Energy-band alignments at $LaAlO3$ and Ge interfaces

The energy-band alignments for $LaAlO3$ films on $p-Ge(001)$ with and without $GeOxNy$ interfacial layer have been studied using photoemission spectroscopy. The valence-band offsets at $LaAlO3∕GeOxNy∕Ge$ and $LaAlO3∕Ge$ interfaces were measured to be 2.70 and $3.06eV$⁠, respectively. The effect of interfacial $GeOxNy$ layer on the band alignments is attributed to the modification of interface dipoles. The conduction-band offsets at $LaAlO3∕Si(001)$ and $LaAlO3∕Ge$ interfaces are found to have the same value of $2.25±0.05eV$⁠, where the shift of valence-band top accounts for the difference in the energy-band alignment at two interfaces.