Browsing by Issue Date, starting with "2013-07-15"

Now showing 1 - 20 of 31173

Broadband terahertz conductivity and optical transmission of indium-tin-oxide (ITO) nanomaterials
(2013-07-15)
Yang, Chan-Shan
;
Chang, Chan-Ming
;
Chen, Po-Han
;
Yu, Peichen
;
Pan, Ci-Ling
Indium-tin-oxide (ITO) nanorods (NRs) and nanowhiskers (NWhs) were fabricated by an electron-beam glancing-angle deposition (GLAD) system. These nanomaterials are of interests as transparent conducting electrodes in various devices. Two terahertz (THz) time-domain spectrometers (TDS) with combined spectral coverage from 0.15 to 9.00 THz were used. These allow accurate determination of the optical and electrical properties of such ITO nanomaterials in the frequency range from 0.20 to 4.00 THz. Together with Fourier transform infrared spectroscopic (FTIR) measurements, we found that the THz and far-infrared transmittance of these nanomaterials can be as high as 70% up to 15 THz, as opposed to about 9% for sputtered ITO thin films. The complex conductivities of ITO NRs, NWhs as well films are well fitted by the Drude-Smith model. Taking into account that the volume filling factors of both type of nanomaterials are nearly same, mobilities, and DC conductivities of ITO NWhs are higher than those of NRs due to less severe carrier localization effects in the former. On the other hand, mobilities of sputtered ITO thin films are poorer than ITO nanomaterials because of larger concentration of dopant ions in films, which causes stronger carrier scattering. We note further that consideration of the extreme values of Re{sigma} and Im{sigma} as well the inflection points, which are functions of the carrier scattering time (tau) and the expectation value of cosine of the scattering angle (gamma), provide additional criteria for accessing the accuracy of the extraction of electrical parameters of non-Drude-like materials using THz-TDS. Our studies so far indicate ITO NWhs with heights of similar to 1000 nm show outstanding transmittance and good electrical characteristics for applications such as transparent conducting electrodes of THz Devices. (C) 2013 Optical Society of America
Time-Resolved Spectroscopic and Imaging Studies on Laser Ablation of Molecular Systems: From Mechanistic Study to Bio/Nano Applications
(2013-07-15)
Masuhara, Hiroshi
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
;
Institute of Molecular science
Studies on laser ablation of polymer films, molecular crystals in solution, protein solution, and culture media containing living cells are summarized and considered. Dynamics and mechanism of laser ablation were systematically studied by utilizing time-resolved spectroscopy and imaging; femtosecond-nanosecond transient absorption and emission spectroscopy, nanosecond shadowgraphy, nanosecond-nanometer interferometry, femtosecond surface light scattering imaging. It was confirmed by integrating both data that primary processes of laser ablation can be well understood in the framework of Jablonski diagram. For nanosecond laser ablation of doped polymers, it was demonstrated that cyclic multiphoton absorption is an efficient photothermal conversion process leading to photothermal ablation. For femtosecond laser ablation of dye films, transient pressure mechanism was proposed indicating photomechanical ablation. As applications of laser ablation, nanoparticle preparation, protein crystallization, and manipulation of living cells are presented. Laser ablation of molecular crystals in poor solvent gives small fragments whose size are in a few tens nm. The fabricated nanocolloids are stable without adding detergents and their size was the smallest as nanoparticles produced by the top-down-method. Multiphoton laser ablation of water generates local impulsive force due to bubble formation, shockwave propagation, and local convection flow. The force triggers molecular and protein crystallization in their supersaturated solutions, whose mechanisms are described and considered. The impulsive force is also very useful for manipulating living cells and its high potential was confirmed by examining cell functions such as division, differentiation, death, and migration. Finally summary and future plan are presented.
