Study On The Structure And Room Temperature Ferromagnetism Of Fe And Cu Co-Doped In₂O₃ Dilute Magnetic Semiconductor

The indium oxide(In₂O₃) is a wide-band-gap(3.75 eV) semiconductor with cubic bixbyite structure.In₂O₃ can be an n-type semiconductor with high conductivity by introducing oxygen deficiencies or by doping,which is good ferromagnetic at room temperature,conductive,transparent,gas-sensing and easily integrated with variety of semiconductor materials,having great prospects on basic research and application of many devices.In this research,(In_0.9-xFe_0.1Cu_x)₂O₃(0≤x≤0.03) bulks and thin films were prepared by high-temperature solid-state reaction and vacuum evaporation method. The crystal structure,magnetic property,surface morphology,optical and electrical transport properties of the samples were investigated by X-ray diffraction,vibrating sample magnetometer,scanning electron microscope,ultraviolet-visible light spectrophotometer and Hall Effect tester.We prior to research that the technological parameters and Cu-doped concentration affect the structure and properties of the block and film samples,and have discussed the role of Cu doped and the possible of magnetic mechanism.It was found that the solubility of Fe was affected by co-doping with Cu in bulk samples,when x＞0.01(Cu 1 at%doped),impurity phase In₂Fe₂CuO₇ was appeared. The main phase of the lattice constants reduced the increase after the first as increasing the value of x,the minimum reach to 1.006 nm when x=0.01.The samples without Cu and with large Cu content were paramagnetic,but the samples with intermediate Cu doped were found to be ferromagnetic at room temperature(FM). With the increasing value of x,saturated magnetic moment has increased and then decreased,the maximum reach to 0.6 emu/g when x=0.01.Optimum study of technological parameters for the preparation of x=0.01 film samples by vacuum evaporation method was carried through orthogonal design.The optimum technological parameters for the best physical properties of thin films were that the substrate temperature was 400℃,the argon oxygen flow ratio was 10/0,the evaporation time of 20 min.It is revealed that the Cu solubility is larger in the films than blocks sample,With the increase in the concentration of Cu-doped,the crystal structure of the film sample does not change,no apparent impurity phase;saturation magnetic moment and there is increasing trend,the largest saturation magnetic moment is 123.8 emu/cm³ when x=0.02.This paper also combines the test results of thin film and bulk samples,and found that the source of magnetic is closely related to dopping and defects caused by the system of concentration.The spin electrons need carders as media to couple each other.Cu incorporation of the system will create mixed valence magnetic cation,the magnetic cation introduced into the crystal structure of In₂O₃ to substitute for In³⁺ site, which can introduce an electronic defect an the neighbouring oxygen,the carrier concentration changes that plays an important role on the magnetic exchange.