Transition metal atom and c-vacancy co-doped 3c-sic composite model and modification method

Abstract

The application provides a transition metal atom and C vacancy co-doped 3C-SiC composite model and a modification method, which mainly comprises the following contents: constructing a 3C-SiC supercell; performing geometric optimization on the 3C-SiC supercell to obtain a 3C-SiC supercell with the lowest total internal energy of atoms; performing transition metal atom doping to obtain a transition metal atom doped 3C-SiC supercell; obtaining an optimized transition metal atom doped 3C-SiC supercell; removing any C atom nearest neighbor to the transition metal atom in the optimized transition metal atom doped 3C-SiC supercell to form a C vacancy, thereby obtaining a C vacancy and transition metal atom co-doped 3C-SiC composite model, and then performing geometric optimization on the obtained C vacancy and transition metal atom co-doped 3C-SiC composite model to obtain an optimized C vacancy and transition metal atom co-doped 3C-SiC composite model; compared with a traditional 3C-SiC-based diluted magnetic semiconductor, the magnetic moment of the 3C-SiC-based diluted magnetic semiconductor doped with a vacancy is obviously improved, the spin polarization of surrounding atoms is strengthened, and the 3C-SiC-based diluted magnetic semiconductor doped with a vacancy can be used for spin electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials technology, specifically relating to a 3C-SiC composite model and modification method co-doped with transition metal atoms and C vacancies. Background Technology

[0002] Traditional semiconductor devices utilize the transport properties of electrons and holes to process and transmit information, which can no longer meet the requirements of information storage modules. Diluted magnetic semiconductors possess both electron charge and spin degrees of freedom. Compared with past semiconductor devices, they are faster, consume less energy, and have higher integration density, attracting the attention of many scholars at home and abroad.

[0003] Due to its wide bandgap, high thermal conductivity, high critical breakdown voltage, high saturation carrier mobility, and low dielectric constant, SiC has become a preferred material for high-temperature, high-pressure, radiation-resistant, and high-power semiconductor devices. SiC-based dilute magnetic semiconductors are mainly produced by doping SiC with transition metal atoms to impart magnetism. However, existing doping modification methods result in dilute magnetic semiconductors with relatively small magnetic moments. Summary of the Invention

[0004] To address the shortcomings and deficiencies of existing preparation techniques, this invention provides a 3C-SiC composite model and modification method co-doped with transition metal atoms and C vacancies, in order to solve the technical problem of small magnetic moments in dilute magnetic semiconductors prepared by doping modification methods in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] Step 1: Construct a 3C-SiC supercell using quantum mechanical simulation software based on first principles of density functional theory;

[0007] Step 2: Use the BFGS algorithm to perform geometric optimization on the 3C-SiC supercell to obtain the 3C-SiC supercell with the lowest total atomic internal energy;

[0008] Step 3: Replace the Si atoms in the 3C-SiC supercell obtained in Step 2 with transition metal atoms to obtain a 3C-SiC supercell doped with transition metal atoms;

[0009] Step 4: Use the BFGS algorithm to perform geometric optimization on the transition metal atom-doped 3C-SiC supercell obtained in Step 3 to obtain the optimized transition metal atom-doped 3C-SiC supercell.

[0010] Step 5: Remove any C atom from the optimized transition metal atom-doped 3C-SiC supercell to form a C vacancy, and obtain a 3C-SiC composite model co-doped with C vacancy and transition metal atom. Then, perform geometric optimization on the obtained 3C-SiC composite model co-doped with C vacancy and transition metal atom to obtain an optimized 3C-SiC composite model co-doped with C vacancy and transition metal atom.

[0011] Among them, the C atom that forms a C vacancy is closest to the transition metal atom in the optimized transition metal atom-doped 3C-SiC supercell.

[0012] The present invention also has the following technical features:

[0013] Specifically, the geometric optimization described in steps 2, 4, and 5 is based on the principle of minimum energy, and the parameters for geometric optimization all include: plane wave cutoff energy E. cut The sampled value at point k of the Brillouin zone integral is 450eV, and the value is 2×2×2.

