A comparative study of ZnO thin film and nanorod samples prepared by wet-chemical methods
We present a comparative study of the optical properties of zinc oxide (ZnO) thin film and nanorods prepared by wet-chemical methods. Crystalline thin film and nanorod samples were successfully fabricated on seeded substrates using spray pyrolysis technique and hydrothermal growth method, respectively. The thin film exhibits flake-like grains, while the nanorods exhibit well-defined hexagonal cross sections. Although both thin film and nanorods show similar optical band gaps of 3.26 eV, intense near-band-edge UV emissions at 380 nm, and broad and weak green emissions around 530 to 560 nm, the thin film exhibits higher visible transparency of 66 to 89% and faster ultraviolet (UV) emission lifetime of 30 ps. These results reveal important insights on selecting and designing ZnO-based optical sensors for future biological applications.