類別:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/157
2024-03-19T08:51:09Z黑色素的奈米化與其在生物醫學上之應用
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51708
標題: 黑色素的奈米化與其在生物醫學上之應用; NANONIZATION OF MELANIN AND ITS APPLICATIONS TO BIOMEDICINE
作者: Yi-Cheng Liu; 劉奕成
摘要: 黑色素是人體組織中最普遍的異質生物聚合物之一,但其分子結構至今還無法完全被解析出來。黑色素具有很寬的吸收光譜,並且可生產永久自由基和光致自由基,皮膚表層的黑色素細胞中有許多與免疫系統相關聯的酶,有助於幫助人體對抗微生物,其中的黑色素可能就扮演重要的角色。此外研究指出黑色素細胞能保護皮膚不受紫外線的傷害,靠的不僅是經由吸收作用衰減紫外線強度,還有清除自由基和活性氧的功能,更多的研究指出黑色素具有抗輻射、抗氧化、抗癌、抗蛇毒、抗病毒和清除重金屬離子等功能。在這些潛在應用中,不論是天然黑色素或人工合成黑色素都無法在適合生物生存的溶劑中被溶解,大量的沉澱聚集形成更大的顆粒,造成其效用大大降低。於是我們著手開發利用飛秒脈衝雷射與機械粉碎的技術將黑色素奈米化,製造黑色素奈米顆粒使之可以分散於水溶液中,以便更可靠地研究黑色素的生物功能,並增強其作為藥物的療效。結果顯示被奈米化的烏賊和合成黑色素呈片狀,顆粒大小約為直徑42.5奈米與高度0.95奈米,可以均勻分散在水溶液中超過一週不會沉澱,理論上,此技術適用於任何種類的黑色素,而且用飛秒脈衝雷射進行奈米化的製程還可用來解析黑色素的結構,我們推斷烏賊黑色素是由許多奈米薄片聚集而成,其間是靠凡得瓦力和疏水作用力來維繫的,而合成黑色素是由許多奈米薄片堆疊而成的微米薄片,其間靠的是π–π相互作用力來維繫的,此作用力比前者大。在生物醫學應用方面,雖然過去研究指出黑色素在皮膚中具有抗微生物能力,但我們的實驗證明並非黑色素奈米顆粒直接殺死微生物,同時也證明黑色素奈米顆粒在有無照光的情況下都不具有細胞毒性,更加確認它做為藥物的可行性。此外,我們證明了奈米化後大大提高黑色素對抗急性氧化壓力和清除重金屬離子的效用,甚至不需要外加照光來增強其效果,對於日後做為注射劑應用到人體會更加方便。; Melanin is one of the most ubiquitous heterogeneous biological polymer widespread in our body tissue. However, its complete molecular hierarchical structure is still unknown. Melanin has a broadband absorption spectrum and it can generate permanent and light-induced free radicals. In the human epidermis, melanocytes have numerous enzymes with capabilities in antimicrobial defense and functional links to the immune system, in which melanin may play an activating role. Furthermore, it is believed that melanocytes in the human epidermis play a key role in protecting our skin from the damaging effects of UV radiation by scavenging free radicals and reactive oxygen species, besides simply attenuating the radiation. It is well established that melanin has multiple functions such as anti-radiation, antioxidant, antitumor, antivenin, anti-virus, and removing heavy metal ions. In all these potential applications, insolubility of both natural melanin and synthetic melanin in bio-compatible solvent leads to quick precipitation and formation of large aggregates, drastically reducing the efficacy in in vivo and in vitro experiments. We deliberately set out to develop techniques based on photo-fragmentation with femtosecond laser pulses and mechanical smashing respectively for nanonization and dispersibilization of melanin, in order to more reliably study the biological functions of melanin and to promote the efficacy of melanin as medicine. It was found that both Sepia melanin and synthetic melanin particles processed with either method represent flaky shape with the diameter of ~42.5 nm and height of ~0.95 nm. Therefore, they can disperse in water and avoid precipitation for more than a week. In principle, the techniques can be applied to any kind of melanin. Amount them, the nanonization process by femtosecond laser pulses also serves as a top-down approach for resolving melanin structure. We