Defect characterization of as-grown Zn1–xBexSe compound semiconductors was studied by positron lifetime and photoluminescence measurements. Both experimental and theoretical evidence was obtained that the bulk lifetime of free positrons decreased linearly with Be alloying. The average positron lifetime increased with temperature; thus indicating that both vacancies and negative ions trap positrons. The decomposition of the lifetime spectra showed that the positron lifetime of the vacancy decreased with an increase in Be content, as predicted by theoretical calculations. The concentration of vacancies and negative ions obtained from positron measurements follows the same trend with Be alloying. A comparison of positron measurements with theoretical calculations and photoluminescence experiments in Zn vapor annealed samples indicated that the vacancy corresponds to a Be vacancy. Besides, the negative ions trapping positrons at low temperatures were attributed to Be interstitial atoms. The intensity of the B photoluminescence band correlates with the concentration of Be vacancies and Be interstitial atoms. It was therefore concluded that the electron levels of those defects were involved in the optical transition that led to the B photoluminescence band.

Defect Characterization of ZnBeSe Solid Solutions by Means of Positron Annihilation and Photoluminescence Techniques. F.Plazaola, J.Flyktman, K.Saarinen, L.Dobrzynski, F.Firszt, S.Legowski, H.Meczynska, W.Paszkowicz, H.Reniewicz: Journal of Applied Physics, 2003, 94[3], 1647-53