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arXiv · 1501.01446

Nanoscale Transport of Surface Excitons at the Interface between ZnO and a Molecular Monolayer

Sebastian Friede·Sergei Kuehn·Sergey Sadofev·Sylke Blumstengel·Fritz Henneberger·Thomas Elsaesser
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Abstract

Excitons play a key role for the optoelectronic properties of hybrid systems. We apply near-field scanning optical microscopy (NSOM) with a $100\,\text{-nm}$ spatial resolution to study the photoluminescence of surface excitons (SX) in a $20\,\text{nm}$ thick ZnO film capped with a monolayer of stearic acid molecules. Emission from SX, donor-bound (DX), and - at sample temperatures $T>20\,\text{K}$ - free (FX) excitons is separated in steady-state and time-resolved photoluminescence spectra. The $4\,\text{meV}$ broad smooth envelope of SX emission at $T<10\,\text{K}$ points to an inhomogeneous distribution of SX transition energies and spectral diffusion caused by diffusive SX transport on a $50\,\text{nm}$ scale with a SX diffusion coefficient of $D(T<10 K)=0.30\,\text{cm$^2$/s}$.

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Sebastian Friede, Sergei Kuehn, Sergey Sadofev, Sylke Blumstengel, Fritz Henneberger, Thomas Elsaesser. 2015-01-07. Nanoscale Transport of Surface Excitons at the Interface between ZnO and a Molecular Monolayer. https://doi.org/10.1103/physrevb.91.121415

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