Direct Growth of GaN Nanowires by Ga and N-2 without Catalysis

摘要

Gallium nitride nanowires (GaN NWs) are commonly synthesized using harsh/toxic conditions (e.g., ultrahigh vacuum, high substrate temperature, toxic materials, etc.) or by catalytic conditions. In this work, GaN NWs were grown on graphite substrates by the direct reaction of Ga atoms with excited N plasma without the need for a catalyst. This was achieved using plasma enhanced chemical vapor deposition (PECVD) under moderate vacuum conditions and temperatures below 900 degrees C. The GaN NWs consisted of polycrystalline nanostructures that appeared as pyramidal islands, with diameters from 90 to 200 nm and lengths from 4 to 20 mu m. A model for the mechanism of nucleation and growth of the GaN NWs is proposed. The morphology and quality of the GaN NWs varied significantly depending on the fabrication parameters that were used. Moreover, they exhibited desirable photoluminescence (PL) and field emission (FE) properties. This method shows great promise for the simple, low cost, and environmentally friendly fabrication of high-purity NWs, which may lead to improved GaN NW-based devices.