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標題: | 超薄閘極氧化層金氧半結構元件在反轉區下受邊緣影響之電流行為 Edge-Dependent I-V Behavior of MOS Structures with Ultrathin Oxides under Inversion Region |
作者: | Pei-Lun Hsu 徐培倫 |
指導教授: | 胡振國(Jenn-Gwo Hwu) |
關鍵字: | 邊緣電場,反轉區電流,金氧半結構,光感測元件,蕭基位障,直接穿隧, fringing field,inversion current,MOS,photodetector,Schottky-barrier,direct tunneling., |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 本篇論文主要探討超薄閘極氧化層金氧半結構元件在反轉區下的穿隧電流行為受元件邊緣影響的現象。首先為了觀察不同的邊緣參數對電流行為的影響,設計並製造出擁有不同電極間隔的元件,並且進行量測。當元件處於反轉區時,在電流-電壓的曲線中觀察到了兩個現象:第一個現象是飽和電流的大小會隨著電極間隔縮短而減少;另一個現象是當元件的電極間隔小於20 um時,其電流飽和的過程中會出現特別的過渡區。本文借由模擬的幫助提出了上述現象的解釋與圖例,認為此現象是受到邊緣空乏區外側少數載子的擴散電流改變所造成。並且根據實驗結果提出穿隧電流是同時受控於電洞與電子穿隧電流的模型,幫助我們更清楚解釋反轉區下穿隧電流的機制。照光下,元件在反轉區的光電流大小同樣受到邊緣擴散電流的影響;但由於電洞穿隧電流會快速飽和並主導電流行為,過渡區消失。
接著,為了證明少數載子的擴散電流是造成電流行為隨電極間隔改變的主因,另設計出擁有不同電極間隔,且相鄰電極間彼此分開的環狀元件圖案。經不同偏壓測量後,從電流-電壓曲線中觀察到與前一組元件完全不同的趨勢:當外環電極偏壓浮接時,飽和電流的大小會隨著電極間隔縮短而增大。經由模擬結果得知由於少數載子的濃度分布不同,擴散電流在兩組元件之間會呈現相反的趨勢。因此上述結果可以證明,隨邊緣條件改變的擴散電流的確是造成電流行為改變的主要原因。最後引入此組元件的光反應做為與前一部分的對照。照光後,飽和光電流隨電極間隔縮小而增大的趨勢同樣存在,再次說明照光下的閘極電流仍會受邊緣擴散電流的影響。 In this thesis, edge-dependent I-V behavior of MOS structures with ultrathin oxides is investigated. Samples with various electrode separations are fabricated and measured in order to understand how edge-related parameters influence tunneling current behavior. We observe two major phenomena from I-V curves when samples are under inversion region: First, the magnitude of saturated currents increases with the electrode separations. Second, I-V curves of samples with electrode separation smaller than 20 um exhibit particular transition regions during the saturation of gate currents. Explanation and illustration are consequently proposed with the help of simulation, supposing that the behavior originates from the changes of minority carrier diffusion currents outside the depletion region. A model that states how hole and electron tunneling currents both control the gate current based on the experimental result is also purposed in order to further explain the tunneling current mechanism under inversion region. Under illumination, the photocurrents are still influenced by edge diffusion currents. However, due to the quick saturation of hole tunneling current, the gate tunneling current is dominated by hole tunneling current, and transition regions disappear. Subsequently, in order to confirm the effect of electron diffusion current on the I-V behavior, patterns with split electrodes and various electrode separations are designed. The I-V curves of new samples exhibit opposite behavior compared to the aforementioned samples; saturated gate currents decrease as the electrode separations increase under inversion region when the bias of outside ring electrode is floating. Since we know that the tendencies of diffusion currents are distinct between two groups of samples because of distinct edge-related electron concentration profiles by simulation, this result perfectly confirms that diffusion current in edge is one of the major reasons that dominates the I-V behavior under inversion region. When under illumination, the saturated photocurrents also exhibit decrements as the electrode separations increase due to the effect of diffusion current. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/62103 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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