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Investigation of temperature dependent efficiency droop for light-emitting diodes on patterned-sapphire substrates with various depths
No full text高功率發光二極體(Light-Emitting Diode, LED)在照明的應用上日趨普遍，因此LED的發光效率衰減(efficiency droop)是一個值得關注的議題。LED的效率衰減可分為兩類，一是由電流增加所造成的發光功率下降，簡稱為J-droop，另一則是由溫度增加所造成的效率衰減，簡稱為T-droop [1]。 本論文在相同的磊晶條件下，設計週期均為3um六角型排列的三種不同深度(深度分別為2.55um、2.65um、2.75um)的圖案化藍寶石基板(Patterned Sapphire Substrates, PSSs)，利用電致發光(Electroluminescence Measurement System)積分球, 搭配溫控器，分別對封裝好後的三種不同深度PSS的LED進行變溫測量(5度C~80度C)，發現對單一樣品而言，溫度越高，T-droop越明顯。且電流密度越高，T-droop越不明顯。 此外吾人亦有一批未封裝的相同wafer，並用266nm的雷射光源對其做光致發光(Photoluminescence Measurement System)，得到磊晶品質的排序，與電致發光得到的結果相呼應。應證了磊晶品質較佳的LED有較好的溫度容忍度(temperature-tolerant)，亦即磊晶品質越好者: 溫度升高，T-droop越小，且在相同溫度下EQE越佳。說明了如需將LED在高溫下操作，則該LED的磊晶品質需越好。GaN-based Light-Emitting Diodes (LEDs) are typically grown on c-plane sapphire, or even patterned sapphire substrates (PSSs). In the same Epitaxy conduction, we designed three different depth Patterned Sapphire Substrates (2.55um, 2.65um, 2.75um). All of them are period of 3um and hexagonal arranged. We use Electroluminescence Measurement System with temperature controller to measure them from 5 ° C to 80 ° C and discuss their T-droop (The efficiency droop caused by increasing temperature) , and temperature tolerant. Moreover, we use the 266nm laser to do the Photoluminescence Measurement. After that, the sequence of the Epitaxy quality of them has been found. Consistent with the result measured by Electroluminescence Measurement System. It proves that LED with a better Epitaxy quality has a high temperature-tolerant
The CO2 adsorption on modified ordered mesoporous carbon
No full text本研究以水熱法合成高比表面積之規則中孔洞碳材（OMC），以硝酸氧化修飾中孔洞碳材（OMCA），增加含氧之官能基，之後以迴流嫁接法接合不同胺基批覆量（5、10及20 wt%）及不同種類之胺基分子（四乙烯戊胺，Tetraethylenepentamine，TEPA；三（2-胺基乙基）胺，Tris（2-aminoethyl）amine，TAEA；聚乙烯亞胺，Polyethylenimine，PEI）進行胺基修飾。利用X光粉末繞射儀（XRD）、氮氣等溫吸附-脫附儀（BET）、場發射式掃描電子顯微鏡（FESEM）及穿透式電子顯微鏡（TEM）鑑定所製備的中孔洞碳材之結構及外觀形貌，以傅立葉轉換紅外光譜儀（FTIR）及元素分析儀（EA）探討材料之表面官能基及元素含量，並鑑定胺基修飾材料之表面接合胺基量及孔徑大小差異。在二氧化碳吸附測定方面，利用重量法及體積法評估材料的二氧化碳吸附量，並計算出胺基之氮原子利用效率（CO2/N ratio）。最後利用原位紅外光譜儀（In-situ FTIR）判斷二氧化碳吸附後之產物，以解釋反應機制。 實驗結果顯示，在TEPA及TAEA方面，10 wt%為最適批覆量，而OMCA- TEPA-10有最高之吸附量，多於OMCA-TAEA-10及OMCA-PEI-10。體積法之結果顯示，OMCA-TEPA-10有最高之化學吸附量，13.23 μg/m2，多於OMCA-TAEA-10之12.96 μg/m2，及OMCA-PEI-10之7.03 μg/m2。然而在氮原子利用效率上，OMCA-TEPA-10卻為最低值0.027，低於OMCA-TAEA-10之0.037及OMCA-PEI-10之0.031，此因TEPA之長直鏈分子的立體障礙所導致。在原位紅外光譜儀的結果，則發現三種胺基有carbamic acid及carbamate的共同吸附產物，且吸附產物在不同溫度下的訊號強弱變化趨勢與化學吸附量之變化趨勢相同。1In this study, the ordered mesoporous carbon (OMC) with high surface areas and high pore volume was prepared by hydrothermal method, and then modified by nitric acid solution, which was named OMCA. OMCA materials were modified by grafting different amine separately, which were tetraethylenepentamine (TEPA) , tris（2-aminoethyl）amine (TAEA) and polyethylenimine (PEI), and loaded with varied amounts (5, 10 and 20 wt%). The textual, structural properties, and surface morphology of all prepared materials were characterized by powder X-ray diffraction (XRD), N2 sorption isotherms, transmission electron microscopy(TEM) and Fourier transform infrared (FTIR) spectroscopy. Carbon dioxide capture capacity of amine-modified mesoporous carbon was obtained by thermogravimetric analysis (TGA) and volumetric adsorption analyzer (BET); the latter was also used to investigate the adsorption performance on CO2/N ratio. The reaction mechanisms of CO2 adsorption