Browsing by Issue Date, starting with "2006-12-14"

Now showing 1 - 20 of 62312

The photoluminescence decay time of self-assembled InAs quantum dots covered by InGaAs layers
(2006-12-14)
Shu, G. W.
;
Wang, C. K.
;
Wang, J. S.
;
Shen, J. L.
;
Hsiao, R. S.
The temperature dependence of the time-resolved photoluminescence (PL) of self-assembled InAs quantum dots (QDs) with InGaAs covering layers was investigated. The PL decay time increases with temperature from 50 to 170 K, and then decreases as the temperature increases further above 170 K. A model based on the phonon-assisted transition between the QD ground state and the continuum state is used to explain the temperature dependence of the PL decay time. This result suggests that the continuum states are important in the carrier capture in self-assembled InAs QDs.
High-throughput pipelined FFT processor
(2006-12-14)
Lee, Chen-Yi
;
Lin, Yu-Wei
The invention proposes a pipelined FFT processor for UWB system, comprising a first module for implementing radix-2 FFT algorithm; a second module is to realize radix-8 FFT algorithm; a third module is to realize radix-8 FFT algorithm; a plurality of conjugate blocks; a division block; and a plurality of multiplexers. The proposed pipelined FFT architecture called Mixed-Radix Multi-Path Delay Feedback (MRMDF) can provide higher throughput rate by using the multi-data-path scheme. The high-radix FFT algorithm is also realized in our processor to reduce the number of complex multiplications.
青檀寺那棵千年相抱銀杏　
(2006-12-15)
管管
青檀寺那棵千年相抱銀杏　
(2006-12-15)
管管
Effect of oxygen on characteristics of nickel oxide/indium tin oxide heterojunction diodes
(2006-12-15)
Chang, Hung-Lu
;
Lu, T. C.
;
Kuo, H. C.
;
Wang, S. C.
;
光電工程學系
p-nickel oxide (NiOx)/n-indium tin oxide heterostructure p-n junction diodes were fabricated on glass substrates and showed rectifying characteristics or negative differential resistance (NDR) characteristics depending on the content of oxygen in the NiOx films. After annealing the heterojunction diodes at 450 degrees C in air for about 30 min, the characteristics of NDR disappeared and transparent rectifying diodes were observed. The oxygen content could be observed by inspecting the characteristics of the NiOx films before and after annealing using x-ray photoelectron spectrum and thermogravimetric analysis as well as atomic force microscopy. The released oxygen in the NiOx films could be responsible for the disappearance of NDR characteristics and the change of the nonideal rectifying diode characteristics. (c) 2006 American Institute of Physics.
Study of leading factors in formation of surface wavy structures on a rubber material
(2006-12-15)
Shih, Teng-Kai
;
Chen, Chia-Fu
;
Ho, Jeng-Rong
;
Liu, Chueh-Yang
;
Chuang, Fang-Tzu
Wavy structures are often observed on the surface of a rubber material (polydimethylsiloxane, PDMS) covered with a thin metallic film. In this study we demonstrate that the orientation, periodicity, location of formation, and range of periodicity of the wavy structures can be regulated by three leading factors including the surface pattern, substrate hardness and the thickness of the metallic film. Results show the orientation of the wavy structures can be adjusted by the location, shape and size of the surface patterns. Enhancement of the substrate hardness can prevent forming random wavy structures. The thickness of surface metallic film significantly influenced the periodicity of the structures. Experimental results revealed an increase of the thickness of surface Au film by 50 nm, the periodicity was increased roughly by 1 mu m. A compound structure, combining longitudinally preset patterns and transversely induced wavy structures, and a parallel wavy structure fabricated, respectively, by suitable arrangement of pattern configurations and adjustment of substrate hardness were demonstrated. The relatively simple approaches proposed here show the potential application in fabrication of designated complicate structures. (c) 2006 Elsevier B.V. All rights reserved.
Green-pumped high-power optical parametric oscillator based on periodically poled MgO-doped stoichiometric LiTaO3
(2006-12-15)
Tu, Shih-Yu
;
Kung, A. H.
;
Gao, Z. D.
;
Zhu, S. N.
;
Kurimura, Sunao
A high-power 532 nm-pumped multikilohertz nanosecond optical parametric oscillator using a periodically poled 1.0 mol. % MgO-doped stoichiometric lithium tantalate crystal that could be operated from room temperature to 200 degrees C without damage is reported. A broad continuous tuning range from 855 to 1410 nM was achieved within a single domain period. Efficient operation of high peak power and watt level average power with a power conversion of 62.5% was measured. These results show that a high-resolution high average power visible tunable source can be realized. (c) 2006 Optical Society of America.
