FLUORESCENCE-LINE NARROWING IN CDSE QUANTUM DOTS - SURFACE LOCALIZATION OF THE PHOTOGENERATED EXCITON
FLUORESCENCE-LINE NARROWING IN CDSE QUANTUM DOTS - SURFACE LOCALIZATION OF THE PHOTOGENERATED EXCITON
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DOI：
10.1103/physrevb.50.2293
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发表时间：
1994-07-15
影响因子：
3.7
通讯作者：
BAWENDI, MG
中科院分区：
文献类型：
--
作者：
NIRMAL, M;MURRAY, CB;BAWENDI, MG
用荧光线窄化光谱研究了纳米级CdSe量子点中浅带边表面陷阱的电学性质。我们发现，当温度从1.75到10K变化时，电子-空穴对的辐射寿命和与LO声子的耦合都发生了很大的变化。我们将这些变化归因于光生空穴在点表面的局域化，并伴随着这些表面局域态之间的热激活运动。基于观察到的激子-LO-声子耦合，建立了一个简单的模型来估计发光状态下空穴局域化的程度。一项与尺寸有关的研究(直径20-80埃)表明，表面效应随着尺寸的增加而迅速减弱。
The electronic properties of shallow band-edge surface traps in nanometer-size CdSe quantum dots are probed using fluorescence-line-narrowing spectroscopy. We find large changes in electron-hole-pair radiative lifetimes and couplings to LO phonons as the temperature is changed from 1.75 to 10 K. We attribute these changes to the localization of the photogenerated hole at the surface of the dots, accompanied by thermally activated motion between these surface localized states. A simple model based on the observed exciton-LO-phonon couplings is constructed to estimate the extent of hole localization in the luminescing state. A size-dependent study (20-80 angstrom diameter) indicates that surface effects diminish rapidly with increasing size.