on amine-grafted OMCA were confirmed by infrared spectroscopy. The experimental results indicated that the optimal amine loaded amount is 10 wt% for OMCA-TEPA and OMCA-TAEA material. OMCA-TEPA-10 has highest adsorption amount. The results of the volumetric method showed that OMCA- TEPA-10 also had the highest chemical adsorption amounts, 13.23 μg/m2,which was more than OMCA-TAEA-10, 12.96 μg/m2 and OMCA-PEI-10, 7.03 μg/m2. The CO2/N molar ratio were 0.027、0.037 and 0.031, respectively. OMCA-TEPA-10 had highest chemical adsorption amounts but lowest CO2/N ratio due to the steric hindrance. By in-situ FTIR spectroscopy, we showed that the amine groups reacted with CO2 and formed carbamic acids and carbamate under dry conditions. The intensities of ammonium carbamate, carbamic acids and carbamate changed with temperature, and the chemical adsorption intensities had the same trends
Whispering-gallery Modes and Light Emission from Silicon-Nanocrystal-Embedded Microdisk Resonators
No full text我們以電漿增強式化學氣相沈積法成長並在高溫熱退火下形成奈米矽晶的薄膜當作主動層，成功製作出了內含奈米矽晶的微碟共振腔，在室溫環境下，在600nm~1000nm的波段之中，量測到明顯的迴音廊模態。 奈米矽晶微碟共振腔分別以兩種不同的微影方式製作，以標準微影製程做出直徑10μm與20μm的微碟，以電子束微影製程做出直徑4、6、8、10μm的微碟，量測直徑8μm的微碟，Q值最高可達到1200，而直徑10μm的微碟可達到2400，我們同時也製作了厚度較厚的直徑10μm的微碟，希望能夠增加在主動層內的侷限。我們也能利用奈米矽晶/二氧化矽超晶格結構製作出微碟共振腔，同時也量測到了迴音廊模態。 最後針對入射功率的改變，量測輸出功率的變化，但沒有觀察到雷射閥值，主要原因為在很低的功率下，奈米矽晶就已經達到飽和狀態，而入射功率與線寬的關係部分應是有受激載子吸收的效應，造成模態擴張線寬增加的趨勢。We have successfully fabricated optically active microdisk resonators with Si nanocrystals grown by plasma enhanced chemical vapor deposition (PECVD) and the post-annealing process. The room-temperature photoluminescence from single microdisk shows the characteristic modal structure of whispering-gallery modes in the wavelength between 600nm and1000nm. We fabricated Si-nanocrystal-embedded microdisk resonators by two different lithography processes. We use standard lithography to fabricate the microdisk resonators with diameters of 10μm and 20μm and electron-beam lithography for 4-μm, 6-μm, 8-μm and 10-μm-diameter disks. The quality factors of 8μm and 10μm disks can reach 1200 and 2400 respectively. We also fabricated thicker 10-μm-diameter disks to increase the confinement of the disk. We can also use Si-nc/SiO2 superlattice as the active layer in the microdisk resonators and the WGMs were observed clearly Finally, we discussed the relation between pump power and output power. We observed the saturation of the excitable nanocrystals at low pump power and the linewidth broadening with pump power increasing due to the excited carrier absorption (ECA)
Using P-wave Triplications to Study the Mantle Transition Zone beneath the Central Iranian Plateau and Surrounding Regions
No full text伊朗高原為阿拉伯板塊與歐亞大陸板塊斜向碰撞所形成，過去研究大多著重於地殼至上部地函岩石圈，對於深部之速度構造了解有限，僅有全球尺度的走時層析成像研究在伊朗高原下方的地函深處發現高速異常，並將其解釋為兩大陸在閉合前新特提斯海洋板塊隱沒下去之殘餘物。 本研究使用高解析度P波多重路徑資料分析大陸碰撞帶（主要針對伊朗高原中部）與鄰近相對穩定區域下之地函過渡帶。當地震波經過深度410及660公里不連續面時，會因為速度不連續而形成多重路徑，其相對振幅及相對到時對於地函過渡帶之一維速度構造非常敏感，可以透過波形模擬來良好約束一維模型。本研究結合數個來自高加索及東土耳其寬頻地震網，在研究區域建立了十組長約800至1300公里之P波多重路徑剖面。 研究結果顯示，地函過渡帶的速度梯度在北邊穩定之圖蘭平台及南邊之伊朗高原皆略比全球平均一維速度模型iasp91高，使得660公里不連續面之速度增幅均明顯小於iasp91之5.6%，其值分別為4.5%及4.1%。然而，伊朗在地函過渡帶之速度只比周遭的圖蘭平台快不到0.6%，與走時層析成像發現之高異常比1至3%有出入。我們推測可能隱沒板塊尚未延伸至過渡帶，或是板塊殘片太小且分散而造成本研究低估異常之強度。另外我們也發現圖蘭平台和其他歐亞大陸及印度穩定地塊下之660公里不連續面速度增幅均介於4%左右，可能為歐亞區域的地函代表特徵。