  Plastic relaxation of the misfit stress in core-shell semi-conducting
nanowires can lead to structural defects, detrimental to applications.
Core-shell Zn{0.7}Mg{0.3}O/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.
