Energy band structure of the single crystalline MgO/n-Ge(001) heterojunction determined by x-ray photoelectron spectroscopy

We report the energy band structure of the single crystalline MgO/n-Ge(001) heterojunction characterized by x-ray photoelectron spectroscopy. The valence band offset of ΔEV=3.64±0.07 eV with a 1.49±0.02 eV band bending was obtained. Given the experimental band gap of MgO (7.83 eV), a type-I band alignment with a conduction band offset of ΔEC=3.52±0.07 eV is found. The band alignment of the MgO/n-Ge heterojunction including the large band bending was analyzed by a theoretical model taking into account the formation of the interface dipole.