Iranian plateau is formed by the continental collision between Arabia and Eurasia. Recent studies of regional seismic tomography show P- and S-wave anomalies in the uppermost mantle beneath Iranian Plateau, but the structure of mantle transition zone (TZ) remains inconclusive. The high-velocity anomalies in the tomographic images are typically interpreted as the remnants of Neo-Tethys slab in the uppermantle that was subducted beneath Iran prior to the collision. In this study, we utilize triplicate waveforms of P-waves to investigate the structure of TZ beneath deformed Iranian Plateau and the surroundings that are tectonically stable. The rays passing through the 410- and 660-km seismic discontinuities form multiple arrivals, whose relative amplitude and timing are most sensitive to the velocity contrast across the TZ boundaries. By combining several broadband arrays in eastern Anatolia and the Caucasus, we construct 10 seismic profiles, each about 800 to 1300 km long, to constrain the vecloties under the study area based on modeling of waveforms. Our results show that the velocity gradient in the TZ under the Turan platform and Iranian plateau are both higher than that of the global average model iasp91. This also makes the contrasts of the two models at the 660 km discontinuity relatively small (about 4.5% for Turan and 4.1% for Iran) comparing to the 5.6% in iasp91. Although the P-wave speed in the base of TZ under Iranian plateau is faster than Turan, the amount of anomaly is inappreciably small (only ~0.6%). This is inconsistent with the tomography result in the previous study which indicates 1-3% of variations in the TZ. Our results infer that the subducted/break-off slab had not reached to the deeper TZ. Alternative interpretation is that, the seismic anomaly is underestimated in our study if the fragments of the slab are small in size and separated apart in the sampled area. Finally, the contrasts at the 660 km discontinuity under Turan is comparable to other tectonically stable areas in Euraisa and India. Perhaps 4% contrast is a representative background value for continental Asia
Radiocarbon dating of terrace sediments from western Taiwan using a temperature stepped-combustion procedure
No full text台灣由於氣候變遷和板塊擠壓持續抬升，一連串的河階沿著河流生成，利用碳十四定年法分析在階地上找到的碳屑或是樹幹，即可得知這些河階的生成年代。然而台灣氣候溫暖潮濕，河階沉積層常有地下水通過，在氧化環境之下，碳屑或是樹幹會快速的被氧化降解，因此在野外，並不容易找到保存良好的碳屑或是樹幹。過去的研究，嘗試利用沉積物中的有機碳來做碳十四定年分析，但在沉積物中的碳循環是屬於開放系統，年代會因為不同碳來源進入這個系統而改變，直到目前為止，沒有一個方法可以完全分離沉積物中不同年代的碳來源。本研究嘗試修改過去的實驗步驟，主要包括兩個階段：1）在化學前處理之前將沉積物先做粒徑分選 2）改單一高溫燃燒為階段式加溫燃燒的方式，希望能分離出沉積物中的多個碳來源，並探討這些分離出來的碳來源的年代意義。 第一個研究地點在苗栗縣南庄鄉南富村，階地選在離獅潭和斗煥坪左右兩斷層之間，中間段的最低位河階，目的是檢視本研究方法，在構造影響最小的情狀之下，沉積物年代是否可以紀錄氣候變遷的可行性。南富階地沉積物經過篩之後分成粗、細兩組分樣 (150-1410 μm and <64 μm)，此兩組分樣分別經過酸-鹼-酸的化學前處理，將溶解在鹼液的腐植酸 (humic acid)，利用再沈澱的方式析出，再以單一高溫燃燒氧化，而化學前處理的產物-腐植質 (humin)，則是採用階段式加溫的方式燃燒氧化，得到多個數據。將標本中選一(1E)的細粒分樣 (<64 μm) 析出的腐植質，經由階段式加溫燃燒的結果中發現，有低溫(LT)年輕和高溫(HT)年老的兩個端成分，以攝氏400度為分界燃燒其他樣本，同樣也有高、低溫兩個端成分的組成。採用合併過篩和階段式加溫的實驗步驟得到的結果，腐質酸呈現最年輕，低溫腐植質次年輕，高溫腐植質最年老的規律性分布。由於過篩將沉積物顆粒分離，將碳來源變異度侷限在小於64 μm粒徑範圍內的有機碳-礦物包裹體，再用階段式加溫方式有效分離其中碳成分，此兩種方法的組合，可成功分離出數個不同年代的碳來源。由此不同年代的分樣可估算出，紀錄在南富階地沉積物中土壤發育的綜合年代，而此一發育年代與台灣過去兩千年到四千年之間的暖、濕氣候時間相當吻合。 第二個研究地點在台南六甲斷層區域，沿著龜重溪開挖了五個槽溝，分別位於不同高度的河階上，由於此河流穿越六甲斷層的上盤區域，因此河階抬升速率應可反應該斷層的活動速率。來自五個槽溝的沉積物，如同上述先過篩，但只採用小於64 μm粒徑的分樣，經過化學前處理之後的腐植質，皆採用階段式加溫方式燃燒氧化，與腐質酸共同比對。根據前人研究，有機碳主要吸附和鍵結在黏土礦物上，所以本研究選取高純度、結晶良好的黏土礦物，同步進行分析；研究結果顯示有機碳以鍵結方式與黏土礦物連結，因此釋放溫度也與礦物結晶結構變形溫度同步，野外沉積物雖然組成複雜，但也有類似的趨勢，證明有相當量的有機碳建結在黏土礦物上。本研究將龜重溪的五個河階沉積物分離出數個不同的分樣分別來定年，將之轉換成抬升速率，並探討不同河階土壤發育方式不同，對抬升速率（沉積物年代）的影響。 本研究修改過去前人針對沉積物碳十四定年的研究方法，利用階段式加溫燃燒小於63um粒徑的有機碳礦物包裹體，成功將碳來源簡化成兩到三個端成分；由於沉積物為開放系統，腐質酸以及低溫腐植質年代，並不表示階地形成年代，而是從階地形成之後，持續混合現生碳，直到封閉不再碳交換的平均年代，因此會比階地形成年代年輕；階地沉積物中，有一部分黏土礦物是從上游沖刷下來沈積，而高溫腐植質則是代表黏土礦物在上游形成時鍵結的有機碳，因此會比階地形成年代老；由此兩方年代的控制，可以估計出階地抬升速度。