As the concentration of intrinsic defects becomes sufficiently high in O-deficient

ZnO, interactions between defects led to a significant reduction in their formation

energies. It was shown that the formation of both O vacancies and Zn interstitials

became significantly enhanced by a strong attractive interaction between them,

making these defects an important source of n-type conductivity in ZnO.

Rich Variety of Defects in ZnO Via an Attractive Interaction Between O Vacancies

and Zn Interstitials: Origin of n-Type Doping. Y.S.Kim, C.H.Park: Physical

Review Letters , 2009, 102[8], 086403