Magnetic-doped diamond film as well as preparation method and application thereof

Abstract

The invention belongs to the field of thin film materials, and discloses a magnetic-doped diamond thin film and a preparation method and application thereof. The preparation method of the magnetic-doped diamond film comprises the steps that hydrogen and methane serve as reaction precursors, alloy (FePt alloy, CoPt alloy or NiPt alloy) containing magnetic elements serves as a hot wire material, and the magnetic-doped diamond film is prepared on the surface of a substrate through a hot wire chemical vapor deposition method. According to the method, the alloy hot wire containing the magnetic elements is used in the hot wire chemical vapor deposition process for the first time, ordered growth of the magnetic-doped diamond film and release and uniform doping of the stable magnetic elements are achieved by accurately controlling the reaction atmosphere and temperature conditions, and the magnetic-doped diamond film with good magnetic performance is obtained. The magnetism-doped diamond film is added with magnetism on the basis of keeping the characteristics of diamond, has extremely high hardness, heat conductivity and chemical stability, and can be suitable for development of multifunctional materials and application in the fields of spintronics and sensors.

Description

Technical Field

[0001] The present invention relates to the technical field of thin film materials, and particularly to a magnetic-doped diamond thin film, a preparation method thereof and an application thereof. Background Art

[0002] Due to its excellent hardness, thermal conductivity and chemical stability, diamond thin films have been widely used in the fields of electronics, optics and machinery. However, pure diamond thin films do not have magnetism, which limits their applications in some electronic and spintronics fields. Therefore, in order to endow diamond thin films with magnetism and make them have multifunctional properties, researchers have tried to dope magnetic metal elements into the thin films. The traditional chemical vapor deposition (CVD) method can be used to synthesize high-quality diamond thin films, and magnetic metal elements can be doped on this basis. Currently, common modification methods include microwave plasma CVD, etc., but there are still disadvantages such as high requirements for equipment, high cost and complex processes. Moreover, in the process of doping magnetic metals into diamond thin films by existing methods, impurities are easily introduced, resulting in structural defects of diamond thin films. In addition, the uniformity and controllability of doped metals are poor, which limits the application range and performance consistency of thin films.

[0003] Therefore, the prior art still needs to be improved and developed. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a magnetic-doped diamond thin film, a preparation method thereof and an application thereof, aiming to solve the problem that impurities are easily introduced in the process of doping magnetic metals into diamond thin films, resulting in structural defects of diamond thin films.

[0005] The technical solution of the present invention is as follows:

[0006] In the first aspect of the present invention, a preparation method of a magnetic-doped diamond thin film is provided, including: using hydrogen and methane as reaction precursors, using an alloy containing magnetic elements as a hot wire material, and preparing the magnetic-doped diamond thin film on the surface of a substrate by a hot wire chemical vapor deposition method;

[0007] Wherein, the alloy is an FePt alloy, a CoPt alloy or a NiPt alloy.

[0008] Optionally, the volume ratio of methane in the reaction precursors is 0.5-2%.

[0009] Optionally, the molar percentage of the magnetic element in the alloy is 50%.

[0010] Optionally, the temperature of the hot wire material is 1200-1500 °C.

[0011] Optionally, in the hot filament chemical vapor deposition method, the growth rate of the magnetic-doped diamond film is 1-2 μm / h. The growth rate of the magnetic-doped diamond film in the present invention is relatively fast, higher than that of the microwave plasma chemical vapor deposition method.

[0012] Optionally, in the hot filament chemical vapor deposition method, the reaction pressure is 12-16 kPa and the reaction time is 1-5 hours.

[0013] Optionally, the substrate is a Si substrate, and the surface temperature of the substrate is 700-900 °C.

[0014] In the second aspect of the present invention, a magnetic-doped diamond film is provided, which is prepared by the method for preparing a magnetic-doped diamond film described above.

[0015] Optionally, the doping rate of the magnetic element in the magnetic-doped diamond film is 0.04%-0.2%.

[0016] In the third aspect of the present invention, an application of the magnetic-doped diamond film in an electronic sensor is provided.

