School of Physics , Northeast Normal University , Changchun 130024 , China.
Clarendon Laboratory, Department of Physics , University of Oxford , Oxford OX1 3PU , U.K.
Nano Lett. 2018 Oct 10;18(10):6188-6194. doi: 10.1021/acs.nanolett.8b02131. Epub 2018 Sep 20.
We found that optical Aharonov-Bohm oscillations in a single GaAs/GaAlAs quantum ring can be controlled by excitation intensity. With a weak excitation intensity of 1.2 kW cm, the optical Aharonov-Bohm oscillation period of biexcitons was observed to be half that of excitons in accordance with the period expected for a two-exciton Wigner molecule. When the excitation intensity is increased by an order of magnitude (12 kW cm), a gradual deviation of the Wigner molecule condition occurs with decreased oscillation periods and diamagnetic coefficients for both excitons and biexcitons along with a spectral shift. These results suggest that the effective orbit radii and rim widths of electrons and holes in a single quantum ring can be modified by light intensity via photoexcited carriers, which are possibly trapped at interface defects resulting in a local electric field.
我们发现，单个 GaAs/GaAlAs 量子环中的光学 Aharonov-Bohm 振荡可以通过激发强度来控制。在弱激发强度为 1.2kW/cm 的情况下，双激子的光学 Aharonov-Bohm 振荡周期被观察到是激子的一半，符合双激子 Wigner 分子的预期周期。当激发强度增加一个数量级（12kW/cm）时，Wigner 分子条件逐渐偏离，激子和双激子的振荡周期和抗磁性系数减小，同时光谱发生位移。这些结果表明，通过光激发载流子，单个量子环中电子和空穴的有效轨道半径和边缘宽度可以通过光强度进行修改，这些载流子可能被陷阱在界面缺陷处，从而产生局部电场。
