Long-range ferromagnetic gan material and preparation method and application thereof

Abstract

The application provides a long-range ferromagnetic GaN material and a preparation method and application thereof. In the preparation method, the low temperature corresponding to the square wave pulse temperature is 500-700 DEG C, a stack mismatched wurtzite GaN structure layer is formed on a substrate during low-temperature deposition, the high temperature corresponding to the square wave pulse temperature is 800-1000 DEG C, a wurtzite structure GaN layer is deposited on the stack mismatched wurtzite GaN structure layer during high-temperature deposition, and the stack mismatched wurtzite GaN structure layer is buried. The stack mismatched grain boundary with long-range ferromagnetic sequence is formed in the GaN by controlling the temperature to change periodically in the square wave pulse, other magnetic impurities are not introduced, and the reaction chamber is not polluted. The energy band of the stack mismatched wurtzite GaN structure is simulated, the spin polarization property is confirmed to exist, on the basis, the Curie temperature is predicted according to the mean field approximation, and it is confirmed that the long-range magnetic sequence can still be kept under the condition that the temperature is higher than room temperature.

Description

Technical Field

[0001] This invention relates to the field of magnetic semiconductor materials technology, and in particular to a long-range ferromagnetic GaN material, its preparation method, and its applications. Background Technology

[0002] In the 1960s, Intel founder Moore predicted that the number of transistors in an integrated circuit per unit area would double every 18 months—a concept commonly known as Moore's Law. However, as device size reaches its physical limits, this law is facing failure. On the other hand, the rapid development of information technology is driving increasing demands for miniaturization, integration, and multifunctionality of devices. To address the limitations of semiconductor electronics technology, introducing additional adjustable degrees of freedom for electrons is an important and feasible solution. Spintronics has become a research hotspot for this problem, focusing on controlling the spin degree of freedom of electrons to obtain corresponding functional devices. Electron spin plays a crucial role in spintronics, atomic-level magnetic access, and the construction of quantum information devices, and spin-excited transitions are significantly correlated with the inelastic electron tunneling effect. Currently, researchers have used magnetic materials to design functional devices such as spin filters, spin-flipping devices, negative differential resistors, and spin valves.

[0003] Currently, most magnetic materials are typically realized in metal nanowires and single-molecule magnets, which present certain technological barriers for large-scale device integration. GaN, as a third-generation semiconductor material, boasts advantages such as a direct bandgap of 3.4 eV, high breakdown field strength, high stability, and compatibility with CMOS processes, making it a crucial material in the semiconductor industry. While some progress has been made in realizing GaN dilute magnetic semiconductors in recent years, related research is still in its initial stages. Currently, there are no published reports on long-range magnetic order GaN materials or spintronic devices based on long-range magnetic order GaN materials. Summary of the Invention

[0004] In view of this, the present invention proposes a long-range ferromagnetic GaN material, its preparation method and application, in order to solve the technical problems existing in the prior art.

[0005] In a first aspect, the present invention provides a method for preparing a long-range ferromagnetic GaN material, comprising the following steps:

[0006] Long-range ferromagnetic GaN material was deposited on a substrate using Ga and N sources as raw materials; the temperature varied periodically with square wave pulses during the deposition process.

[0007] Among them, the low temperature corresponding to the square wave pulse temperature is 500-700℃, and a stacking mismatch zinc sphalerite GaN structure layer is formed on the substrate during low-temperature deposition.

[0008] The high temperature corresponding to the square wave pulse temperature is 800-1000℃. During high-temperature deposition, a wurtzite GaN layer is deposited on the stacked mismatched zinc sphalerite GaN structure layer, and the stacked mismatched zinc sphalerite GaN structure layer is buried.

[0009] Preferably, in the method for preparing the long-range ferromagnetic GaN material, in the step of forming a stacked mismatched zinc sphalerite GaN structure layer on the substrate during low-temperature deposition, the molar ratio of N source to Ga source is 700 to 900.

[0010] Preferably, in the method for preparing the long-range ferromagnetic GaN material, the low-temperature deposition time is 5 to 10 seconds in the step of forming a stacked mismatched zinc sphalerite GaN structure layer on the substrate during low-temperature deposition.

[0011] Preferably, in the method for preparing the long-range ferromagnetic GaN material, in the step of depositing a wurtzite GaN layer on a stacked mismatched zinc sphalerite GaN structure layer during high-temperature deposition, the molar ratio of N source to Ga source is 1800–2200.

[0012] Preferably, in the method for preparing the long-range ferromagnetic GaN material, the deposition pressure is 10 to 100 Torr in the steps of depositing a stacked mismatched zinc sphalerite GaN structure layer on a substrate and depositing a wurtzite structure GaN layer on the stacked mismatched zinc sphalerite GaN structure layer.

