Interfacial Structure of SrZr$_{x}$Ti$_{1-x}$O$_3$ films on Ge

TL;DR

This study investigates the atomic-scale interfacial structure of SrZr$_{x}$Ti$_{1-x}$O$_3$ films on Ge substrates, revealing polarization effects and band offset correlations crucial for integrating oxides with semiconductors.

Contribution

It combines experimental and theoretical methods to elucidate how Zr content influences interfacial bonding, polarization, and electronic properties in oxide/semiconductor interfaces.

Findings

Interfacial layers are polarized due to ionic displacements.

Buckling correlates with valence band offsets.

Theoretical valence band offsets match experimental data.

Abstract

The interfacial structure of SrZr$_{x}$Ti$_{1-x}$O$_3$ films grown on semiconducting Ge substrates are investigated by synchrotron X-ray diffraction and first-principles density functional theory. By systematically tuning Zr content x, the effects of bonding at the interface and epitaxial strain on the physical structure of the film can be distinguished. The interfacial perovskite layers are found to be polarized as a result of cation-anion ionic displacements perpendicular to the perovskite/semiconductor interface. We find a correlation between the observed buckling and valence band offsets at the SrZr$_{x}$Ti$_{1-x}$O$_3$/Ge interface. The theoretical valence band offsets for the polar structures are in agreement with reported X-ray photoelectron spectroscopy measurements. These results have important implications for the integration of functional oxide materials with established semiconductor based technologies.