Excitons, biexcitons, and phonons in ultrathin CdSe/ZnSe quantum structures

Article

关键词: OPTICAL INVESTIGATIONS;    LOCALIZED EXCITONS;    DOT STRUCTURES;    SEMICONDUCTOR NANOCRYSTALS;    SOLID-SOLUTIONS;    WELL STRUCTURES;    ZNSE MATRIX;    PHOTOLUMINESCENCE;    GAIN;    SPECTROSCOPY;   

DOI  :  10.1103/PhysRevB.60.8773

来源: SCIE

【 摘 要 】

The optical properties of CdSe nanostructures grown by migration-enhanced epitaxy of CdSe on ZnSe are studied by time-, energy-, and temperature-dependent photoluminescence and excitation spectroscopy, as well as by polarization-dependent four-wave mixing and two-photon absorption experiments. The nanostructures consist of a coherently strained Zn1-xCdxSe/ZnSe quantum well with embedded islands of higher Cd content with sizes of a few nanometer due to strain-induced CdSe accumulation. The local increase in CdSe concentration results in a strong localization of the excitonic wave function, in an increase in radiative lifetime, and a decrease of the dephasing rate. Local LO-phonon modes caused by the strong modulation of the Cd concentration profile are found in phonon-assisted relaxation processes. Confined biexcitons with large binding energies between 20 and 24 meV are observed, indicating the important role of biexcitons even at room temperature.

【 授权许可】

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