此一方法在找不到碳屑或是樹枝的沉積層的條件之下，可以提供年代的參考範圍。 本研究方法成功分離河階沉積物中多個不同年代的碳來源，證明此簡單的物理方法加上過去長期使用的化學前處理，即可將碳來源的變異度降低，進而討論碳來源的年代意義。此方法亦可應用在其他沈積環境的沉積物中，尤其在找不到其他定年物質的情形之下，沉積物中數個分樣的碳來源年代亦可當作重要參考年代指標。Radiocarbon (14C) has been widely used in determining the age of various geological materials and events. The validity of ages, particularly for sediments, has often been questioned due to the incorporation of carbon-bearing components with different abundances of 13C and 14C. For the purpose of isolating various carbon sources in sediment, a procedure is adopted in this study including 1) size fractionation before regular sample pretreatment and 2) temperature stepped-combustion in place of conventional high temperature oxidation. Then, this procedure was applied on terrace sediments from two study areas at western Taiwan. The first step in this study was to carry out a radiocarbon study of sediment samples collected from Nanfu terrace in western Taiwan. Humic acids (HA) and humins were extracted from the very fine and coarse grain-size fractions of sediment using a standard acid-base-acid (ABA) pretreatment. The humin extracts were combusted at 400 and 1100 °C by stepped-combustion, to yield a low-temperature (LT) carbon component and a high-temperature (HT) carbon component. A consistent relationship can be observed by comparing the ages of the LT and HT humin fractions to the HA fractions of samples collected at 2 depths within the Nanfu terrace profile. The HA ages are the youngest on average, and overlap with the LT ages, and the carbon contained in the HT fraction is always distinctly older than both the LT and HA ages. To better understand the relationship between 14C age and combustion temperature, incremental stepped-combustion experiments were conducted with one of the samples (1E) using 50 °C steps that ranged from 300°C to 1100 °C. The 14C results of the stepped-combustion products show a clear division between 2 isotopically identifiable carbon constituents, from carbon released below 400 °C and carbon released above 550 °C. By comparing the δ13C and 14C results, a third carbon isotopic component is identified in the humin that is released when combusted at ~500 °C. Since organic matter is mainly bound to clay minerals in fine sediments, the next phase of this study was to focus on carbon contained in clays. The same temperature stepped-combustion procedure was applied to well-crystalized clay minerals (kaolinite, illite and illite-smectite) in a series of experiments ranging from 350°C to 1100°C. Distinct carbon components were identified in the samples using both their 13C and 14C contents. Two carbon end-members were observed for all of the clay minerals: a low temperature component (<400°C), relatively depleted in 13C and enriched in 14C; and a high temperature component (>550°C), relatively enriched in 13C and depleted in 14C. The high temperature carbon component is relatively old and not released until the clay is completely oxidized. This observation suggests that this carbon was incorporated into the clay mineral when it first formed by weathering. The same procedure was applied to field sediments collected from terraces along the Kueichung River, in southwestern Taiwan, sieved to <64 μm. The results from sediments are similar to the well-crystallized clay minerals, with distinct low temperature (relatively young) and high temperature (relatively old) end members. One of the sediments also contained a