Heteroepitaxial registry and band structures at the polar-to-polar STO/ZnO(0001¯) interfaces

Abstract The interface between ZnO and SrTiO3 (STO) provides a paradigm for combining perovskite oxides and wurtzite-structure semiconductors. However, the heteroepitaxial and energy band structures of the polar-to-polar STO/ZnO(000 1 ¯ ) interfaces has rarely been studied. In this study, it is shown that the STO films prepared on the ZnO(000 1 ¯ ) substrate by pulsed laser deposition possess [0 1 1]STO and [1 1 1]STO azimuth orientations, which exhibit three- and two-fold rotation domains respectively, as demonstrated by X-ray diffraction and transmission electron microscopy. The band structures of the STO(0 1 1)/ZnO ( 000 1 ¯ ) and STO(1 1 1)/ZnO ( 000 1 ¯ ) interfaces are bending downward as shown in the I-V characteristic spectra and first principle calculations. These results are different from the single orientation ZnO films grown on STO-(0 1 1) and -(1 1 1) substrate, as reported in previous literatures, showing the heteroepitaxial asymmetry between STO/ZnO and ZnO/STO interfaces. This work presents an approach towards the physical modeling of combinations between perovskite oxides and wurtzite-structure semiconductors.