Study On Stress Control Of Photoelectric Properties Of Thin Crystals PtS₂

Two-dimensional materials are expected to replace traditional semiconductors and become popular candidates for the development and preparation of nanoelectronic devices in the future because of their excellent physical properties.Although researchers have studied many photodetectors based on two-dimensional(2D)materials,there is still a lack of analysis on the mechanism of photocurrent generation.This article demonstrates an approach to tune the photoelectric properties of Platinum sulfide(PtS₂)by using a ferroelectric substrate PMN-PT as a strain generator.The main research contents include:firstly,using the Chemical vapor transmission and phosphorus as the transport agent,we have prepared high-quality PtS₂single crystals,and performed XRD characterization,Raman spectroscopy characterization and SEM energy spectrum analysis on the single crystals.Next,the bulk PtS₂was peeled off into ultra-thin flakes on the PMN-PT substrate by scotch tap method,and the samples were characterized by Raman spectroscopy,which proved that the prepared PtS₂samples had high crystalline quality.After selecting a suitable single crystal,the PtS₂device was fabricated by UV lithography,and Ti/Au(10 nm/80 nm)was deposited as the contact electrode.Use a semiconductor characterization system to test the PtS₂transistor.The results show that the drain current and responsivity of the PtS₂photodetector are directly coupled with the electrostriction of PMN-PT,showing a high switching ratio of?10²,a high responsivity as high as 2.69×10³A/W,a detectivity as high as 2.7×10¹²Jones and photogain?1.9×10⁵.Moreover,the research in this paper shows that applying a proper range of stress to the few-layers of PtS₂can increase the photocurrent,the photodetector displays a strains-modulated photocurrent generation mechanism,that is,from the photoconductive effect dominant to photogating effect dominant under electric field induced strain.This provides a new idea and method for optimizing the electrical and optical properties of two-dimensional layered materials,and the electrical properties of few-layers PtS₂are greatly regulated by micro-stress,and PtS₂can also be used as an excellent candidate material for piezoelectric sensors.