inferred that in Sepia melanin the aggregation of nano-flakes is mediated by van der Waals interaction and hydrophobic interaction, whereas in synthetic melanin the formation of micro-flakes from nano-flakes is mediated by π–π interaction, which is substantially stronger than the former. As for the biomedical applications, experiments on the antimicrobial efficacy concluded that even if melanin plays a role in antimicrobial capability of skin, as proposed previously by others, it does not result from direct killing of microbe by melanin nanoparticle. In addition, this shows that melanin nanoparticle whether illuminated or not is not cytotoxic, therefore promises its use as medicine. Moreover, we demonstrated that nanonization dramatically improves the efficacy of melanin against acute oxidative stress and heavy metal ions. The effect was even more prominent without simultaneous light irradiation, promising for effective in vivo intravenous application to the whole body.2015-01-01T00:00:00Z黑磷及二維材料電晶體之開發與黑磷及金屬接觸電極
之研究
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/67685
標題: 黑磷及二維材料電晶體之開發與黑磷及金屬接觸電極
之研究; Development of Black Phosphorus and Two-Dimensional Material Field-Effect Transistors and Investigation of Black phosphorus Metal Contacts
作者: Hsun-Ming Chang; 張洵銘
摘要: 在摩爾定律即將面臨挑戰的時代,二維材料之材料特性的優勢使其成為未來可能替換掉傳統矽的材料。常見的二維材料包含石墨烯、過渡金屬二硫化物等等;而其中又以同時具備高載子遷移率與能隙的黑磷的材料特性較為突出。然而,金屬與黑磷的接觸電阻為限制其元件特性的重大議題,因此,本論文將研究如何降低黑磷的接觸電阻以及分析金屬與黑磷的介面特性。
本研究以機械式剝離法,將數層黑磷撕至二氧化矽基板上並以原子力顯微鏡及拉曼光譜分析黑磷之品質。並透過電子束微影的製程定義出源汲極,接著鍍上金屬,完成背閘極之黑磷電晶體。其電洞載子遷移率為340 cm2/Vs,並有103的開關比。另外也成功開發了二維材料異質結構堆疊的技術,完成以石墨烯為電極的二硫化鉬電晶體,其電洞載子遷移率為87.6 cm2/Vs,並有105的開關比。
為了降低黑磷的接觸電阻,我們以鍺作為黑磷電晶體的接觸金屬,在快速熱退火後成功地將鍺參雜入黑磷的源/汲極,退火後電洞遷移率最大可達227 cm2/Vs,載子遷移率增幅最大可達超過25倍,其接觸電阻可降低至0.365 kΩ∙μm,為目前文獻中的最低值。透過低溫量測的分析此接觸之金屬性,最後以X射線光電子能譜驗證了磷與鍺的鍵結。
為了分析鈦與黑磷的接面,我們透過活化能來萃取其蕭特基能障高度。經由理論的估計與穿隧電子顯微鏡的分析,我們發現此蕭特基能障高度為被低估的值。因此,我們改為利用接觸電阻的方法,成功的萃取出與理論較相符的蕭特基能障。
此研究可被高度應用在未來黑磷電晶體的發展,參雜鍺以降低接觸電阻的方式可應用於高頻及尺寸微縮,蕭特基能障萃取的方法可更廣泛的應用於不同金屬,能夠更精確地描述金屬與黑磷的接面關係。; In an era of post-Moore’s law, 2D materials become a promising platform for future electronic devices for their superior material properties. Although graphene and TMDs are the most discussed 2D materials, black phosphorus becomes more and more noticeable due to the high mobility and tunable band gap. However, the issue of contact resistance often limits the performance. Therefore, in this thesis, we will focus on the reduction of contact resistance and analysis of Schottky barrier height.
We mechanically exfoliate few-layer BP onto SiO2 substrate and characterize the properties of BP flakes by OM, Raman spectroscopy, AFM. The back-gated BP FET is successfully fabricated, with an ION/IOFF of 103 and an extrinsic hole mobility of 340 cm2/Vs. A graphene contact MoS2 transistor by 2D heterostructure stacking graphene/MoS2/graphene heterostructure, and achieve an ION/IOFF ratio of 103 and extrinsic electron mobility of 87.6 cm2/Vs.
