Study Of The Native Point Defects In ZnS And ZnO And Optical Properties In SrO

ZnS crystal and ZnO crystal both are important II–VI luminous semiconductor material.They are wide ditect band gap and very important light-emitting semiconductor materials.The exciton binding energy of ZnO is bigger?60 meV?,and it has high transparency,widely used in light-emitting diodes,fluorescent material,photocatalysis,solar photovoltaic materials,variable resistor and piezoelectric materials,etc.ZnS is administered in CRT phosphor,electroluminescent devices,nonlinear optics,photocatalyst and solar cells have great potential applications.As we know,the native point defects of ZnS and ZnO often influence or control the conductive type?n-type or p-type?of semiconductors.At present,there are many studies about codoping control materials conductive type.But want to better control the conductive type,the further research of intrinsic point defects is very important.SrO as alkaline-earth oxide,is important material with extensive application such as catalysis and microelectronic.The properties of anion vacancy in the alkaline-earth oxides MgO and CaO have been studied in many aspects.Besides,these properties have also been obtained a satisfactory theoretical understanding.However,the research of anion vacancies in SrO crystal have not received too many attentions up till now.Currently,the GW method has been widely used in electronic structure calculation of the alkaline-earth oxides,the calculation results and the experimental results achieved good identity.Therefore,first we calculated point defect properties of ZnS crystal and ZnO crystal.Finally,we apply many-body perturbation in the G0W0 approximation and Bethe-Salpeter approach to calculate electronic structures and the optical spectra of SrO.Section one:Mainly to study the background,basic characteristics,the research significance,and the present research status of ZnO,ZnS,SrO,the purpose of this paper.Section two:Mainly introduce alculation theory and calculation software,including,the first principles density functional theory,the multi-body perturbation theory,GW approximation method,BSE equation and VASP,WANNIER90.Section three:Based on the density functional theory,the electronic structure of intrinsic point defect is determined in this paper.Considering the influence of vibrational entropy,the point defect stability in ZnS is achieved with thermodynamic method with VASP.Section four:Based on the density functional theory,the electronic structure of intrinsic point defect is determined in this paper.Considering the influence of vibrational entropy,the point defect stability in ZnO is achieved with thermodynamic method with VASP.Section five:We apply many-body perturbation in the G₀W₀ approximation and BSE approach to calculate electronic structures and the optical spectra of SrO.Section six:Summarize of this full paper.