青檀寺那棵千年相抱銀杏　
(2006-12-15)
管管
青檀寺那棵千年相抱銀杏　
(2006-12-15)
管管
高產量管線式快速傅立葉轉換處理器
(2006-12-16)
李鎮宜
;
林昱偉
本案提出一種應用於超寬頻(UWB)系統的管線快速傅立葉轉換(FFT)處理器，包括：用以實行根–2(radix–2)FFT演算的一第一模組、用以實行根–8FFT演算的一第二模組、用以實行根–8FFT演算的一第三模組、複數個共軛區塊(conjugateblocks)、一除法區塊以及複數個多工器。所提出之被稱為混合根多路徑延遲迴授(Mixed–RadixMulti–PathDelayFeedback)的管線FFT結構係藉由使用多資料路徑配置而能夠提供較高的產量率，本案之處理器係使用高根FFT演算法以降低複雜之乘法演算的數目。
動態頻率計數之全數位倍頻器
(2006-12-16)
李鎮宜
;
陳寶龍
本發明係揭露一種動態頻率計數之全數位倍頻器，其係利用動態頻率計數的方式來計算及調整數位式震盪器的輸出頻率，且為了簡化硬體架構，更採用2的次方來進行運算；而習知之可程式除頻器及相頻偵測器則被簡單之漣波計數器所取代，且於作為DCO輸出時序計數器之漣波計數器中取值的方式係區分為商數值Q與餘數值R的方式，而非直接讀取整數值。由於本發明採用動態時間方式計算，使得頻率解析度得以提高，對於輸出頻率亦具有較低的抖動量。
異次投影硬性決定色彩內插法
(2006-12-16)
蔡奇謚
;
宋開泰
本發明提供一種異次投影硬性決定色彩內插法(Heterogeneity–ProjectionHard–Decision,HPHD)，其係使用異次投影去估測最佳的邊緣方向後，再使用硬性決定規則去決定最佳的內插方向，得到綠色色彩元素資訊，再利用綠色色彩元素資訊，經由綠色色彩元素平面之高頻資訊加入紅色與藍色色彩元素平面處理程序，來降低紅色與藍色色彩元素平面的重建誤差。因此本發明可達到降低內插方向發生錯誤的情況，並且在信號雜訊比(PeakSignaltoNoiseRatio,PSNR)與視覺比較上可獲得更好的效果。
近場光纖探針
(2006-12-16)
趙遠鳳
;
楊宗哲
;
蔡定平
本創作係一近場光纖探針，藉由改良傳統式裸光纖探針式鍍金屬膜光纖探針的收光或送光特性，經由適當比例的鍍膜於裸光纖探針上，使增強其光纖探針的收光或送光的通光效率，可擴展應用至電子束及微顯影技術應用於半導體之精密製程的應用上。
Highly efficient deep blue organic electroluminescent device based on 1-methyl-9,10-di(1-naphthyl)anthracene
(2006-12-18)
Ho, Meng-Huan
;
Wu, Yao-Shan
;
Wen, Shih-Wen
;
Lee, Meng-Ting
;
Chen, Teng-Ming
The author have developed 2-methyl-9,10-di(1-naphthyl)anthracene (alpha,alpha-MADN) as an effective wide band gap host material for Forster energy transfer to the unsymmetrical mono(styryl)amine deep blue fluorescent dopant (BD-1). This guest/host emitting system, at the optimal doping concentration of 3%, can also increase the probability of carrier recombination near the hole-transport/emitting layer interface for the blue organic light emitting device which produces electroluminescence efficiencies of 3.3 cd/A and 1.3 lm/W and a deep blue CIEx,y color coordinates of (0.15, 0.13) that are 50% better than those of the traditional beta,beta-isomeric host (MADN) with the same dopant. (c) 2006 American Institute of Physics.
Intriguing conducting properties of HfOxNy thin films prepared from the Hf[N(C2H5)(2)](4)
(2006-12-18)
Chou, Yi-Hsuan
;
Chiu, Hsin-Tien
;
Kuo, Teng-Fang
;
Chi, Cheng-Chung
;
Chuang, Shiow-Huey
Hafnium nitride films were prepared on the Si(100) substrates by the metal-organic chemical vapor deposition method using Hf[N(C2H5)(2)](4). The prepared samples were then oxidized in air, followed by rapid-thermal annealing to produce HfOxNy thin films, meanwhile the associated physical properties were investigated. The x-ray photoelectron spectroscope analysis unveiled that the composition of the films is HfOxNy. In addition, the films after the rapid-thermal annealing treatments at various temperatures revealed salient features in their physical properties, such as capacitance and conductivity. On this basis, the feasibility of using the HfOxNy layers as high-k dielectrics in complementary metal oxide semiconductor transistors was also discussed. (c) 2006 American Institute of Physics.
