HIGH-RESOLUTION ELECTRON-MICROSCOPY OF EXTENDED DEFECTS IN WURTZITE CRYSTALS

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 iii BeO. By high-resolution lattice image observation. both dissociated and undissociated 60-degrees-dislocations were observed in ZnO, AIN and InN. Stacking fault energies were estimated from the separation of partials to be 0.10 +/- 0.02 J/m2 in ZnO, 0.041 +/- 0.009 J/m2 in BeO, 0.22 +/- 0.07 J/m2 in AIN and 0.041 +/- 0.008 j/M2 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.