The Electrical Transport And Magnetic Properties Of Co-Doped SnO₂ Based Diluted Magnetic Semiconductors

The ever-increasing demand for super-high speed and super-high capacity of information promotes the development of the information age,while the demand for information processing and storage in the information age promotes the development of diluted magnetic semiconductors with excellent performance.Giant magnetic moment and high Curie temperature are the research focus and goal in this field.SnO₂ is excellent performance in a wide bandgap transparent semiconductor material.In this paper,?Fe,Sb?co-doped SnO₂ films and?Fe,N?co-doped SnO₂ films were prepared by radio frequency magnetron sputtering.By characterizing the crystal structure,local structure of atoms and valence analysis,the relationship between structure and magnetism was studied in detail,including optical properties,electrical properties and magnetic properties.On this basis,the origin of magnetism is discussed and the following conclusions are drawn:?1?Sn_0.97-xSb_0.03Fe_xO₂?x=0,0.0023,0.0042 and 0.0078?films.All the films exhibited excellent tetragonal rutile structure.The doping Fe ion exist two valence,which are Fe²⁺and Fe³⁺,according to XPS and EXAFS analysis.There are no Fe clusters and related oxides,which ensure the intrinsic properties of the films.The results of XANES and multiple scattering calculation show that the Fe substitute Sn sites.The decreasing carrier concentration and the resistivity increasing continuously with the increase of Fe doping concentration according to the Hall measurements.The electrical transport properties is attribute to the Mott transition mechanism.The local radius of carriers decreases as increasing the concentration of Fe doped,which cannot the possibility of carrier-induced ferromagnetism.The concentration of these oxygen vacancies increases with the increase of Fe doping concentartion.All films exhibit excellent transparency and the emission peaks formed may be due to oxygen vacancies.The band gap redshift and the transmittance decrease with the increase of doping concentration.The saturated magnetic moment of the films indicating that doping would effect the magnetic moment.The magnetic source excludes the effect of carrier mechanism,and there is no second phase in the film,which ensures the intrinsic nature of magnetism.The produce of oxygen vacancies can verified that the production of ferromagnetism driven from theBMPs mechanism.?2?(Sn_1-xFe_x)O_1.982N_0.018.018 films,x=0,0.023,0.042,0.075 and Sn_0.987Fe_0.013(O_2-y-y N_y)films,y=0,0.038,0.091,0.130.Phase analysis showed that?Fe,N?doping not change the original tetragonal rutile structure of SnO₂.No diffraction peaks of other impurities were observed in the range allowed by sensitivity.XANES results show that Fe is doped into SnO₂ lattice in the form of substitution,and no Fe clusters and oxide second phase are produced in the lattice.Electron paramagnetic results show that the doping of?Fe,N?produces oxygen vacancies.The generation of oxygen vacancies may come from the lattice positions of?Fe,N?substituted tin and oxygen,respectively.The spin density of these Vo influence the polarization of magnetic poles,which also provides the basis for the magnetic source.With the increase of doping concentration,the intensity of the photoluminescence peak increases.The corresponding position of the photoluminescence peak in the ultraviolet-visible range is caused by oxygen vacancy,which forms the acceptor level in the forbidden band,and the electrons are stimulated to produce ultraviolet-visible light.Both films exhibit good conductivity,and the samples are semiconductor.The conductivity of the films decreases with the increase of doping concentration.Carriers have strong localization.Meanwhile,saturation magnetization is positively correlated with doping concentration.Therefore,single-electron oxygen vacancies play the role of n-type carriers.These single-electron oxygen vacancies have low concentration and strong locality.On the contrary,the spin polarization of these electrons forms magnetic polarons and contributes to ferromagnetism.The bound magnetic pole model is the most reasonable way to explain the ferromagnetic source of?Fe,N?co-doped SnO₂ thin films.