Controllable Preparation And Photoelectric Properties Of Nanoscale Platinum Sulfide Films

Two-dimensional layered semiconductors have received extensive attention due to their unique electronic and optoelectronic properties,with PtS having a tunable bandgap as a function of thickness compared to zero-bandgap graphene and other larger-bandgap transition metal chalcogenides.The semiconductor band gap of single-layer PtS₂is 0.25e V.With the increase of the number of layers,one is that the band gap of PtS₂can be increased from 0.25 e V to 1.6 e V;the other is that the material properties change from semiconductor to semi-metal.The preparation of PtS₂with controllable thickness and size with good optoelectronic properties has important theoretical and practical value for the industrialization of PtS₂.In this paper,PtS₂films were prepared by chemical vapor deposition method using sulfur powder and platinum substrate as raw materials.The effects of growth temperature and heating rate on the morphology of PtS₂were discussed.The composition,structure,morphology and optoelectronic properties of PtS₂were characterized in order to establish the correlation between the optoelectronic properties and morphology of PtS₂.The specific research contents are as follows:（1）Using sulfur powder as raw material,a PtS₂film was prepared by chemical vapor deposition on a platinum sheet with a size of about 4 cm~2and a thickness of 3.03nm.The prepared films were characterized by atomic force microscopy,X-ray photoelectron spectroscopy,Raman spectroscopy and other techniques,and it was proved that the prepared material was multilayer PtS₂.（2）The influencing factors of the preparation of PtS₂were explored.The effects of heating rate and growth temperature on the morphology of PtS₂were studied.The growth mechanism of PtS₂films was explained from chemical kinetics and thermodynamics,respectively.（3）Construction of PtS₂film optoelectronic devices.Au and Cr electrode blocks were evaporated on the PtS₂film by physical mask method,and the photoelectric properties were detected.（4）The optoelectronic properties of PtS₂films at high temperature were investigated.By changing the temperature of the hot stage in the optoelectronic test platform,the PtS₂film was heated to explore its optoelectronic properties at different temperatures.（5）The PtS₂film was transferred to the surface of the BFO substrate by wet transfer technology to construct a PtS₂-BFO heterojunction.The research results obtained are summarized as follows:（1）In the process of exploring the influencing factors of the preparation of PtS₂,it is found that the platinum metal agglomerates in the process of heating up the nano-platinum to form granular PtS₂.By adjusting the heating rate,the reaction rate of S and Pt is reduced,and the S-Pt-S bond is formed to prevent the agglomeration of nano-platinum.The PtS₂films prepared at a growth temperature of 600℃and a heating rate of 2℃/min had better film formation.（2）In the exploration of the optoelectronic properties of the PtS₂film,it was found that the prepared PtS₂film has a stable infrared broad spectrum（532 nm-2200 nm）.Further exploration found that the PtS₂film with a thickness of 6.9nm has the highest photoelectric response IT image signal-to-noise ratio.,with the best response,with a photocurrent of up to 70 n A.（3）In the study of high temperature photoelectric properties of PtS₂films,it was found that with the increase of temperature,the output current,dark current and photocurrent all increased.It is concluded that PtS₂can be used as a new type of electronic device and high temperature optoelectronic device.（4）Under 2V bias,the photoelectric response of PtS₂-BFO heterojunction was explored.It is found that under the irradiation of 1550 nm wavelength laser,with the increase of gate voltage,the on/off of the photocurrent signal is obvious,the curve is linear,repeatable and stable.The photocurrent rise time reaches the millisecond level.Compared with the pure PtS₂film,the response time is improved by two orders of magnitude.