First-principles Calculations For The Analysis Of New Materials In A New Infrared Detector

In this thesis,a new type of novel infrared detector is designed,which consists of four modules.Infrared detection module uses InSb infrared detection device,the data storage and recall module uses ferroelectric memory based on ABi₂Nb₂O₉?A = Ba,Pb,Sr,Ca?,the data processing analysis module uses graphene high-performance processors that are still in the theoretical demonstration,energy module uses VS₂substrate as a catalyst for hydrogen evolution reaction hydrogen battery.Through a theory,density functional theory,and the first-principles approach based on it,there are four new materials for each of the four modules that are analyzed throughout the process,specific analysis is as follows:1.In this study,we compared the difference between oxygen and sulfur adsorption on the InSb?110?surface by using first-principle calculations.From the calculation results,it is found that the advantages of sulfur adsorption can be shown theoretically.Thus,the reason of selecting sulfur passivation on the InSb surface in technology can be well given.2.We conduct a research on the structure,electronic properties,chemical bonds and spontaneous polarization of the ABibNb₂O₉?A=Ba,Pb,Sr,Ca?system using the first principle calculations based on density function theory.The analysis of chemical bonds also combines the Atom-in-molecule?AIM?theory of Bader.The purpose of this thesis is to explain the origin of ferroelectric in ABi₂Nb₂O₉ferroelectric materials and to understand the change trend of electronic structures and polarization properties of these materials when A-site ions change.This thesis calculates and analyzes the SBN ferroelectric polarization using modern polarization theories and shows origins of great polarization in SBN films,moreover,the thesis gives a theoretical prediction for polarization intensity of BBN,PBN and CBN.3.We present a survey of the hitherto reported structural defects in graphene.We will discuss the formation of defects and their influence on the properties of graphene.As will be clear from the following discussion,an essentially infinite number of various lattice defects can exist but we consider only the simplest ones. We will particularly focus on defects in single-layer grapheme because defects typical for bi-and multilayer graphene also exist in graphite and have been discussed long before the graphene era.At last,we analysis the density of states and band structure of different structural defects.4.Two-dimensional VS₂ nanomaterials have emerged as highly efficient and inexpensive electrocatalysts for the hydrogen evolution reaction?HER?,and the further improvement of their HER performance depends on the understanding of the catalytic mechanism and activity in various pristine and defective structures. Here structural stability,electronic properties,and HER activity of monolayer VS₂nanosheets with various intrinsic point defects are studied by using first-principles calculations.Compared to the most studied 2H-phase MoS₂ basal plane,both 2H-and 1T-phase VS₂ basal planes exhibit superior catalytic activity due to their metallic properties.With the introduction of intrinsic point defects onto VS₂ basal planes,we find that there are four types of stable defects in 2H phase?i.e.,Sad,Svac,Vad,and Vs?and three types of stable defects in 1T phase?i.e.,Sad,Svac,and Vad?,respectively.Moreover,the formation of Svac,Vad,and Vs structures in 2H phase and Vad in 1T phase can enhance the HER activity of basal planes,which implies that the synthesis of VS₂ nanosheets at the V-rich condition facilitates to achieve high HER performance.The HER activity of pristine and defective VS₂ structures can be well understood by a Fermi-abundance model that is also suitable to describe a broad class of electrocatalytic HER systems.This work provides a deep insight into the HER activity of single-layer VS₂ and the guidance for synthesizing highly active electrocatalysts in transition-metal dichalcogenides.