Photoluminescence observation of electron-hole droplets in a GaAs/AlAs type-II superlattice

6th International Conference on Optical, Optoelectronic and Photonic Materials and Applications 2014

Furukawa, Yoshiaki^1 ; Nakayama, Masaaki^1

Department of Applied Physics, Graduate School of Engineering, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka

558-8585, Japan^1

关键词: Electron-hole droplets;    Excitation power density;    Line shape analysis;    Mott transitions;    Photoluminescence properties;    Prominent features;    Type-II superlattices;    Typical properties;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/619/1/012005/pdf
DOI  :  10.1088/1742-6596/619/1/012005

来源: IOP

【 摘 要 】

We have investigated the photoluminescence (PL) properties of a (GaAs)12/(AlAs)12type-II superlattice (SL) at 10 K from the viewpoint of the formation of electron-hole droplets (EHDs). In the type-II SL, the lowest-energy exciton consists of an X-electron and a Γ-heavy-hole confined in the AlAs and GaAs layers, respectively; namely, the optical transition is indirect in momentum and real space. The excitation-power density was widely changed from ∼1 mW/cm2to ∼1 kW/cm2for precisely observing changes of PL spectra. It was found that a broad PL band appears with a threshold-like nature in the energy region lower than the biexciton. This suggests the occurrence of the Mott transition. The prominent feature of the broad PL band is the fact that the spectral profile hardly depends on the excitation-power density, which is one of typical properties of EHDs. From the line-shape analysis of the PL spectra, we estimated the stability energy of the EHD to be ∼2.9 meV relative to the biexciton energy. The above results consistently demonstrate the formation of the EHD.