[0014] The convergence condition of the BFGS algorithm includes: the convergence value of the total energy of the system is 2.0 × 10⁻⁶. -5 eV / atom, convergence value of interatomic interaction is 0.05 eV / nm, stress deviation is less than 0.05 GPa, and tolerance offset is less than

[0015] Furthermore, the U-value of the transition metal atoms is corrected during the geometry optimization process in steps 4 and 5.

[0016] Furthermore, the transition metal atoms include at least one of chromium atoms, manganese atoms, iron atoms, and cobalt atoms.

[0017] Furthermore, the quantum mechanical simulation software based on first-principles calculations of density functional theory includes VASP and Materials Studio.

[0018] Furthermore, the composite model is constructed using the following steps:

[0019] Step 1: Use Materials Studio software to build a 3C-SiC supercell;

[0020] Step 2: Use the BFGS algorithm to perform geometric optimization on the 3C-SiC supercell to obtain the 3C-SiC supercell with the lowest total atomic internal energy;

[0021] Step 3: Replace the Si atoms in the 3C-SiC supercell with Cr atoms to obtain a Cr-doped 3C-SiC supercell;

[0022] Step 4: Use the BFGS algorithm to perform geometric optimization on the Cr atom-doped 3C-SiC supercell to obtain the optimized Cr atom-doped 3C-SiC supercell;

[0023] Step 5: Remove the C atom closest to Cr in the optimized Cr-doped 3C-SiC supercell to form a C vacancy, and obtain a 3C-SiC composite model co-doped with C vacancy and Cr atom. Then, perform geometric optimization on it to obtain a structurally stable 3C-SiC composite model co-doped with C vacancy and Cr atom.

[0024] Among them, the C atom that forms a C vacancy is closest to the transition metal atom in the optimized transition metal atom-doped 3C-SiC supercell;

[0025] The parameters for geometric optimization in steps 2, 4, and 5 include: plane wave cutoff energy E. cut The value is 450 eV, the sampling value of the k-point of the Brillouin zone integral is 2×2×2, and the U value of the Cr atom is corrected during the geometry optimization process described in steps 4 and 5, wherein the U value is 3.0;

[0026] The convergence condition for the BFGS algorithm includes: the convergence value of the total energy of the system is 2.0 × 10⁻⁶. -5 eV / atom, convergence value of interatomic interaction is 0.05 eV / nm, stress deviation is less than 0.05 GPa, and tolerance offset is less than

[0027] This invention also protects a 3C-SiC modification method, which uses the above-mentioned 3C-SiC composite model of transition metal atoms and C vacancies to modify 3C-SiC.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The method of the present invention is based on 3C-SiC supercell, calculates the formation energy of Si vacancy and C vacancy in 3C-SiC supercell, confirms that C vacancy is selected to improve the magnetism of SiC-based dilute magnetic semiconductor, and realizes the co-doping of 3C-SiC supercell by transition metal atoms and vacancy; the calculation method based on first principle is simple to operate, highly accurate, widely applicable and reproducible.

[0030] (2) The method of the present invention constructs a 3C-SiC composite model co-doped with transition metal atoms and C vacancies, providing a theoretical model for the preparation of related materials and devices.

[0031] (3) Using this invention, the density of states, spin charge density, partial wave density of doped atoms, partial wave density of atoms around vacancies, and magnetic moment of the 3C-SiC composite model co-doped with transition metal atoms and C vacancies were calculated, and the degree of magnetic modification of 3C-SiC was qualitatively and quantitatively analyzed. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a structural diagram of the 3C-SiC supercell obtained after geometry optimization in Example 1;

[0034] Figure 2 This is a structural diagram of the Cr-doped 3C-SiC supercell in Example 1;

[0035] Figure 3 This is a structural diagram of the 3C-SiC composite model co-doped with Cr atoms and C vacancies in Example 1;

[0036] Figure 4 The total density of states and partial density of states of each atom are shown in the 3C-SiC composite model co-doped with Cr atoms and C vacancies in Example 1.

