Transmission electron microscopy characterization of CrN films on MgO(001)

Two CrN(001) films with different thickness were grown on MgO(001) substrates using unbalanced d.c. magnetron sputtering. The morphology and interfacial structure of the films are characterized by using conventional transmission electron microscopy, weak-beam dark-field microscopy and spherical aberration (C_S)-corrected high-resolution transmission electron microscopy. The microscopy studies revealed the well-known cube-on-cube orientation relationship. While an interface dislocation network with b^→=½a_CrN<100> edge dislocations was identified, only part of the lattice mismatch is relaxed. The misfit dislocation structure and growth defects are analyzed and discussed based on the weak-beam dark-field and high-resolution transmission electron microscopy results. - Highlights: • Two CrN films were sputtered on MgO(001) substrates under various deposition conditions. • The CrN films nucleate epitaxially with a cube-on-cube orientation relationship. • Transmission electron microscopy shows the existence of interface dislocation networks. • The misfit between the CrN films and MgO substrates is only partially relaxed. • CrN deposition at higher bias voltage leads to an increased defect density