[0017] Beneficial effects: The present invention for the first time uses an alloy containing a magnetic element (FePt alloy, CoPt alloy or NiPt alloy) as the hot filament material in the hot filament chemical vapor deposition process. By precisely controlling the reaction atmosphere and temperature conditions, the orderly growth of the magnetic-doped diamond film and the release and uniform doping of stable magnetic elements are achieved, and a magnetic-doped diamond film with good magnetic properties is obtained. The method of the present invention is simple and the process controllability is high. On the basis of maintaining the characteristics of diamond, the prepared magnetic-doped diamond film not only increases magnetism, but also has extremely high hardness, thermal conductivity and chemical stability. Therefore, it is suitable for the development of multifunctional materials and applications in the fields of spintronics and sensors. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the hot filament chemical vapor deposition device used in the preparation of the magnetic-doped diamond film in Example 1 of the present invention.

[0019] Figure 2 It is a schematic diagram of the mechanism during the growth process of the magnetic-doped diamond film prepared in Example 1 of the present invention.

[0020] Figure 3 It is the hysteresis loop measured for the magnetic-doped diamond film prepared in Example 1 of the present invention. Detailed Embodiments

[0021] The present invention provides a magnetically doped diamond film, a preparation method thereof and an application thereof. To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] An embodiment of the present invention provides a method for preparing a magnetically doped diamond film, including: using hydrogen and methane as reaction precursors, using an alloy containing a magnetic element as a hot wire material, and preparing the magnetically doped diamond film on the surface of a substrate by a hot wire chemical vapor deposition method;

[0024] Wherein, the alloy is an FePt alloy, a CoPt alloy or a NiPt alloy, that is, the magnetic element can be Fe, Co or Ni.

[0025] In the method for preparing a magnetically doped diamond film provided by the present invention, when hydrogen and methane enter the cavity of the hot wire chemical vapor deposition device, they will crack into various groups at high temperature. At the same time, the magnetic element (denoted as M) is released from the alloy hot wire at high temperature and diffuses to the surface of the substrate in the form of M, M n C. Various groups flow on the surface of the substrate to find suitable active reaction sites. As carbon atoms continue to diffuse and reach saturation on the surface of the substrate, atomic hydrogen will terminate the surface chains, causing a sp 2 、sp 3 mixed carbon film to form on the surface of the substrate. Subsequently, hydrogen radicals remove non-diamond-structured carbon, and the remaining active diamond carbon arranges to form diamond crystals. Magnetic atoms may exist in diamond crystals in a substitutional or interstitial filling manner during the diffusion and reaction process of carbon atoms, realizing the stable release and uniform doping of magnetic elements in the diamond film, avoiding the introduction of impurities, and preparing a magnetically doped diamond film with excellent magnetic properties, extremely high hardness, thermal conductivity and chemical stability. The method of the present invention is simple, has high process controllability, and can effectively ensure the uniformity of magnetic element doping, thereby obtaining a magnetically doped diamond film with excellent magnetic and chemical stability.

[0026] In some embodiments, the volume ratio of methane in the reaction precursor is 0.5-2%. By adjusting the ratio of methane in the reaction precursor, the structure and doping effect of the magnetically doped diamond film can be affected, so as to obtain different characteristics.

[0027] In some embodiments, the molar percentage of the magnetic element in the alloy is 50%.

[0028] In some embodiments, the temperature of the hot wire material is 1200 - 1500 °C. By precisely controlling the reaction atmosphere and temperature conditions, the orderly growth and uniform doping of diamond films can be achieved.

[0029] In some embodiments, in the hot wire chemical vapor deposition method, the growth rate of the magnetic-doped diamond film is 1 - 2 μm / h.

[0030] In some embodiments, in the hot wire chemical vapor deposition method, the reaction pressure is 12 - 16 kPa, and the reaction time is 1 - 5 hours. High-quality magnetic-doped diamond films can be grown within the range of the reaction pressure and time.

[0031] In some embodiments, the substrate is a Si substrate, and the surface temperature of the substrate is 700 - 900 °C.