High spectral efficient W-band OFDM-RoF system with direct-detection by two cascaded single-drive MZMs
(2013-07-15)
Huang, Hou-Tzu
;
Lin, Chun-Ting
;
Ho, Chun-Hung
;
Liang, Wan-Ling
;
Wei, Chia-Chien
W-band wireless transmission has attracted a lot of interest due to its wider available bandwidth (i.e. 75-110 GHz). In this article, we propose a direct-detection orthogonal frequency division multiplexing radio over fiber (OFDM-RoF) system via two cascaded single-drive MZMs at center frequency of 103 GHz. We discuss maximum bandwidth of different modulation formats under forward error correction (FEC) threshold (3.8x10(-3)). Up to 40-Gbps 16-QAM OFDM signals is achieved over 25-km fiber and 2-m wireless transmission. To overcome the penalty from uneven frequency response, bit-loading algorithm is applied to discuss data rate and spectral efficiency with signal bandwidth from 5 to 10 GHz. With 10-GHz bandwidth, 46.4-Gb/s data rate and 4.64-bit/s/Hz spectral efficiency was achieved. To achieve 40-Gbps data rate, the required bandwidth of OFDM signal with bit-loading is 2 GHz less than that without bit-loading. (C) 2013 Optical Society of America
Coherently wavelength injection-locking a 600-mu m long cavity colorless laser diode for 16-QAM OFDM at 12 Gbit/s over 25-km SMF
(2013-07-15)
Li, Yi-Cheng
;
Chi, Yu-Chieh
;
Cheng, Min-Chi
;
Lu, I-Cheng
;
Chen, Jason
The coherent injection-locking and directly modulation of a long-cavity colorless laser diode with 1% end-facet reflectance and weak-resonant longitudinal modes is employed as an universal optical transmitter to demonstrated for optical 16-QAM OFDM transmission at 12 Gbit/s over 25 km in a DWDM-PON system. The optimized bias current of 30 mA (similar to 1.5Ith) with corresponding extinction ratio (ER) of 6 dB and the external injection power of -9 dBm is (are) required for such a wavelength-locked universal transmitter to carry the 16-QAM and 122-subcarrier formatted OFDM and data-stream. By increasing external injection-locking from. 9 dBm to 0 dBm, the peak-to-peak chirp of the OFDM data stream reduces from 7.7 to 5.4 GHz. The side mode suppression ratio (SMSR) of up to 50 dB is achieved with wider detuning range between -0.5 nm to 2.0 nm under an injection power of 0 dBm. By modulating such a colorless laser diode with an OFDM data stream of 122 subcarriers at a central carrier frequency of 1.5625 GHz and a total bandwidth of 3 GHz, the transmission data rate of up to 12 Gbit/s in standard single-mode fiber over 25 km is demonstrated to achieve an error vector magnitude (EVM) of 5.435%. Such a universal colorless DWDM-PON transmitter can deliver the optical OFDM data-stream at 12 Gbit/s QAM-OFDM data after 25-km transmission with a receiving power sensitivity of -7 dBm at BER of 3.6x10(-7) when pre-amplifying the OFDM data by 5 dB. (C) 2013 Optical Society of America
Mechanism of Schottky barrier height modulation by thin dielectric insertion on n-type germanium
(2013-07-15)
Tsui, Bing-Yue
;
Kao, Ming-Hong
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Although high channel electron mobility has been reported after some passivation techniques, the performance of n-channel Ge metal-oxide-semiconductor field-effect transistor is still limited by the high Schottky barrier height at the metal/n-Ge contact interface, which comes from the Fermi level pinning effect. Recent experiments demonstrated that the Schottky barrier height can be reduced by inserting a thin dielectric layer between metal and Ge. However, the mechanism has not been well clarified. In this paper, the metal induced gap state model, the dipole layer model, and the fixed charge model are verified by varying contact metals, dielectric thicknesses, as well as the annealing temperatures. The pinning factor is improved slightly by dielectric insertion but its value is independent of the dielectric thickness and is still much lower than the ideal value of the non-pinning case. This pinning effect is consistent with the Fermi level pinning at the metal/TiO2 interface. After thermal process, no interfacial layer forms at the TiO2/Ge interface and the TiO2 crystallizes gradually after annealing but the Schottky barrier height increases. Since the amount of fixed charges in the thin dielectric layer estimated from a metal-insulator-semiconductor structure is about 2 x 10(11) cm(-2) and is insufficient to produce the observed 0.5 eV Schottky barrier height reduction, it is thus recommended that the main mechanism comes from the change of interface dipoles and the annealing effect is attributed to the short-range ordering of the TiO2 layer. Furthermore, dielectric with low conduction band offset which has good thermal stability should be explored. (C) 2013 AIP Publishing LLC.
