Characterization of prismatic slip in PVT-grown AlN crystals

•Prismatic slip of dislocations is observed in AlN bulk crystals grown by PVT.•Regions where BPDs generated from prismatic dislocations in PVT grown AlN are expected and demonstrated.•The critical resolved shear stress estimated from experiment and theoretical calculation can match very well.•Results show that radial thermal gradient provides driving force for the formation of prismatic dislocations in PVT grown AlN.