Observation of vacancy type defects in Ga-doped ZnSe using a monoenergetic positron beam

We studied vacancy type defects in Ga-doped ZnSe films grown by molecular beam epitaxy using an energy-variable monoenergetic positron beam. We found that the concentration of negative charged vacancies, such as Zn vacancies, increases as the Ga atom concentration increases. This result indicates that the doping by Ga atoms induces the formation of Zn vacancies in a ZnSe film. We believe that these defects will cause the saturation of active carriers in n-type ZnSe films.