Electronic relaxation and coherent phonon dynamics in semiconducting single-walled carbon nanotubes with several chiralities
(2013-07-15)
Kobayashi, Takayoshi
;
Nie, Zhaogang
;
Du, Juan
;
Okamura, Kotaro
;
Kataura, Hiromichi
Coherent phonon (CP) dynamics and electronic relaxation in single-walled carbon nanotubes (SWNTs) are investigated in femtosecond pump-probe experiments. Using a sensitive multichannel lock-in amplifier, chirality-specific electronic relaxation and vibrational dynamics are resolved in SWNT ensembles composed of several chiral systems without the need for selective isolation of the different species by purification. The dynamics of vibrational wave packets are studied based on oscillatory changes in the absorbance of the systems. Modulations corresponding to the radial breathing mode (RBM), observed in the time traces of the absorbance change for the four chiral systems (6,4), (6,5), (7,5), and (8,3), have been analyzed in detail. The vibrational modes of the CP spectra are identified from the two-dimensional distribution of probe photon energy versus Fourier frequency. Resonance conditions and mode frequencies lead to definite chirality assignments. Coherent RBM phonon generation is analyzed using the probe photon energy-dependent amplitude profiles as a result of the spectral shift induced by wave-packet motion on the potential surface. The present study clarifies that the observed probe photon energy dependence is due to both the imaginary and real parts of the third-order susceptibility, corresponding to Raman (and Raman-like) gain and loss processes and to molecular phase modulation, respectively. The imaginary part is the dominant contribution to the modulation in the difference absorbance. It shows probe photon energy dependence in the form of a difference in absorbed photon energy between the spectra that are shifted and unshifted with vibrational frequency. The size of the Huang-Rhys factors from the difference fitting to the (6,4), (6,5), and (8,3) systems are 0.26, 0.32, and 0.75, respectively. The trend of the factors originates in the stiffness differences of the SWNT structures. The real part depends on the derivative of the absorbed photon energy spectrum due to cross-phase modulation, resulting from the change in refractive index during the molecular vibrations. This process induces a probe spectral change, as evidenced by first-derivative fitting using a small number of data points of probe photon energies. The effective nonlinear refractive index for each chiral system is determined to range from 0.2 to 3.1 x 10(-17) cm(2)/W.
High-Accuracy Waveguide Leaky-Mode Analysis Using a Multidomain Pseudospectral Frequency-Domain Method Incorporated With Stretched Coordinate PML
(2013-07-15)
Wang, Chih-Yu
;
Liu, Hsuan-Hao
;
Chung, Shih-Yung
;
Teng, Chun-Hao
;
Chen, Chung-Ping
A recently developed pseudospectral frequency-domain (PSFD) method employing a penalty scheme is further incorporated with stretched coordinate perfectly matched layers (PMLs) in order to solve waveguide leaky modes. Several standard leaky-mode slab and circular waveguides, including the W-type and M-type ones, are examined first by solving their complex effective indexes and field profiles, showing that the PSFD method achieves computational accuracy on the order of. Then, this high-accuracy solver is used to analyze waveguide structures with more complicated geometries, such as the leaky six-air-hole fiber, for which self convergence of accuracy in calculated effective indexes is demonstrated to be on the orders of, and two rectilineal waveguides with sharp corners, i.e., the rib waveguide and the photonic wire. Comparison of the PSFD method obtained results for these more complicated waveguide structures with those from other methods in the literature is presented and discussed.
High-power high-repetition-rate subpicosecond monolithic Yb:KGW laser with self-mode locking
(2013-07-15)
Zhuang, W. Z.
;
Chang, M. T.
;
Liang, H. C.
;
Chen, Y. F.
