Synthesis of InN@SiO₂ Nanostructures and Fabrication of Blue LED Devices

We synthesized InN@SiO(2) nanostructures (i.e., nanoparticles and nanowires) by varying the annealing temperature and nitridation conditions of In(2)O(3)@SiO(2) nanoparticles in the presence of ammonia. The In(2)O(3)@SiO(2) nanoparticles were synthesized using a urea-based homogeneous precipitation of indium hydroxide on the surface of the SiO(2) (15 nm) nanoparticles, followed by annealing at 600 °C in air. Subsequently, nitridation of In(2)O(3)@SiO(2) nanoparticles in ammonia at 600 °C for 2 h resulted in InN@SiO(2) nanoparticles. The sizes of InN nanoparticles are ∼5 nm on the silica surface. Nitridation at the same temperature for 3-5 h gave InN nanoparticles of size ∼20 nm. Furthermore, on annealing above 650 °C the InN nanoparticles grew in the form of nanowires. The nanowires are 4-5 μm in length and have a diameter of 100 nm. The photoluminescence peak of both InN@SiO(2) nanoparticles and nanowires is centered at 442 nm (λ(exi) = 325 nm). Subsequently, the surface of InN@SiO(2) nanoparticles was modified by reacting with dodecyltriethoxysilane at 80 °C, which enabled them to be dispersible in toluene. The surface-modified InN@SiO(2) nanoparticles were used to fabricate blue electroluminescence devices which showed blue electroluminescence peak centered at 442 nm. The Commission Internationale de I'Eclairage (CIE) coordinates of InN@SiO(2) nanoparticles are X = 0.15 and Y = 0.13, which is well within the blue region and commercially appropriate.