An influence of the local strain on cathodoluminescence of GaN/AlxGa1-xN nanowire structures

Near-band-edge excitonic emission shift is investigated as a measure of the local strain in GaN nanowires with single AlxGa1-xN sections of various Al contents (x = 0.0, 0.22, 0.49, 1.0). Complementary data obtained by spatially and spectrally resolved cathodoluminescence spectroscopy and imaging of individual nanowires at low temperature, high resolution X-ray diffraction, and transmission electron microscopy are used to determine the correspondence between the cathodoluminescence emission energy and the strain in the GaN core of the nanowire surrounded by the AlxGa1-xN shell formed during the growth of AlxGa1-xN sections by catalyst-free plasma-assisted molecular beam epitaxy. In majority of nanowires, the blue-shift of GaN cathodoluminescence follows the evolution expected for the GaN core under uniaxial compressive strain along the axis of the structure. Published by AIP Publishing.