X‐ray photoelectron spectroscopy characterization of band offsets of MgO/Mg 2 Si and SiO 2 /Mg 2 Si heterojunctions

MgO and SiO 2 are the natural oxide layer on the surface of Mg 2 Si and the excellent gate dielectric layer materials. MgO/Mg 2 Si and SiO 2 /Mg 2 Si heterojunctions were successfully prepared by magnetron sputtering. The valence band offset (VBO) and conduction band offset (CBO) of the two heterojunctions were measured by X‐ray photoelectron spectroscopy (XPS) method, and the values were 2.64 and 3.90 eV for MgO/Mg 2 Si and 3.24 and 4.43 eV for SiO 2 /Mg 2 Si, respectively. Different degree of band bending occurs on the two interfaces. As a result, the band diagrams of the both interfaces are all Type‐I (Straddled) band alignment. Such high VBO and CBO can provide suitable barrier heights for both electrons and holes (>1 eV); therefore, both MgO and SiO 2 can be suitable candidates for the preparation of Mg 2 Si‐based thin film transistors.