Browsing by Author "Lee, MH"

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A novel methodology for extracting effective density-of-states in poly-Si thin-film transistors
(2004)
Lin, HC
;
Yeh, KL
;
Lee, MH
;
Su, YC
;
Huang, TY
A novel methodology that greatly simplifies the procedure of extracting the effective density-of-states (DOS) in polycrystalline-Si thin-film transistors (poly-Si TFTs) is proposed and demonstrated. The characterization is performed on a Schottky barrier (SB) TFT with electrical source/drain extensions induced by a field-plate. Only one single device and two simple subthreshold I-V measurements at room temperature are needed for full band-gap DOS extraction. Impacts of different process treatments are clearly resolved using this methodology.
A simple and low-cost method to fabricate TFTs with poly-Si nanowire channel
(2005-09-01)
Lin, HC
;
Lee, MH
;
Su, CJ
;
Huang, TY
;
Lee, CC
A very simple and low-cost scheme is proposed for fabricating thin-film transistors with poly-Si nanowire (NW) channels. In this scheme, the poly-Si NW channel is formed by cleverly employing the poly-Si sidewall spacer technique. In addition, the poly-Si NW channel is genuinely exposed to the environment after the poly-Si sidewall spacer formation in the new scheme. This unique feature, together with its simplicity and low-cost, makes this approach very suitable for applications and manufacturing of bio-logic sensing devices. Good device performance is demonstrated in this letter.
Ab initio study of the structural and optical properties of orthorhombic ternary nitride crystals
(2001-11-19)
Huang, JY
;
Tang, LC
;
Lee, MH
;
光電工程學系
;
Department of Photonics
The structural, optical and mechanical properties of orthorhombic ternary nitride crystals have been analysed theoretically with first-principles calculation. Our results indicate that these nitrides possess fairly large optical bandgap (4-6 eV), second-order nonlinear optical susceptibility (13-18 pm V-1), and bulk modulus 170-370 GPa. Therefore these materials could be useful for optical and protective coating applications. Our analysis with the band-by-band and atomic species projection techniques not only yields useful information about material properties, but also provides deep insight into the fundamental understanding of the mechanical and optical properties of orthorhombic ternary nitrides.
Cation substitution effects on structural, electronic and optical properties of nonlinear optical AgGa(SxSe1-x)(2) crystals
(2003-09-10)
Tang, LC
;
Lee, MH
;
Yang, CH
;
Huang, JY
;
Chang, CS
The structural, electronic and optical properties of tetragonal nonlinear optical (NLO) crystals, AgGa(SxSe1-x)(2) (x = 0.0, 0.25, 0.5, 0.75, and 1.0), were investigated theoretically and experimentally. The results obtained indicated that the electronic bandgaps, optical properties and bulk moduli of these compounds were linearly dependent on the substitution concentration of cations. From partial density of state analysis, it was found that the electronic states near the band edges of AgGa(SxSe1-x)(2) were a simple proportional mixture of the atomic orbitals of sulfur and selenium. A cell-volume effect was proposed as the major cause of the linear dependence of material properties on the substitution concentration. It was calculated that the second-order NLO susceptibilities were scaled with the cubic power of bandgap, although a minor deviation existed. This deviation arose from the optical transition moment products.
Characteristics of Schottky barrier poly-Si thin film transistors with excimer laser annealing treatment
(2003)
Yeh, KL
;
Lin, HC
;
Tsai, RW
;
Lee, MH
;
Huang, TY
Poly-Si Schottky barrier poly-Si thin-film transistors (SB TFT) with field-induced drain (FID) have recently been demonstrated. Such devices exhibit ambipolar operation capability with low off-state leakage current. In this study, we investigate and compare the characteristics of poly-Si SB TFTs with channel layer prepared by either excimer laser crystallization (ELC) or solid-phase crystallization (SPC) method. It is shown that the use of ELC could greatly improve the device characteristics compared to the SPC counterparts. Excellent device performance in terms of steep subthreshold slope and high on/off current ratio (>10(8)) for both p- and n-channel operations are demonstrated on a single device with ELC channel. The effects of sub-gate bias, channel length, and offset channel length, on device characteristics are also explored.