[0037] Figure 5 The spin charge density diagram of the 3C-SiC composite model co-doped with Cr atoms and C vacancies in Example 1 is shown.

[0038] Figure 6 This is a supercell diagram of Mn-doped 3C-SiC in Example 2;

[0039] Figure 7 This is a structural diagram of the 3C-SiC composite model co-doped with Mn atoms and C vacancies in Example 2;

[0040] Figure 8 The total density of states and partial density of states of each atom are shown in Example 2 for the 3C-SiC composite model co-doped with Mn atoms and C vacancies.

[0041] Figure 9 The spin charge density diagram of the 3C-SiC composite model co-doped with Mn atoms and C vacancies in Example 2 is shown.

[0042] Figure 10The total density of states and partial density of states of each atom are shown in Comparative Example 1 for the Cr-doped 3C-SiC supercell.

[0043] Figure 11 The spin charge density diagram is shown for the Cr-doped 3C-SiC supercell of Comparative Example 1.

[0044] Figure 12 The total density of states and partial density of states of each atom in the Mn-doped 3C-SiC supercell of Comparative Example 2 are shown.

[0045] Figure 13 The spin charge density diagram is shown for the Mn-doped 3C-SiC supercell in Comparative Example 2.

[0046] Figure 14 The total density of states diagram and the partial density of states diagram of each atom in the 3C-SiC supercell of Comparative Example 3 are shown. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0048] The cutoff energy E in this invention cut Convergence test at K-point: First, keep the K-point value constant, change the cutoff energy, calculate the system's energy, and then compare the final energy difference to see if it is within the allowable error range. By comparing the energies, a suitable cutoff energy is obtained. Then, using the determined cutoff energy, change the K-point, calculate the system's energy, and again compare the final system energies to determine the K-point. The purpose of the convergence test is to reduce errors caused by manually set parameters through calculation.

[0049] In this invention, "geometric optimization" refers to using the CASTEP module in quantum mechanics simulation software based on the first principles of density functional theory, such as Materials Studio (MS), to perform geometric optimization and property calculations on the constructed structural model using existing algorithms in the module, thereby completing the geometric structure optimization task.

[0050] Example 1:

[0051] Following the above technical solution, this embodiment presents a 3C-SiC composite model co-doped with transition metal atoms and C vacancies. This composite model is constructed using the following steps:

[0052] Step 1: Use Materials Studio software, which is based on first principles of density functional theory, to build a 2×2×2 3C-SiC supercell;

[0053] Step 2: Use the BFGS algorithm to perform geometric optimization on the 3C-SiC supercell to obtain the 3C-SiC supercell with the lowest total atomic internal energy, such as... Figure 1 As shown, the lattice constant of the geometry-optimized 3C-SiC supercell is

[0054]

[0055] Among them, the parameters for geometric optimization all include: plane wave cutoff energy E cut The sampled value at point k of the Brillouin zone integral is 450eV, and the value is 2×2×2.

[0056] The convergence condition for the BFGS algorithm includes: the convergence value of the total energy of the system is 2.0 × 10⁻⁶. -5 eV / atom, convergence value of interatomic interaction is 0.05 eV / nm, stress deviation is less than 0.05 GPa, and tolerance offset is less than

[0057] Step 3: Replace the Si atoms in the 3C-SiC supercell obtained in Step 2 with Cr atoms to obtain a Cr-doped 3C-SiC supercell;

[0058] Step 4: Use the BFGS algorithm to perform geometric optimization on the obtained 3C-SiC supercell doping model to obtain the optimized Cr atom-doped 3C-SiC supercell, such as... Figure 2 As shown;

[0059] The parameters for geometric optimization all include: plane wave cutoff energy E cut The sampling value at k-point of the Brillouin zone integral is 450 eV and 2×2×2. During the geometric optimization of the Cr-doped 3C-SiC supercell, the U value of the Cr atoms is corrected. In this embodiment, the selected U value is 3.0.

