The effect of adding GaAsSb strain reducing layer on the performance of InAs/GaAs Quantum dot infrared photodetectors
Date Issued
2012
Date
2012
Author(s)
Huang, Chia-Tze
Abstract
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.
Subjects
Quantum dots
photodetectors
InAs
Type
thesis
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