Room-temperature optical emission properties of hydrothermal grown zinc oxide nanostructures
We report on the room-temperature optical emissions of hydrothermal-grown zinc oxide (ZnO) nanostructures. The nanostructures were fabricated on seeded silicon (Si) substrates by hydrothermal growth method using different zinc acetate dihydrate [Zn(CH3COO)·2H2O, ZnAc] concentrations. Regardless of the ZnAc concentration, all nanostructures exhibit well-defined hexagonal facets and intense near-band-edge ultraviolet (UV) emissions. However, increasing the ZnAc concentration leads ZnO nanostructures which exhibit longer emission lifetimes and a secondary red-shifted UV emission around 392 nm. These changes in the nanostructures' UV emission properties are attributed to the multiple excitation/absorption and emission processes of coalescent structures and/or structures sharing common sides or boundaries. Our results suggest that for UV scintillator applications, this phenomenon in ZnO nanostructures can be reduced by using lower (< 100 mM) ZnAc concentrations during hydrothermal growth.