Research About Preparation,Properties And Ultraviolet Photoelectric Devices Of Two-dimensional FePS₃

Following the success of graphene and transition metal dichalcogenides,multielement phosphorus semiconductor materials including BP,doped BP and related alloy,metal phosphorus trichalcognides(MPTs)have drawn intensive attention for their abundant band-structure and impressively novel properties.However,the report about the scalable synthesis of these materials in high quality is rare.In addition,the potential intrinsic magnetism down to monolayer,suitable wide bandgap and theoretically predicted high mobility suggest FePS3 to be splendid candidate for UV detection and 2D magnetoelectricity.In this thesis,we firstly synthesized some representative multielement phosphorus materials through CVT method,including Fe doped BP and FePS3.XRD,Raman and XPS were used to analyze and confirm the crystal structure,chemical constitution,etc..Further characterizations on their microstructure,by employing TEM,SEAD,EDS and HRTEM,suggest the high quality with high crystallinity and uniform atomic distribution of our synthesized samples.The atomic doping and growth route developed here provides a good basis for the further optimization and scalable synthesis of multielement phosphorus materials Secondly,the magnetism of FePS3 was systematically characterized.The measurement shows that FePS3 bulk crystals display phase transition of antiferromagnetism at 125 K.Hall devides were fabricated with mechanically exfoliated 2D FePS3 nanosheets with thickness of 10-20 nm.A preliminary magnetoelectricity characterization on the FePS3 was hence carried out.From our observation,we have summarized some key factors and challenges for the further exploring of magnetoelectricity based on 2D MPTs as FePS3.Thirdly,the photoresponse characteristic of UV detectors based on FePS3 has been comprehensively investigated.The photoresponse of the device under 254 nm shows impressive response characteristics,with very short rise time and decay time measured to be 105 ms and 120 ms,respectively.The responsivity of the photodetector,which is observed to be determined by bias gate voltage,may achieve as high as 171.6 mAW-1 under the illumination of 254 nm wavelength weak light,which has a more than 3 times enhancement from-20 V to-40 V.Notably,both negative and positive photoconductivities exist in the FePS3 photodetectors and can be controllably switched with bias voltage.The eminent and novel photoresponse property paves way for the further development and practical use of 2D MPTs in high-performance UV photodetections.