Electrostatically trapping indirect excitons in coupled In x Ga 1-x As quantum wells
Electrostatically trapping indirect excitons in coupled In x Ga 1-x As quantum wells
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DOI：
10.1103/physrevb.83.165308
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发表时间：
2011-04
影响因子：
3.7
通讯作者：
G. Schinner;E. Schubert;M. Stallhofer;J. Kotthaus;D. Schuh;A. Rai;D. Reuter;A. Wieck;A. Govorov
中科院分区：
文献类型：
--
作者：
G. Schinner;E. Schubert;M. Stallhofer;J. Kotthaus;D. Schuh;A. Rai;D. Reuter;A. Wieck;A. Govorov
本文报道了在InGaAs耦合双量子阱器件中空间间接激子的光致发光实验，该器件采用半透明栅极来调节平面内势场。我们引入了一种捕获配置，其中激子的产生在空间上与激子捕获势分离。适当偏置的栅极控制间接偶极激子从产生区流向静电定义的阱。因此，阱只被预冷到晶格温度的间接激子填充。利用液氦温度下的共聚焦显微镜，绘制了不同栅极电压和光照条件下激子的平面内分布。我们的带有预冷激子的小而强约束阱显示出有趣的多体效应，可以从静电屏蔽、库仑结合和激子流的角度来解释。我们样品中PL能量的栅极电压依赖性不是单调的，可以通过考虑我们结构元素之间的非线性激子流动来解释。在强光照下，捕获激子居群的滞后开关反映了自一致捕获势的非线性特征。阱发射的不寻常的非线性增加可能来自于密集激子气体中在高光强下存在无序势的多体相互作用。本文提出和实现的静电阱设计允许更强的约束和更低的温度，并将用于寻找密集激子气体中的相干现象。
We report on photoluminescence experiments on spatially indirect excitons in an InGaAs coupled double quantum well device in which semitransparent gates are employed to tune the in-plane potential landscape. We introduce a trapping configuration in which exciton generation is spatially separated from the excitonic trapping potential. Suitably biased gates control the flow of indirect dipolar excitons from the generation area to the electrostatically defined trap. Thus the trap is filled only with indirect excitons precooled to the lattice temperature. Using a confocal microscope at liquid helium temperatures we map the in-plane distribution of excitons at various gate voltages and illumination conditions. Our small and strongly confining traps with precooled excitons demonstrate interesting many-body effects which can be interpreted in terms of the electrostatic screening, the Coulomb binding, and excitonic flows. Gate voltage dependencies of PL energy in our samples are not monotonic and can be explained by considering the nonlinear exciton flows between the elements of our structure. At strong illumination hysteretic switching of the trapped exciton population reflects a nonlinear character of the self-consistent trapping potential. An unusual nonlinear increase of the emission of the trap is likely coming from the many-body interactions in a dense exciton gas in the presence of a disorder potential at high light intensity. The designs of electrostatic traps proposed and realized here allow for stronger confinements and lower temperatures and will be used to search for coherent phenomena in dense exciton gases.