;
電子物理學系
We report on a high-power subpicosecond monolithic self-mode-locked Yb:KGW laser with the pulse repetition rate up to several tens of gigahertz. Experimental results reveal that not only the repetition rate but also the pulse width depend on the length of the laser crystal. Using a coated Yb:KGW crystal with a length of 3.36 mm, mode-locked pulses with pulse duration of 850 fs at the repetition rate of 22.4 GHz have been achieved. With an incident pump power of 10.5 W, an average output power of 3.6 W was achieved which corresponds to the optical conversion efficiency of 34.3%. (C) 2013 Optical Society of America
Unipolar resistive switching behavior in Pt/HfO2/TiN device with inserting ZrO2 layer and its 1 diode-1 resistor characteristics
(2013-07-15)
Lee, Dai-Ying
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Tsai, Tsung-Ling
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Transition of resistive switching (RS) behavior from bipolar to unipolar is observed in Pt/ZrO2/HfO2/TiN device. Due to the lower oxygen vacancy concentration of the HfO2 layer, formation/rupture of the conducting filament is confined in the HfO2 layer. To fulfill one diode and one resistor (1D1R) structure, the electrical relation between the RS device and diode is investigated. A Pt/InZnO/CoO/Pt/TiN oxide diode is fabricated to provide enough forward current and large forward/reverse current ratio to achieve unipolar RS behavior. The 1D-1R structure with Pt/ZrO2/HfO2/TiN resistive random access memory shows robust retention and nondestructive readout property at 85 degrees C. (C) 2013 AIP Publishing LLC.
打結裝置
(2013-07-16)
徐文祥
;
潘政宏
一種打結裝置，包含固定結構、槽夾結構及傳動元件。其中該槽夾結構係配置於該固定結構之中，該傳動元件係部分地設置於該固定結構和該槽夾結構之間，並響應一作用力而轉動該槽夾結構，以執行一打結操作。
具有高電子遷移率之氮化鎵電晶體結構
(2013-07-16)
張翼
;
張嘉華
;
林岳欽
;
陳宥綱
;
劉世謙
一種具有高電子遷移率之氮化鎵電晶體結構，包括一基板、一位於基板上之氮化鎵磊晶層、至少一位於氮化鎵磊晶層上之歐姆接觸層、一位於氮化鎵磊晶層之上的金屬閘極層、以及一位於金屬閘極層與氮化鎵磊晶層之間的擴散阻擋層。利用此一擴散阻擋層，可用以阻擋金屬閘極層之擴散，使得氮化鎵電晶體結構具有較佳之元件特性及可靠度。
Method for buffering clock skew by using a logical effort
(2013-07-16)
Hsieh Chung-Ying
;
Chang Ming-Hung
;
Hwang Wei
A method buffers clock skew by using a logical effort, and is applicable to a clock tree that stays in a strong-inversion region, a moderate-inversion region, or a weak-inversion region. The method includes establishing in the clock tree a temperature sensor and a tunable-width buffer, and establishing width and temperature comparative lists according to a logical effort equation, for the tunable-width buffer to be individually applied to the strong-inversion region, the moderate-inversion region, and the weak-inversion region; selecting one from the width and temperature comparative lists that corresponds to one of the inversion regions in which the clock tree stays, enabling the temperature sensor to sense a temperature, and searching the selected width and temperature comparative list for a width that corresponds to the temperature sensed by the temperature sensor; and enabling the tunable-width buffer to perform a width modulation process according to the searched width.
