Atomic and electronic structures of inversion domain boundary in MgO doped AlN

AlN has been used as electrostatic chucks due to its high volume resistivity. It has been reported that the doping of MgO can further increase the volume resistivity even at high temperature. The enhancement was proposed to be correlated with its internal defects: inversion domain boundaries (IDBs), but the detailed mechanism is still not clear. In this study, we clarify the origin of increased volume resistivity from the atomic and electronic structures of the IDBs. We performed atomic-scale structural analysis of IDBs in MgO doped AlN using aberration corrected scanning transmission electron microscope (STEM) and energy dispersive X-ray spectroscopy (EDS). It was found that two types of IDBs coexist alternately in the MgO doped AlN, with strong segregation of Mg and O at both IDBs. Furthermore, band structure calculations were performed using the hybrid density functional theory (hybrid DFT) method, and it was found that the interfacial segregation of Mg and O may form a potential barrier at the IDB. These results suggest that the segregation of Mg and O at IDBs should be the origin of increased volume resistivity in the MgO doped AlN.