[0060] The convergence condition for the BFGS algorithm includes: the convergence value of the total energy of the system is 2.0 × 10⁻⁶. -5 eV / atom, convergence value of interatomic interaction is 0.05 eV / nm, stress deviation is less than 0.05 GPa, and tolerance offset is less than

[0061] Step 5: Remove any C atom from the optimized transition metal atom-doped 3C-SiC supercell to form a C vacancy, obtaining a 3C-SiC composite model co-doped with C vacancies and transition metal atoms. Then, perform geometric optimization on the obtained 3C-SiC composite model co-doped with C vacancies and transition metal atoms to obtain an optimized 3C-SiC composite model co-doped with C vacancies and transition metal atoms, as shown below. Figure 3 As shown.

[0062] Among them, the C atom that forms a C vacancy is closest to the transition metal atom in the optimized transition metal atom-doped 3C-SiC supercell;

[0063] The parameters for geometric optimization all include: plane wave cutoff energy E cut The sampling value at k-point of the Brillouin zone integral is 450 eV and 2×2×2. During the geometric optimization of the Cr-doped 3C-SiC supercell, the U value of the Cr atoms is corrected. In this embodiment, the selected U value is 3.0.

[0064] The convergence condition for the BFGS algorithm includes: the convergence value of the total energy of the system is 2.0 × 10⁻⁶. -5 eV / atom, convergence value of interatomic interaction is 0.05 eV / nm, stress deviation is less than 0.05 GPa, and tolerance offset is less than

[0065] Then, the magnetic properties of the 3C-SiC composite model co-doped with C vacancies and Cr atoms obtained in this embodiment are calculated. The calculations include the total density of states, the partial density of states of Cr atoms and atoms surrounding the vacancies, the spin charge density map, and the magnetic moment.

[0066] The total density of states of the 3C-SiC composite model co-doped with C vacancies and transition metal atoms obtained in this embodiment is as follows: Figure 4 As shown in (a), the dashed line represents the density of states with spin up, and the solid line represents the density of states with spin down. Clearly, the density of states with spin up and spin down is asymmetrical, indicating a split in the electronic density of states between them. This results in magnetism in the 3C-SiC composite model where C vacancies are co-doped with transition metal atoms.

[0067] Figure 4 Images (b) to (d) show the partial density of states (DSO) diagrams of Cr, Si, and C atoms in the 3C-SiC composite model co-doped with C vacancies and transition metal atoms, respectively. From the DSO diagrams of Cr and C atoms, it is clear that at the Fermi level, spin-up electronic states are greater than spin-down electronic states, exhibiting a certain spin polarization effect. Furthermore, the broadened peak values ​​and positions of the peaks appearing at the Fermi level for the Cr-3d, Cr-3p, C-2p, and Si-3p orbitals are similar, indicating orbital hybridization coupling and electron spin exchange at the Fermi level between Cr atoms, surrounding C atoms, and Si atoms surrounding C vacancies. This suggests that the magnetism in this composite model mainly originates from Cr atoms, surrounding C atoms, and Si atoms surrounding vacancies.

[0068] The distribution of magnetic moments in the composite model can be visually observed from the spin charge density plot. For example... Figure 5As shown, the magnetic moments of the 3C-SiC composite model co-doped with C vacancies and Cr atoms are mainly distributed on the doped Cr atoms and the surrounding C atoms, with the magnetic moments generated by the two atoms having opposite spin directions. However, the magnetic moment of the doped Cr atoms extends towards the vacancy direction. This is due to orbital hybridization between the Cr atoms and the Si atoms surrounding the vacancy. However, the magnetic moments generated by the Si atoms surrounding the vacancy are relatively small and are not shown in the figure.

[0069] The magnetic moment can be used to quantitatively analyze the influence of each atom on the magnetism of the composite model. The calculation results of the magnetic moment are shown in Table 1.

[0070] Table 1

[0071]

[0072] The data in Table 1 show that the total magnetic moment of the composite model is mainly provided by the doped Cr atoms, followed by the three C atoms surrounding the Cr atoms. The Si atoms surrounding the C vacancies also contribute a small amount of magnetic moment to the composite model, which is consistent with the analysis of the partial density of states and spin charge density plots. The data also show that the electron spin directions of the Cr atoms and the surrounding C atoms are opposite, which is consistent with the conclusion drawn from the spin charge density plot.