多重開關偵測電路系統
(2013-07-16)
胡竹生
;
孫冠群
;
李哲宇
本發明係有關於一種多重開關偵測電路系統，包括：複數個串聯電路單元，每一串聯電路單元係由一電阻元件及一開關元件互相串聯而形成，而每一串聯電路單元係互相並聯連接；一外部電容元件，係與一串聯電路單元連接；以及一外部電阻元件，係與一串聯電路單元連接；其中，每一電阻元件之電阻值皆互不相同。
消除色差之稜鏡系統及其方法
(2013-07-16)
林聖涵
;
潘瑞文
;
王祥驊
本發明提供一種消除色差之稜鏡系統及其方法，係應用於微型投影機之照明系統內，首先，光束自第一稜鏡之入光面進入且由第一稜鏡之出光面射出，接著，光束由第二稜鏡之第一介面進入，並經第二稜鏡之第二介面射至第二稜鏡旁的一數位微型反射鏡元件，而光束經過該數位微型反射鏡元件反射後會射至第二稜鏡之第一介面，最後，光束經第一介面全反射後自第二稜鏡之第三介面射出。透過本發明之稜鏡系統不僅可解決習知之數位微型反射鏡元件主動區的橫向色差問題，同時可降低照明設備成本且提供良好投射效果。
具有判斷方向性濾波器適用性功能之影像處理方法
(2013-07-16)
洪朝雄
;
杭學鳴
;
蔣迪豪
本發明揭示一種具有判斷方向性濾波器適用性功能之影像處理方法。該方法係使用移動平均演算法來判斷影像在頻域是否有波峰的存在，藉以判斷該頻域所對應的小波轉換次頻帶是否適用方向性濾波器作拆解。該方法結合所提出的使用於位元平面編碼的相鄰表，使得整體的壓縮效果提升且時間減少。
Geometry based efficient decoder for underdetermined MIMO systems and decoding method thereof
(2013-07-16)
Huang Chung-Jung
;
Wu Chih-Yung
;
Lee Ta-Sung
A decoder for underdetermined MIMO systems with low decoding complexity is provided. The decoder consists of two stages: 1. Obtaining all valid candidate points efficiently by slab decoder. 2. Finding the optimal solution by conducting the intersectional operations with dynamic radius adaptation to the candidate set obtained from Stage 1. A reordering strategy is also disclosed. The reordering can be incorporated into the proposed decoding algorithm to provide a lower computational complexity and near-ML decoding performance for underdetermined MIMO systems.
鍺次氧化物移除方法
(2013-07-16)
劉柏村
;
黃震鑠
本發明提供一種用於移除形成於一鍺半導體基材與一介電層之間的鍺次氧化物的方法，包含準備一組成份包括一種二氧化碳超臨界流體和一氧化劑的超臨界流體組成物，且以該二氧化碳超臨界流體的體積百分比為100%計，該氧化劑的體積百分比不大於該二氧化碳超臨界流體體積的5~10%，接著在溫度不高於200℃的條件下，利用該超臨界流體組成物處理該鍺半導體元件，令該氧化劑與高介電常數材料及鍺次氧化物之間產生氧化還原反應，即可在低溫(<200℃)條件下將形成於該鍺半導體基材與介電層之間的鍺次氧化物移除。
時間可調性視訊編碼之快速時域預測模式選擇方法
(2013-07-16)
林鴻志
;
杭學鳴
;
蔣迪豪
本發明提供一種時間可調性視訊編碼之快速時域預測模式選擇方法，其藉由收集不同大小巨集區塊之切割模式之前向與後向預測的有效資訊，以建立臨界數值，並用以斷定其雙向預測是否需要測試。該訪法可減少視訊編碼時所需之運算複雜度，排除非必要之時域選擇預測模式，以減少編碼時間及維持一定的編碼效能與視訊品質等優點。
立體積體電路裝置
(2013-07-16)
陳冠能
;
賴明芳
;
陳宏明
一種立體積體電路裝置，包含第一晶粒、第二晶粒、複數導電通道，及焊墊單元。第一晶粒包括主要電路，第二晶粒與第一晶粒堆疊並包括避免主要電路受破壞的保護電路，導電通道自保護電路延伸至與第一晶粒的主要電路連接，焊墊單元包括與導電通道連接而對主要電路及保護電路傳送來自外界電訊號的輸出入焊墊(I/O pad)。本發明以主要電路與保護電路分設相異基板，再堆疊及配合導電通道電連接兩晶粒，而不需如目前所有電路置於同一晶片時，須保留預定距離以防止保護電路產生的脈衝影響主要電路導致過熱或失效，並進而有效減少整體的面積。
可調性視訊多層編碼控制快速決策模式演算法
(2013-07-16)
彭文孝
;
蔣迪豪
;
蔡閏旭
本發明揭示一種可調性視訊多層編碼控制快速決策模式演算法。該方法係使用時間性編碼模式分數(Temporal Mode Score,TMS)之概念，可以準確的預測出增進層的編碼模式，並且找出基礎層和增進層的編碼模式並可隨視訊序列的性質做不同的配對計算。