| Summary: | 碩士 === 元智大學 === 光電工程學系 === 104 === The effects of thermal annealing treatment on a vertically aligned InGaAs/GaAs(Sb)/AlGaAsSb quantum dot (QD) structure with the purpose of tailoring energy band alignment are studied. In contrast to the typical blueshift in the emission upon annealing because of In-Ga intermixing in the typical InGaAs/GaAs QDs, thermally annealed InGaAs/GaAs(Sb)/AlGaAsSb QDs exhibit a redshift upon annealing at 700 oC, owing to Sb aggregation on top of the InGaAs QDs, resulting in tailoring of the band alignment and strain reduction for the reduced emission energy. Power-dependent and time-resolved photoluminescence were utilized herein to extend the carrier lifetime from 1.63 to 6.38 ns and to elucidate mechanisms of the aggregation of antimony that cause band alignment tailoring from type-I to type-II after rapid thermal annealing. In addition, the thermal stability of the columnar QDs was improved by capping QDs with a GaAsSb overgrown layer, because In-Ga intermixing was suppressed, helping to preserved QD heterostructures. Therefore, the flexible modulation of energy band alignment for columnar InGaAs/GaAs(Sb)/AlGaAsSb QD structures as type-I or type-II by thermal annealing has potential and flexible application to versatile QD-related optoelectronic devices.
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