Coulomb effects in spatially separated electron and hole layers in coupled quantum wells
Coulomb effects in spatially separated electron and hole layers in coupled quantum wells
复制标题
耦合量子阱中空间分离的电子和空穴层的库仑效应
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
A. Gossard
中科院分区：
文献类型：
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作者：
L. Butov;A. Imamoğlu;K. Campman;A. Gossard
我们报告了在低温 (T = 1.4 K) 下，在广泛的电子空穴 (e-h) 密度下，GaAs/AlxGa1−xAs 耦合量子阱 (CQW) 中空间分离的电子和空穴层中的（磁）光学研究。研究发现，对于所有朗道能级跃迁，库仑效应会随着 e-h 密度的增加而导致间接（井间）光致发光 (PL) 能量的增强；这与单量子阱中的电子空穴系统形成对比，其中的主要特征是通过带隙重整化导致PL能量降低来解释的。观察到的空间分离的电子和空穴层系统的基态能量随着 e-h 密度的增加而增强，这表明真实空间凝聚成液滴在能量上是不利的。在分离电子和空穴的高密度下，观察到一种新的直接（孔内）PL 线：随着密度的增加，其 PL 和吸收（通过间接 PL 激发测量）的相对强度都增加；它与直接激子线的能量分离与之前在单量子阱中测量的 X− 和 X+ 结合能非常吻合。因此，该线归因于直接多粒子复合物。
We report on the (magneto-) optical study of many-body effects in spatially separated electron and hole layers in GaAs/AlxGa1−xAs coupled quantum wells (CQWs) at low temperatures (T = 1.4 K) for a broad range of electron-hole (e-h) densities. Coulomb effects were found to result in an enhancement of the indirect (interwell) photoluminescence (PL) energy with increasing the e-h density both for a zero magnetic field and at high fields for all Landau level transitions; this is in contrast to the electron-hole systems in single QWs where the main features are explained by the band-gap renormalization resulting in a reduction of the PL energy. The observed enhancement of the ground state energy of the system of the spatially separated electron and hole layers with increasing the e-h density indicates that the real space condensation to droplets is energetically unfavorable. At high densities of separated electrons and holes, a new direct (intrawell) PL line has been observed: its relative intensity increased both in PL and in absorption (measured by indirect PL excitation) with increasing density; its energy separation from the direct exciton line fits well to the X− and X+ binding energies previously measured in single QWs. The line is therefore attributed to direct multiparticle complexes.