Synthesis,Heat Transport Manipulation And Optical Modulation Of 2D Matrerials

Ever since the discovery of graphene,the two-dimensional materials(such as graphene,disulfide tungsten and molybdenum)have shown excellent physical and chemical properties.It is expected for the two-dimensional material to be widely applied in computer,energy storage,water purification and other fields.The understanding of two-dimensional materials is relatively scarce compared to the traditional bulk materials.Growth,transfer and characterization of large two-dimensional material single crystals is still the worldwide research hotspot.In addition,effective modulation of two-dimensional materials’ optical,electrical and thermal properties is still difficult to archive.Therefore,to benefit the researches on the two-dimensional materials,this paper focuses on the preparation,characterization and modulation of the two-dimensional materials,using chemical vapor deposition technique,micro-zone Raman spectrum technology,etc.The research mainly includes the two-dimensional material chemical vapor deposition,thermal transport modulation,inelastic light scattering characterization and modulation,and related two-dimensional heterostructure fabrication and modulation.The progress made in this paper can be summed as follows:Large area single crystal graphene and disulfide tungsten was obtained using chemical vapor deposition method.We found out that Raman peak width at half height of graphene was highly affected by the beneath metal ions,indicating the change of phonon lifetime.In addition,we found out that Raman scattering intensity could be used for adsorption layer growth and torsion angle determination.We built a non-contact thermal conductivity measurement platform,and determined the thermal conductivity of graphene.The cold plasma was used to modulated graphene defect concentration,and the graphene thermal conductivity response speed of the defect concentration was determined for the first time.In addition,a set of interface thermal conductivity measurement system was built using femtosecond laser,and the response speed of the interface thermal conductivity of graphene to the defect concentration was also determined for the first time.The effective modulation of optical inelastic scattering properties of two-dimensional disulfide tungsten thin films were carried out.Using the gold particles,Raman scattering of tungsten disulfide can be enhanced,revealing the original Raman silent peaks.It is proposed that the scattering enhancement can be attributed to the electron spin orbit splitting for the first time.The intensity of the applied excitation laser can be used to effectively adjust the photoluminescence intensity and emission wavelength of tungsten sulfide.In addition,effective control of the fluorescence quenching intensity was achieved by applying external mechanical stress to graphene and its composite structure.We developed a method for the accurate localization of two-dimensional material onto substrate,which can be used for the fabrication of heterojunction with non-contaminated interface.This thesis also used graphene for tungsten disulfide Raman scattering enhancement,where the two-dimensional material Raman enhancement was truly observed for the first time.