Time-resolved studies of annealed InAs/GaAs self-assembled quantum dots
Time-resolved studies of annealed InAs/GaAs self-assembled quantum dots
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DOI：
10.1103/physrevb.63.155313
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发表时间：
2001-04-15
影响因子：
3.7
通讯作者：
Murray, R
中科院分区：
文献类型：
--
作者：
Malik, S;Le Ru, EC;Murray, R
我们研究了光学跃迁的能级分离可以在68和19 meV之间调谐的退火量子点中的载流子动力学。用随机居群模型很好地描述了基态和激发态不同激发密度下的光致发光瞬态，并提取了激子寿命值。发现基态辐射寿命从生长样品的800 ps到最高温度退火样品的490 ps不等。这是由于在退火过程中，随着点尺寸的增大，发射能量的变化以及电子和空穴波函数重叠的变化。当亚能级间能级分离远小于lo -声子能量时，我们没有发现载流子抑制弛豫（声子瓶颈）的证据。在低激发密度下，瞬态的上升时间仍然很快，而库仑散射的概率预计会很低，这意味着另一种机制，可能是多声子散射，是自组装量子点中观察到的快速弛豫的原因。
We have investigated the carrier dynamics in annealed quantum dots where the energy-level separation of the optical transitions can be tuned between 68 and 19 meV. Photoluminescence transients obtained for different excitation densities for the ground and excited states are well described by a random population model, and values of the exciton lifetimes extracted. The ground-state radiative lifetimes are found to vary from 800 ps in the as-grown sample to 490 ps in the sample annealed at the highest temperature. This is attributed to shifts in the emission energy and changes in the electron and hole wave-function overlap as the dot size increases with annealing. We find no evidence of inhibited relaxation of carriers (phonon bottleneck) when the intersublevel energy-level separation is much less than the LO-phonon energies. The rise times of the transients remain fast at low excitation density, where the probability of Coulomb scattering is expected to be low, meaning that another mechanism, possibly multiphonon scattering, is responsible for the fast relaxation observed in self-assembled quantum dots.