Room-Temperature Dual Excitonic Emission from Amorphous ZnO

Optical properties of amorphous ZnO have been investigated at room temperature. It is demonstrated that the ultraviolet emission components due to the recombination of two different excitons were verified by examining their relative energy positions and ultraviolet integrated photoluminescence intensity dependence on reaction time. The dual excitonic emissions are derived from amorphous ZnO and crystallized ZnO nanocrystallite, respectively. On the optimized condition, the photoluminescence spectrum of amorphous ZnO shows a strong ultraviolet emission while the visible emission is almost fully quenched. The enhanced ultraviolet emission is attributed to quantum confinement effect.