在本論文中，利用分子束磊晶以及超高真空化學氣相沉積方式將矽鍺材料成長在矽基板上，作為光檢測器的光吸收層。但由於在矽鍺與矽之間存在有百分之四的晶格不匹配，因此當矽鍺中的鍺含量高時，其臨界厚度幾乎小於100nm，由於我們所成長的材料其厚度皆大於臨界厚度許多，因此可以從HR-XRD分析結果中發現，當成長之材料其鍺含量愈高，半高寬也愈寬，這是由於內部缺陷造成磊晶品質不佳所致。
　　而以鍺含量不同的材料製作金半金光檢測器來做比較亦可以發現鍺含量愈高的試片，其光暗電流比愈小，這是由於鍺含量愈高的試片其內部缺陷愈多，造成暗電流愈大所致。而我們藉由使用氧化銦錫透明電極及回火方法，皆可小幅改善元件之光暗電流比，但我們認為造成暗電流過大的關鍵原因在於金半金光偵測器吸光之後產生之載子，其被電極收集的路徑分佈於試片的表面，所以受到試片表面缺陷所形成的表面態位影響甚深，而藉由在試片表面以光照射式化學氣相沉積法沉積30nm厚的二氧化矽層以對表面缺陷作披覆。而以該試片製作的金半金光偵測器其暗電流著實獲得很大的改善，降低的幅度達到1000倍，但由於蕭基能障變厚使得光電流同時也被犧牲。
　　因此我們採用陽極氧化方法在試片表面成長氧化層，以施加不同的電流密度來製作試片，並以試片同時製作金半金光偵測器及金氧半電容器，藉此比較金半金光偵測器光暗電流比與金氧半電容器之介面態位密度之關係，結果與我們的論點完全吻合，元件之光暗電流比的確與介面態位密度成負相關的關係，並且以陽極氧化試片製作的元件其光暗電流比較先前之元件提升了將近30倍，相較光照射式化學沉積法成長氧化層之試片製作之元件，光暗電流比亦提升了約15倍，而在歐傑電子光譜儀縱深分析結果亦可發現，我們的確以陽極氧化方式成長出薄且品質佳的氧化層。

In this thesis, SiGe epi-layer was used as the absorption layer of photodetector grown on Si substrate by Molecular beam epitaxy (MBE) and Ultra-high vacuum chemical vapor deposition (UHV-CVD). Due to the 4 % lattice mismatch between SiGe and Si, the critical thickness of SiGe epi-layer was less than 100nm when Ge content was higher than 30%. Because the epi-layer thickness of our sample was much larger than theoretical critical thickness, there were many defects in the epi-layer obviously. Such a result also causes a wider FWHM for higher Ge content in the analysis of HR-XRD.
The SiGe compounds with different Ge contents bulk material was used to fabricate MSM photodetectors. I-V results shown that sample with higher Ge content has lower photo-to-dark current ratio. This is because that more defects resulted from more serious lattice mismatch were the reason for high dark current. By using ITO transparent electrodes and annealing technique, the current ratio of devices can be improved. But the most critical reason for high dark current was that the carrier path of MSM photodetector was distributed on the surface of sample. The performance of devices was affected by surface state. We used photo-CVD to grow oxide layer on the surface of sample to passivate the surface defect and fabricated MSM photodetector. The dark current was reduced for 3 orders by surface passivation method. At the same time, the Schottky barrier was thicken to sacrifice photo current.
Anodic oxidation method was employed in order to enhance the performance of SiGe/Si MSM photodetectors. The same samples were also used to fabricate MOS capacitance to calculate the interface state density. By comparing the I-V results of MSM photodetectors with C-V results of MOS capacitances, it is found that current ratio was relative to interface state density. The results also proved our initial argument. Current ratio of device with anodic oxide was improved 30 times larger than that of original device and 15 times larger than that of device with photo-CVD oxide. In addition, AES results shown that anodic oxidation is best suited for growing thin oxide layer.

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