Preparation And Properties Of Rare Earth Doped Gallium Nitride Based Diluted Magnetic Semiconductor Materials

Diluted magnetic semiconductors have both the charge and spin properties of electrons,which provides a broad space for improving the integration and circuit performance of the chip.Dilute magnetic semiconductors have a broad application prospect in magnetic sensors,high density nonvolatile memory,optical isolator,semiconductor laser and spin quantum computer and other fields.As a semiconductor material with wide band gap,GaN has attracted more and more attention,because of the superior semiconductor performance and high Curie temperature that can achieved in theory.What's more,there are some achievements have been made in both theory and experiment.However,the preparation parameters are not optimal,the magnetic properties of the material are difficult to control and the origin of ferromagnetism is still controversial.In this paper,GaN:Dy and GaN:Dy:C diluted magnetic semiconductor thin films with room temperature ferromagnetism were prepared by ion implantation method under vacuum conditions.The properties of the thin films were studied by means of X ray diffraction?XRD?,Raman spectroscopy?Raman?,integrated physical measurement system?PPMS?and Hall test?Hall?,and the origin of magnetism was also discussed.?1?GaN:Dy thin films were prepared by Dy ion implantation in GaN films.The effects of Dy ion implantation dose and annealing temperature on the properties of GaN:Dy thin films were investigated.The results show that the Dy ion implantation into the GaN wafers introduces defect,which results in the formation of the Ga vacancy(V_Ga),and the lattice damage was repaired to some extent and the crystal quality was improved due to the thermal annealing process.The magnetic properties of GaN:Dy thin films are affected by the implantation dose and annealing temperature.When the implantation condition of the sample was 150 keV,2×10¹44 cm^-2;300 keV,7×10¹⁴ cm^-2 and annealed at 800?,the ferromagnetic properties are best.The saturation magnetization?M_s?and the magnetic moment of per Dy atom?M_s/Dy?are 8.68 emu/cm³ and 312?_B/atom,respectively.V_Ga can introduce magnetic moments into GaN films,and the bound magnetic polaron formed by the impurity potential of Dy ions bound the surrounding carriers creates the magnetic field.The origin of ferromagnetism is related to V_Ga and bound magnetic polaron.?2?The Dy and C ions were co-doped into GaN films to prepare GaN:Dy:C films.The effects of Dy ions and C ions co-doped on the properties of GaN:Dy:C thin films were investigated.The results show that the implantation of C ions contributes to the magnetization of the GaN:Dy:C film samples.When the implantation condition of the sample was Dy:150 keV,2×10¹⁴ cm^-2;C:300 keV,7×10¹⁴ cm^-2 and annealed at 800?,the ferromagnetic properties are best.The saturation magnetization?Ms?and the magnetic moment of per Dy atom?M_s/Dy?are 15.91 emu/cm³ and 1029?_B/atom,respectively,which were significantly higher than those of GaN:Dy films.The substitution between the C and N ions?C_N?occurs and V_Gaa introduce magnetic moments and the V_Ga-C_N structure formed by adjacent VGa and CN also contributes to the ferromagnetism at room temperature,so that the ferromagnetism V_Ga,C_N and bound magnetic poles.