The Preparation Of C-SN Codoped GaN Nanowires And Study Of First-Principle

As a kind of import III-V,the third generation of wide bandgap semiconductors,Gallium nitride(Ga N)has stable physical and chemical properties,excellent photoelectric properties,so it can be used for ultraviolet detectors,high temperature and radiation detectors,high frequency and high power microwave devices,etc.In recent years,with the successful design of the Ga N blue LED,and won the 2014 Nobel Prize in physics,Ga N has become one of the most popular researchs topic in the field of semiconductor material in present.With the development of nano science and technology,it has provided a strong theoretical and technical support for the scientific research of Ga N nanometer material.Many researchers have conducted extensive research and exploration about Ga N nanowires.In the theoretical part,based on first principles density functional theory,we calculated binding energy,electronic structure and the work function of the C-Sn codoping Ga N nanowires with different location,replacing different atoms,and analysed the structure and features of C-Sn co-doping Ga N nanowires'electronic state.The results of calculation show that Ga N nanowires structure is the most stable when C atomic and Sn atomic both replaced Ga atomic,doping in the outermost layers.C,Sn atoms both repalcing Ga atoms caused the impurity peak appeared in the band gap,and with the deeper of the doping position,Fermi level guided more for bottom of conduction band.When C atoms repalced N atoms,and Sn atoms repalced Ga atoms,impurity peak appeared in the band gap,but Fermi level did not appear obvious move up.Compared with pure Ga N nanowires,C and Sn only instead of Ga codoping Ga N nanowires,C-Sn co-doping slightly reduced the work function.In the experimental part,we synthesized C-Sn co-doping Ga N nanowires by chemical vapor deposition(CVD)method,and Ga₂O₃as Ga source,Sn O₂and C as doped source,NH₃ as the carrier gas and N source.We synthesized many group of C-Sn co-doped Ga N nanowires'samples by change the annealing temperature,the mass ratio of the doping,the NH₃ flow ammoniated time and other conditions.In order to study the effect of preparation conditions on the morphology of the nanowires,these samples'morphology were characterized by SEM.Through EDS spectrum tests to characterize the elemental composition and content of C-Sn co-doped Ga N nanowires.The lattice structure of these samples were haracterized by XRD,and the prepared C-Sn co-doped Ga N nanowires are hexagonal wurtzite structure.The prepared samples were tested by field emission measurement.Compared with pure Ga N nanowires,we found that the turn-on field of C-Sn codoped Ga N nanowires were less than the pure Ga N nanowires.The introduction of C,Sn atoms reduces the improve the emission current density.The samples present good field emission properties.