Charge transfer from Cu inCu2Oepitaxially grown on MgO(001) by dc-reactive magnetron sputtering

Abstract

The ${\mathrm{Cu}}_{2}\mathrm{O}$ film is epitaxially grown on air-cleaved MgO(001) by dc-reactive magnetron sputtering. From the reflection high-energy electron diffraction patterns two orientations are identified: (I) ${\mathrm{Cu}}_{2}\mathrm{O}(001)\ensuremath{\Vert}\mathrm{MgO}(001)$ and ${\mathrm{Cu}}_{2}\mathrm{O}[100]\ensuremath{\Vert}\mathrm{MgO}[100]$ and (II) ${\mathrm{Cu}}_{2}\mathrm{O}(110)\ensuremath{\Vert}\mathrm{MgO}(001)$ and ${\mathrm{Cu}}_{2}\mathrm{O}[11\ifmmode\bar\else\textasciimacron\fi{}0]\ensuremath{\Vert}\mathrm{MgO}[110].$ The charge transfer $\ensuremath{\Delta}{q}^{\mathrm{Cu}}$ from Cu to O is also estimated by Auger electron spectroscopy. Both the Auger intensity ratio O/Cu and $\ensuremath{\Delta}{q}^{\mathrm{Cu}}$ increased for the film annealed in ${\mathrm{O}}_{2},$ which indicates the as-deposited film is O deficient. From the annealed film $\ensuremath{\Delta}{q}^{\mathrm{Cu}}$ for ${\mathrm{Cu}}_{2}\mathrm{O}$ is tentatively taken as $0.65e$ though still O deficient.