Preparation method of Fe < 1-x > Al < x > alloy through molecular beam epitaxy vacuum evaporation

Abstract

The invention discloses a preparation method of a molecular beam epitaxy vacuum evaporation Fe < 1-x > Al < x > alloy, which realizes real-time monitoring of component proportion in the evaporation process through a quartz crystal oscillation and mass spectrum coupling technology. According to the method, the evaporation temperature of metal iron and aluminum is adjusted through an in-situ monitoring dynamic feedback system, meanwhile, a substrate temperature changing process is introduced to inhibit interface diffusion and eliminate lattice defects, compared with a traditional MBE process, atomic-scale component control is achieved through accurate evaporation source temperature control and element component monitoring, and the method is suitable for large-scale production. The problems of stress accumulation and component deviation in alloy epitaxy are solved. The prepared Fe < 1-x > Al < x > single crystal film has the characteristics of large-area flatness, controllable thickness and good interface mutability, and is suitable for soft X-ray conversion materials in magnetoelectric coupling devices, high-frequency soft magnetic elements and inertial confinement fusion experiments.

Description

Technical Field

[0001] The present invention relates to the field of vacuum coating technology and single crystal coating preparation technology, specifically to a molecular beam epitaxial vacuum evaporation Fe 1-x Al x Alloy preparation method. Background Art

[0002] In the field of thin film fabrication, molecular beam epitaxy (MBE) technology, which precisely controls an atomic or molecular beam in an ultra-high vacuum environment to achieve layer-by-layer thin film growth along specific crystal orientations on single crystal substrates, is a key method for producing high-quality single-crystal thin films. Due to their excellent magnetostrictive effect and high magnetic permeability, FeAl alloy thin films have shown significant application potential in magnetoelectric coupling devices, high-frequency soft magnetic components, and high-density information storage. In particular, FeAl alloy films with precise atomic ratios can serve as highly efficient soft X-ray conversion materials in inertial confinement fusion (ICF) experiments, directly impacting energy efficiency. However, conventional fabrication methods face significant challenges: interfacial diffusion is prone to occur during metal / metal heteroepitaxy, leading to compositional deviations and crystal defects. Furthermore, maintaining atomically sharp interfaces at heat treatment temperatures exceeding 150°C is difficult, compromising the stability of the film's magnetoelectric properties. Existing technologies rely heavily on empirical trial-and-error to control growth parameters (such as temperature and beam ratio) and lack in-situ real-time feedback mechanisms, making precise optimization of single crystal quality, thickness uniformity, and interface control difficult. In addition, the stress accumulation caused by the lattice mismatch of the heterogeneous substrate, as well as the problems of low-temperature polycrystallization and high-temperature phase transition, further restrict the development of Fe 1-x Al x The performance ceiling and application reliability of single-crystal thin films require the development of an MBE process that combines in-situ monitoring and dynamic control to overcome the technical bottlenecks of interface control and crystal quality optimization. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a molecular beam epitaxial vacuum evaporation Fe 1-x Al x Alloy preparation method.

[0004] In order to solve the above technical problems, the present invention provides a technical solution: a molecular beam epitaxial vacuum evaporation Fe 1- x Al x The method for preparing the alloy is characterized by comprising the following steps:

[0005] Step 1: Clean the substrate and place it in the MBE injection chamber. The injection chamber is vacuumed to 1×10 -7 Torr or above;

[0006] Step 2: When the vacuum in the injection chamber matches the vacuum in the growth chamber, transfer the substrate to the growth chamber.

[0007] Step 3: Set the substrate degassing temperature and observe the RHEED. When clear diffraction fringes appear, stop degassing and set the substrate temperature to the substrate temperature for the first stage of epitaxial growth.

