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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/65135


    Title: 矽鍺薄膜及其應用於光偵測器之研製;Investigation of Investigation of Investigation of Investigation of SiGe SiGe Thin Films and hin Films and hin Films and hin Films and hin Films and hin Films and Their Their Application in Application in Application in Application in Application in Photodetectors Photodetectors Photodetectors Photodetectors
    Authors: 陳薇婷;Chen,Wei-Ting
    Contributors: 光電科學與工程學系
    Keywords: 矽鍺合金;光偵測器;Silicon germanium;photodetector
    Date: 2014-07-24
    Issue Date: 2014-10-15 14:41:36 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 由於光纖通訊的發展,使得紅外光偵測器的重要性與日俱增。傳統紅外光檢測器大多使用三五族材料來製作,但是三五族材料的製程難以和矽製程技術整合,所以使用吸收波長較矽更為寬廣的矽鍺材料取代三五族材料製備紅外光偵測器可使製程成本降低並可將其整合至矽基積體電路上。目前常見的PIN矽鍺紅外光偵測器大多使用磊晶材料做為其吸收層,但磊晶薄膜的成長溫度大多都在500度以上,在製程整合上高溫將會使元件製程受限且成本提高,若能使用低溫成長技術成長高結晶矽鍺薄膜將其應用於光偵測器即可達到低成本、製程易整合等優點。
       本論文是利用電子迴旋共振化學氣相沉積法(Electron Cyclotron Resonance Chemical Deposition, ECR-CVD) 低溫沉積結晶矽鍺薄膜探討其特性並應用於紅外光偵測器。矽鍺薄膜研究使用光放射光譜儀可即時監控矽鍺含量比和利用電漿中Hα*/(SiH*+GeH*)解離量可以推測薄膜的結晶趨勢。薄膜之光學能隙可藉由調變矽鍺薄膜中鍺含量的比例從0至0.56使光學能隙從2.02 eV變化至1.33 eV。接著為我們於鍺含量為0.56之薄膜改變微波功率、氫氣稀釋比,發現微波功率在1000 W和氫氣稀釋比為40的時候有最好的結晶率。
      在光偵測器的表現中,暗電流的大小和響應度的高低是評估偵測器好壞的重要因素。過高的暗電流會嚴重影響元件的訊雜比,而響應度則是在照光的時候光偵測器對光源的反應,所以一個好的偵測器必須具有暗電流值小、光響應強的特性。暗電流的降低可藉由減少內部缺陷和利用表面鈍化(passivation)來改善。實驗發現對薄膜進行退火可有效改善暗電流值,使暗電流從2.27×10-5 A降至7.41×10-6 A。而光電流(響應)影響因素則是鍺含量的改變對其影響較劇烈,因為鍺含量的增加會增加長波長部份的吸收,使得鍺含量從0增加為0.56時其響應可由0.034 A/W提高至0.195 A/W。

    ;Recently, infrared photodetectors have attracted much attention because of the development of optical communication system. Although infrared photodetectors have been built in III-V compound semiconductors, the use of SiGe is advantageous in terms of compatibility with Si integrated circuit technology and lower cost of fabrication. Several techniques for growing epi-SiGe photodetector have been reported. However, high temperature (>500oC) growth is disadvantage for device fabrication and more expensive, so in order to solve this problem, many researches have been doing efforts to grow the SiGe films and photodetector under low substrate temperature.
      In this thesis, we use the electron cyclotron resonance chemical vapor deposition (ECR-CVD) to deposit high-crystallinity SiGe thin films at a low temperature and apply it to fabricate phtodetector. During film deposition, We use optical emission spectroscopy (OES) to monitor the plasma distribution where the Ge*/(Si*+Ge*) can be predicted the germanium content in the SiGe films and the Hα*/(SiH*+GeH*) intensity ratio represents the trend of films crystallinity. As the Ge fraction increase from 0 to 0.58, the optical bandgap decreases from 2 eV to 1.4 eV. When the microwave power is 1000 W and hydrogen dilution ratio is 40, respectively, the films has best crystallinity.
      The requirement of photodetector are high responsivity and low dark current .The reduction of dark current can be improve by reduction of defect in the film and interface. With 300 oC annealing process for 5 minutes, the dark current was significant reduced from 2.27×10-5 A to 7.41×10-6 A. It was found that as germanium content increase from 0 to 0.58, the responsivity increase from 0.034 A/W to 0.195 A/W.
    Appears in Collections:[光電科學研究所] 博碩士論文

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