[0032] An embodiment of the present invention also provides a magnetic-doped diamond film prepared by the preparation method of the magnetic-doped diamond film.

[0033] In some embodiments, the doping rate of the magnetic element in the magnetic-doped diamond film is 0.04% - 0.2%.

[0034] An embodiment of the present invention also provides the application of the magnetic-doped diamond film in an electronic sensor.

[0035] The following is a detailed description through specific examples.

[0036] Example 1

[0037] In this example, a NiPt alloy containing 50% Ni and 50% Pt is used as the hot wire. The silicon substrate is preheated to 800 °C, and a hydrogen-methane mixed gas with a methane concentration of 2% is introduced into the chamber of the hot wire chemical vapor deposition (the device schematic diagram is as Figure 1 shown), the pressure is controlled at 16 kPa, the reaction temperature is 1400 °C, and the deposition time is 5 hours to prepare the magnetic-doped diamond film.

[0038] As Figure 2 shown, after hydrogen and methane enter the chamber of the hot wire chemical vapor deposition device, they will crack into various groups at high temperature. At the same time, Ni elements are released from the NiPt alloy hot wire at high temperature and diffuse to the substrate surface in the forms of Ni and Ni3C. Various groups flow on the substrate surface to find suitable active reaction sites. As carbon atoms continue to diffuse and reach saturation on the substrate surface, atomic hydrogen will terminate the surface chains, causing the substrate surface to form sp 2 , sp 3A mixed carbon film. Subsequently, hydrogen radicals remove non-diamond-structured carbon, and the remaining active diamond carbon arranges to form diamond crystals. Ni atoms may exist in diamond crystals in a substitutional or interstitial filling manner during the diffusion and reaction of carbon atoms. In the embodiments of the present invention, the release and uniform doping of nickel elements as stable magnetic elements in diamond films are achieved, and the introduction of other impurities is avoided. Finally, a high-quality magnetic-doped diamond film with magnetic function, extremely high hardness, thermal conductivity, and chemical stability is prepared.

[0039] The composition of the magnetic-doped diamond film is uniform, and the surface is relatively flat. The characteristic peak of Ni can be seen in XRD, and a typical hysteresis loop can be measured using a vibrating magnetometer, as Figure 3 shown, which proves that the magnetic-doped diamond film has in-plane soft magnetism.

[0040] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description. All such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for preparing a magnetic-doped diamond film, characterized in that, Comprising: Using hydrogen and methane as reaction precursors, and an alloy containing magnetic elements as the hot wire material, the magnetically doped diamond thin film is prepared on the substrate surface by hot wire chemical vapor deposition; Among them, the alloy containing magnetic elements is FePt alloy, CoPt alloy or NiPt alloy.

2. The preparation method of the magnetically doped diamond film according to claim 1, characterized in that, The volume ratio of methane in the reaction precursor is 0.5 - 2%.

3. The method for preparing the magnetic-doped diamond film according to claim 1, wherein The molar percentage of the magnetic element in the alloy is 50%.

4. The preparation method of the magnetically doped diamond film according to claim 1, characterized in that, The temperature of the hot wire material is 1200 - 1500 °C.

5. The preparation method of the magnetically doped diamond film according to claim 1, wherein, In the hot wire chemical vapor deposition method, the growth rate of the magnetically doped diamond thin film is 1 - 2 μm / h.

6. The preparation method of the magnetic-doped diamond thin film according to claim 1, wherein In the hot wire chemical vapor deposition method, the reaction pressure is 12 - 16 kPa, and the reaction time is 1 - 5 hours.

7. The preparation method of the magnetic-doped diamond thin film according to claim 1, wherein, The substrate is a Si substrate, and the surface temperature of the substrate is 700 - 900 °C.

8. A magnetic-doped diamond film, characterized in that, Prepared by the method for preparing a magnetically doped diamond thin film according to any one of claims 1 - 7.

9. The magnetically doped diamond thin film according to claim 8, characterized in that, The doping rate of the magnetic element in the magnetically doped diamond thin film is 0.04% - 0.2%.

10. An application of the magnetically doped diamond thin film according to claim 8 or 9 in an electronic sensor.

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