High-Resolution Electron Microscopy of Extended Defects in Wurtzite Crystals

Abstract

Lattice defects in five wurtzite crystals, ZnO, BeO AlN GaN and InN, have been studied by high-resolution electron microscopy for samples pulverized at room temperature. High-density stacking faults were produced in BeO and GaN. With the weak-beam technique, dissociation of basal dislocations was observed in BeO. By high-resolution lattice image observation, both dissociated and undissociated 60°-dislocations were observed in ZnO, AlN and InN. Stacking fault energies were estimated from the separation of partials to be 0.10±0.02 J/m 2 in ZnO, 0.041±0.009 J/m 2 in BeO, 0.22±0.07 J/m 2 in AlN and 0.041±0.008 J/m 2 in InN. Stacking fault energies in wurtzite crystals have been correlated with the c / a ratio of the crystals. a+c dislocations climb-dissociated along the basal plane were also observed in ZnO and BeO.