Temperature dependent optical properties of self-organized InAs GaAs quantum dots
Temperature dependent optical properties of self-organized InAs GaAs quantum dots
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DOI：
10.1007/s11664-999-0105-z
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发表时间：
1999-05-01
影响因子：
2.1
通讯作者：
Bimberg, D
中科院分区：
文献类型：
--
作者：
Heitz, R;Mukhametzhanov, I;Bimberg, D
我们报道了不同尺寸的InAs/GaAs量子点（QDs）随温度变化的光致发光（PL）、时间分辨FL和PL激发实验。结果表明，系综的非均匀性质和单量子点的本征性质对于理解光学性质的温度依赖性都很重要。随着温度的升高，激子在局域量子点态之间呈现局域平衡分布，而与位置无关的费米能级的形成则被载流子损失到主导热激横向载流子转移的势垒所阻止。发现载流子捕获率随温度升高而降低，并且在室温下，估计长逸出限制基态寿命约为10ps。在基态跃迁中共振激发的PL光谱显示出基态吸收和发射的匹配，表明量子点中激子复合的本质。最后，PL激发光谱显示了量子点吸收的尺寸选择性，证明了激发态分裂的量子尺寸效应。
We report photoluminescence (PL), time-resolved FL, and PL excitation experiments on InAs/GaAs quantum dots (QDs) of different size as a function of temperature. The results indicate that both the inhomogeneous properties of the ensemble and the intrinsic properties of single QDs are important in understanding the temperature-dependence of the optical properties. With increasing temperature, excitons are shown to assume a local equilibrium distribution between the localized QD states, whereas the formation of a position-independent Fermi-level is prevented by carrier-loss to the barrier dominating thermally stimulated lateral carrier transfer. The carrier capture rate is found to decrease with increasing temperature and, at room temperature, long escape-limited ground state lifetimes of some 10 ps are estimated. PL spectra excited resonantly in the ground state transition show matching ground state absorption and emission, indicating the intrinsic nature of exciton recombination in the QDs. Finally, the PL excitation spectra are shown to reveal size-selectively the QD absorption, demonstrating the quantum-size effect of the excited state splitting.