Study On Electronic Structure And Optoelectric Properties Of P-type SrTiO₃

SrTiO₃ is a typical material of a perovskite structure,belong to the wide band gap metal oxide.The width of band gap of it is 3.2eV.Intrinsic SrTiO₃ is non-conductive,but it can also be turned into a semiconductor even superconductor through appropriate doping or modified at room temperature.Modified SrTiO₃ Will light in a specific wavelength of light irradiation,also can decompose water into hydrogen,decompose organic pollutants and photochemical battery with light condition.It is a promising optoelectronic material.The main research contents and results are as follows:1.We study the P-type SrTiO₃ in this paper.Firstly,the theory of P-type SrTiO₃ is studied by using the first principles,We use the CASTEP software package in Materials Studio 6.1 to calculate the system,we selected the third main group elements doped SrTiO₃ as the research object according to the information available,we choose the aluminum,gallium and indium to calculate them,The lattice constants,formation enthalpy,band structure,density of States,charge properties and optical properties of Al,Ga and In doped SrTiO₃ at the same doping concentration were calculated,the mechanism of the influence of doping elements on the electronic structure and optical properties of SrTiO₃ was revealed?The results show that the Al,Ga and In doped SrTiO₃ is p-type doping,compared with the intrinsic SrTiO₃,the absorption occurs at the visible light after doping,which provides a new research direction for the study of the photocatalytic properties of SrTiO₃2.Through the first part of the study,we obtained that the third main group elements?Al,Ga,In?doped SrTiO₃ can achieve P-type doping.We calculated the Al-doped SrTiO₃ with different concentrations,The concentrations were 1.11at%,2.22at%,3.33at%.The calculations include crystal structure,formation enthalpy,band structure,total state density,density of States and optical properties.The results show that,the stability of the doped system decreases gradually,the band gap of the system increases gradually and the absorption of visible light decreases gradually with the increase of the doping concentration of Al in a certain concentration range.The results show that the 1.11at% concentration of Al doped SrTiO₃ has good stability and strong optical absorption,which can provide reference for the experiment.3.Intrinsic SrTiO₃ and Al doped SrTiO₃ films with different concentrations were prepared by RF magnetron sputtering at room temperature.Based on the previous results,we prepared 1.1%,2.2%,3.3% films of three concentrations,annealing treatment was carried out.We measured the transmittance,absorption and photoluminescence intensity of the films,.Analysis of the data,we obtained that the transmittance is reduced and the absorption enhancement of Al doped SrTiO₃ thin films in visible light.in a certain concentration range,with the increase of doping concentration,the optical band gap decreases first and then increases.We also found that the doping had no effect on the emission position,but only increased the emission intensity.4.We calculate the electronic structure,band structure,formation enthalpy,density of States and optical properties of N doped SrTiO₃,N-Al codoped SrTiO₃ byfirst principles.We have find that the N doped SrTiO₃ is P-type doping from the calculation results,the band gap get narrowed.Compared with N doping,the hole concentration of N-Al codoped SrTiO₃ have increased.There is a strong absorption in the visible region of N-Al codoped SrTiO₃.It has shown superior performance.