In recent years, zinc oxide has become a particularly interesting metal oxide material because of its unique properties. ZnO is a semiconductor with a wide band gap (3.3 eV), large exciton binding energy, abundant in nature and environmentally friendly. These characteristics make this material attractive for many applications such as solar cells, optical coatings, photocatalysts, antibacterial activities, electrical devices, active medium in uV semiconductor lasers and in gas sensors [1].