A low-energy positron beam was used to investigate defects in N-doped and undoped ZnSe layers which were grown onto ZnSe or Si-doped GaAs. In the case of N-doped material, positron trapping at vacancies (identified as being VSeNSe complexes) and at negative ions was observed. The results suggested that, in addition to forming isolated NSe acceptors or VSeNSe pairs, incorporated N also formed donor-type defects which led to the compensation of holes. In the case of undoped ZnSe layers, the results indicated the presence of Zn vacancies in concentrations of 1016 to 1017/cm3. The Zn vacancy concentration was related to the dislocation density at the ZnSe/GaAs interface.

Native Vacancies in Nitrogen-Doped and Undoped ZnSe Layers Studied by Positron Annihilation. P.Desgardin, J.Oila, K.Saarinen, P.Hautojärvi, E.Tournié, J.P.Faurie, C.Corbel: Physical Review B, 2000, 62[23], 15711-7