Ge-doped S/D contacts of BP transistors are formed after RTA treatment. The mobility is enhanced by 25 times after RTA treatment. In addition, the contact resistance after RTA can be as low as 0.365 kΩ∙μm, which is the lowest value in literature and is comparable to III-V devices. Moreover, the PGex contact shows metallic properties, which is for the first time a metallic contact is shown in BP devices. XPS characterization further verify the P-Ge bonding after RTA.
Schottky barrier height extraction of Ti-BP contact by activation energy method is also demonstrated. Through theoretical estimation and material characterization, an underestimated SBH is found which results from the hysteresis at higher temperature. Hence, a modified method is proposed by SBH extraction from contact resistance. A more accurate SBH is extracted, which can describe the Ti-BP contact more properly.
The research in this thesis can be highly applied to BP devices in the future. Ge-doping technique can be applied to device scaling and high frequency devices, and SBH extraction can be applied to the analysis of metal-BP contact.2017-01-01T00:00:00Z鰭狀砷化銦鎵高載子遷移率電晶體之研究
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/19209
標題: 鰭狀砷化銦鎵高載子遷移率電晶體之研究; Investigation of the InGaAs Fin Structure High Electron Mobility Transistors
作者: Chia-Ming Chang; 張家銘
摘要: 引入半導體產業最重要的摩爾定律做為引子後,簡述半導體製造在各節點技術演進上,碰上對應的製程技術挑戰與如何克服之過程,以及藉由現今研究之趨勢,對未來10奈米以下節點技術發展做預測,同時簡單介紹何為短通道及窄通道效應。
本論文第一部分簡述三五族材料特性、高載子遷移率電晶體之發展歷史與現況,並提出鰭狀結構之高載子遷移率電晶體,透過TCAD進行模擬,並由模擬結果建立其閘極控制機制之理論,同時透過製程實作出元件並進行量測分析,可成功的以該理論解釋量測分析之結果。
第二部分簡述鐵電材料之材料特性,並以電路學與能量兩個不同角度切入解釋負電容之成因,透過製程實作出電容元件,並進行量測與分析,探討鐵電材料於不同結晶溫度下,在不同頻率下的電容電壓特性及漏電流特性,同時以電導法分析其介面特性,探討不同退火溫度對介面特性之影響。
第三部分簡述鐵電材料應用於電晶體之發展與其優缺點,以製程實作出元件,同時進行量測與分析,探討不同退火溫度對元件特性造成之影響,並以TCAD模擬,探討不同模擬條件下之元件特性,作為未來的改進方向。; After describing Moore’s Law, we introduce node technology progression of semiconductor manufacturing in this thesis, including the corresponding challenges and the solution to them. After studying research trends, we predict sub-10nm node technology development, and introduce short-channel effects (SCEs) and narrow-channel effects (NCEs) briefly.
In the first part, we introduce III-V material characteristics, and their developing history and operating principles of high electron mobility transistors (HEMTs). We propose fin structures of HEMTs, and use TCAD to simulate. From simulation results, the theory of gate control mechanisms is proposed. We fabricate and measure the device, the measurement results can be explained by the proposed theory successfully.
In the second part, we introduce ferroelectric material to form negative capacitance (NC), and use two different viewpoints of circuit and energy to explain it. We fabricate MOS capacitances and discuss their C-V, I-V, and interface characteristics at different crystalline temperatures and frequencies.