[0013] Preferably, in the method for preparing the long-range ferromagnetic GaN material, the Ga source includes any one of trimethylgallium and triethylgallium.

[0014] Preferably, in the method for preparing the long-range ferromagnetic GaN material, the N source is ammonia.

[0015] Preferably, in the method for preparing the long-range ferromagnetic GaN material, the substrate includes any one of a sapphire substrate, a SiC substrate, a Si substrate, and a GaN substrate.

[0016] Secondly, the present invention also provides a long-range ferromagnetic GaN material, which is prepared by the aforementioned preparation method.

[0017] Thirdly, the present invention also provides a long-range ferromagnetic GaN material prepared by the preparation method described above, or the application of the long-range ferromagnetic GaN material in the preparation of spintronic devices.

[0018] The method for preparing long-range ferromagnetic GaN materials according to the present invention has the following advantages over the prior art:

[0019] The method for preparing long-range ferromagnetic GaN materials of the present invention employs a periodic square-wave pulse temperature variation. The low temperature corresponding to the square-wave pulse temperature is 500–700°C, during which a stacked mismatched zincblende GaN structure layer is formed on the substrate. The high temperature corresponding to the square-wave pulse temperature is 800–1000°C, during which a wurtzite structure GaN layer is deposited on the stacked mismatched zincblende GaN structure layer, and the stacked mismatched zincblende GaN structure layer is buried, ultimately yielding the long-range ferromagnetic GaN material. This method, by controlling the temperature to vary periodically with square-wave pulses during deposition, forms stacked mismatched grain boundaries with long-range ferromagnetic order in the GaN, without introducing other magnetic impurities and without contaminating the reaction chamber. Density functional theory is used to simulate the band structure of the stacked mismatched zincblende GaN, confirming the existence of spin polarization. Based on this, the Curie temperature is predicted according to the mean-field approximation, confirming that the long-range magnetic order can still be maintained at temperatures above room temperature. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a diagram showing the periodic square wave pulse variation of temperature during the deposition process of the present invention.

[0022] Figure 2 This is a schematic diagram of the formation process of the long-range ferromagnetic GaN material of the present invention;

[0023] Figure 3 A schematic diagram of a stacked mismatched zinc sphalerite GaN structure formed according to the method in Example 1;

[0024] Figure 4 The image shows the spin-splitting band structure of the long-range ferromagnetic GaN material prepared according to the method in Example 1.

[0025] Figure 5 The simulation results show the Curie temperature of the long-range ferromagnetic GaN material prepared according to the method in Example 1. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] To better understand the invention and not to limit its scope, all figures indicating amounts, percentages, and other numerical values ​​used in this application should, in all cases, be understood to be modified by the word "approximately." Therefore, unless specifically stated otherwise, the numerical parameters listed in the specification and appended claims are approximate values ​​and may vary depending on the desired properties being sought. Each numerical parameter should at least be considered as obtained based on reported significant figures and through conventional rounding methods.

[0028] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0029] This invention provides a method for preparing long-range ferromagnetic GaN materials, comprising the following steps:

[0030] Long-range ferromagnetic GaN material was deposited on a substrate using Ga and N sources as raw materials; the temperature varied periodically with square wave pulses during the deposition process.

[0031] Among them, the low temperature corresponding to the square wave pulse temperature is 500-700℃, and a stacking mismatch zinc sphalerite GaN structure layer is formed on the substrate during low-temperature deposition.

[0032] The high temperature corresponding to the square wave pulse temperature is 800-1000℃. During high-temperature deposition, a wurtzite GaN layer is deposited on the stacked mismatched zinc sphalerite GaN structure layer, and the stacked mismatched zinc sphalerite GaN structure layer is buried.

[0033] It should be noted that the preparation method of the long-range ferromagnetic GaN material of the present invention uses Ga and N sources as raw materials and employs a periodic square wave pulse temperature change to prepare the long-range ferromagnetic GaN material on a substrate; for details, please refer to... Figure 1 As shown, during the deposition process, the temperature exhibits... Figure 1 The square wave pulse variation shown in the diagram has a high temperature of T1 and a low temperature of T2. The high temperature of T1 is 800–1000°C, and the low temperature of T2 is 500–700°C. When the temperature is low (T2), a stacking mismatched zinc sphalerite GaN structure layer is formed on the substrate during deposition. When the temperature changes to high (T1), a wurtzite GaN layer is deposited on the stacking mismatched zinc sphalerite GaN structure layer, and the wurtzite GaN layer buries the stacking mismatched zinc sphalerite GaN structure layer. In this invention, the temperature can be a single-period square wave pulse or multiple-period square wave pulses. If the temperature is a single-period square wave pulse, stacking mismatch grain boundaries can be generated; if the temperature is a multi-period square wave pulse, multiple stacking mismatch grain boundaries can be generated. This invention employs a periodically varying temperature using square-wave pulses. First, a stacked mismatched zincblende GaN structure layer is formed on a substrate. Then, a wurtzite GaN layer is deposited on top of this layer, and the stacked mismatched zincblende GaN structure layer is buried, ultimately yielding a long-range ferromagnetic GaN material. The preparation method of this invention, by controlling the temperature during deposition to exhibit periodic square-wave pulse variations, forms stacked mismatch grain boundaries with long-range ferromagnetic order in the GaN, without introducing other magnetic impurities and without contaminating the reaction chamber.

