Composition analysis of coaxially grown InGaN multi quantum wells using scanning transmission electron microscopy

T Aschenbrenner and M Schowalter and T Mehrtens and K Muller-Caspary and M Fikry and D Heinz and I Tischer and M Madel and K Thonke and D Hommel and F Scholz and A Rosenauer, JOURNAL OF APPLIED PHYSICS, 119, 175701 (2016).

DOI: 10.1063/1.4948385

GaN nanotubes with coaxial InGaN quantum wells were analyzed by scanning transmission electron microscopy in order to determine their structural properties as well as the indium distribution across the InGaN quantum wells. For the latter, two process steps are necessary. First, a technique to prepare cross-sectional slices out of the nanotubes has been developed. Second, an existing scanning transmission electron microscopy analysis technique has been extended with respect to the special crystallographic orientation of this type of specimen. In particular, the shape of the nanotubes, their defect structure, and the incorporation of indium on different facets were investigated. The quantum wells preferentially grow on m-planes of the dodecagonally shaped nanotubes and on semipolar top facets while no significant indium signal was found on a-planes. An averaged indium concentration of 6% to 7% was found by scanning transmission electron microscopy analysis and could be confirmed by cathodoluminescence measurements. Published by AIP Publishing.

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