Study Of Low-dimensional Phosphor/Germanium-based Materials On The First Principles

The advent of graphene has brought the scientific research of human beings into the two-dimensional world,more and more two-dimensional materials are obtained in experiments.First,inspired by the successful synthesis of bilayer silica materials in experiments,we have explored the crystal structure and electronic properties of the graphene-like bilayer GeO₂ thin film materials through the calculation of the first principle.In addition,two more stable two-dimensional germanium-based oxides?4-GeO₂ and 6-GeO₂?thin film materials were constructed by using particle swarm search.The results show that the three kinds of two-dimensional germanium-based oxides are wideband gap semiconductors,and the stability of the three materials can be proved by the phonon dispersion curve and molecular dynamics simulation.For wideband gap semiconductors,comparing these three materials,bandgap of the smallest class of graphene-like bilayer GeO₂ material in the solar cell can be used as a luminous structure,and the one with the largest band gap of 6-GeO₂ can serve as an electrode material of solar cell.In terms of optical properties,graphene-like bilayer GeO₂ and 4-GeO₂materials show very similar characteristics in x and y directions,and found that the imaginary part of the dielectric function and absorption spectrum showed consistent band gaps with the band structure diagram.In addition,the light absorption in the deep ultraviolet region is strong,which indicates the possibility of its being used as ultraviolet photodetector.About carrier mobility,two-dimensional 6-GeO₂ materials,holes in the y direction of the migration rate of 1.2×10⁴ cm²V^-1s^-1,slightly less than two graphene structure of carrier mobility is relatively high((MoS₂³.0 cm²V^-1s^-1).Therefore,the three germanium-based oxides materials with appropriate band gaps have the characteristics of good stability,high carrier mobility and good light absorption,and have broad application prospects in the fields of electronics and optoelectronics.On the other hand,starting from the hot spot material phosphorus dilute,on the basis of the particle swarm optimization algorithm,combined with the calculation of the first principle,in a number of x/y ratio of two-dimensional monolayer structure,we selected the ratio of x/y=1:1 and 1:2 four kinds of stable structure film.The results show that these novel monolayers also have unique electronic properties.The Pmc2₁-SnP₂ monolayer film can be converted from non-magnetic to ferromagnetic by hole doping,and the Pmc2₁-SnP₂ structure is a direct-like gap semiconductor with in-plane elastic anisotropy is found to possess high electron mobility as high as 800 cm²V^-1s^-1 along the K_b direction.These desirable properties of the multifunctional Sn_xP_y monolayers provide promising great applications in electronics and optoelectronics.In addition to synthetic compounds,we will also phosphorene thin roll fold a one-dimensional nanotubes was studied APNTs nanotubes material is indirect bandgap semiconductor materials,with smaller size effect and strain effect is studied and doped impurity atoms on the properties of one-dimensional phosphorus nanotube electronic bandgaps can be regularly adjust and by strain adjustment can cover the entire scope of infrared light,infrared device is preparation of alternative materials.Studies have shown that the influence of size effect on APNTs nanotubes obvious,if we suppose size increasing nanotube will eventually make the transition from semiconductor to metal properties in addition to that,doped impurity atoms,APNTs electronic band structure of nanotube system finished semiconductor-metal-semiconductor-regular change of metal as a result,small band gap adjustable significant strain effect size effect and doping effect that APNTs infrared detector in the nano-scale thin film effect transistor and strain sensors,and other fields has a broad application prospect.Finally,we studied the electronic properties and band structure of bilayer phosphorene doped system.We determined that the electronic properties of bilayer phosphorene are sensitive to the type of dopant atoms.Doped systems in which the dopant had an odd number of valence electrons maintained the semiconducting character,while the dopants with even numbers of valence electrons caused the system to acquire a metallic character.Our results will open a new direction for the application of phosphors in electronic devices.