Hydrogen-assisted pulsed-laser deposition of (001)CeO2 on (001) Ge

The growth of epitaxial $\text{(001)}{\mathrm{CeO}}_{\mathrm{2}}$ on a (001) Ge surface using a hydrogen-assisted pulsed-laser deposition method is reported. Hydrogen gas is introduced during film growth in order to reduce or eliminate the presence of the ${\mathrm{GeO}}_{\mathrm{2}}$ from the semiconductor surface during the initial nucleation of the metal–oxide film. The hydrogen partial pressure and substrate temperature are selected to be sufficiently high such that the germanium native oxides are thermodynamically unstable. The Gibbs free energy of ${\mathrm{CeO}}_{\mathrm{2}}$ is larger in magnitude than that of the Ge native oxides, making it more favorable for the metal–oxide to reside at the interface in comparison to the native Ge oxides. By satisfying these criteria, the metal–oxide/semiconductor interface is shown to be atomically abrupt with no native oxide present.