Since the
DMS contain a few percent of transition metal impurities, thermal stability of the impurities and induced defects which determine the material physical propertie s, are very important in terms of both practical applications and fundamental physical understa nding. Cobalt ions are also used to reduce the defects in the samples. Various techniqu es have been used to synthesize undoped and Co2+ doped ZnO nanoparti cles and can be categorized into either chemical or physical methods [4,5].