Structure evolution and optical properties of hierarchical ZnO micro/nanorods fabricated by a two-step growth method

A large scale of hexagonal ZnO microrods were firstly fabricated by a hydrothermal method, then the secondary growth was performed using a vapor phase transport method. During the second growth stage, the structural evolution from hexagonal microrod to dodecagonal microrod was realized, and the regular nanorods array epitaxially grew up on the microrods' end surfaces. P-band emission ascribed to exciton-exciton scattering process was observed from the hexagonal and dodecagonal microrods. In addition, a single dodecagonal microrod was employed as a microlaser cavity where the whispering gallery mode lasing was stimulated under the excitation of the nanosecond pulsed laser at 355 nm.