Screening of excitonic states by low-density 2D charge carriers in GaAs/AlGaAs quantum wells
Screening of excitonic states by low-density 2D charge carriers in GaAs/AlGaAs quantum wells
复制标题
GaAs/AlGaAs 量子阱中低密度二维电荷载流子筛选激子态
DOI：
--
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
W. Wegscheider
中科院分区：
文献类型：
--
作者：
S. Gubarev;I. Kukushkin;S. Tovstonog;M. Y. Akimov;J. Smet;K. Klitzing;W. Wegscheider
研究了 GaAs/AlGaAs 单量子阱中二维电子（或空穴）系统对激子态的屏蔽。随着二维载流子浓度的增加，在发光和反射光谱中观察到激子态的阈值型消失。 2D系统的质量越高，相应的阈值浓度越低。在最好的系统中，激子态的崩溃发生在意想不到的低电子密度 ne=5×109 cm−2 下，这对应于粒子之间的平均无量纲距离 rs=8。这个值远远超过了3D系统观察到的阈值（rs≈2），以及之前研究中针对量子阱获得的值。通过应用三维磁等离子体共振光学检测方法解决了光激发条件下测量低密度二维载流子浓度的问题。该方法可以可靠地测量 2D 系统的密度，测量值约为 109 cm−2。
Screening of excitonic states by a system of 2D electrons (or holes) in GaAs/AlGaAs single quantum wells is studied. With increasing concentration of 2D charge carriers, a threshold-type disappearance of excitonic states is observed in both luminescence and reflectance spectra. The higher the quality of the 2D system, the lower the corresponding threshold concentration. In the best systems, the collapse of excitonic states occurs at unexpectedly low electron densities ne=5×109 cm−2, which correspond to the mean dimensionless distance between the particles rs=8. This value far exceeds the threshold values observed for 3D systems (rs≈2), as well as the values obtained for quantum wells in previous studies. The problem of measuring the concentration of low-density 2D charge carriers in photoexcitation conditions is solved by applying the method of optical detection of the dimensional magnetoplasma resonance. This method provides reliable measurements of the density of a 2D system to the values about 109 cm−2.