Effect of electron-hole separation on optical properties of individual Cd(Se,Te) Quantum Dots

Abstract

Cd(Se,Te) Quantum Dots (QD) in ZnSe barrier typically exhibit a very high spectral density, which precludes investigation of single dot photoluminescence. We design, grow and study individual Cd(Se,Te)/ZnSe QDs of low spectral density of emission lines achieved by implementation of a Mn-assisted epitaxial growth. We find an unusually large variation of exciton-biexciton energy difference (3 meV $\le$ $\Delta {\mathrm{E}}_{\mathrm{X}-\mathrm{XX}}$ $\le$ 26 meV) and of exciton radiative recombination rate in the statistics of QDs. We observe a strong correlation between the exciton-biexciton energy difference, exciton recombination rate, splitting between dark and bright exciton, and additionally the exciton fine structure splitting ${\delta }_1$ and Landé factor. Above results indicate that values of the ${\delta }_1$ and of the Landé factor in the studied QDs are dictated primarily by the electron and hole respective spatial shift and wavefunctions overlap, which vary from dot to dot due to a different degree of localization of electrons and holes in, respectively, CdSe and CdTe rich QD regions.

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Cited by in corpus (3)

• Bright-exciton fine structures splittings in single perovskite nanocrystals
• Excitonic fine structure of epitaxial Cd(Se,Te) on ZnTe type-II quantum dots
• Advanced material system for the design of an intermediate band solar cell: type-II CdTe quantum dots in a ZnCdSe matrix