Determination of effective density-of-states using a novel Schottky barrier poly-Si thin-film transistor
(2005)
Lin, HC
;
Lee, MH
;
Yeh, KL
;
Huang, TY
;
電子工程學系及電子研究所
We demonstrate that it is possible to extract the defect density distribution within the entire energy gap of a poly-Si layer by using a novel Schottky barrier thin-film transistor test structure. Our methodology, albeit based on the well-known field-effect conductance method, does not require two separate n- and p-channel test devices necessary in the conventional methods. This unique and much simplified single-test-device feature is made possible thanks to the ambipolar characteristics and the suppression of subthreshold leakage current in the new test scheme. Effects of process treatments such as plasma hydrogenation could also be clearly resolved using the new test structure. (c) 2005 The Electrochemical Society. All rights reserved.
Exploring high school students' and teachers' preferences toward the constructivist Internet-based learning environments in Taiwan
(2005-06-01)
Lee, MH
;
Tsai, CC
;
教育研究所
;
Institute of Education
This paper explores high school students' and teachers' preferences towards constructivist Internet-based learning environments. The study proposes a framework, including two dimensions and five aspects, to illustrate the features of the Internet-based learning environments. Based upon this framework, the Constructivist Internet-based learning environment survey improvement (CILESI) was developed, which includes the scales of ease of use, multiple sources, student negotiation, reflective thinking, critical judgement and epistemological awareness. Questionnaire responses gathered from 630 high school students in Taiwan suggested that the CILESI showed adequate reliability in assessing students' preferences. Male students placed more emphasis on the student negotiation, critical judgement and epistemological awareness enhanced by the Internet-based learning environments than female students did. In addition, the teachers of the sampled students ( n = 78) were also surveyed by CILESI. The teachers tended to express stronger preferences on the ease of use of the Internet-based learning environments than did their students. However, students, when compared with their teachers, seemed to express more preferences towards the features of student negotiation, reflective thinking, critical judgement and epistemological awareness of Internet-based learning environments.
Fabrication and characterization of Schottky barrier polysilicon thin-film transistors with excimer-laser crystallized channel
(2003-04-01)
Yeh, KL
;
Lin, HC
;
Tsai, RW
;
Lee, MH
;
Huang, TY
Schottky barrier thin-film transistors (SB TFT) with field-induced drain (FID) have recently been demonstrated to exhibit ambipolar capability with low off-state leakage current. In this study, we investigate and compare the characteristics of poly-Si SB TFTs with channel layer prepared by excimer laser crystallization (ELC) and solid-phase crystallization (SPC). It is shown that the use of ELC could greatly improve the device characteristics, comparing to the SPC counterparts. Excellent device performance with steep subthreshold slope and on/off current ratio higher than 10(8) for both p- and n-channel operations are demonstrated on a single device with ELC channel. The effects of sub-gate bias, channel length, and channel offset length, on device characteristics are also explored.
New infrared nonlinear optical crystal CsGeBr3: synthesis, structure and powder second-harmonic generation properties
(2005-11-23)
Tang, LC
;
Huang, JY
;
Chang, CS
;
Lee, MH
;
Liu, LQ
An innovative infrared nonlinear optical crystal CsGeBr3 was synthesized. Ab initio calculations on CsGeBr3 were also carried out in order to analyse the second-order nonlinear susceptibilities. From its powder x-ray diffraction pattern, this crystal was characterized as a rhombohedral structure with an (R3m, No 160) space group symmetry. The reflection powder second-harmonic generation (PSHG) measurement of CGBr showed that its nonlinear optical efficiency is 1.62 times larger than that of rhombohedral CsGeCl3 and is 9.63 times larger than that of KH2PO4 (KDP), and most important of all that CsGeBr3 is phase-matchable. The rescaled d(eff)((2)) of CGBr was about 2.45 times larger than that of rhombohedral CsGeCl3, and this trend was coincident with the ab initio calculation results. The infrared transparent spectrum of rhombohedral CsGeBr3 was extended to more than 22.5 mu m. The rhombohedral CsGeBr3 shows the potential in the realm of nonlinear optics and can be applied to the infrared region.
Spatially resolving the hot carrier degradations of poly-Si thin-film transistors using a novel test structure
(2006-07-01)
Lin, HC
;
Lee, MH
;
Chang, KH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel thin-film transistor test structure is proposed for monitoring the device hot-carrier (HQ degradations. The new test structure consists of several source/drain electrode pairs arranged in the direction perpendicular to the normal (i.e., lateral) channel of the test transistor. This unique feature allows, for the first time, the study of spatial resolution of HC degradations along the channel of the test transistor after stressing. The extent of degradation as well as the major degradation mechanisms along the channel of the test transistor can be clearly identified.