third carbon component, possibly detrital carbon. The radiocarbon dates on these various carbon fractions provide a range of dates enabling us to place constraints on the timing of terrace development in Taiwan. The procedure used in this study successfully separates carbon sources in terrace sediments. Organic carbon bound on minerals is well accepted in previous researches, but this study is the first to provide 14C ages of distinct carbon sources from organo-mineral complex. It implies by this procedure radiocarbon dating technique can be applied on any kind of sediment, and its age interpretation will be varied based on the binding mechanism
Geochemical Characteristics and Petrogenesis of Adakites in Sikhote-Alin, Russian Far East
No full text亞洲大陸東緣，包括俄羅斯遠東、日本、菲律賓以及印尼等西南太平洋群島，為亞洲最年輕的「西太平洋造山帶」的範圍。大量新生大陸物質於此增積造山帶形成，因而西太平洋造山帶之研究對探討大陸地殼增生的機制具有重大意義。本研究著重於研究俄羅斯遠東Sikhote-Alin地區東南側的岩石成因。 Sikhote-Alin地區大致分為兩個地質單元：(1)西側的新元古代布瑞亞–佳木斯–興凱地塊(Bureya–Jiamusi–Khanka terrane)，和(2)東側的中生代Sikhote-Alin Orogenic Belt。白堊紀至新生代早期的火成岩帶—East Sikhote-Alin volcano-plutonic belt (ESAVPB)的火山岩與深成岩廣泛覆蓋、侵入在這兩個地質單元中。近幾年，ESAVPB的鋯石鈾鉛定年與全岩微量元素、同位素的報導陸續發表，對Sikhote-Alin地區的晚中生代、新生代的地體構造演化有進一步的認識。本研究在Sikhote-Alin地區南部發現兩期埃達克岩，年代分別為早白堊紀(130–100 Ma)與始新世(~45Ma)。埃達克岩是高壓基性岩發生部分熔融而產生的火山岩，其岩石成因常與特殊的地體構造環境有關。本研究針對兩期埃達克岩進行全岩主量、微量與鍶釹同位素分析，與鋯石鈾鉛定年的結果，討論其岩石成因、以及對東北亞地體構造演化的意義。 早白堊紀與始新世埃達克岩大多分布於興凱地塊(Khanka terrane)中。鋯石定年結果顯示這些岩體在132–98 Ma與46–39 Ma形成，地球化學分析表明有埃達克岩性質： SiO2= 57–73%；Al2O3= 15–18%；Na2O= 3.5–5.9%；K2O= 0.7–3.7%； Na2O/K2O= 1.3–3.9；Sr/Y= 30–140；(La/Yb)N= 11–53，重稀土與高場力鍵結元素皆有虧損情形。早白堊紀埃達克岩的銣、鍶同位素成分為：εNd(T)= -1.0–3.2；ISr= 0.705227–0.708967；始新世埃達克岩則是εNd(T)= -1.9–2.1；ISr= 0.704318–0.705758。 本研究認為，兩期埃達克岩的岩石成因為隱沒海洋地殼與沉積物的熔融，並標誌著Sikhote-Alin地區隱沒帶岩漿作用的開始與結束。早白堊紀埃達克岩於東北亞已有許多前人報導，噴發時間長達三千萬年，空間、時間分布皆十分廣泛。同時期的島弧岩漿ESAVPB也開始噴發。隱沒初始以及高溫的年輕海洋地殼隱沒，可能是產生這一期埃達克質岩漿作用的機制。始新世埃達克岩伴隨基性岩與酸性岩一同出現，顯示同期有數個岩漿源區。同時期的島弧岩漿活動，出現於東側的庫頁島、日本北海道。一次海洋板塊的回捲(Slab roll-back)可能在此時發生，增強的地函熱對流使海洋地殼發生部分熔融，也令島弧岩漿的噴發向東移至庫頁島、北海道。 此外，日本本州Kitakami地區的早白堊紀與始新世TTG、埃達克岩，具有與Sikhote-Alin埃達克岩相似的年代與地球化學特性。分布於兩個地區的埃達克岩可能來自同一個岩漿系統，並且可作為一對比證據，支持在日本海張裂以前，Sikhote-Alin與Kitakami地區為東亞大陸邊緣相鄰區域的古地理重建模式。The Mesozoic-to-Cenozoic Sikhote-Alin orogenic belt and late Precambrian Khanka block are two major tectonic units in the southmost Russian Far East. The Sikhote-Alin belt comprises several tectonostratigraphic terranes, including late Precambrian nappes, and Mesozoic accretionary prisms and turbidite basins. These terranes are overlain by Cretaceous to Paleocene felsic to intermediate volcanic rocks and intruded by granitoids. The magmatic rocks are collectively known as “the East Sikhote-Alin volcano-plutonic belt” (ESAVPB), and mainly characterized by acid-to-intermediate compositions. This work concerns a petrogenetic study of adakitic rocks from Sikhote-Alin, and discusses its tectonic implications. Adakitic rocks of Sikhote-Alin were emplaced in two main periods: Early Cretaceous (132–98 Ma) and Eocene (46–39 Ma). They mainly occur in the Khanka block, with a subordinate amount in the ESAVPB. The adakites show a large range of chemical composition: SiO2 = 57–74%, Al2O3 = 15–18%, Na2O = 3.5–6.1%, K2O = 0.7–3.2%, Na2O/K2O = 1.1–3.9, Sr/Y = 33–145, and (La/Yb)N = 11–53. HREE and HFSE are remarkably depleted. The Early Cretaceous adakites show Nd(T) = -1.0 to +3.2；ISr = 0.7040 – 0.7090, and the Eocene adakites have Nd(T) = -2.0 to +2.2；ISr = 0.7042 – 0.7058. Thus, the Sr-Nd isotopic compositions of Cretaceous and Eocene adakites are not readily