Study On The Influence Of Surface Modification On Two-dimensional Gallium Nitride

In 2004,the experimental synthesis of graphene overturned the recognition that "the thermodynamic fluctuation does not allow any two-dimensional crystal to exist at a finited temperature".Since then,the research of two-dimensional nano materials has developed rapidly.Two dimensional nanomaterials are sheet materials with a thickness of only a few atomic layers,but a horizontal scale larger than 100 nanometers.The special layered crystal structure makes the two-dimensional nano materials have special physical and chemical properties,so they have great potential applications in the fields of electronics,catalysis,sensors,flexible energy storage devices and so on.Compared with other nano materials,the two-dimensional nano materials have a large specific surface area,and their properties are easily controlled by surface adsorption atoms.Because of its excellent properties,2D GaN has become a research hotspot of 2D nanomaterials.This paper focuses on the large specific surface area of two-dimensional Gan to spread related research,and study the influence of different atoms adsorbed on the surface of two-dimensional Gan on the properties of two-dimensional Gan.The research is divided into two parts:theoretical calculation and experiment.Firstly,based on the density functional theory,the electronic and optical properties of two-dimensional GaN with monolayer,bilayer and three-layers structure,as well as the modified systems with CS,S and O atoms adsorbed on 2d-GaN surfaces,are studied.The result shows that as the number of layers increases,the valence band of Cs-modified 2D-GaN moves to the high energy direction.The electronic state of S-modified monolayer GaN system at the top of valence band is 100%spin down,and the system has a magnetic property of 2.000uB.The O-modified three-layers GaN system was shown to be of metallic property and has a little magnetism.The modification of 2D-GaN by Cs,O and S atoms is due to the termination of the dangling bonds on the 2D-GaN surface and the weakening of the surface quantum effect.Then,GaN nanosheets were prepared by liquid metal catalysis method using liquid Ga which is reactant,catalyst and substrate.The effects of ammonia flow rate,growth temperature,reaction time and gallium thickness on the morphology of samples were studied.SEM and XRD images show that the sample are two-dimensional GaN nanomaterial with hexagonal wurtzite structure,which has good crystallinity.Two-dimensional GaN was obtained by ammoniating gallium oxide with NH3.XRD and EDS results show that the precursor is Ga2O3 which changes to GaN after ammoniation.