ZnO is a II-VI semiconducting compound that forms as ionic crystals of the wurtize structure. ZnO has found a wide range of industrial applications from skin care, phosphors, varistors, to transparent conductive oxides for ¬at screen displays. Recently, ZnO has received much attention for its potential as an optoelectronic material. It has a wide, direct electronic band gap of approximately 3.37 eV at room temperature. Under photoexcitation, it emits light in the ultraviolet (UV) spectrum at a corresponding band-edge wavelength of approximately 380 nm. –is photoluminescence (PL) is due to the radiative recombination of excitons. ZnO possesses a very large exciton-binding energy of about 60 meV, making excitons stable at room temperature. –erefore, ZnO is a promising candidate for blue and UV lightemitting diodes (LEDs) and lasers.