Strain relaxation by dislocation glide in ZnO/ZnMgO core-shell nanowires

Plastic relaxation of the misfit stress in core-shell semi-conducting nanowires can lead to structural defects, detrimental to applications. Core-shell Zn0.7Mg0.3O/ZnO quantum well heterostructures were deposited on ZnO nanowires. Strain along the a and c axes of the wurtzite structure is relaxed through the glide of dislocation half-loops from the free surfaces, within pyramidal and prismatic planes. Some half-loops are closed up in the barriers to accommodate the misfit at two consecutive interfaces of the quantum well stack. Dislocations are also observed within the nanowire core: contrary to two-dimensional structures, both the core and the shell can be plastically relaxed.