- 概述
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The second half of the 20th century has seen the emergence of semiconductor quantum struc-tures driven by promises of far superior performances in particular regarding light emission.The dimensionality was reduced down to point-like quantum dots (QDs). QDs exhibit intriguing similarities with atoms and tremendous efforts were made to assess their properties.
This limit can be overcomed with cathodoluminescence measurements, which makes possible the investigations on the position of QDs and their appearance depending on the properties of the host NW. For our structures, made of GaAs and AlGaAs, the Attolight CL-SEM allows us to work at cryogenic temperature, a necessary condition to observe light emission from the QDs.
Furthermore, the Attolight microscope provides the following advantages compared to traditional system :
– The large numerical aperture ensures a very high signal-to-noise ratio, leading to a shorter exposure of the QDs to the electron beam and hence reducing the risk of bleaching as well as speeding up the experiment.
– The higher signal allows to use straightforwardly a spectrometer-CCD detection channel, without the need of photomultiplier tube, yielding directly fast hyper- spectral mapping. The wide emission spectral range is then captured (in our case from 650 nm to 900 nm).
– The spatial resolution permits to resolve closely lying dots as well as local features such as changes in the matrix crystal phase.
– The large numerical aperture ensures a very high signal-to-noise ratio, leading to a shorter exposure of the QDs to the electron beam and hence reducing the risk of bleaching as well as speeding up the experiment.
– The higher signal allows to use straightforwardly a spectrometer-CCD detection channel, without the need of photomultiplier tube, yielding directly fast hyper- spectral mapping. The wide emission spectral range is then captured (in our case from 650 nm to 900 nm).
– The spatial resolution permits to resolve closely lying dots as well as local features such as changes in the matrix crystal phase.