Investigations on the growth of manifold morphologies and optical properties of ZnO nanostructures grown by radio frequency magnetron sputtering

The growth of ZnO nanostructures under various combinations of argon and oxygen pressures by radio frequency magnetron sputtering has been reported. The anisotropic transformation of nanostructures from the vertical standing nanorods to self branched lateral nanowires has been observed due to the change in the migration length of the adatoms owing to the deposition pressure and temperature. A dominant (002) reflection having narrow full width at half maximum of the vertical standing nanorods depicts the preferential orientation along c-axis of wurtzite ZnO with high crystalline nature. It is further substantiated by a sharp E2high phonon mode of ZnO nanorods at 437.2 cm−1. A broad green emission at 2.28 eV pertaining to oxygen vacancies that quenches with increasing the oxygen pressure due to the compensation of oxygen vacancies while zinc vacancy mediated emission at 3.01 eV is enhanced.