Coherent dynamics of localized excitons and trions in ZnO/(Zn,Mg)O quantum wells studied by photon echoes

Article

关键词: ZNO;    TEMPERATURE;    DISORDER;   

DOI  :  10.1103/PhysRevB.97.245406

来源: SCIE

【 摘 要 】

We study optically the coherent evolution of trions and excitons in a delta-doped 3.5-nm-thick ZnO/Zn-0.91 Mg0.09O multiple quantum well by means of time-resolved four-wave mixing at a temperature of 1.5 K. Employing spectrally narrow picosecond laser pulses in the x((3)) regime allows us to address differently localized trion and exciton states, thereby avoiding many-body interactions and excitation-induced dephasing. The signal in the form of photon echoes from the negatively charged A excitons (T-A, trions) decays with coherence times varying from 8 up to 60 ps, depending on the trion energy: more strongly localized trions reveal longer coherence dynamics. The localized neutral excitons decay on the picosecond time scale with coherence times up to T-2 = 4.5 ps. The coherent dynamics of the XB exciton and T-B trion are very short (T-2 < 1 ps), which is attributed to the fast energy relaxation from the trion and exciton B states to the respective A states. The trion population dynamics is characterized by the decay time T-1, rising from 30 to 100 ps with decreasing trion energy.

【 授权许可】

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