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標題: | 四族合金之電傳導及三五族閘極元件 Electric Conduction of Group IV Alloy and Group III-V as Metal Gate Device |
作者: | Huang-Siang Lan 藍偟翔 |
指導教授: | 劉致為(Chee-Wee Liu) |
關鍵字: | 鍺錫合金,電子遷移率,應變矽,金屬閘極, GeSn,pseudopotential,mobility,strain Silicon,metal gate, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 在本篇論文之中,主要研究分成三個部份,探討四族半導體內有潛力及可應用在未來的光電元件和電子元件的特性。
長久以來,四族半導體在光電上的應用ㄧ直受限於其間接能隙,因需外加如聲子等使其達成動量守衡,相較於三五半導體直接能隙有較低的效率。在理論計算,應變鍺在可以形成直接能隙,但實際上不容易被製作出來;然而鍺錫合金結構在實驗上已經被成功製造出來,鍺錫合金可形成狹窄直接能隙材料,可以應用在遠紅外光偵測器上;本論文第一部份討論 透過模擬計算出鍺錫合金的能帶結構,並求出多少含量的錫合金,可以形成直接能隙。 應變矽技術是目前當今半導體的主流,然而隨著對電子元件效率的需求,矽鍺通道、鍺通道、三五族半導體通道,更被廣泛的研究希望有朝一日可以取代目前的矽通道,此研究主題在於模擬應變矽鍺通道在電晶體(N-MOSFETs) 內電子遷移率受到合金散射機制的影響。 隨著高介電質(High-k)取代二氧化矽應用在場效電晶體(MOSFETs)內的絕緣體,多晶矽閘極也必須被不同的金屬閘極所取代,此主題第一次使用三五族半導體材料製作成在金屬氧化半導體元件(MOS)的閘極電極,運用三五族半導體的能隙大小來調變其功函數,並對實驗結果做探討分析。 Abstract In this thesis, three topics are included. One is the direct band gap Ge1-xSnx alloys simulated by valence band anti-crossing method and nonlocal empirical pseudopotential method and the other is the Si-like (x<0.85) strained Si1-xGex N-MOSFETs mobility calculations which include alloy scattering, phonon scattering and roughness scattering. Lastly, Poly-III-V compound semiconductor was proposed to be used as gate electrode first time. Part I : For a long time, group IV semiconductors applied on photoelectric devices have been limited in efficiency by nature indirect band gap. Tensile strained Ge can also be a direct band gap material in theoretical simulations, but not easy to fabricate in practice. However, Ge1-xSnx alloys can form the narrow direct band gap and have been fabricated in the reported experiments successfully. Ge1-xSnx alloys can be applied on infrared optoelectronic applications and may be fabricated new high speed transistors further. In this thesis, chapter 2, energy band structures of Ge1-xSnx alloys are simulated to find the possible direct band gap in group IV semiconductors. Part II : Strained silicon is the main stream to produce higher mobility in transistors. However, the reasons of increase mobility in N-MOSFETs are not only split the lower delta 2 subband and higher delta 4 subband but also change some important elements under strain. In this topic, chapter 3, we simulate the mobility of Si on Si1-xGex substrates and Si1-xGex on Si1-xGex substrates N-MOSFETs and include difference kinds of scattering effects. Part III : As High-k dielectrics were used to replace conventional SiO2 as insulators of MOSFETs, poly-silicon gate must also been replaced by different kinds of metals. In this topic, chapter 4, ploy-III-V semiconductor was fabricated as gate electrode of metal-oxide semiconductors (MOS) first time. Utilizing band gap of III-V semiconductor can adjust the work function and the results of experiments were discussed. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/26722 |
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顯示於系所單位: | 電子工程學研究所 |
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