Cathodoluminescence of GaN nanorods and nanowires grown by thermal evaporation

摘要

GaN nanorods and nanowires have been grown by thermal evaporation of GaN on Au/Si (100) substrates. The nanorods recorded a surface decorated with numerous grains with an average size of about 100 nm. The nanowires grew onto the surface of the nanorods exhibiting multiple bends along them. TEM measurements revealed the formation of irregular porous and a polycrystalline structure in the nanowires with diameter higher than 100 nm, while the nanowires with lower diameter showed a tubular structure with wall thickness of 10 nm. The luminescence of the samples recorded three bands centered at about 2.1, 2.74, and 3.2 eV, attributed to the GaN yellow emission and to the blue and UV emissions of the β-Ga_2O_3, respectively. Ga-ion irradiation in samples revealed a decrease in the intensity of the β-Ga_2O_3 blue emission attributed to the elimination of gallium vacancies. A thermal annealing treatment at 800 ℃ in N_2 atmosphere generated a quenching of the GaN yellow emission, due to the elimination of nitrogen vacancies.