Abstract
The authors report on the modification of optical properties of GaN nanowires by growing a thin Ga 2 O 3 overlayer on GaN surface, forming a core/shell heterostructure. The GaN/Ga 2 O 3 core/shell nanowires were formed first by the axial growth of GaN nanowires, followed by the radical growth of the Ga 2 O 3 overlayer. The GaN core possesses single crystalline wurtzite structure, whereas the Ga 2 O 3 shell layer is monoclinic polycrystalline. For the GaN/Ga 2 O 3 core/shell nanowires, a pronounced blueshift of the Raman A 1 (LO) mode was found, indicating a compressive stress on the core wire due to the lattice mismatch with the outer shell. This picture is also supported by the photoluminescence spectrum, in which the peak shifts to higher energy after the overgrowth of Ga 2 O 3 on GaN. © 2012 American Vacuum Society.