[0034] In some embodiments, during the step of forming a stacking mismatch zincblende GaN structure layer on the substrate during low-temperature deposition, the molar ratio of N source to Ga source is 700–900. This molar ratio ensures a relatively high proportion of the corresponding metal source (i.e., gallium source), thereby ensuring that the boundaries of the resulting stacking mismatched island structures are composed of metal atoms.

[0035] In some embodiments, during the step of forming a stacked mismatch zinc sphalerite GaN structure layer on the substrate during low-temperature deposition, the low-temperature deposition time is 5 to 10 seconds; ensuring that the growth time corresponds to only one atomic layer, thereby introducing a single-layer stacked mismatch zinc sphalerite GaN structure layer on the substrate.

[0036] In some embodiments, during the step of depositing a wurtzite GaN layer on a stacked mismatched sphalerite GaN structure layer at high temperature, the molar ratio of N source to Ga source is 1800 to 2200; the specific high-temperature deposition time is determined according to the actual situation, as long as the deposition time of the grown wurtzite GaN structure layer can cover the stacked mismatched sphalerite GaN structure layer.

[0037] For details, please refer to the following again. Figure 1 As shown, Figure 1 The deposition time t2 for medium and low temperature sedimentation is 5 to 10 seconds, while the deposition time t1 for high temperature sedimentation is determined based on the actual situation.

[0038] Specifically, the deposition method used is MOCVD.

[0039] In some embodiments, the deposition pressure is 10 to 100 Torr in the steps of depositing a stacked mismatched zinc sphalerite GaN structure layer on a substrate and depositing a wurtzite structure GaN layer on the stacked mismatched zinc sphalerite GaN structure layer.

[0040] In some embodiments, the Ga source includes either trimethylgallium or triethylgallium.

[0041] In some embodiments, the N source is ammonia.

[0042] In some embodiments, the substrate includes any one of a sapphire substrate, a SiC substrate, a Si substrate, and a GaN substrate.

[0043] Furthermore, a GaN homogeneous substrate is preferred as the epitaxial substrate, and further reference is made to... Figure 2 The diagram illustrates the formation process of the long-range ferromagnetic GaN material according to the present invention. Initially, a GaN substrate is used as the substrate. In step 1, a square wave pulse deposition temperature of 500–700°C (i.e., the low temperature mentioned above) is used, combined with a molar ratio of N source to Ga source of 700–900, to form localized stacking mismatch island structures on the surface of the GaN substrate. These structures expand and merge, eventually forming a stacking mismatched zincblende GaN structure layer. In steps 2–4, a square wave pulse deposition temperature of 800–1000°C (i.e., the high temperature mentioned above) is used, combined with a molar ratio of N source to Ga source of 1800–2200, to grow wurtzite GaN layers layer by layer until the resulting stacking mismatched zincblende GaN structure layer is embedded in the GaN bulk material.

[0044] Based on the same inventive concept, this embodiment of the invention also provides a long-range ferromagnetic GaN material, which is prepared using the above-described preparation method.

[0045] Based on the same inventive concept, this embodiment of the invention also provides an application of the above-mentioned long-range ferromagnetic GaN material in the fabrication of spintronic devices.

[0046] The following specific embodiments further illustrate the preparation method of the long-range ferromagnetic GaN material of the present invention. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0047] Example 1

[0048] This invention provides a method for preparing long-range ferromagnetic GaN materials, comprising the following steps:

[0049] Long-range ferromagnetic GaN materials are deposited on GaN substrates using Ga and N sources as raw materials; the temperature changes periodically with square wave pulses during the deposition process.

[0050] Among them, the low temperature corresponding to the square wave pulse temperature is 600℃, the low temperature deposition time is 8s, the molar ratio of N source to Ga source during the low temperature deposition process is 800, the low temperature deposition pressure is 50Torr, and a stacking mismatch zinc sphalerite GaN structure layer is formed on the GaN substrate during the low temperature deposition process.

