The emphasize here will be on the fundamental properties of ZnO, like growth, electrical and optical properties, since the potential for optoelectronic devices based on ZnO is also one of the main motivations for the present work. ZnO is a direct wide band-gap (3.37 eV at room temperature) II-VI binary compound semiconductor and crystallizes in three forms: hexagonal wurtzite, cubic zincblende, and the rarely observed cubic rocksalt [11]. The hexagonal wurtzite structure of ZnO is the most common phase having a crystal structure C6v or P63mc, which occurs almost exclusively at ambient conditions [12, 13].