Observation of a quantum-confinement effect with GaN nanoparticles synthesized through a new gas reaction route

Spherical wurtzite GaN nanoparticles with diameters of 5–8 nm were synthesized through a new gas reaction route. The concave-surface-induced nucleation process based on the surface roughness of the substrate played an important role in the formation of quantum dots. Photoluminescence spectrum revealed the quantum-confined excited states in the nanoparticles with features at 3.73 eV (332 nm) and 3.85 eV (322 nm), which show significant blueshift compared with the band-gap emission from bulk GaN crystals. Four blue emission bands with low intensity, centered at 2.85 eV (435 nm), 2.75 eV (451 nm), 2.67 eV (464 nm), 2.62 eV (473 nm) respectively, were also observed. These blue bands may originate from surface states.