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標題: | 自組裝光活化摻雜層於高性能N型黑磷電晶體之研究 High Performance n-type Black Phosphorus Transistors with Self-Encapsulated Photoactive Doping Layers |
作者: | Min-Ken Li 李明格 |
指導教授: | 陳俊維(Chun-Wei Chen) |
關鍵字: | 黑磷,氧化鈦,穩定性,光活化,N型摻雜, black phosphorus,TiOx,stability,photoactive,n-type doping, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | “黑磷”是磷(P)的同素異形體之一,也是其中熱力學最穩定且化學性質最不活潑的一個。其結構上為層狀堆疊的二維材料,換言之每層磷原子層間,僅以微弱的凡得瓦作用力鍵結在一起。而黑磷也是除石墨烯之外第二個被發現是僅由單一種元素所構成的二維材料。在近期研究中,利用機械剝離法所得原子層級薄的黑磷,因擁有許多優異的光電特性,引起眾多學者的研究興趣。如高電洞(P型)載子遷移率~1000 cm2V-1s-1、高電流開關比~105、可調控之直接能隙、非等向性晶格等,都是黑磷所具備的良好且獨特性質,也使得黑磷在未來二維材料實際應用上,佔有一席之地。
然而也有不少近期研究發現,原子層級薄的黑磷,當曝露在大氣環境下時並不甚穩定。許多黑磷良好的特性,如高載子遷移率或高電流開關比等,皆會隨著在大氣環境中曝露時間越久而惡化,限制了黑磷後續的相關研究與實際應用的可行性。因此,尋找合適於黑磷的鈍化技術以解決其大氣下的不穩定性成了一個急需解決的議題。 在本研究的第一部分(第四章),我們將介紹一種新穎的鈍化技術以提升黑磷的大氣穩定性。此鈍化技術主要乃是將低成本且可用水溶液法製備的TiOx覆蓋於原子層級薄的黑磷上。利用其易於成膜且會自我組裝的特性,我們發現,僅僅是幾個奈米尺度厚的TiOx薄膜,已可大幅改善黑磷其暴露在大氣下時的不穩定性質。 此外,黑磷其本質上是一種P型半導體已被發現許久,因此,要製備出擁有N型半導體特性的黑磷元件相對下是較為困難的。在本研究第二部分中(第五章),我們試著整合些TiOx的良好特性於黑磷電晶體中以做出具N型表現的黑磷電晶體。事實上,TiOx在先前有機電子元件及石墨烯元件研究中,已被發現其可扮演鈍化層、載子傳輸層或光敏化N型摻雜層等的能力。因此,同時結合了些TiOx的性質於黑磷元件中,我們成功製備出具高穩定性且可精準調控的N型黑磷電晶體。此研究可使黑磷更有機會於往後被實際應用在互補式金屬氧化物半導體元件上。 Black phosphorus, the most stable allotrope of phosphorus, is a layered material and each atomic layer is held together by weak van der Waals interactions, which is similar to graphite. Other than graphene, black phosphorus is the second known two-dimensional material which is formed by a single element. Recently, exfoliated few-layer black phosphorus, also named as phosphorene, has drawn great interest because of its innovative optical and electrical properties. Its high hole mobility (intrinsic p-type semiconductor) up to ~1000 cm2V-1s-1, high current on/off ratio of ~105, thickness-tunable direct bandgap, anisotropy, and so on make black phosphorus a promising candidate in the future two-dimensional transistors, optoelectronic devices, and logic devices. However, few-layer black phosphorus has also been widely investigated for its instability upon exposure to ambient condition. The quality of phosphorene in many respects, such as carrier mobility and current on/off ratio gradually deteriorate when exposed to ambient air. Phosphorene would even totally disintegrate in the long run and its further researches and applications are then severely restricted. In this regard, suitable passivation techniques for black phosphorus to enhance the stability have turned into an urgent issue. In the first part of this work (chapter 4), we introduced a novel passivation approach by covering few-layer black phosphorus with self-encapsulated, ultra-thin film titanium suboxide (TiOx) which is low-cost and solution-processable. With the passivation of ultra-thin film TiOx which is merely a few nanometers on phosphorene, the unstable nature of black phosphorus under ambient condition can be significantly improved. Besides, black phosphorus is well known as an intrinsic p-type semiconductor. Thus, to obtain a high performance n-type black phosphorus transistor would be more difficult than its p-type counterpart. In the second part of this work (chapter 5), we integrated the innovative characteristics of TiOx with black phosphorus transistors. In fact, TiOx has been well studied as passivation layer, charge transport layer, and even light-sensitized n-type dopant in organic electronics or graphene-based transistors. With these properties, we not only solved the instability problem of black phosphorus but also successfully demonstrated a high performance and precisely controllable n-type black phosphorus transistor at the same time, which can be of great impact for developing practical complementary metal–oxide–semiconductor devices based on black phosphorus. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/53797 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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