distinguishable. Adakites may have different modes of generation. However, according to a modal calculation, partial melting of meta-basic rocks in a subduction zone is considered as the most likely mode for the present case. The two periods of adakites have probably formed in the following scenario. The early Cretaceous (130–100 Ma) emplacement time for the adakites and the oldest granitoids of the ESAVPB, is considered as the time of initiation of the Paleo-Pacific subduction in NE Asia. Furthermore, to explain a slab melting process with such long period of time, the generation of the adakites was probably connected with subduction of a young slab. The Eocene (~45 Ma) adakites were also generated in subduction zone, and during the generation, a small amount of andesite and rhyolite was also produced. Contem- poraneous granitoids were emplaced 200-400 km to the east of the study area in Sakhalin as well as in Hokkaido (Japan). With this scenario, we may speculate a roll-back of subducting Pacific plate during the Eocene, and a shifting of arc magmatism from the ESAVPB to Sakhalin Island and Hokkaido. Note that abundant adakitic rocks of early Cretaceous and Eocene ages also occur in the Kitakami and Abukuma Mountains of NE Japan. Consequently, geological correlation between Sikhote-Alin and Kitakami-Abukuma is highly probable, particularly before the opening of the Japan Sea that took place in late Cenozoic
High Transmittance Polymer-Stabilized Blue-Phase LCDs With Double-Sided Patterned Electrodes
No full textLiquid crystal technologies have been used in our daily life. In addition to displays such as LCD TVs, tablet PCs, smart phones and large advertising panels, liquid crystal’s bright and dark states can also be used for the application in electro-optic switches, such as electronic windows. Liquid Crystal plays an important role in products of technology for people’s life. Manpower and resources have been invested in all of the mentioned technology. In recent decades, scientists have been investigating and developing of a new type of liquid crystal material called Blue Phase Liquid Crystal (BPLC). BPLC occurs as a highly twisted chiral nematic liquid crystal cooling down from the isotropic phase. However, its temperature range is only about 1K. In recent years, researchers proposed to use polymers to improve the temperature range of BPLC from 1K to around 60K, so-called polymer-stabilized blue phase liquid crystal (PS-BPLC). As a result, PS-BPLC has been actively researched in recent years for next-generation displays due to its attractive features such as fast response time of sub-millisecond, no alignment required and isotropic off-state. However, PS-BPLC display has so far not been in mass production. One of the major obstacles that needs to be solved is its high operation voltage. This thesis is the use of simulation software (Techwiz) to design the doubled sided electrode, so that it can reduce the operating voltage of polymer-stabilized blue phase LCDs. Although its fabrication may be difficult, it offers a potential way of achieving a very low operation voltage for PS-BPLCD. In this thesis, we demonstrate a further possible improvement on this design by including a protrusion electrode scheme to this double sided IPS electrode design. This results in the generation of stronger horizontal electric fields to reduce the disclination or “dead zone” areas resulting in higher transmission and lower operation voltage. We tried to vary different