Collective Properties of Excitons in Semiconductors
Collective Properties of Excitons in Semiconductors
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DOI：
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发表时间：
1968-09
影响因子：
1.1
通讯作者：
L. Keldysh;A. Kozlov
中科院分区：
文献类型：
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作者：
L. Keldysh;A. Kozlov
半导体中的激子相互作用问题是在多电子形式下考虑的。表达式得到，在近似线性的浓度，基态能量和基本激发的色散定律。研究了激子玻色凝聚的条件，表明低密度激子系统表现为弱非理想玻色气体。此外，所有数量在非理想玻色气体情况下，依赖于两粒子散射振幅的化学势（集体激发率）通过四费米子相互作用振幅在我们的分析中被表示为相同的公式（两个电子和两个空穴），除了两个激子散射幅度之外，两个和三个费米子的散射振幅，以及与电子和空穴的泡利统计有关的项，以及激子是复合粒子这一事实的结果。这些条款产生的激子散射振幅的一个重要的积极贡献，原则上可以确保地面玻色凝聚态的稳定性，即使有一个弱的激子之间的吸引力。
The problem of exciton interaction in semiconductors is considered in its multi-electron formulation. Expressions are obtained, in the approximation linear in the concentration, for the ground-state energy and for the law of dispersion of elementary excitations. Conditions for the Bose condensation of excitons are investigated and it is shown that low-density system of excitons behaves like a weakly nonideal Bose-gas. Furthermore, all quantities (the chemical potential, the rate of collective excitations) that depend on the two-particle scattering amplitude in the nonideal Bose-gas case are expressed in our analysis by the same formulas through the four-fermion interaction amplitude (two electrons and two holes) which includes, apart from the two-exciton scattering amplitude, the scattering amplitudes of two and three fermions as well as the terms connected with the Pauli statistics for the electrons and holes, and resulting from the fact that excitons are compound particles. These terms yield an essential positive contribution to the exciton scattering amplitude and may in principle ensure the stability of the ground Bose-condensed state even if there is a weak attraction between the excitons.