磁场和量子点尺寸对激子性质的影响

Effects of magneic field and quantum dot size on properties of exciton

在In_(0.6)Ga_(0.4)As/GaAs量子点中,采用一维等效势模型和有限差分法理论计算了激子态的性质,得到了激子跃迁能和束缚能随磁场、横向束缚强度以及量子点尺寸的变化关系.结果表明:加入磁场后,Zeeman效应使得激子的能级简并度解除,激子的基态跃迁能与实验符合得很好;横向束缚强度或磁场强度的增加使得激子的束缚增强;量子点的尺寸对激子的束缚产生重要的影响;通过电子-空穴间平均距离以及激子体系波函数分布图像分析了其产生的物理机制.

In In0.6Ga0.4As/GaAs quantum dot, using a one-dimensional effective potential model and the finite difference method, we theoretically study the properties of an exciton under the influence of an applied magnetic field, such as the transition energy, the binding energy, the spatial distributions of the electron and the hole. The effects due to the applied magnetic filed and the quantum confinement on the binding energy are analyzed, and the following results are obtained： the ground state transition energy of the heavy-hole exciton can split into four energy levels due to the Zeeman effect, of which the results are in good agreement with experimental results; the binding energy increases monotonically with the increase of lateral confinement or magnetic field; the size of the quantum dot has a significant influence on the binding energy of the exciton, which can be seen both from the average distance between the electron and the hole and from the wave function distributions of the exciton.