The influence of size distribution on the luminescence decay from excited states of InAs/GaAs self-assembled quantum dots
The influence of size distribution on the luminescence decay from excited states of InAs/GaAs self-assembled quantum dots
复制标题
DOI：
10.1063/1.3073934
复制
发表时间：
2009-02-01
影响因子：
3.2
通讯作者：
Murray, Ray
中科院分区：
文献类型：
--
作者：
Harbord, Edmund;Spencer, Peter;Murray, Ray
我们比较了具有重合基态发射峰的两个样品的时间积分和时间分辨光谱：一个由高度均匀的量子点组成，另一个在产生广泛的量子点尺寸分布的条件下生长。两个样品中基态的光致发光衰减都是单指数的，由此我们推断出与激发功率无关的大约 1100 ps 的寿命。两个样品的激发态衰减呈双指数，快分量和慢分量分别接近 300 皮秒和接近 1100 皮秒。这些也与激励功率无关，但它们对衰减曲线的贡献随功率而变化。这些数据使我们能够明确地将快分量与较大点的激发态衰变联系起来，将慢分量与以相同能量发射的较小点的基态衰变联系起来。此外，考虑到基态的简并性和受限系统中激子复合的光学选择规则，我们表明激发态的寿命与费米黄金法则预测的基态一致。
We compare the time integrated and time resolved spectra of two samples having coincident ground state emission peaks: one consisting of highly uniform quantum dots, the other grown under conditions which produce a broad distribution of quantum dot sizes. The photoluminescence decay of the ground states in both samples is monoexponential from which we deduce a lifetime of similar to 1100 ps independent of excitation power. The excited state decays for the two samples are biexponential with fast and slow components of similar to 300 and similar to 1100 ps, respectively. These are also independent of excitation power but their contribution to the decay curve changes with power. The data allow us to unequivocally associate the fast component with the excited state decay of larger dots and the slow component with the ground state decay of smaller dots which emit at the same energy. Furthermore, taking into account the degeneracy of the ground state and the optical selection rules for exciton recombination in a confined system we show that the lifetime of the excited state is consistent with the ground state as predicted from Fermi's golden rule.