Cathodoluminescence imaging and spectroscopy of InGaN/GaN core-shell nanostructures



Core-shell InGaN/GaN structures are attractive as light emitters due to the non-polar facets that result from cores oriented in the [0001] c-direction. These facets do not suffer from the quantum-confined Stark effect which limits the thickness of quantum wells and efficiency in conventional light-emitting devices. Understanding InGaN growth on these sub-micron 3D structures is important to optimize performance.

This dataset contains the results of cathodoluminescence hyperspectral imaging measurements carried out on such nanostructures in order to characterize the emission properties of their various crystal facets. The structures were grown by our collaborators at the University of Bath (I. Girgel, E. Le Boulbar, P.-M. Coulon, D. W. E. Allsopp and P. A. Shields), and consist of arrays of GaN nanorods each with an outer shell of InGaN. Three samples were studied, using the following InGaN growth temperatures and pressures:
1) "3873" (750 °C, 300 mbar)
2) "3874" (700 °C, 300 mbar)
3) "3875" (750 °C, 100 mbar)

Cathodoluminescence (CL) hyperspectal images were measured from the samples using a custom-built CL acquisition system on an FEI Quanta 250 FEG scanning electron microscope. An accelerating voltage of 5 kV was used, with the beam scanned over 200×200 pixels in 25 nm steps to produce images 5×5 µm in size. For each sample we present:
1) A "real-colour" image, in 24-bit TIFF format, generated by calculating the CIE chromaticity co-ordinates from the spectrum at each pixel in the hyperspectral image.
2) Spectra extracted by averaging over various 4×4 pixel regions of the hyperspectral image. For each sample we show such spectra extracted from the following crystal facets:
a) a-plane {11-20} non-polar facet
b) c-plane (0001) polar facet
c) m-plane {10-10} non-polar facet
d) {1-101} sem-polar facet
Each spectrum is saved as a tab-delimited ASCII text file (.dat), with the first column containing the photon energy (eV) and the second column containing the CL intensity (counts/eV).

Further analysis of the results is presented in the accompanying Journal of Nanophotonics paper by I. Girgel et al.
Date made available2016
PublisherUniversity of Strathclyde

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