In the third part, we introduce development, pros and cons of negative capacitance field effect transistors (NCFETs). We fabricate and discuss their I-V characteristics in different crystalline temperatures. Finally, we use TCAD to simulate different conditions of NCHEMTs, and the results are regarded as improving ways in the future.2016-01-01T00:00:00Z鰭式結構之雙通道氮化鋁鎵/氮化鎵高電子遷移率電晶體射頻功率元件製作與分析
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/92087
標題: 鰭式結構之雙通道氮化鋁鎵/氮化鎵高電子遷移率電晶體射頻功率元件製作與分析; Fabrication and Analysis of Radio Frequency Double Channel AlGaN/GaN HEMT with Fin Structure
作者: 許博勳; Po-Hsun Hsu
摘要: 由於氮化鎵擁有傑出的材料特性,在射頻元件與功率元件應用上迅速發展,預期於未來的市場上將佔有一席之地。以氮化鋁鎵/氮化鎵高電子遷移率電晶體作為高頻元件的發展主流,此種異質結構會於接面處生成二維電子氣,進而提高元件載子遷移率與電子濃度。然而,隨著電子濃度的提升,載子遷移率將會有所下降,使元件特性不如預期。因此雙層的氮化鋁鎵/氮化鎵異質結構被提出,此種結構可以形成兩層二維電子氣,以彌補載子濃度不足的問題,但此種磊晶結構會使元件閾值電壓有很大的負偏移,透過鰭式結構可以改善此現象,閘極環繞鰭式通道結構以增加閘極控制力,除了能使元件較易關閉之外,更預期能夠有效抑制因高頻元件微縮線寬而產生的短通道效應。
本論文分做四部分,第一部分介紹了氮化鎵的材料特性與操作原理,並說明本論文研究動機,為論文概述; 第二部分首先針對單通道氮化鎵做奈米閘極元件製程介紹與直流特性分析,接著介紹高頻量測架設與氮化鋁鎵/氮化鎵高電子遷移率小訊號模型,並對元件之最佳偏壓點進行高頻特性分析; 第三部分進行雙通道元件的磊晶結構介紹與鰭式通道的微米閘極製程開發並簡述其特性,後續針對不同的通道距離做平面電晶體與鰭式電晶體的直流特性分析; 最後第四部分將透過電子束微影對雙通道元件進行閘極線寬的微縮,同樣針對不同通道距離做平面電晶體與鰭式電晶體的直流特性分析。最後建立雙通道氮化鋁鎵/氮化鎵高電子遷移率電晶體與鰭式結構之小訊號模型,透過變偏壓的量測分析電晶體之本質參數,觀察其高頻特性。; Due to the outstanding material properties of gallium nitride, there has been rapid development in its applications for RF and power devices, and it is expected to have a significant presence in the future market. The mainstream development of high-frequency devices relies on the use of AlGaN/GaN high-electron-mobility transistors, where a two-dimensional electron gas is formed at the interface, enhancing carrier mobility and electron concentration. However, as the electron concentration increases, the carrier mobility may decrease, affecting the device characteristics. Therefore, a double channel AlGaN/GaN heterostructure is proposed to address the issue of insufficient carrier concentration by creating two layers of two-dimensional electron gas. Nevertheless, this structure may lead to a substantial negative shift in the threshold voltage. The introduction of a fin structure is suggested to mitigate this phenomenon, employing a gate-surrounding fin-shaped channel to enhance gate control. This not only facilitates easier device turn-off but is also expected to effectively suppress short-channel effects resulting from the downscaling of high-frequency devices.
This thesis is divided into four parts. The first part introduces the material properties and operational principles of gallium nitride and outlines the research motivation, serving as an overview of the thesis. The second part begins with the nano gate device fabrication process and DC characteristics analysis for single channel GaN devices. It further covers the setup of high-frequency measurements, the AlGaN/GaN high-electron-mobility transistor (HEMT) small-signal model, and high-frequency characterization at the optimal bias point. The third part delves into the introduction of the double channel device''s epitaxial structure and the development of the fin-shaped channel for micrometer gate fabrication. It briefly describes the characteristics, followed by DC analysis for planar transistors and fin-shaped transistors with different channel distances. The fourth part involves electron beam lithography for gate width scaling of double-channel devices. Similar DC characteristic analyses are performed for planar and fin-shaped transistors with different channel distances. Finally, a small-signal model is established for the double channel AlGaN/GaN high-electron-mobility transistor and fin-shaped structure, and the intrinsic parameters are analyzed through bias-dependent measurements to observe their high-frequency characteristics.2024-01-01T00:00:00Z