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標題: | 增加銻砷化鎵應變層對砷化銦/砷化鎵量子點紅外線偵測器之特性影響 The effect of adding GaAsSb strain reducing layer on the performance of InAs/GaAs Quantum dot infrared photodetectors |
作者: | Chia-Tze Huang 黃珈擇 |
指導教授: | 李嗣涔 |
關鍵字: | 量子點,紅外線偵測器,砷化銦, Quantum dots,photodetectors,InAs, |
出版年 : | 2012 |
學位: | 博士 |
摘要: | 近來,以砷化鎵銦量子井結構包覆砷化銦量子點得到了很大的關注。實驗已經證明了,以砷化鎵銦做為應力減弱層,可提昇量子點紅外線偵測器的光學特性。然而,因為砷化鎵銦材料較低能隙,因此對於砷化銦量子點的量子侷限有負面影響,再加上材料本身所含的銦,也加重了砷化銦量子點與覆蓋層的材料混合程度,影響了元件內部量子點的體積一致性。本論文,提出以銻砷化鎵作為砷化銦量子點的應力減弱材料,不但因為五族原子銻的加入,抑制了砷化銦量子點與覆蓋層之間介面處的材料混合,還能夠在應力減弱的同時,於傳導帶一側提供較砷化鎵銦更高的障壁,提昇了砷化銦量子點的量子侷限效應。我們分成了幾個步驟,對銻砷化鎵的應力減弱特性完成了系統性的研究,先分別以砷化鎵銦與銻砷化鎵作為應力減弱層,比較量子點型態與光學特性在材料之間的差異,由於砷化鎵銦材料是相對熟悉的,因此這樣的比較可以提供一個很好的參考。元件的部份,第一個主題,我們先以銻砷化鎵作為量子點覆蓋層,並發現有巨大的元件響應提昇。接著第二個主題,將量子點成長在具有隔離層的銻砷化鎵上方,重現了提昇量子點密度的效果,也清楚的觀察到量子點密度與元件響應、操作溫度的正相關特性。最後一個主題,基於前面兩個主題的成功,因此綜合前面兩種結構,將透過銻砷化鎵應力減弱層提高密度的量子點層,再以銻砷化鎵層做覆蓋,在這個主題中,得到了響應強度最高的元件。 Recently, InAs quantum dots embedded in InGaAs quantum-well structures have attracted much attention. Experimental evidences have demonstrated that QDIPs exhibit improved optical properties by adding an InGaAs strain reducing layer. However, for InGaAs-capped QDIPs the quantum confinement is not very good due to their low bandgap. Furthermore, it has been shown that excess In atoms will degrade the optical performance in many aspects. It was found that the InAs/GaAs1-xSbx quantum dots exhibit a type-II band structure when Sb composition X exceeds 0.15. This transition provided a relative high barrier as well as improved strain reducing effect for n-i-n structured QDIP. First, InGaAs or GaAsSb to form a strain reducing layer to adjust the strain of quantum dots were studied. Second, The improvement of a GaAs1-xSbx capping layer on the performance of InAs/GaAs QDIPs was investigated. Third, another way to enhance the characteristics of QDIPs is to improve the quantum dot density. High responsivity can be achieved with high quantum dot density. The GaAsSb strain buffer layer can suppress migration of indium and increase quantum dot density. Fourth, based on the result of previously subjects, the integrated structure of double GaAsSb strain reducing layers with GaAs separation layer was designed and added into the active region of QDIPs. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64315 |
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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