The orientation of defect pairs with respect to the crystallographic axes was determined. In a particular orientation of the strain with respect to the c-axis of the crystal, and the k-vector, the defect pair emission lines became split due to combined strain and spin exchange. The polarization of the split components, when correlated with knowledge concerning the specific orientation of the crystal and the k-vector, permitted the determination of the orientation of defect pairs in the crystal.

Determination of Defect Pair Orientation in ZnO. Reynolds, D.C., Look, D.C., Jogai, B., Litton, C.W., Cantwell, G., Harsch, W.C.: Solid State Communications, 1999, 109[6], 419-22