Preparation And Characterization Of Layered GaS And GaSe Two-dimensional Nanosheets

The unique properties of graphene in two-dimensional materials make it shining in the field of optoelectronics,biosensing and biomedicine,and it has received enthusiastic attention in the world.However,graphene also has its own defects,such as the band gap structure of zero band gap,which hinder the application of graphene in various basic fields.In recent years,researchers have developed a large number of new two-dimensional materials,such as 2D-TMDs,and maken in-depth study of their properties and applications.Two-dimensional materials have interesting physical properties,such as semiconductivity,superconductivity,metality,magnetism,insulation,and thermoelectricity.Since most of two-dimensional materials do not have dangling bond,layers of different two-dimensional materials can be intergrated by Van der Waals forces,regardless of lattice mismatch.which will bring new breakthroughs and progress to the academic community and push forward the development of different fields.One can also obtain a new kind of two-dimensional material by means of CVD growth or stripping,and study its featured properties and develop new application in different technical fields.However,the controlled growth of a specific layered two-dimensional materials is still a huge challenge.In this paper,layered GaS and GaSe two-dimensional nanosheets are grown by physical vapor deposition,and their morphology and structure are studied.The main contents of this paper are as follows:(1)Preparation of two-dimensional layered GaS nanosheets.In this paper,the physical vapor deposition method is used to synthesize two-dimensional GaS nanosheets in a single-temperature zone tube furnace.Through systematic experiments,the effects of different experimental conditions,such as the growth temperature,carrier gas flow rate,growth time and distance from the product to the reactants on the morphology,size and quality of GaS nanosheets are systematically studied.The GaS nanosheets are characterized through optical microscope(OM),atomic force microscope(AFM),scanning electron microscope(SEM),laser confocal inverted microscope Raman spectroscopy,X-ray diffraction(XRD)and transmission electron microscope(TEM): the GaS nanosheets are triangular,the lateral dimension is 1-4 ?m,the atomic force microscope shows the thickness of the nanosheets is between 2.5-23.4 nm;the selected area electron diffraction(SAED)analysis indicates that the GaS nanosheets are single Crystal,high-resolution transmission electron micrographs show the lattice fringes of the hexagonal structure,which indicates that the crystallinity is good.(2)Preparation of two-dimensional layered GaSe nanosheets.The physical vapor deposition method is used to synthesize two-dimensional GaSe nanosheets in a single-temperature zone tube furnace.Through systematic experiments,th e effects of different experimental conditions,such as the growth temperature,carrier gas flow rate,growth time and distance from the product to the reactants on the morphology,size and quality of GaSe nanosheets are systematically studied.Optical microscope(OM),atomic force microscope(AFM),scanning electron microscope(SEM),laser confocal inverted microscope Raman spectroscopy,X-ray diffraction(XRD)and transmission electron microscope(TEM)instrumentation were usd to characterize the product: the GaSe nanosheets are triangular or hexagon under optical microscopy,with the lateral dimension of 1-4 ?m or 2-5 ?m.Atomic force microscopy data show that the thickness of the nanosheets was 0.85-29 nm.The selected area electron diffraction(SAED)nanosheets show that the GaSe nanosheets were single crystals,and the high resolution transmission electron micrographs showed the lattice fringes of the hexagonal structure,indicating good crystallinity.