Spin lifetime from Hanle-effect measurements in samples with InAs quantum dots embedded in different AlxGa1−xAs matrices
Spin lifetime from Hanle-effect measurements in samples with InAs quantum dots embedded in different AlxGa1−xAs matrices
复制标题
不同 AlxGa1−xAs 矩阵中嵌入 InAs 量子点的样品中汉勒效应测量的自旋寿命
DOI：
10.1088/0268-1242/20/2/019
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
K. Zhuravlev
中科院分区：
文献类型：
--
作者：
J. Fürst;H. Pascher;V. A. Abalmassov;T. Shamirzaev;K. Zhuravlev
圆偏振光对电子空穴对的激发在嵌入AlxGa 1 −xAs的InAs自组装量子点中产生电子自旋极化。这种自旋极化导致光致发光光的圆极化，其程度在垂直于电子的初始自旋矢量的磁场中减小（汉勒效应）。随着铝含量x的增加，Hanle曲线的宽度从x = 0时的约100 mT减小到x = 1时的17.5 mT。相应的电子自旋寿命随着x的增加而增加。对于在间接间隙基质材料AlAs中具有量子点的样品，自旋寿命超过1.5ns。有限的光致发光偏振证明量子点内激子的自旋寿命不可能比它的复合时间小得多。一个单一的洛伦兹形状所获得的汉勒曲线和所观察到的光致发光偏振的场无关的部分可以解释为一个小的（零）激子g-因子的点在中等磁场，这可能源于零空穴g-因子由于电子-空穴交换相互作用。在这种情况下，从Hanle曲线推导出的自旋寿命可以归因于量子点中的热化电子捕获时间。
Excitation of electron hole pairs by circularly polarized light yields an electron spin polarization in InAs self-assembled quantum dots embedded in AlxGa1−xAs. This spin polarization causes circular polarization of the photoluminescence light, its degree decreasing in a magnetic field perpendicular to the initial spin vector of the electrons (Hanle effect). With increasing aluminium content x the width of the Hanle curve is reduced from about 100 mT for x = 0 to 17.5 mT for x = 1. The corresponding electron spin lifetime increases with increasing x. For samples with QDs in the indirect gap matrix material AlAs, the spin lifetimes exceed 1.5 ns. A finite photoluminescence polarization evidences that the exciton spin lifetime inside a quantum dot cannot be much smaller than its recombination time. A single Lorentzian shape of the obtained Hanle curves and the observed field-independent part of the photoluminescence polarization could be explained by a small (zero) exciton g-factor in the dots at moderate magnetic fields, which could stem from the zero hole g-factor due to the electron–hole exchange interaction. The spin lifetime deduced from the Hanle curves could in this case be attributed to the thermalized electron capture time in the quantum dots.