[0073] In summary, the composite model provided in this embodiment achieves co-doping of transition metal atoms Cr and C vacancies in the 3C-SiC supercell, thereby improving the magnetic properties of the 3C-SiC supercell.

[0074] Example 2:

[0075] Following the above technical solution, this embodiment provides a 3C-SiC composite model co-doped with Mn atoms and C vacancies. The construction method used in this embodiment is the same as in Embodiment 1, except that the transition metal atom used for doping is Mn atom, and the U value selected for U-value correction of Mn atoms during geometry optimization is 2.8. The finally obtained structurally stable 3C-SiC composite model co-doped with C vacancies and Mn atoms is as follows. Figure 7 As shown.

[0076] Then, the magnetic properties of the 3C-SiC composite model co-doped with C vacancies and Mn atoms obtained in this embodiment are calculated. The calculations include the total density of states, the partial density of states of Mn atoms and atoms surrounding the vacancies, the spin charge density map, and the magnetic moment.

[0077] Figure 8(a) shows the total density of states in the 3C-SiC composite model co-doped with C vacancies and Mn atoms, where the dashed line represents the spin-up density of states and the solid line represents the spin-down density of states. Clearly, the spin-up and spin-down densities of states are asymmetrical, indicating a split in the electronic density of states between them, and the system exhibits magnetism. Figure 8 Figures (b) to (d) show the partial density of states (DSO) diagrams of Mn, Si, and C atoms in the 3C-SiC composite model co-doped with C vacancies and Mn atoms. The DSO diagrams clearly show that each atom exhibits spin polarization at the Fermi level. Furthermore, the orbital hybridization at the Fermi level exists not only between Mn atoms and their surrounding C atoms, but also between Mn atoms and the Si atoms surrounding the vacancies. The figures show that the Mn-3d, Mn-3p, C-2p, and Si-3p orbitals exhibit orbital hybridization coupling and electron spin exchange at the Fermi level. This indicates that the magnetism in this composite model primarily originates from the Mn atoms and their surrounding C atoms, as well as the Si atoms surrounding the vacancies.

[0078] Figure 9 Spin charge density plots for the 3C-SiC composite model co-doped with C vacancies and Mn atoms are presented. The plots show that the magnetic moment is mainly concentrated on the doped Mn atoms. Figure 8 Analysis reveals that the Mn atom undergoes orbital hybridization with the surrounding C atoms, resulting in a small magnetic moment being generated in the surrounding C atoms. Furthermore, the magnetic moment generated by the Mn atom tends to shift towards the C vacancies, which is also due to the influence of orbital hybridization.

[0079] Table 2 presents the net magnetic moment provided by Mn atoms, the net magnetic moment provided by Mn and the atoms surrounding the vacancies, and the total magnetic moment of the system. It can be seen that the total magnetic moment of the system is primarily provided by Mn atoms and the C atoms surrounding them. A small amount also comes from Si atoms surrounding the vacancies, which is consistent with the analysis of the partial wave density of states and spin charge density diagrams.

[0080] Table 2

[0081]

[0082] Comparative Example 1:

[0083] This comparative example presents a Cr-doped 3C-SiC supercell, which is constructed using the following main steps:

[0084] Step 1: Use Materials Studio software, which is based on first principles of density functional theory, to build a 2×2×2 3C-SiC supercell;

[0085] Step 2: Use the BFGS algorithm to perform geometric optimization on the 3C-SiC supercell to obtain the 3C-SiC supercell with the lowest total atomic internal energy. See [link / reference]. Figure 3 The optimized lattice constant is

[0086] Step 3: Replace the Si atoms in the 3C-SiC supercell obtained in Step 2 with Cr atoms to obtain a Cr-doped 3C-SiC supercell;

[0087] Step 4: Use the BFGS algorithm to perform geometric optimization on the obtained 3C-SiC supercell doping model to obtain the optimized Cr atom-doped 3C-SiC supercell;

[0088] The magnetic properties of the Cr-doped 3C-SiC supercell obtained in this comparative example were calculated, including the total density of states, the partial density of states of Cr atoms and atoms surrounding vacancies, the spin charge density diagram, and the magnetic moment.

