Microroughness and exciton localization in (Al,Ga)As/GaAs quantum wells
Microroughness and exciton localization in (Al,Ga)As/GaAs quantum wells
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(Al,Ga)As/GaAs 量子阱中的微观粗糙度和激子局域化
DOI：
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发表时间：
1997
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影响因子：
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通讯作者：
C. Deparis
中科院分区：
文献类型：
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作者：
R. Grousson;V. Voliotis;N. Grandjean;J. Massies;M. Leroux;C. Deparis
我们报告了在精确取向的 (001) GaAs 衬底上生长的薄 Al0.3Ga0.7As/GaAs 量子阱的显微光致发光和光致发光激发。该实验是在低温下通过以低激发强度选择性地激发几μ m(2) 的样品来完成的。在这些条件下进行的光致发光光谱显示，在主线的低能量侧出现约0.1meV宽度的尖锐峰。这些特征归因于有效量子阱厚度波动时的局域激子态。另一方面，在 2x4 重建的 GaAs (001) 表面上进行的扫描隧道显微镜清楚地证明存在单层深的细长“孔”，这些孔沿 [1(1) over bar0$] 方向规则定向，平均宽度为 6 nm。在 2x4 重建的 Al0.3Ga0.7As 表面（量子阱生长在其上）上观察到相同的特征，尽管宽度规律性不太明显。这强烈表明低温下的激子位于这样的盒子中。我们还讨论了使用两种技术（微光致发光和扫描隧道显微镜）在邻位（001）基板上生长的量子阱上获得的截然不同的结果。
We report on microscopic photoluminescence and photoluminescence excitation of thin Al0.3Ga0.7As/GaAs quantum wells grown on exactly oriented (001) GaAs substrates. The experiments are done at low temperature by selectively exciting a few mu m(2) of the sample with a low excitation intensity. The photoluminescence spectrum performed under these conditions shows sharp peaks appearing on the low-energy side of the main line of about 0.1-meV width. These features are attributed to localized exciton states at fluctuations of the effective quantum well thickness. On the other hand, scanning tunneling microscopy performed on 2x4 reconstructed GaAs (001) surfaces clearly evidences the presence of one-monolayer-deep elongated 'holes' regularly oriented along the [1(1) over bar0$] direction with an average width of 6 nm. The same features are observed on 2x4 reconstructed Al0.3Ga0.7As surfaces (on which quantum wells are grown), though the width regularity is less pronounced. This strongly suggests that excitons at low temperature are localized in such boxes. We also discuss the very different results obtained using both techniques (micro-photoluminescence and scanning tunneling microscopy) on quantum wells grown on vicinal (001) substrates.