Fabrication of Conductive Domain Walls in x-cut Congruent Thin-film Lithium Niobate Using an Electrical-field Poling Technique(Invited)

Conductive ferroelectric domain walls have attracted increasing research interest in the field of nanoelectronics,and the fabrication technique for such domain walls is vital.In this study,we investigated in detail the fabrication of conductive domain walls in x-cut congruent thin-film lithium niobate(TFLN)using an electrical-field poling technique.The ferroelectric domain structures can be controlled through the applied electrical field and applied pulse numbers,and the domain inversion process is related to the conduction characteristics of the domain walls.The domain structures in TFLN are revealed using confocal second-harmonic microscopy and piezoresponse force microscopy.The results provide further directions for the development and application of conductive domain walls in TFLN.

Controlled manipulation of conductive ferroelectric domain walls and nanoscale domains in BiFeO_(3) thin films

Recently,there is a surge of research interest in configurable ferroelectric conductive domain walls which have been considered as possible fundamental building blocks for future electronic devices.In this work,by using piezoresponse force microscopy and conductive atomic force microscopy,we demonstrated the controlled manipulation of various conductive domain walls in epitaxial BiFeO_(3) thin films,e.g.neutral domain walls(NDW)and charged domain walls(CDWs).More interestingly,a specific type of nanoscale domains was also identified,which are surrounded by highly conductive circular CWDs.Similar nano-scale domains can also be controlled created and erasured by applying local field via conductive probe,which allow nondestructive current readout of different domain states with a large on/off resistance ratio up to 102.The results indicate the potential to design and develop high-density non-volatile ferroelectric memories by utilizing these programable conductive nanoscale domain walls.

Enhanced domain wall conductivity in photosensitive ferroelectrics Sn_(2)P_(2)S_(6) with full-visible-spectrum absorption

Recent optical stimulation suggests a vital non-contact pathway to manipulate both macroscopic and microscopic ferroelectric properties and paves the foundation for optoelectronics devices.However,up to date,most optical-related manipulation of ferroelectric properties is restricted due to their intrinsic bandgap and limited visible light spectrum absorption.Here,we reveal non-oxide Sn_(2)P_(2)S_(6) single crystal possesses full-visible-spectrum absorption(from 300 to 800 nm)with a unique disproportionation mechanism of photoexcited Sn ions and Urbach tail,which is not contradicting to the intrinsic band gap.Interestingly,we observed the existence of conductive domain walls(c-DW)and the light illumination induced significant enhancement of the domain wall conductivity caused by such disproportionation reaction.In addition,the domains separated by c-DW also exhibited noticeable electrical conductivity difference in the presence of optical illumination owing to the interfacial polarization charge with opposite signs.The result provides a novel opportunity for understanding the electrical conductivity behavior of the domains and domain walls in ferroelectrics with full-visible-spectrum absorption and achieving greatly enhanced performances for optoelectronics.