Reserch On Schottky Barrier Photodetector Based On Tin Disulfide

Tin disulfide（SnS₂）has broad prospects in the field of optoelectronics devices due to its unique layered structure and stable chemical properties.But there is still few research focused on device structure of the photodetectors based on SnS₂.In this thesis,the photodetection performance of SnS₂photodetector based on Schottky barrier was explored.Therefore,SnS₂ nanosheets and thin films were fabricated via hydrothermal and mechanical exfoliation methods,respectively.The photodetector of SnS₂ based on Schottky barrier was fabricated and the visible photodetection performance was systematically analyzed.The details are as below:1.Photodetector based on SnS₂ nanosheets with Ohmic electrodes:SnS₂nanosheets were synthesized via hydrothermal method,and the morphology,phase and elemental composition were characterization.The average thickness of hexagonal SnS₂nanosheets were 20.7 nm,and the transverse diameter of 190 nm,with high crystallinity and purity.The aluminum electrode was deposited by DC sputtering,and photodetector based on SnS₂ nanosheets with aluminum electrodes was fabricated.The peak responsivity and detectivity are 152μA/W and 3.99×10⁵ Jones.The response time is0.24 s.2.Schottky barrier photodetector based on SnS₂ nanosheets:The electron transport process and I-V curves were simulated and analyzed after establishing an Au/SnS₂/Al Schottky barrier diode model.Au/SnS₂/Al and Pt/SnS₂/Al Schottky barrier photodetectors were fabricated via DC sputtering method,and the visible photodetection performance was determined under the illumination of 405 nm and 532nm laser,the result shows that the dark current of Au/SnS₂/Al and Pt/SnS₂/Al photodetectors are 5.4 n A and 5.2 n A,respectively,which are about one order of magnitude lower than the Al/SnS₂/Al photodetector.And the photoresponsivity,detectivity,and response time of Au/SnS₂/Al and Pt/SnS₂/Al photodetectors are about one order of magnitude higher than the Al/SnS₂/Al photodetector.3.Schottky barrier photodetector based on SnS₂ thin films:The SnS₂ single crystal was synthesized via a chemical vapor transport technique,and SnS₂ thin film were fabricated via mechanical exfoliation.The sample were characterized by atomic force microscopy,optical microscopy,transmission electron microscopy and Raman spectroscopy.The thickness of SnS₂ film was 0.55 nm,and the size 15μm.Then,Al/SnS₂/Al,Au/SnS₂/Al and Pt/SnS₂/Al photodetectors based on SnS₂ films were fabricated via PDMS-assisted pattern transfer method.The photoresponsivity,detectivity and external quantum efficiency of Schottky barrier photodetectors are higher than the Al/SnS₂/Al photodetector.The dark current of the Pt/SnS₂/Al photodetector is 2.1 n A,which is lower than the Ohmic photodetector obviously.The photoresponsivity is 2550 A/W,which is about an order of magnitude higher than the Al/SnS₂/Al（244 A/W）photodetector.