Epitaxial Growth of SrMnO3 Films on SrTiO3 Substrates by Off-Axis Angle Radio Frequency Magnetron Sputtering

Abstract

ABSTRACTIn this study, high-quality SrMnO3 (001) film was grown on a SrTiO3(001) substrate using a 4 N purity target by 90° off-axis RF magnetron sputtering. In this study, the influence of the plasma center and surrounding positions on the growth of the SrMnO3 film was investigated under different sputtering temperatures and working pressure conditions. The results revealed that the SrMnO3 film exhibited the best crystallinity at the sputtering center under a high working pressure (135 mTorr), high substrate temperature (750 °C), and Ar to O ratio of 1:1. After investigating the relationship between the growth rate and the working pressure through the Alpha step, the film was grown at a lower sputtering rate of 2 nm/min. X-ray diffraction confirmed that the SrMnO3 film was epitaxially grown on the SrTiO3 substrate with an orientation relationship of SrMnO3(001)//SrTiO3(001). The growth state of SrMnO3 on the crystal SrTiO3 substrate was investigated by scanning electron microscopy (SEM); the results revealed that the surface was smooth and compact. In addition, the atomic force microscopy results were consistent with the SEM result; the results revealed that the surface of the film was atomically flat, and the atomic level flatness was 0.906 nm. Furthermore, the contact angle measurement results revealed that the film and substrate surface energy were almost similar and exhibited similar adhesion and internal stress. In addition, energy-dispersive X-ray spectroscopy analysis revealed that the atomic composition ratio in the high-temperature sputtered SrMnO3 film was consistent with the stoichiometric ratio of SrMnO3. The scope and results of this study will lay a foundation on the further research of the performance of SrMnO3 film.