Epitaxial Antiferroelectric BiOS Films with Superior Photoresponse.

Two-dimensional bismuth oxychalcogenide is a rising material system with superior electronic properties. However, a lack of high-quality synthesis impedes the exploration of fundamental understanding and practical applications. This work presents high-quality epitaxial BiOS films on (LaAlO)(SrTaAlO) with diverse properties by taking advantage of lattice compatibility. The atomically resolved sharp interface of BiOS/(LaAlO)(SrTaAlO) heteroepitaxy is observed with the verification of centrosymmetric breaking through microscopic evidence and macroscopic characterizations. Such an epitaxial feature of the BiOS film provides an essential step for applications compared to those of chemically synthesized nanomaterials. The interior polarization and piezoelectricity can be investigated through atomic-scale observation and RhB degradation of BOS. Meanwhile, this synthesized system can achieve a strong photoresponse with an on/off ratio of ∼10 and a responsivity of ∼60 mA/W in the range of red light (620-750 nm). With these advantages, the demonstrated epitaxial BiOS shows a huge potential for applications in high-performance optoelectronic devices.