Research On The Preparation Of Photodetector And Its Photoelectric Properties Based On MoS₂/MoO₃ Heterojunction

Molybdenum disulfide（MoS₂）is a representative material of two-dimensional（2D）transition metal dichalcogenides（TMDCs）,which has a good electron mobility(200cm²·V^-1·s^-1),tunable bandgap by changing the number of layers（1.2～1.8 e V）,high light absorption efficiency（10%）,and other advantages.Therefore,MoS₂is widely used in contemporary field effect transistors,solar cells,sensors,photodetectors and other fields,and shows great application prospects superior to graphene.For the preparation of high-performance photodetectors,the synthesis of large-scale,thin-layer,and high-quality MoS₂films has become a key research content.In addition,the total amount of light absorption is limited due to its atomic thickness（single layer about 0.65 nm）,which hinders the development of high-performance photodetectors based MoS₂.Therefore,in view of the limitations of the above two MoS₂films in the application of photodetectors,the work of this paper is mainly carried out from the following points:（1）Systematic study of vulcanized large-scale,thin-layer MoS₂materials:In the experiment,the MoO₃precursor was pre-grown on the Si/Si O₂substrate by atomic layer deposition（ALD）method,and then the MoS₂nucleation site was fixed by sulfided the pre-grown precursor on the substrate to realize the large-scale MoS₂films.The experimental design realizes the regulation of MoS₂nucleation density by controlling the deposition period of MoO₃material,and systematically explores the thickness of the synthesized MoS₂film.Further,the temperature at which MoO₃on the Si/Si O₂substrate is completely sulfided was explored to realize the preparation of high-quality MoS₂thin films.Through the adjustment of the above two experimental conditions,the experiment finally successfully realized the preparation of large-scale（>500μm）and thin（1～3 L）MoS₂films.（2）Study on the construction of MoS₂/MoO₃heterostructure and its photoelectric detection performance:（1）The effect of the thickness of the capping layer on the photoelectric performance of the heterojunction was investigated.The ultrathin MoO₃capping layer and MoS₂are used to construct a heterostructure by layer-by-layer controllable ALD method,and different MoO₃thicknesses can be achieved by different deposition cycles.The experimental results show that the thinner the cover layer of the heterojunction,the better the light transmittance and the better the light absorption performance.（2）2D/0D MoS₂/MoO₃heterojunctions were fabricated in one step by physical vapor deposition of MoO₃quantum dots during vulcanization.While the built-in electric field promotes photogenerated carriers,interface defects trap holes to reduce exciton recombination and achieve photocurrent enhancement.The test results show that the heterojunction photodetector realizes the enhancement of optoelectronic performance,and the responsivity is about 14.6 times higher than that of the single MoS₂.（3）Design and implementation of localized surface plasmon resonance（LSPR）:The design utilizes Au nanoparticles（Au-NPs）to induce LSPR to enhance the light absorption of MoS₂/MoO₃heterojunctions in the visible light range,while inducing an enhanced built-in electric field to further facilitate photogenerated carrier separation.In the experiment,the particle size（20 nm）of Au-NPs,which can realize the experimental design,was simulated by finite difference time domain（FDTD）.Secondly,Au-NPs were prepared by a small ion sputtering instrument,which was confirmed to be consistent with the simulation results by the actual absorption test.Finally,LSPR was constructed by compounding Au-NPs on the surface of MoS₂/MoO₃heterojunction.The photoelectric test results show that the responsivity of the MoS₂/MoO₃@Au photodetector is further enhanced by about 1.5 times after the realization of LSPR.