Calibration of binding energy and clarification of interfacial band bending for the Al₂O₃/diamond heterojunction

Due to the presence of an intrinsic C 1s peak in diamond, it is impossible to calibrate its binding energies using the adventitious C 1s peak (284.8 eV) during x-ray photoelectron spectroscopy measurement. The absence of accurate binding energy measurement makes it challenging to determine the interfacial band bending for the oxide/diamond heterojunction. To overcome this issue, a net-patterned gold (Au) mask is applied to the boron-doped diamond (B-diamond) to suppress the charge-up effect and calibrate the binding energy using the standard Au 4f peak (83.96 eV). The B-diamond epitaxial layer shows downward band bending toward the surface with a valence band maximum of 0.85 eV. Upon the formation of Al₂O₃ using an ozone precursor through the atomic layer deposition technique, the B-diamond continues to exhibit downward band bending toward the Al₂O₃/B-diamond interface. However, the bending energy has reduced, potentially attributed to the modification of the oxygen vacancies on the B-diamond surface by the ozone precursor during the Al₂O₃ deposition.