Evolution of Fermi level position and Schottky barrier height at Ni/MgO(0 0 1) interface

Fermi level evolution and Schottky barrier height (SBH) for Ni/MgO(0 0 1) interfaces have been studied using X-ray photoelectron technique. It was found that upward band bending occurred at the initial Ni growth stage and Ni bulk properties recovered after 6–8 Å thickness. The measured Schottky barrier heights are strongly interface structure-dependent, with the variation in the range of 3.1 eV for perfect interface to 1.6 eV for defect-rich interface. First-principles calculations on the evolution of SBH for the initial growth of Ni on perfect MgO(0 0 1) surface are combined with experimental results to investigate the underlying microscopic mechanism. Adatom-induced states (or interfacial bonding states), MIGS and defects states were used to rationalize the evolution of Fermi level and corresponding SBH for various interface structures. This work shows that SBH can be engineered by interface structure control, and is expected to shed light on the effect of interface structures on the formation mechanism of SBH at metal/oxide interface.