Investigation of populated InAs/GaAs quantum dots by photoluminescence and photoreflectance |
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Authors: | Jia-Ren Lee Chien-Rong Lu Wei-I Lee Shih-Chang Lee |
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Institution: | aDepartment of Physics, National Taiwan Normal University, Taipei 116, Taiwan, ROC;bDepartment of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan, ROC |
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Abstract: | We studied self-assembled InAs/GaAs quantum dots by contrasting photoluminescence and photoreflectance spectra from 10 K to room temperature. The photoluminescence spectral profiles comprise contributions from four equally separated energy levels of InAs quantum dots. The emission profiles involving ground state and excited states have different temperature evolution. Abnormal spectral narrowing occurred above 200 K. In the photoreflectance spectra, major features corresponding to the InAs wetting layer and GaAs layers were observed. Temperature dependences of spectral intensities of these spectral features indicate that they originate from different photon-induced modulation mechanisms. Considering interband transitions of quantum dots were observed in photoluminescence spectra and those of wetting layer were observed in photoreflectance profiles, we propose that quantum dot states of the system are occupied up to the fourth energy level which is below the wetting layer quantum state. |
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Keywords: | Photoreflectance Photoluminescence InAs/GaAs Quantum dots |
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