Vacancy-type defects were studied in Ga-doped films which had been grown via molecular beam epitaxy, using a variable-energy mono-energetic positron beam. It was found that the concentration of negatively charged vacancies, such as Zn vacancies, increased as the Ga concentration increased. It was suggested that doping with Ga provoked the formation of Zn vacancies in ZnSe films. It was proposed that such defects could lead to the saturation of active carriers in n-type ZnSe films.

T.Miyajima, H.Okuyama, K.Akimoto, Y.Mori, L.Wei, S.Tanigawa: Applied Physics Letters, 1991, 59[12], 1482-4