully compatible with the state-of-the-art CMOS logic technology. The result shows that the memory cell exhibits high retention and good endurance. With proper use of RW-OTP, the users can not only reduce error jobs cost-efficiently but also can develop various applications for their needs. This memory cell is very promising for embedded applications.
Admittance spectroscopy of the electric properties of 1,4-bis[N-(1-naphthyl)-N '-phenylamino]-4,4 ' diamine doped with tungsten oxide
(2006)
Hsieh, M. T.
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Chang, C. C.
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Hu, C. A.
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Huang, Y. T.
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Yang, S. L.
We report an efficient p-type doping of NPB layer using WO(3) as a p-dopant. We find that increasing the WO(3) volume percentage can reduce the activation energy of the NPB layer and increase the hole concentration in NPB layer. As a result, the hole-injection can be improved via tunneling through a narrow depletion region due to the increasing band bending which corresponds to the difference of Fermi level position between the ITO and the NPB layer.
An integrated healthcare enterprise information portal and healthcare information system framework
(2006)
Hsieh, S. L.
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Lai, Feipei
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Cheng, P. H.
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Chen, J. L.
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Lee, H. H.
The paper presents an integrated, distributed Healthcare Enterprise Information Portal (HEIP) and Hospital Information Systems (HIS) framework over wireless/wired infrastructure at National Taiwan University Hospital (NTUH). A single sign-on solution for the hospital customer relationship management (CRNI) in HEIP has been established. The outcomes of the newly developed Outpatient Information Systems (OIS) in HIS are discussed. The future HEIP blueprints with CRM oriented features: e-Learning, Remote Consultation and Diagnosis (RCD), as well as on-Line Vaccination Services are addressed. Finally, the integrated HEIP and HIS architectures based on the middleware technologies are proposed along with the feasible approaches. The preliminary performance of multi-media, time-based data exchanges over the wireless HEIP side is collected to evaluate the efficiency of the architecture.
Arithmetic geometry over hypertranscendental fields
(2007-09-30)
Chen, C. H.
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電子物理學系
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Department of Electrophysics
An overview of hypertranscendency in sciences is discussed. The theoretical framework comes to be articulated.
Compositional grading in GaAsSb grown on GaAs substrates
(2014-09-15)
Lin, Y. M.
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Chen, C. H.
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Wu, J. S.
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Lee, C. P.
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電子工程學系及電子研究所
The composition profile and lattice strain of GaAsSb grown on GaAs substrates by molecular beam epitaxy have been investigated using the Rutherford backscattering spectrometry (RBS) and X-ray reciprocal space mapping. Through RBS, we found that the Sb content in the layer increases from the interface to the top surface. The X-ray reciprocal space mapping shows that the GaAsSb lattice also gradually relaxes as the layer becomes thicker. The behavior of composition grading and gradual lattice relaxation is quite different from those of III-V ternary compounds with two group Ill atoms. (C) 2014 Elsevier B.V. All rights reserved.
Compositional grading in GaAsSb grown on GaAs substrates
(2014-09-15)
Lin, Y. M.
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Chen, C. H.
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Wu, J. S.
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Lee, C. P.
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電子工程學系及電子研究所
The composition profile and lattice strain of GaAsSb grown on GaAs substrates by molecular beam epitaxy have been investigated using the Rutherford backscattering spectrometry (RBS) and X-ray reciprocal space mapping. Through RBS, we found that the Sb content in the layer increases from the interface to the top surface. The X-ray reciprocal space mapping shows that the GaAsSb lattice also gradually relaxes as the layer becomes thicker. The behavior of composition grading and gradual lattice relaxation is quite different from those of III-V ternary compounds with two group Ill atoms. (C) 2014 Elsevier B.V. All rights reserved.
DNA double-strand breaks induced along the trajectory of particles
(2011-12-15)
Cho, I. C.
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Niu, H.
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Chen, C. H.
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Yu, Y. C.
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Hsu, C. H.
It is well-known that the DNA damage caused by charged particles considerably differs from damage due to electromagnetic radiation. In the case of irradiation by charged particles the DNA lesions are more complex and clustered. Such clustered damage is presumed difficult to be repaired, and is potentially lethal. In this study, we utilize a 90 degrees-scattering system and related imaging techniques to investigate the accumulation of gamma-H2AX along the trajectory of charged particles. By immunostaining the gamma-H2AX protein, optical images of corresponding double strand breaks were observed using a high resolution confocal microscope. We demonstrate the difference in the accumulation of gamma-H2AX from irradiation by 1 MeV protons and that of 150 key X-rays. The acquired images were arranged and reconstructed into a 3D image using ImageJ software. We discovered that the gamma-H2AX foci, following irradiation by protons, have a tendency to extend in the beam direction, while those from X-ray irradiation tend to be smaller and more randomly distributed. These results can be explained by the physical model of energy deposition. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.
Effect of interfacial layer on the crystal structure of InAs/AlAs0.16Sb0.84/AlSb quantum wells
(2014-04-28)
Lin, Y. M.