[0089] Figure 10 (a) shows the total density of states of a Cr-doped 3C-SiC supercell, where the dashed line represents the spin-up density of states and the solid line represents the spin-down density of states. As can be seen from the figure, the spin-up and spin-down densities of states are asymmetrical, indicating that there is a net magnetic moment in the Cr-doped 3C-SiC supercell. Figure 10 (b)-(d) show the partial density of states (DSO) diagrams of Cr, Si, and C atoms in a Cr-doped 3C-SiC supercell, respectively. The partial DSO diagrams clearly show that the DSO at the Fermi level of the Cr-doped 3C-SiC supercell mainly originates from the Cr-3d and C-2p states. Furthermore, the Cr-3d and C-2p states exhibit similar DSO broadenings and peak positions at the Fermi level, indicating a very strong orbital coupling between them, i.e., pd hybridization. The total magnetic moment of the Cr-doped 3C-SiC supercell is the result of the combined effect of these two states.

[0090] Figure 11 Spin charge density plots of Cr-doped 3C-SiC supercells are presented. The plots show that the magnetic moment is mainly concentrated on the doped Cr atoms and the surrounding C atoms. Figure 10 Analysis shows that this is due to the pd exchange interaction between the Cr atom and the surrounding C atoms.

[0091] In the Cr-doped 3C-SiC supercell, the Cr atom provides a magnetic moment of 2.96 μB, and the magnetic moments provided by the three C atoms surrounding the Cr atom are all -0.32 μB, totaling -0.96 μB. Therefore, the total magnetic moment of the Cr-doped 3C-SiC supercell is 2.00 μB.

[0092] Comparative Example 2:

[0093] This comparative example presents a 3C-SiC supercell doped with Mn atoms. The construction method used in this comparative example is the same as that in Comparative Example 1, except that the transition metal atom used for doping is Mn atom. The U value of Mn atoms is corrected, and the U value is 2.8. Finally, the optimized 3C-SiC supercell doped with Mn atoms is obtained.

[0094] The magnetic properties of the Mn-doped 3C-SiC supercell obtained in this comparative example were calculated, including the total density of states, the partial density of states of Mn atoms and atoms surrounding vacancies, the spin charge density diagram, and the magnetic moment.

[0095] Figure 12 (a) shows the total density of states of a Mn-doped 3C-SiC supercell, where the dashed line represents the spin-up density of states and the solid line represents the spin-down density of states. The figure shows that the spin-up and spin-down densities of states are asymmetrical, indicating the presence of a net magnetic moment in the system. Figure 12 (b) to (d) show the partial density of states (DSO) diagrams of Mn, Si, and C atoms in a Mn-doped 3C-SiC supercell, respectively. The partial DSO diagrams clearly show that the DSO at the Fermi level of the Mn-doped 3C-SiC supercell mainly originates from the Mn-3d and C-2p states. Furthermore, the Mn-3d and C-2p states exhibit similar DSO broadenings and peak positions at the Fermi level, indicating a very strong orbital coupling between them, i.e., pd hybridization. The total magnetic moment of the Mn-doped 3C-SiC supercell is the result of the combined effect of these two states.

[0096] from Figure 13 As can be seen, the magnetic moment is mainly concentrated on the doped Mn atoms and the surrounding C atoms. Figure 12 Analysis shows that this is due to the pd exchange interaction between Mn atoms and the surrounding C atoms.

[0097] In the Mn-doped 3C-SiC supercell, the Mn atom provides a magnetic moment of 3.94 μB, and the magnetic moments provided by the three C atoms surrounding the Mn atom are all -0.31 μB, totaling -0.92 μB. The total magnetic moment of the Mn-doped 3C-SiC supercell is 3.01 μB, indicating that the magnetism of the Mn-doped 3C-SiC supercell is mainly provided by the Mn atom and the surrounding C atoms.

