Post-Synthesis Decomposition of III-Nitride Nanowires Into Quantum Wires

A post-synthesis strategy is employed for shrinking the diameters of group III-nitride nanowires. This simple strategy involved the decomposition of pre-synthesized III-nitride nanowires at elevated temperatures in the presence of ammonia. Experiments performed using the compound semiconductors gallium nitride (GaN) and indium nitride (InN) as examples indicated that the decomposition is dependent on the initial diameter of the nanowires. The decomposition of GaN nanowires with diameters greater than 100 nm resulted in polycrystalline powder, while GaN nanowires with diameters of 20 nm underwent layer-by-layer decomposition to result in quantum wires with average diameters less than 5 nm. It is expected that this layer-by-layer decomposition in thin GaN nanowires is a direct result of the ballistic diffusion of gallium adatoms along the length of the nanowires. Similar results were also observed in the case of InN nanowires. These diameter- and growth direction-dependant decomposition phenomena along with the kinetics of decomposition will be discussed.