Trenched epitaxial lateral overgrowth of fast coalesced a-plane GaN with low dislocation density
(2006-12-18)
Wang, Te-Chung
;
Lu, Tien-Chang
;
Ko, Tsung-Shine
;
Kuo, Hao-Chung
;
Yu, Min
The crystal quality of a-plane GaN films was improved by using epitaxial lateral overgrowth on trenched a-plane GaN buffer layers. Not only the threading dislocation density but also the difference of anisotropic in-plane strain between orthogonal crystal axes can be mitigated by using trenched epitaxial lateral overgrowth (TELOG). The low threading dislocation density investigated by the cross-sectional transmission electron microscopy was estimated to be 3x10(7) cm(-2) on the N-face GaN wing. On the other hand, the Ga-face GaN wing with a faster lateral overgrowth rate could be influenced by the thin GaN layer grown on the bottom of the trenches, resulting in higher dislocation density generated. As a result, the authors concluded that a narrower stripped GaN seeds and deeper stripped trenches etched into the surface of sapphire could derive a better quality a-plane GaN film. Finally, they demonstrated the fast coalescence process of TELOG GaN films below 10 mu m thick. (c) 2006 American Institute of Physics.
Sol-gel-derived double-layered nanocrystal memory
(2006-12-18)
Ko, Fu-Hsiang
;
You, Hsin-Chiang
;
Lei, Tan-Fu
;
材料科學與工程學系奈米科技碩博班
;
電子工程學系及電子研究所
The authors have used the sol-gel spin-coating method to fabricate a coexisting hafnium silicate and zirconium silicate double-layered nanocrystal (NC) memories. From transmission electron microscopic and x-ray photoelectron spectroscopic analyses, the authors determined that the hafnium silicate and zirconium silicate NCs formed after annealing at 900 degrees C for 1 min. When using channel hot electron injection for charging and band-to-band tunneling-induced hot hole injection for discharging, the NC memories exhibited superior V-th shifting because of the higher probability for trapping the charge carrier. (c) 2006 American Institute of Physics.
MO(CO)(6)-mediated synthesis of calix[4]arenes carrying beta-hydroxy ketones or alpha,beta-unsaturated-beta-amino ketones
(2006-12-18)
Senthilvelan, Annamalai
;
Tsai, Ming-Tsung
;
Chang, Kai-Chi
;
Chung, Wen-Sheng
;
應用化學系
MO(CO)(6)-mediated ring opening reactions of calix[4]arene isoxazolines/isoxazoles provide a new synthetic methodology for calix[4]arenes carrying bifunctional beta-hydroxy ketones or alpha,beta-unsaturated-beta-amino ketones. MO(CO)(6) is a highly selective and convenient reagent for the ring opening process of these supramolecular isoxazolines/isoxazoles. (c) 2006 Elsevier Ltd. All rights reserved.
Highly power efficient organic light-emitting diodes with a p-doping layer
(2006-12-18)
Chang, Chan-Ching
;
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Hwang, Shiao-Wen
;
Chen, Chin H.
In this letter, the authors demonstrate p-i-n organic light-emitting diodes (OLEDs) incorporating a p-doped transport layer which comprises tungsten oxide (WO3) and 4,4('),4(')-tris(N-(2-naphthyl)-N-phenyl-amino)triphenylamine (2-TNATA) to replace the volatile tetrafluro-tetracyanoquinodimethane. The authors propose the 2-TNATA:WO3 composition functions as a p-doping layer which significantly improves hole injection and conductivity of the device that leads to the fabrication of tris(8-quinolinolato)aluminum based p-i-n OLEDs with long lifetime, low driving voltage (3.1 V), and high power efficiency (3.5 lm/W) at 100 cd/m(2). (c) 2006 American Institute of Physics.
Fractal aggregates of conjugated polymer in solution state
(2006-12-19)
Li, Yen-Cheng
;
Chen, Kuei-Bai
;
Chen, Hsin-Lung
;
Hsu, Chain-Shu
;
Tsao, Cheng-Si
Semirigid conjugated polymers have received much scientific and technological interest due to their unique electrical and photonic semiconducting properties. Spectroscopic studies have indicated that these polymers underwent interchain aggregation in the solution state even at large dilution; however, the origin of this event and the structure of the resultant aggregates remained the crucial issues to be resolved. In the present study, we revealed that the interchain aggregation of a conjugated polymer, poly(2,3-diphenyl-5-hexyl-1,4-phenylenevinylene) (DP6-PPV), in solutions with chloroform and toluene generated network aggregates with the hydrodynamic radii of several micrometers. Small angle neutron scattering (SANS) demonstrated that the internal structure of these aggregates could be characterized by the mass fractal dimensions of 2.2-2.7. The networks were looser in chloroform but became highly compact in the poorer toluene solvent due to severe segmental association. Increasing the temperature alleviated the segmental association in toluene while largely retaining the mass fractal dimension of the aggregates. However, the interchain aggregation was never completely dissipated by the heating, suggesting the existence of two types of segmental association with distinct stability. The highly stable segmental association that could neither be solvated by chloroform nor be disrupted thermally in toluene was attributed to the d-d complex already present in the DP6-PPV powder used for the solution preparation. The chains tied firmly by this complex formed network aggregates in the solution and hence reduced the entropy of mixing of the polymer. In the poorer toluene solvent, further segmental association took place within the preexisting aggregates, making the networks more compact. This type of segmental association could be disrupted by moderate heating, and its occurrence was ascribed to the poor affinity of the aliphatic side chains of DP6-PPV for toluene.