STEM Cathodoluminescence of Individual GaN/AlN Quantum Disks within a single Nanowire

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• Luiz Fernando Zagonel, Electron Microscopy Laboratory, Brazilian Synchrotron Light Laboratory
• Friday 24 June 2011, 15:00-16:00
• T001 [Tower Seminar Room], Materials Science and Metallurgy, Department of.

If you have a question about this talk, please contact Caterina Ducati.

In a real devices, quantum objects might be assembled in close proximity to better enhance or employ their properties.[1] This creates a great challenge for characterization, modelling and understanding of such complex nano-structures. Here, an optimized cathodoluminescence (CL) system implemented in a STEM is employed to access the emission energy of individual GaN/AlN Quantum Disks (QDisks) of a stack within single GaN nanowires (NW). [2] CL maps with a full spectrum for each point were acquired to distinguish the contribution of different parts of the NWs with high spatial and spectral resolutions. QDisks as small as 1 nm separated by few nanometers had their luminescence singled out. Moreover, the emission wavelength of each QDisk could be unambiguously related to their individual size (measured with atomic resolution) and to the morphology of the NW. The results give a clear evidence of the Quantum Confined Stark Effect (QCSE – that is the red shift of the emission due to the electric field) due to internal fields.

References: [1] L. Rigutti et al. Nano Lett. 2010, 10, 2939. [2] L. F. Zagonel et al. Nano Lett. 2011, 11, 568.

This talk is part of the Electron Microscopy Group Seminars series.

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