Low-temperature near-field spectroscopy of CdTe quantum dots.
A near-field optical microscope has been developed for operation at low temperature. This microscope is used to study the photoluminescence of CdTe-based quantum dots. Spectra collected upon approaching the optical tip into the near-field region of the sample reveal the evolution from a broad far-field luminescence band - that is typical for a large ensemble of dots - to a near-field structure made up of a few sharp peaks originating from individual dots. Experiments carried out in the excitation-collection mode through the optical tip allow study of the effect of an increase in excitation power on the near-field spectra. It is found that upon increasing the excitation by two orders of magnitude, a spatially resolved spectrum progressively transforms back into a broad 'far-field-like' spectrum. Photoluminescence images taken by scanning the sample under the tip are used to discriminate various contributions coming from individual dots.
Brun
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M
Laboratoire de Spectrométrie Physique (LSP), CNRS UMR 5588, Université Joseph Fourier Grenoble I, BP 87, 38402 Saint Martin d'Hères, France.
Huant
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Woehl
J C
JC
Motte
J F
JF
Marsal
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Mariette
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