Study On Energy State Structure Of Zinc Oxide Under Different Vacancy Concentration And Doping Conditions

With the rapid development and wide application of mobile electronic devices and the internet of things,memory used for data storage has huge application prospects,but it also faces severe challenges.Resistive random access memory is a very representative type of nonvolatile memory and is expected to replace the most widely used flash memory.Zinc oxide(ZnO)is known as the most potential resistive storage material.The formation and fracture of conductive filaments in the resistive layer control data writing and erasing.The formation of conductive filaments is accompanied by the changes of crystal structure and atomic migration barrier.In this paper,by constructing an atomic-level theoretical calculation model,using the first-principles calculation method based on density functional theory,the energy state structure of ZnO materials with different vacancy defects and element doping is studied.First,establish the ZnO unit cell calculation model,the two-concentration oxygen vacancy defect model,and the zinc vacancy defect model.By calculating the band structure,density of states and electronic local function,it was found that the energy gap of ZnO system with Zn vacancy increased,and the performance of ZnO system had a tendency to change towards the insulating material with poor electrical conductivity.The ZnO system with O vacancy defect is an n-type semiconductor,the energy gap value increases,the electron density of states near the Fermi level decreases,and the conductivity gradually decreases.Then,the influence of doping impurity elements on the ZnO system was studied,and the calculation models of ZnO doped with Ag replacing Zn sites and Ag replacing O sites were established respectively.Through simulation calculations,it is found that after the metal Ag element is doped,the impurity energy level near the top of the valence band appears in the system,which reduces the energy gap value of ZnO.When the value on the Fermi level increases,the conductivity gradually increases,but as the Ag doping concentration increases to a certain value,the conductivity tends to deteriorate.Studies have shown that a certain concentration of O vacancy defects and a certain concentration of Ag doping are beneficial to the formation of conductive filaments in ZnO materials,which can improve the performance of ZnO-based resistive switching devices.The research results provide certain theoretical guidance for the performance improvement of ZnO-based resistive random access memory.