DOI: 10.15125/bath-00150
title: Dataset for Structural and optical emission uniformity of m-plane InGaN single quantum wells in core-shell nanorods

description: This dataset contains the results of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Energy Dispersive X-ray (EDX) measurements carried out on InGaN/GaN core-shell nanostructures. The samples are highly regular arrays of GaN plasma etched cores onto which wide InGaN layer capped with a GaN layer were grown using different metal organic vapour phase epitaxy (MOVPE) growth parameters.

Three different growth temperature were used to grow the InGaN layer: 750°C, 700°C and 650°C. SEM images were used to characterize the describe the fabrication, growth and assess nanorod morphologies. TEM were used to investigate the structural properties and assess the InGaN thickness along the entire length of the m-plane facets. EDX measurements were used to assess the homogeneity of the InGaN layer composition at different position along the m-plane facet and on the semi-polar facets.
description: Secondary electron images were captured using a Hitachi S-4300 scanning electron microscope (SEM). An accelerating voltage of 5 kV was used to collect the images.

Atomic resolution STEM images were acquired using a FEI TITAN 80-300 microscope that was equipped with a CEOS CESCOR spherical aberration (Cs) corrector in the probe forming lens and high-brightness FEI XFEG electron source. Atomic resolution HAADF STEM images were acquired at an accelerating voltage of 300 keV and probe convergence semi-angle of 17.9 mrad and col-lection semi-angle of 55-200 mrad.

Energy dispersive X-Ray spectroscopy analyses were carried out using FEI Tecnai Osiris. This microscope was equipped with XFEG and Super X system EDS detectors. This detector comprises 4 Bruker silicon detectors (SDD) arranged symmetrically around the optic axis of the microscope for high collection efficiency and high count rate. Spectrum images were acquired at a spatial sampling of 2 nm/pixel and 1 s/pixel dwell times with a probe current of approximately 0.5 nA, at an accelerating voltage of 200 keV.
description: Samples for TEM were prepared by a dual beam focused ion beam system. The nanorods were protected by a platinum layer prior to etching to reduce damage that could occur with the use of ion beam system. The samples for EDX measurements and atomic resolution STEM were prepared by a tripod polishing method using an Allied Tech Multiprep unit. Specimens were then ion-milled with a Gatan Precision Ion Polishing System (PIPS) using 1.5–5 keV argon ions for further thinning and removing the residue of polishing contamination from the specimens.

Using principal component analysis and independent component analysis (implemented in HyperSpy46), two independent and uncorrelated components were identified in the spectrum images. The first component contains Ga and N X-ray peaks and the second component contain Ga, In, and N X-ray peaks. To obtain the composition of the InGaN shell, the intensities of Ga Kalpha and In Lalpha peaks were quantified using the Cliff-Lorimer method and the k-factor provided by the manufacturer of the EDX system (Bruker). The errors were also estimated from Poisson statistics.
description: Hitachi S-4300 scanning electron microscope (SEM)