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Chen, C. H.
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Lee, C. P.
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電子工程學系及電子研究所
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奈米科技中心
Ion channeling technique using MeV C2+ ions and high resolution X-ray diffraction were used to study the crystal quality of an InAs/AlSb-based quantum wells. We found that the InAs quality has a strong dependence on the type of the interface used. With the addition of the InSb-like interface, the crystal quality of the InAs channel was greatly improved. The InAs lattice was fully strained and aligned with the lattice of the buffer layer without any lattice relaxation. On the other hand, if the interface was of the AlAs type, the lattice of the InAs quantum well was relaxed and the crystal quality was poor. This explains why a superior InAs quantum well with high electron mobility and good surface morphology can be achieved with the use of the InSb interface. (C) 2014 AIP Publishing LLC.
EXPERIMENTAL MODAL TEST AND TIME-DOMAIN AERODYNAMIC ANALYSIS OF A CABLE-STAYED BRIDGE
(2011-02-01)
Chen, C. H.
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Ou, C. I.
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土木工程學系
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Department of Civil Engineering
To determine its actual dynamic responses under the wind loads, modal identification from the field tests was carried out for the Kao Ping Hsi cable-stayed bridge in southern Taiwan. The dynamic characteristics of the bridge identified by a continuous wavelet transform algorithm are compared with those obtained by the finite element analysis. The finite element model was then modified and re fined based on the field test results. The results obtained from the updated finite element model were shown to agree well with the field identified results for the first few modes in the vertical, transverse, and torsional directions. This has the indication that a rational finite element model has been established for the bridge. With the re fined finite element model, a nonlinear analysis in time domain is employed to determine the buffeting response of the bridge. Through validation of the results against those obtained by the frequency domain approach, it is con firmed that the time domain approach adopted herein is applicable for the buffeting analysis of cable-stayed bridges.
Experimental Techniques on the Understanding of the Charge Loss in a SONOS Nitride-storage Nonvolatile Memory
(2016)
Hsieh, E. R.
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Wang, H. T.
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Chung, Steve S.
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Chang, Wayne
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Wang, S. D.
The endurance and charge loss are the most critical issue in the design of a SONOS memory cell. The origin of the window closure and charge loss was partly caused by the electrons and holes mismatch along the channel lateral direction during the cycling. In this paper, two measurement techniques to observe the mismatch of programmed electrons and erased holes have been developed. It was demonstrated on an MTP (Multi-Time-Programming) SONOS flash memory. By observing the charge distribution, the mismatch which led to window closure and charge loss can be well understood, and better operating schemes can then be developed.
Ferromagnetic GeMn thin film prepared by ion implantation and ion beam induced epitaxial crystallization annealing
(2012-06-11)
Chen, C. H.
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Niu, H.
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Yan, D. C.
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Hsieh, H. H.
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Lee, C. P.
Ferromagnetic GeMn was prepared by Mn implantation followed by ion beam-induced epitaxial crystallization annealing. The damage caused by Mn implantation was repaired by subsequent helium ion irradiation. Various structural analyses were performed and Mn ions were found to incorporate uniformly into the Ge lattice without the formation of any secondary phases. The remnant magnetic moment exhibited room temperature ferromagnetism. Anomalous Hall effect and field dependent magnetization were measured at the same time at room temperature indicating spin polarized free carrier transport. Additional measurement using x-ray magnetic circular dichroism also revealed that the carriers were spin-polarized. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729752]
Hidden lattice instabilities as origin of the conductive interface between insulating LaAlO3 and SrTiO3
(2016-09-01)
Lee, P. W.
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Singh, V. N.
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Guo, G. Y.
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Liu, H. -J.
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Lin, J. -C.
The metallic interface between insulating LaAlO3 and SrTiO3 opens up the field of oxide electronics. With more than a decade of researches on this heterostructure, the origin of the interfacial conductivity, however, remains unsettled. Here we resolve this long-standing puzzle by atomic-scale observation of electron-gas formation for screening hidden lattice instabilities, rejuvenated near the interface by epitaxial strain. Using atomic-resolution imaging and electron spectroscopy, the generally accepted notions of polar catastrophe and cation intermixing for the metallic interface are discounted. Instead, the conductivity onset at the critical thickness of 4-unit cell LaAlO3 on SrTiO3 substrate is accompanied with head-to-head ferroelectric-like polarizations across the interface due to strain-rejuvenated ferroelectric-like instabilities in the materials. The divergent depolarization fields of the head-to-head polarizations cast the interface into an electron reservoir, forming screening electron gas in SrTiO3 with LaAlO3 hosting complementary localized holes. The ferroelectriclike polarizations and electron-hole juxtaposition reveal the cooperative nature of metallic LaAlO3/SrTiO3.
High Efficiency Silicon Solar Cells with Bilayer Passivation Structure
(2009)
Sun, W. C.
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Chang, W. L.
