Hot exciton relaxation in multiple layers CdSe/ZnSe self-assembled quantum dots separated by thick ZnSe barriers

2nd International School and Conference Saint-Petersburg OPEN on Optoelectronics, Photonics, Engineering and Nanostructures

Eremenko, M.^1 ; Budkin, G.^1 ; Reznitsky, A.^1

Ioffe Institute, Politekhnicheskaya 26, St. Petersburg

194021, Russia^1

关键词: Asymmetric double quantum wells;    Exciton relaxation;    Exciton-binding energy;    Multiple layers;    Oscillating structures;    Self assembled quantum dots;    Short wavelengths;    Wide energy range;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/643/1/012075/pdf
DOI  :  10.1088/1742-6596/643/1/012075

来源: IOP

【 摘 要 】

We have studied PL and PLE spectra of two samples (A and B) of MBE grown CdSe/ZnSe asymmetric double quantum wells with different amount of deposited CdSe layers separated by 14 nm ZnSe barrier. It has been found that PLE spectra of the states forming short wavelength side of the PL spectra of both deep and shallow QWs of the sample A as well as that of deep QW of the sample B demonstrate oscillating structure in the spectral ranges corresponding to exciton states of self-assembled quantum dots only. Meanwhile PLE spectra of the short wavelength states of shallow QW the sample B revealed pronounced oscillating structure with energy period of ZnSe LO phonon under excitation with photons in a wide energy range both in the regions of quantum-dot states and in that of free states in the ZnSe barrier. In these spectra creating of excitons with kinetic energies more than 0.3 eV was observed which considerably exceed the exciton binding energy as well as LO phonon energy (both appr. 0.03 eV). It has been concluded that oscillating structure of the PLE spectra arises due to cascade relaxation of hot excitons. We discuss the model which explains these experimental findings.