The effect of non-stoichiometry on the implantation of ytterbium of cadmium telluride

Cathodoluminescence emission at 77 K has been used to monitor the production of optically active Yb3+ centres by implantation of 50 kV ytterbium ions into doped and undoped cadmium telluride samples of different degrees of non-stoichiometry. Isochronal annealing studies of the different types of implanted samples show that early stages of anneal produce Type I Yb3+ centres at interstitial sites and further annealing causes conversion of Type I Yb3+ centres to Type II Yb3+ centres which occur at substitutional sites. Efficient emission by Type I centres and efficient conversion of Type I to Type II centres is produced in those samples which have been shown by electrical measurements and edge emission studies to contain an excess of cadmium vacancies. (author)