[0051] The high temperature corresponding to the square wave pulse temperature is 800℃. During the high-temperature deposition process, the molar ratio of N source to Ga source is 2000, and the high-temperature deposition pressure is 50 Torr. During the high-temperature deposition, a wurtzite GaN layer is deposited on the stacked mismatched zinc sphalerite GaN structure layer, and the stacked mismatched zinc sphalerite GaN structure layer is buried, thus obtaining a long-range ferromagnetic GaN material.

[0052] In this process, the Ga source is trimethylgallium, the N source is ammonia, and the temperature changes in a single-cycle (i.e., one cycle) square wave pulse.

[0053] Figure 3 This is a schematic diagram of a stacked mismatched zinc sphalerite GaN structure formed according to the method in Example 1.

[0054] Figure 4 This is a spin splitting band diagram of the long-range ferromagnetic GaN material prepared according to the method in Example 1.

[0055] Figure 5 The simulation results show the Curie temperature of the long-range ferromagnetic GaN material prepared according to the method in Example 1.

[0056] from Figure 3 As can be seen from the example, by using the method in Example 1, the temperature changes periodically with square wave pulses during the deposition process to obtain a stacked mismatched zinc sphalerite GaN structure layer. Figure 4In the middle QZGB, there are high-symmetric K points in reciprocal space, Q(0.0,0.5,0.5), Z(0.0,0.0,0.5), G(0.0,0.0,0.0), B(0.5,0.0,0.0). α and β correspond to the energy bands caused by the grain boundaries due to stacking mismatch within the band gap. Different colors correspond to different spin channels.

[0057] according to Figure 5 Calculations show that the magnetic moment decreases to zero at temperatures above 1500 K, indicating that the magnetic moment is generated via a stoner mechanism involving itinerant electrons. Furthermore, it was found that the system retains over 90% of the magnetic moment at room temperature (300 K) that is at absolute zero (0 K).

[0058] Density functional theory was used to simulate the band structure of stacked mismatched zinc sphalerite GaN, confirming the existence of spin polarization. Based on this, the Curie temperature was predicted according to the mean field approximation, confirming that the long-range magnetic order can still be maintained at temperatures above room temperature.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a long-range ferromagnetic GaN material, characterized in that, Includes the following steps: Long-range ferromagnetic GaN materials are deposited on a substrate using Ga and N sources as raw materials. The temperature exhibits periodic square-wave pulse changes during the deposition process; Among them, the low temperature corresponding to the square wave pulse temperature is 500-700℃, and a stacking mismatch zinc sphalerite GaN structure layer is formed on the substrate during low-temperature deposition. The high temperature corresponding to the square wave pulse temperature is 800-1000℃. During high-temperature deposition, a wurtzite GaN layer is deposited on the stacked mismatched zinc sphalerite GaN structure layer, and the stacked mismatched zinc sphalerite GaN structure layer is buried.

2. The method for preparing long-range ferromagnetic GaN material as described in claim 1, characterized in that, In the step of forming a stacked mismatched zinc sphalerite GaN structure layer on the substrate during low-temperature deposition, the molar ratio of N source to Ga source is 700 to 900.

3. The method for preparing long-range ferromagnetic GaN material as described in claim 2, characterized in that, In the step of forming a stacked mismatched zinc sphalerite GaN structure layer on the substrate during low-temperature deposition, the low-temperature deposition time is 5 to 10 seconds.

4. The method for preparing long-range ferromagnetic GaN material as described in claim 1, characterized in that, In the step of depositing a wurtzite-structured GaN layer on a stacked mismatched sphalerite GaN structure layer during high-temperature deposition, the molar ratio of N source to Ga source is 1800–2200.

5. The method for preparing long-range ferromagnetic GaN materials according to any one of claims 1 to 4, characterized in that, In the steps of depositing a stacked mismatched zinc sphalerite GaN structure layer on a substrate and depositing a wurtzite structure GaN layer on the stacked mismatched zinc sphalerite GaN structure layer, the deposition pressure is 10 to 100 Torr.

6. The method for preparing long-range ferromagnetic GaN material as described in claim 1, characterized in that, The Ga source includes either trimethylgallium or triethylgallium.

7. The method for preparing long-range ferromagnetic GaN material as described in claim 1, characterized in that, The N source is ammonia.

8. The method for preparing long-range ferromagnetic GaN material as described in claim 1, characterized in that, The substrate includes any one of sapphire substrate, SiC substrate, Si substrate, and GaN substrate.

9. A long-range ferromagnetic GaN material, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 8.

10. The application of a long-range ferromagnetic GaN material prepared by any one of the preparation methods described in claims 1 to 8, or the long-range ferromagnetic GaN material described in claim 9, in the preparation of spintronic devices.

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