[0098] Comparative Example 3:

[0099] In this comparative example, the performance of the 3C-SiC supercell is calculated. The calculations mainly involve the total density of states of the 3C-SiC supercell and the partial density of states of each atom.

[0100] from Figure 14As can be seen in (a), the density of states of spin-up and spin-down in the 3C-SiC supercell is completely symmetrical, indicating that it has no magnetism. Figure 14 As can be seen from (b) and (c), the conduction band of SiC material is mainly contributed by the Si-3p state, and the valence band is mainly contributed by the C-2p and Si-3p electronic states. Furthermore, there is strong orbital hybridization between the Si-3p and C-2p states, indicating that Si atoms and C atoms are bonded together in the form of covalent bonds.

[0101] (A) As can be seen from Example 1, Comparative Example 1 and Comparative Example 3:

[0102] The intrinsic 3C-SiC supercell is a non-magnetic semiconductor, but doping with Cr atoms or co-doping with C vacancies will induce magnetism. The difference is that the total magnetic moment of the composite model obtained in Example 1 is significantly higher than that of the composite model obtained in Comparative Example 1. The total magnetic moment of the composite model in Example 1 is 4.01 μB, while that in Comparative Example 1 is 2.00 μB. The increase in the total magnetic moment of the composite model is mainly attributed to the increase in the net magnetic moment provided by Cr atoms. The addition of vacancies greatly enhances the spin polarization of Cr atoms, increasing the magnetic moment provided by Cr atoms from 2.96 μB to 4.40 μB.

[0103] In addition, the introduction of vacancies magnetizes the Si atoms surrounding them, generating a small magnetic moment. Without vacancies, the total magnetic moment provided by the surrounding Si atoms is 0.03 μB, which increases to 0.12 μB after the addition of vacancies. The addition of C vacancies provides electrons to the recombination model, causing a redistribution of electrons between Cr and the surrounding Si atoms. This increases the number of unpaired electrons, enhances spin polarization, and significantly improves the magnetism of the Cr-doped SiC supercell.

[0104] (B) As can be seen from Example 2, Comparative Example 2 and Comparative Example 3:

[0105] The intrinsic 3C-SiC supercell is a non-magnetic semiconductor, but doping with Mn atoms or co-doping with C vacancies will induce magnetism. The difference lies in the total magnetic moment: the total magnetic moment of the composite model in Example 2 is significantly higher than that of the doped composite model in Comparative Example 2. The total magnetic moment of the composite model in Example 2 is 5.32 μB, while that in Comparative Example 2 is 3.01 μB. The increase in the total magnetic moment of the composite model is mainly attributed to the increase in the net magnetic moment provided by Mn atoms. The addition of vacancies greatly enhances the spin polarization of Mn atoms, increasing the magnetic moment provided by Mn atoms from 3.94 μB to 4.69 μB.

[0106] After the introduction of vacancies, the Si atoms surrounding the vacancies are also magnetized, generating a small magnetic moment. Without vacancies, the total magnetic moment provided by the surrounding Si atoms is 0.06 μB, which increases to 0.09 μB after the addition of vacancies. The addition of C vacancies provides electrons to the recombination model, causing a redistribution of electrons between Mn and the surrounding Si atoms. The number of unpaired electrons increases, spin polarization is enhanced, and the magnetism of the Mn-doped SiC supercell is greatly improved.

[0107] As can be seen from the above comparison results, in the 3C-SiC composite model co-doped with transition metal atoms and C vacancies provided by the present invention, the vacancies have a significant impact on the magnetism of 3C-SiC-based dilute magnetic semiconductors, providing a new approach for their application in the field of spintronic devices.

[0108] The 3C-SiC composite model obtained by the method of this invention, which is co-doped with transition metal atoms and C vacancies, can be used as a dilute magnetic semiconductor material to fabricate spintronic devices.