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Chen, C. H.
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Du, C. H.
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Wang, T. Y.
lThe effects of passivation on monocrystalline silicon solar cells were investigated. Al(2)O(3) and SiO(2) films, prepared by atomic layer deposition and thermal oxidation, respectively, were used as passivation layers. Passivation using a monolayer (SiO(2)) yielded a cell efficiency of 17.5%. However, the Al(2)O(3)/SiO(2) bilayer structure drastically increased cell efficiency to 20.1%. Quantum efficiency results revealed a significant improvement in the IR range, suggesting that bilayer passivation was effective on the back of a solar cell in providing a high energy conversion efficiency. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3194252] All rights reserved.
Identifying the Modal Parameters of a Structure from Ambient Vibration Data via the Stationary Wavelet Packet
(2014-11-01)
Su, W. C.
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Huang, C. S.
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Chen, C. H.
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Liu, C. Y.
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Huang, H. C.
Ambient vibration tests are conducted widely to estimate the modal parameters of a structure. The work proposes an efficient wavelet-based approach to determine the modal parameters of a structure from its ambient vibration responses. The proposed approach integrates the time series autoregressive (AR) model with the stationary wavelet packet transform. In addition to providing a richer decomposition and allowing for an improved time-frequency localization of signals over that of the discrete wavelet transform, the stationary wavelet packet transform also has significantly higher computational efficiency than the wavelet packet transform in terms of decomposing time-shifted signals because the former has a time-invariance property. The correlation matrices needed in determining the coefficient matrices in an AR model are established in subspaces expanded by stationary wavelet packets. The formulation for estimating the correlation matrices is shown for the first time. Because different subspaces contain signals with different frequency subbands, the fine filtering property enhances the ability of the proposed approach to identify not only the modes with strong modal interference, but also many modes from the responses of very few measured degrees of freedom. The proposed approach is validated by processing the numerically simulated responses of a seven-floor shear building, which has closely spaced modes, with considering the effects of noise and incomplete measurements. Furthermore, the present approach is employed to process the velocity responses of an eight-storey steel frame subjected to white noise input in a shaking table test and ambient vibration responses of a cable-stayed bridge.
Improved carrier injection in GaN-based VCSEL via AlGaN/GaN multiple quantum barrier electron blocking layer
(2015-10-19)
Hsieh, D. H.
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Tzou, A. J.
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Kao, T. S.
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Lai, F. I.
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Lin, D. W.
In this report, the improved lasing performance of the III-nitride based vertical-cavity surface-emitting laser (VCSEL) has been demonstrated by replacing the bulk AlGaN electron blocking layer (EBL) in the conventional VCSEL structure with an AlGaN/GaN multiple quantum barrier (MQB) EBL. The output power can be enhanced up to three times from 0.3 mW to 0.9 mW. In addition, the threshold current density of the fabricated device with the MQB-EBL was reduced from 12 kA/cm(2) (9.5 mA) to 10.6 kA/cm(2) (8.5 mA) compared with the use of the bulk AlGaN EBL. Theoretical calculation results suggest that the improved carrier injection efficiency can be mainly attributed to the partial release of the strain and the effect of quantum interference by using the MQB structure, hence increasing the effective barrier height of the conduction band. (C) 2015 Optical Society of America
Ion beam studies of InAs/GaAs quantum dots after annealing
(2008-04-01)
Niu, H.
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Chen, C. H.
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Wang, H. Y.
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Wu, S. C.
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Lee, C. P.
The microstructure changes of self-assembled InAs/GaAs quantum dots during RTA treatment was investigated using ion channeling and photoluminescence (PL). A small blueshift of the PL emission is observed for annealing temperatures of 650-800 degrees C and an obvious blueshift at 850 degrees C. The yield of channeled spectra decreased as annealing temperature was increased, but the yield increased while temperature above 800 degrees C in RTA. These results imply the strain of QD varied during RTA treatments. In addition, the As/Ga atomic ratio near the surface was determined from the surface peaks of the channeled spectrum. (c) 2008 Elsevier B.V. All rights reserved.
Local structure and magnetic properties of ferromagnetic GaMnAs made by helium ion induced epitaxial crystallization annealing
(2014-08-15)
Chen, C. H.
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Niu, H.
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Yan, D. C.
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Hsieh, H. H.
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Huang, R. T.
In this study we show GaMnAs preparation by Mn implantation in GaAs followed by helium ion beam induced epitaxial crystallization annealing. The characteristics of the Mn-implanted layer were investigated by X-ray diffraction, and transmission electron microscopy. The magnetic nature of the Mn-implanted layer was investigated with a superconducting quantum interference device. Structure analysis showed that Mn ions were incorporated substitutionally into the GaAs lattice without the formation of any detectable secondary phases. The remanent magnetic moment exhibited room temperature ferromagnetism. Additional measurement using X-ray magnetic circular dichroism also revealed that the carriers were spin polarized. (C) 2014 Elsevier B.V. All rights reserved.