Structure of the Basal Edge Dislocation in ZnO

Abstract

Basal dislocations having a Burgers vector of 1/3<2 1 ¯ 1 ¯ 0> in zinc oxide (ZnO) with the wurtzite structure are known to strongly affect physical properties in bulk. However, the core structure of the basal dislocation remains unclear. In the present study, ZnO bicrystals with a {2 1 ¯ 1 ¯ 0}/<01 1 ¯ 0> 2° low-angle tilt grain boundary were fabricated by diffusion bonding. The resultant dislocation core structure was observed by using scanning transmission electron microscopy (STEM) at an atomic resolution. It was found that a basal edge dislocation in α-type is dissociated into two partial dislocations on the (0001) plane with a separation distance of 1.5 nm, indicating the glide dissociation. The Burgers vectors of the two partial dislocations were 1/3<1 1 ¯ 00> and 1/3<10 1 ¯ 0>, and the stacking fault between the two partials on the (0001) plane has a formation energy of 0.14 J/m2. Although the bicrystals have a boundary plane of {2 1 ¯ 1 ¯ 0}, the boundary basal dislocations do not exhibit dissociation along the boundary plane, but along the (0001) plane perpendicular to the boundary plane. From DFT calculations, the stacking fault on the (0001) plane was found to be much more stable than that on {2 1 ¯ 1 ¯ 0}. Such an extremely low energy of the (0001) stacking fault can realize transverse dissociation of the basal dislocation of ZnO.

Keywords

• zinc oxides (ZnO)
• wurtzite structure
• line defects
• low-angle grain boundaries
• scanning transmission electron microscopy (STEM)
• generalized stacking fault (GSF) energy