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Transmission Electron Microscopy as a tool for time-resolved cathodoluminescence spectroscopies

Jeudi 19 mars 2020 à 14:00, Salle de séminaire 445, bâtiment 1005, CEA-Grenoble

Publié le 19 mars 2020
Sophie Meuret
Centre d'élaboration de matériaux et d'études structurales (CEMES) du CNRS, Toulouse

The development of time resolved Cathodoluminescence (TR-CL) enabled the measurement of the lifetime of excited state in semiconductor with a sub-wavelength spatial resolution. It was used for example to measure the influence of stacking fault on the GaN exciton [1], to probe the role of a silver layer on the dynamic of a YAG crystal [2] or to show the influence of stress on the optical properties of ZnO nanowires [3]. Recently, the first pump-probe cathodoluminescence experiment using diamond reveals the effect of electrons excitation on the nitrogen vacancy color center [4]. These results demonstrate that time-resolved cathodoluminescence is essential to study the correlation between semiconductor optical and structural properties (composition, defects, strain…). While all these pioneer studies were done using a scanning electron microscope, the improvement of the spatial resolution and the combination with other electron based spectroscopy offered by transmission electron microscope will be a step forward for TR-CL.
In this presentation, we will discuss two ways of measuring the lifetime whitin a transmission electron microscope. The first is based on the measurement of the cathodoluminescence autocorrelation function [5]. Where we measured the probability to have a certain delay between the two photon emitted by the sample. The emission of a bunch of photons by a single electron allows the measurement of the emitter lifetime with a continuous electron beam [6]. In a second time we will discuss the first time-resolved cathodoluminescence experiments within a transmission electron microscope (see Figure1). They were performed in a unique microscope, based on a cold-FEG electron gun [7]. This technology allows to reach a spatial resolution of a few nanometers. In this presentation we will discuss the advantages and drawbacks of this two techniques to measure the lifetime and performed pump-probe cathodoluminescence spectroscopy.

[1] P. Corfdir et al., “Exciton localization on basal stacking faults in a-plane epitaxial lateral overgrown GaN grown by hydride vapor phase epitaxy,” J. Appl. Phys., vol. 105, no. 4, p. 043102, 2009
[2] R. J. Moerland, I. G. C. Weppelman, M. W. H. Garming, P. Kruit, and J. P. Hoogenboom, “Time-resolved cathodoluminescence microscopy with sub-nanosecond beam blanking for direct evaluation of the local density of states,” Opt. Express, vol. 24, no. 21, p. 24760, 2016
[3] X. Fu et al., “Exciton Drift in Semiconductors under Uniform Strain Gradients: Application to Bent ZnO Microwires,” ACS Nano, vol. 8, no. 4, pp. 3412–3420, 2014
[4] M. Solà-Garcia, S. Meuret, T. Coenen, and A. Polman, “Electron-induced state conversion in diamond NV centers measured with pump-probe cathodoluminescence spectroscopy,” ACS Photonics 2020, 7, 1, 232-240
[5] S. Meuret et al., “Lifetime Measurements Well below the Optical Diffraction Limit,” ACS Photonics, vol. 3, no. 7, pp. 1157–1163, 2016
[6] S. Meuret et al., “Photon Bunching in Cathodoluminescence,” Phys. Rev. Lett., vol. 114, no. 19, pp. 1–5, 2015
[7] F. Houdellier, G. M. Caruso, S. Weber, M. Kociak, and A. Arbouet, “Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source,” Ultramicroscopy, vol. 186, pp. 128–138, 2018
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