Preparation And First Principle Study Of Al-Eu Codoped ZnO Thin Films

As a third-generation semiconductor material,ZnO has high exciton binding energy,good chemical and thermal stability,relatively low growth temperature and cheap raw materials.It is a very potential transparent conductive thin film material.However,intrinsic defects exist in intrinsic zinc oxide,the crystallization quality is low and the conductivity is poor.Doping technology is usually used to improve the performance of intrinsic zinc oxide.It has been documented that doping of Al and Eu elements can improve the photoelectric properties of ZnO-based materials,but few studies have been reported on the related properties of Al-Eu doped ZnO and the preparation technology of its films.In this paper,the photoelectric properties of Al-Eu co-doped ZnO films were simulated and calculated by first-principles method.Then,Al-Eu co-doped ZnO films were prepared by magnetron sputtering and the optimum preparation parameters were explored.Firstly,according to the first principle,the supercell models of intrinsic ZnO,Al-doped ZnO,Eu-doped ZnO and Al-Eu-doped ZnO are established by Material Studio software,and their electrical properties(band structure,density of states,Mulliken population,conductivity)and optical properties(dielectric function,absorption,reflectivity and transmittance)are simulated and calculated.It is found that the doping of Al and Eu atoms makes the Fermi level enter the conduction band,and the system exhibits n-type conductivity,and the band gap decreases.It can be seen from the density of states that the the 4f state electrons of Eu occupy the main quantum states at the Fermi level,and Al contributes 3p and 3s states at the bottom of the conduction band.Compared with intrinsic ZnO,the conductivity of AEZO is obviously improved.The average Mulliken population distribution of atoms and bonds of ZnO in different doping systems is calculated.The doping of Al and Eu atoms provides a large number of electrons and enhances the ionicity of bonding.When calculating the optical properties,it is found that the peak positions of the real and imaginary parts of AEZO dielectric function are redshifted,the absorption and reflection coefficients are increased in the visible region,and the transmittance is slightly lower than that of intrinsic ZnONext,using magnetron sputtering method to prepare Al-Eu co-doped ZnO thin films.The effects of sputtering power and substrate temperature on the phase structure,surface morphology and photoelectric properties of the films were investigated,in order to find out the best process parameters for AEZO films.Through XRD,SEM,Hall tester,UV-Vis spectrometer and other characterization equipment and means,it was found that when the sputtering power is 80 W and the substrate temperature is 200 °C,the 002 diffraction peak produced by AEZO has the lowest half-height value and the largest average grain size,the grain is full and uniform,the surface roughness is low,and the crystal quality is optimal;moreover,the conductivity of the film is the highest,and the carrier concentration and Hall mobility are also significantly increased.;in the visible region average transmittance is more than 85%.It can be seen that when the sputtering power is 80 w and the substrate temperature is 200 ?,the comprehensive properties of the films prepared are the best.This study shows that Al-Eu co-doped ZnO is a very superior transparent conductive oxide film material,which lays a solid foundation for its production and application in practice.