Fano resonance of low-dimensional excitons

低维激子的法诺共振

基本信息

批准号：
11640308
负责人：
HINO Kenichi
金额：
$ 2.5万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Fano resonance (FR) of low-dimensional excitons manifests itself due to couplings of subbands generated by spatial quantum confinement. The resulting FR states belong to multi-channel scattering (MCS) states. However, there were a lot of difficulties in conventional theoretical methods because of little account of MCS problems. In the present study, one has succeeded to overcome all of these problems and to establish a novel MCS theory of low-dimensional excitons, which enables us to evaluate natural spectra and resonance widths of FR in ab initio manner. This approach consists of the adiabatic expansion and the R-matrix propagation based on the Luttinger Hamiltonian incorporating the effect of valence-band mixing (VBM). This theory has been applied to a single quantum-well (QW) and superlattices (Wannier Stark ladder (WSL)) of GaAs/Al_xGa_<1-x>As semiconductors, and variance of FR spectra due to changes of well-thickness and strength of electric- and magnetic-fields is examined in de tail. Above all, the following new findings are obtained. In relatively wide QW's, overlap resonance of FR ascribable to VBM is substantial. In an asymmetric double QW's, a hy bridized exciton states generated by an electron and hole pair pertaining to different wells has a somehow pronounced oscillator strength, which is also discernible in the existing experiment. Furthermore, FR plays decisive roles in dimensionality transition of WSL from a quasi-two dimensional system to a bulk one with decreasing an applied electric field.

低维激子的法诺共振（FR）由于空间量子限制产生的子带耦合而显现出来。由此产生的 FR 状态属于多通道散射 (MCS) 状态。然而，由于很少考虑MCS问题，传统的理论方法存在很多困难。在本研究中，我们成功地克服了所有这些问题，并建立了一种新颖的低维激子MCS理论，使我们能够从头开始评估FR的自然光谱和共振宽度。该方法由绝热展开和基于 Luttinger Hamiltonian 的 R 矩阵传播组成，并结合了价带混合 (VBM) 的效果。该理论已应用于GaAs/Al_xGa_<1-x>As半导体的单量子阱（QW）和超晶格（Wannier Starkladder（WSL）），以及由于阱厚度和强度变化引起的FR光谱的变化详细研究了电场和磁场的变化。最重要的是，获得了以下新发现。在相对较宽的 QW 中，归因于 VBM 的 FR 重叠共振相当大。在不对称双量子阱中，由属于不同阱的电子和空穴对产生的杂化激子态具有某种显着的振荡强度，这在现有实验中也是可以辨别的。此外，随着外加电场的减小，FR在WSL从准二维系统到大体系统的维数转变中起着决定性作用。