Interfacial Structure of SrZrxTi1−xO3 films on Ge

Chen T, Ahmadi-Majlan K, Lim ZH, Zhang Z, Ngai JH, Kemper A, Kumah D
Appl. Phys. Lett. 113, 201601 (2018)


The interfacial structure of SrZrxTi1−xO3 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 SrZrxTi1−xO3/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.