OPTICAL-ABSORPTION AND SOMMERFELD FACTORS OF ONE-DIMENSIONAL SEMICONDUCTORS - AN EXACT TREATMENT OF EXCITONIC EFFECTS
OPTICAL-ABSORPTION AND SOMMERFELD FACTORS OF ONE-DIMENSIONAL SEMICONDUCTORS - AN EXACT TREATMENT OF EXCITONIC EFFECTS
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DOI：
10.1103/physrevb.44.8138
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发表时间：
1991-10-15
影响因子：
3.7
通讯作者：
TAKAGAHARA, T
中科院分区：
文献类型：
--
作者：
OGAWA, T;TAKAGAHARA, T
本文从理论上研究了激子效应对一维半导体光学性质的影响。特别是，带边附近的吸收光谱精确计算的有效质量近似的一维系统与直接允许或禁止的差距。我们采用两种类型的相互作用势之间的电子和空穴描述修改的库仑相互作用和短程相互作用，这两种都是免费的著名的发散问题的一维库仑系统。索末菲因子，这是吸收强度比的未结合的（连续）激子的自由电子空穴对以上的带边，被发现是小于统一的直接允许的过渡，在鲜明的对比的3D和2D的情况下。这一特殊的功能被解释在最低的离散激子状态的振子强度的强烈浓度方面。另一方面，对于直接禁戒跃迁，一维系统的索末菲因子大于1，表现出与三维和二维系统相似的行为。这些性质的电子-空穴吸引势的相互作用范围无关。模型电位的可行性进行了研究，库仑势具有尖型截止被发现是最有效的描述在一个实际的半导体线的电位。线结构中的介电效应示出，以增强这些特有的功能的1D系统。
We investigate theoretically excitonic effects on the optical properties of one-dimensional (1D) semiconductors. In particular, absorption spectra near a band edge are exactly calculated within the effective-mass approximation for the 1D system with a direct allowed or forbidden gap. We employ two kinds of interaction potentials between an electron and a hole describing a modified Coulomb interaction and a short-range interaction, both of which are free from the well-known divergence problem of the 1D Coulomb system. The Sommerfeld factor, which is the absorption intensity ratio of the unbound (continuum) exciton to the free-electron-hole pair above the band edge, is found to be smaller than unity for the direct allowed transition, in striking contrast to the 3D and 2D cases. This peculiar feature is interpreted in terms of the anomalously strong concentration of the oscillator strength on the lowest discrete exciton state. On the other hand, for the direct forbidden transition, the Sommerfeld factor in the 1D system is larger than unity and shows similar behavior to those in the 3D and 2D cases. These properties hold irrespective of the interaction range of the electron-hole attractive potential. The feasibility of the model potentials is examined, and the Coulomb potential having a cusp-type cutoff is found to be the most effective to describe the potential in an actual semiconductor wire. A dielectric effect in the wire structure is shown to enhance these peculiar features of the 1D system.