Interfacial properties in ultrathin MgO films on TiN(001) surfaces: Ab-initio calculations

By using ab-initio electronic structure calculations based on the density functional theory, we systematically investigated the interfacial properties of the MgO/TiN(001) system with increasing MgO film thickness from one to three monolayers (ML). Atomic geometries and adhesion characteristics of the MgO/TiN(001) systems in the range of 1- to 3-ML MgO are presented. O-Ti and Mg-N bonds were formed across the interfaces. Our calculated energetics indicate that the interfacial adhesion of the MgO films to the TiN substrates was stronger than that for the metal-oxide systems of MgO/Ag(001) and MgO/Fe(001). An analysis of the electronic properties of the MgO/TiN(001) systems was also performed. Upon the adsorption of the MgO overlayers, the work function of the TiN(001) surface was found to exhibit a significant decrease due to the large interface dipole formed at the interface of this system. Very interestingly, the obtained work functions of 1.89-1.96 eV for 1- to 3-ML MgO films on TiN(001) were lower than those for other metal-supported MgO films.