[0109] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0110] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for constructing a 3C-SiC composite model co-doped with transition metal atoms and C vacancies, characterized in that, The following steps are used to build it: Step 1: Construct a 3C-SiC supercell using quantum mechanical simulation software based on first principles of density functional theory; Step 2: Use the BFGS algorithm to perform geometric optimization on the 3C-SiC supercell to obtain the 3C-SiC supercell with the lowest total atomic internal energy; Step 3: Replace the Si atoms in the 3C-SiC supercell obtained in Step 2 with transition metal atoms to obtain a 3C-SiC supercell doped with transition metal atoms; Step 4: Use the BFGS algorithm to perform geometric optimization on the transition metal atom-doped 3C-SiC supercell obtained in Step 3 to obtain the optimized transition metal atom-doped 3C-SiC supercell. Step 5: Remove any C atom from the optimized transition metal atom-doped 3C-SiC supercell to form a C vacancy, and obtain a 3C-SiC composite model co-doped with C vacancy and transition metal atom. Then, perform geometric optimization on the obtained 3C-SiC composite model co-doped with C vacancy and transition metal atom to obtain an optimized 3C-SiC composite model co-doped with C vacancy and transition metal atom. Among them, the C atom that forms a C vacancy is closest to the transition metal atom in the optimized transition metal atom-doped 3C-SiC supercell; The geometric optimization described in steps 2, 4, and 5 is based on the principle of minimum energy, and the parameters for geometric optimization all include: plane wave cutoff energy E. cut The sampled value at point k of the Brillouin zone integral is 450eV, and the value is 2×2×2. The convergence condition of the BFGS algorithm includes: the convergence value of the total energy of the system is 2.0 × 10⁻⁶. -5 eV / atom, the convergence value of interatomic interaction is 0.05 eV / nm, the stress deviation is less than 0.05 GPa, and the tolerance offset is less than 0.002 Å; The U-value of the transition metal atoms is corrected during the geometry optimization process in steps 4 and 5.

2. The method for constructing the 3C-SiC composite model co-doped with transition metal atoms and C vacancies as described in claim 1, characterized in that, The transition metal atoms include at least one of chromium atoms, manganese atoms, iron atoms, and cobalt atoms.

3. The method for constructing the 3C-SiC composite model co-doped with transition metal atoms and C vacancies as described in claim 1, characterized in that, The quantum mechanical simulation software based on first-principles calculations of density functional theory includes VASP and Materials Studio.

4. The method for constructing the 3C-SiC composite model co-doped with transition metal atoms and C vacancies as described in claim 2, characterized in that, The composite model is constructed using the following steps: Step 1: Use Materials Studio software to build a 3C-SiC supercell; Step 2: Use the BFGS algorithm to perform geometric optimization on the 3C-SiC supercell to obtain the 3C-SiC supercell with the lowest total atomic internal energy; Step 3: Replace the Si atoms in the 3C-SiC supercell with Cr atoms to obtain a Cr-doped 3C-SiC supercell; Step 4: Use the BFGS algorithm to perform geometric optimization on the Cr atom-doped 3C-SiC supercell to obtain the optimized Cr atom-doped 3C-SiC supercell; Step 5: Remove the C atom closest to Cr in the optimized Cr-doped 3C-SiC supercell to form a C vacancy, and obtain a 3C-SiC composite model co-doped with C vacancy and Cr atom. Then, perform geometric optimization on it to obtain a structurally stable 3C-SiC composite model co-doped with C vacancy and Cr atom. Among them, the C atom that forms a C vacancy is closest to the transition metal atom in the optimized transition metal atom-doped 3C-SiC supercell; The parameters for geometric optimization in steps 2, 4, and 5 include: plane wave cutoff energy E. cut The value is 450 eV, the sampling value of the k-point of the Brillouin zone integral is 2×2×2, and the U value of the Cr atoms is corrected during the geometry optimization process described in steps 4 and 5, and the U value is 3.

0. The convergence condition for the BFGS algorithm includes: the total energy of the system converges to a value of 2.0 × 10⁻⁶. -5 eV / atom, the convergence value of interatomic interaction is 0.05 eV / nm, the stress deviation is less than 0.05 GPa, and the tolerance offset is less than 0.002 Å.

5. A method for modifying 3C-SiC, characterized in that, 3C-SiC is modified using a 3C-SiC composite model constructed using the construction method described in any one of claims 1 to 4.

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