| Dilute Magnetic Semiconductors?DMSs?are currently an excellent backup material for spintronics in the world and have quickly become a hot topic in spintronics materials research.It has the band structure of semiconductors,and its lattice constant is similar to that of the base semiconductor.It not only can be well compatible with existing semiconductor technology in the manufacture of devices,but also has the characteristics of magnetic materials.However,the room temperature ferromagnetism of dilute magnetic semiconductors has not been solved,such as the generation mechanism of room temperature ferromagnetism of ferromagnetic semiconductors and the origin of ferromagnetism.Gallium oxide?Ga2O3?is a III-V wide bandgap semiconductor material with a band gap of4.9 eV.Its excellent conductivity and luminescent properties have long attracted attention,and as a transparent oxide semiconductor,in the area of optoelectronic devices widely used.The main application is deep ultraviolet transparent conductive film,solar blind ultraviolet detector,field effect transistor,gas sensor and so on.Diluted magnetic semiconductors of?-Ga2O3 base have a huge space for industrial application.If they can be doped by ion implantation to make them ferromagnetic at room temperature,they not only have the properties of semiconductors but also take into account the properties of magnetic materials,and will become a new type of lean.The application of magnetic semiconductor materials and Ga2O3 based dilute magnetic semiconductor materials will also usher in a new development and application.The ion implantation technology is more controllable.Throughout the entire implantation process,the implantation depth,ion concentration,energy selection,and ion implantation profile can be well controlled.In combination with these advantages,ion implantation is used to implant the Mn and Cr ions into the?-Ga2O3 substrate.Preparations were made to study the reasons for the room temperature ferromagnetism.First,ferromagnetism with a Curie temperature higher than room temperature was observed in an Mn implanted?-Ga2O3 substrate implanted at doses of 5×1014 cm-2,1×1015 cm-2,and5×1015 cm-2.The temperature dependence of the zero-field cooling?ZFC?and field refrigerated?FC?curves reveals superposition of phases that may originate from Mn ions and oxygen vacancy distributions.The Raman spectrum shows the deformation of the GaO4tetrahedron and GaO6 octahedron in the injected sample.The change trend of the GaO4tetrahedron is related to the value of the saturation magnetization and the coercive force.The distribution of Mn ions is determined by SIMS analysis and used to explain the ferromagnetic coupling mechanism and PL spectra.Therefore,it is believed that the impurity band exchange model is suitable for interpreting ferromagnetism by combining experimental results.The room temperature ferromagnetism of 54Cr+ion implantation in?-Ga2O3 single crystal was studied.The ferromagnetism with a Curie temperature higher than room temperature was observed in three specimens implanted with?-Ga2O3 at doses of 5×1014 cm-2,1×1015cm-2,and 5×1015 cm-2.The saturation magnetization was 0.00018 emu./g,0.0005 emu/g and0.0082 emu/g.The temperature dependence of the zero-field cooling?ZFC?and field-cooled?FC?curves shows a superposition of phases that may originate from the distribution of Cr ions and oxygen vacancies.The XRD diffraction pattern shows the formation of a new compound CrO2.The Raman spectrum shows the distortion of the GaO4 tetrahedron and the GaO6 octahedron in the injected sample.The change trend of the GaO4 tetrahedron is related to the values of the saturation magnetization and the coercive force.So oxygen vacancies form delocalized impurity bands and couple Cr cations,which is a reasonable explanation for ferromagnetism above room temperature. |
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