parameters such as electrode gap (L)、electrode height (H) and cell gap (G) in order to get the best possible results. Moreover, we will also design other possible new potential designs such as the use of a new double-sided slanting electrode to lower the operation voltage of a PS-BPLC display. By using oblique electric field to increase the level of the horizontal electric field, this new design can improve interference effect of the electric fields in the middle part of liquid crystal cell that is caused by the double sided IPS electrodes. It can enhance the transmittance and reduce the operating voltage of PS-BPLCD. Finally, we make some analysis and comparisons between two designs of double sided electrode structures
Growth mechanism of twin defects in (111)B GaAsSb studied by X-ray diffraction spectroscopy
No full text本論文利用HRXRD提出一套重新判定基板斜切方向的方法，並藉由{220} 360° phi角掃描來研究[111]B GaAsSb內部雙晶缺陷成長的結構特性。 首先，我們經由phi角掃描中{220}繞射點出現的位置，將樣品分為兩類，分別為類型1：phi=60°、180°和300°，以及類型2：phi=0°、120°和240°。接著，由於樣品基板有經過[001]方向斜切處理，在量測HRXRD前須先進行[111]向量的校正，我們藉此反推出樣品平放時的[111]方向及基板斜切方向[001]，並推測基板表面因斜切處理產生的台階，會朝[001]反方向降階。最後，也討論了此判定方法可靠性。 在{220} 360° phi角掃描部份，我們觀察到隨著成長溫度降低，Sb成分比例會上升，雙晶缺陷密度也會提高，此顯示高Sb成分比例的晶體在成長時，會傾向藉由產生雙晶缺陷以釋放應力。此外，當雙晶密度逐漸提高，樣品的{220}繞射點寬度會急遽增加，其中(202)和(022)繞射點譜形會由對稱形狀轉變為不對稱，最後再變回對稱分布。我們認為因為雙晶區域受邊緣缺陷影響而傾斜後，會使{220}繞射點中的雙晶訊號偏移造成譜形改變。同時，也觀察到不對稱譜形的分布和基板斜切方向有關，並利用台階成長模型分析[1-1-1]、[-1 1-1]以及[-1-1 1]三種方向下成長的雙晶，其受台階影響而產生的偏轉效應，成功地解釋當雙晶密度中等時的{220}繞射點寬度不對稱變化。In this work, we utilized the HRXRD measurement to recover the missing off-cut direction of substrates and qualitatively compared the twin defects density of [111]B GaAsSb samples to study its growth mechanism by the {220} 360° phi-scans. First, we classified the samples into two categories by the phi angles of {220} diffraction points. The one is for phi= 60°, 180°, and 300°; the other is for phi= 0°, 120°, and 300°. Later, from the analyses of calibration angles of [111] vector, which is deviated from the sample normal direction under the substrate off-cut, we suggested that the surface steps of substrate would terrace down in the direction against to the [001]. In addition, the reliability of this re-determination method was also discussed. Second, in the {220} 360° phi-scan, we observed the twin defect density increases as the sample growth temperature decreases, which reveals that the formation of twin defects is good for strain releasing during the sample growth of high Sb composition. Furthermore, we found that the higher the twin defect density, the much broader the {220} diffraction peaks. We suggest that the broadening behavior is resulting from the shift of twin signals, which coincide with the original {220} diffraction points firstly, under the tilting of defects at twin domain boundaries. Also, we noticed that the broadenings of (202) and (022) points are asymmetric at first, becoming symmetric eventually. And, the asymmetric broadening is related to the substrate off-cut direction. Thus, the step-growth model was used successfully, in the regime of medium twin defect density, to explain the asymmetry of {220} line-shapes by examining the tilting influences coming from surface steps during the twin defect growth
Mechanism of Out-Coupling Efficiency Enhancement and Blur Effect Reduction in Organic Light-Emitting Diodes with Micro-Lens Array Films
