Threading dislocations in wurtzite ZnO films, grown on the (11•0) plane of sapphire, were studied by means of transmission electron microscopy. Most of the

threading dislocations were found to be of screw or mixed type. Dislocation half-loops, elongated along the c-axis, were observed. It was suggested that they were formed when 2 screw dislocations of opposite sign attracted each other during growth, and combined.

Transmission Electron Microscopy of Threading Dislocations in ZnO Films Grown on Sapphire. Lim, S.H., Washburn, J., Liliental-Weber, Z., Shindo, D.: Journal of Vacuum Science and Technology A: 2001, 19[5], 2601-3