No full text有機發光二極體在顯示應用及照明應用中,未來都是重要的主流技術。作為 顯示器時,比起薄膜電晶體液晶顯示器,可以有更好的色域表現、更快的反應時 間及可製作於軟性基板的特性,故有機發光二極體可說是帄面顯示器中的終極技 術。作為照明應用時,可提供超高衍色性、可調整色溫及面光源照明特性,使得 在室內照明領域中,有機發光二極體為一項極具潛力且快速發展的技術。 目前有機發光二極體遇到的最大問題之一為出光效率的提升,由於其層狀堆 疊結構,造成大部份光線會在結構內全反射而無法從結構中被耦合至空氣中,使 得出光效率低落,也同時使得有機發光二極體的使用壽命大幅地降低。利用在有 機發光二極體的玻璃基板上貼附微米等級的微透鏡陣列,可有效地降低玻璃與空 氣介面的全反射,提高光耦合效率; 但同時卻會造成嚴重的影像模糊情形,使得微 透鏡陣列應用於有機發光二極體顯示器為一項較不實際的技術。 我們發現若單純地減低貼附微透鏡的有機發光二極體之玻璃基板厚度,其光 耦合效率可以大幅提升,對於玻璃基板厚度為 25 微米且貼附微透鏡陣列的有機發 光二極體,其出光效率可以達到 84%的增益,且其模糊效應也同時會大幅降低。 在本論文中,根據微透鏡的出光機制,我們將微透鏡分成三個區域來解釋其 增益的原因。並基於我們的理論可以計算出在玻璃基板厚度為 25 微米時,若兩個 畫素的距離大於 247.88 微米,其畫素與畫素之間的發光區域重疊現象會大幅減 低,故根據此規格設定的有機發光二極體可以達到在各視角下都可以有高影像品質的效果
Tsunami and shaking simulations of potential large subduction zone earthquake along the southernmost Ryukyu Trench
No full text台灣位處於環太平洋地震帶上，其附近的琉球海溝及馬尼拉海溝存在引發大型隱沒帶地震的構造地質條件，其中台灣東北外海的琉球海溝最南段，透過地球物理及地質資料分析指出，其於未來具有發生大型地震之可能性。前人以花蓮-蘇澳沿海的間震期CGPS資料分析此區域的應力累積狀況，推估最大地震規模可達Mw 8.7，其所產生之地震波將會對台灣東北部及台北都會區造成嚴重威脅。另外，藉由歷史地震與海嘯紀錄顯示，除了地震本身所造成之強地動之外，亦可能引發大規模海嘯侵襲台灣本島及鄰近海域。本研究以琉球海溝南段為研究目標，透過數值模擬分析此區大型地震發生時可能產生的強地動與海嘯傳播情境。研究中採用強地震預估準則建構四種不同震源破裂模型，同時亦利用間震期CGPS資料進行震源逆推，透過實際觀測資料求得未來地震發生時斷層破裂面上之錯動量分布。進一步透過譜元素法(Spectral-Element Method, SEM)進行三維地震波傳模擬，分析此五種隱沒帶地震的破裂情境對台灣各地的強地動過程，了解各地區地表最大加速度(Peak ground acceleration, PGA)分佈。同時利用彈性半空間錯位模型(Elastic half-space dislocation model)計算各破裂情境之海底同震變形，將之作為海嘯初始波高模型，並以Dispersive海嘯傳播模式來模擬與分析所有破裂情境所產生的海嘯傳播至台灣各沿海地區之情形。由數值模擬結果得知，儘管地震發生於台灣東北外海，由於破裂方向加成效應(Directivity effect)，台灣島上部分區域將可能產生超過2g的強烈震動，其主要位於近震源區之台灣東部宜蘭、花蓮一帶。台北都會區因所處之台北盆地產生的放大效應，儘管其距離震源區達150公里，產生之PGA量值仍可超過1g。所有情境之海嘯傳播模擬結果於台灣東岸皆產生顯著的海水抬升量(> 5m)，如宜蘭、花蓮及台東沿海。若考量斷層錯動所造成的同震地殼下陷，宜蘭地區將可能遭受到的海嘯波高甚至達20公尺以上。透過本研究之數值模擬結果，可評估此段隱沒帶未來發生大型地震時可能的影響程度與範圍，包括地震波的震動與海嘯的襲擊，同時，這些情境地震之模擬結果，亦可作為將來研擬地震防災對策的參考。During the last century, many big earthquakes with magnitude larger than 9 had occurred along the subduction zones. For example, the 1960 Chile earthquake (M9.5), the 2004 Sumatra-Andaman earthquake (M9.3), and the 2011 Tohoku earthquake (M9.0). In this study, we focus on the southernmost Ryukyu Trench which is extremely close to northern Taiwan. Interseismic GPS data in northeast Taiwan shows a pattern of strain accumulation suggests that the maximum likely magnitude of a potential future large earthquake in this area is probably about moment magnitude 8.7. In order to evaluate the influence of the potential megathrust event, we consider a 3-D fault plane along this portion of subduction zone at depths shallower than 50 km. We apply the interseismic GPS data to invert the source slip pattern on the subducting fault plane. In addition, several source rupture scenarios with different characterized slip patterns are considered to simulate the ground shaking based on 3-D spectral-element method. We analyze ShakeMap and ShakeMovie from the simulation results to evaluate the influence over the island between different source models. A dispersive tsunami propagation simulation is also carried out to evaluate the maximum tsunami wave height along the coastal areas of Taiwan due to coseismic seafloor deformation of different source models. From the results of all rupture scenarios, the peak ground acceleration larger than 1g can be observed in many areas even though the rupture occurs off northeastern coast of Taiwan. The tsunami simulation results show that the sea level raised significantly along the eastern coast, especially in the offshore area of Ilan where tsunami high can over 20 meters. The results of this numerical simulation study can provide a physically based information of megathrust earthquake scenario for the emergency response agency to take the appropriate action before the really big one happens