[0008] Step 4: Set the Fe and Al evaporation source temperatures, raise the temperature to the target temperature at a certain heating rate, and open the evaporation source baffles;

[0009] Step 5: Monitor the deposition rate using a quartz crystal oscillator and correct the evaporation source temperature;

[0010] Step 6: After a period of evaporation, turn on the mass spectrometer to monitor the elements and content of the evaporated elements on the substrate and correct the evaporation source temperature;

[0011] Step 7: Set the substrate temperature to the substrate temperature of the second stage of epitaxial growth and maintain the vacuum in the growth chamber;

[0012] Step 8: Real-time detection of the crystal quality of the sample growth by RHEED;

[0013] Step 9: When the film grows to a certain thickness, stop the growth and anneal the sample at the corresponding temperature;

[0014] The above steps use 10 -8 Torr ultra-high vacuum chamber system, which is equipped with independently controlled Fe and Al source crucible evaporation sources and shutter systems. The purity of the Fe and Al sources is ≥99.999%;

[0015] The above steps are achieved by dynamic feedback control through the combination of RHEED diffraction intensity oscillation, quadrupole mass spectrometer and quartz crystal oscillator. The PID algorithm is used to adjust the crucible source power in real time to keep the Fe / Al beam ratio within the range of (1-x) / x±0.1.

[0016] The above steps implement a three-stage variable temperature growth process, in which a 5 nm transition layer is evaporated at 200-250° C. in the first stage, a main layer is evaporated at 400-450° C. in the second stage, and annealing is performed at 300° C. for 10-30 minutes in the third stage.

[0017] Furthermore, the substrate is a MgO substrate.

[0018] Furthermore, in step 4, the Fe source is heated to 1250° C. at a rate of 10° C. / min, and the Al source is heated to 850° C. at a rate of 5° C. / min.

[0019] Furthermore, the sample Fe 1-x Al x Component deviation Δx≤0.1.

[0020] After adopting the above method, a molecular beam epitaxial vacuum evaporation Fe 1-x Al x The alloy preparation method has the following advantages: 1. Through the combination of quartz crystal oscillation and mass spectrometry technology, the Fe / Al atomic ratio can be controlled in real time, avoiding the component deviation problem of traditional processes;

[0021] 2. The in-situ monitoring system shortens the parameter debugging cycle from one week in the traditional trial-and-error method to within 12 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a molecular beam epitaxial vacuum evaporation Fe 1-x Al x Example 1 of the preparation method of the alloy to obtain Fe 80 Al 20 Schematic diagram of high-quality diffraction fringes (RHEED) of alloy coating.

[0023] Figure 2 It is a molecular beam epitaxial vacuum evaporation Fe 1-x Al x Example 1 of the preparation method of the alloy to obtain Fe 80 Al 20 Schematic diagram of high-resolution X-ray diffraction (HRXRD) spectrum of alloy coating.

[0024] Figure 3 It is a molecular beam epitaxial vacuum evaporation Fe 1-x Al x Example 2 of the preparation method of the alloy to obtain Fe 75 Al 25 Schematic diagram of high-resolution X-ray diffraction (HRXRD) spectrum of alloy coating. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings.

[0026] Combined with attachment Figure 1-3 , a molecular beam epitaxial vacuum evaporation Fe 1-x Al x The method for preparing the alloy is characterized by comprising the following steps:

[0027] Step 1: Clean the substrate and place it in the MBE injection chamber. The injection chamber is vacuumed to 1×10 -7 Torr or more, the substrate is a MgO substrate;

[0028] Step 2: When the vacuum in the injection chamber matches the vacuum in the growth chamber, transfer the substrate to the growth chamber.

[0029] Step 3: Set the substrate degassing temperature and observe the RHEED. When clear diffraction fringes appear, stop degassing and set the substrate temperature to the substrate temperature for the first stage of epitaxial growth.

[0030] Step 4: Set the Fe and Al evaporation source temperatures, raise them to the target temperature at a certain heating rate, and open the evaporation source shutters. The Fe source is heated to 1250°C at 10°C / min, and the Al source is heated to 850°C at 5°C / min.

[0031] Step 5: Monitor the deposition rate using a quartz crystal oscillator and correct the evaporation source temperature;

[0032] Step 6: After a period of evaporation, turn on the mass spectrometer to monitor the elements and content of the evaporated elements on the substrate and correct the evaporation source temperature;

[0033] Step 7: Set the substrate temperature to the substrate temperature of the second stage of epitaxial growth and maintain the vacuum in the growth chamber;

[0034] Step 8: Real-time detection of the crystal quality of the sample growth by RHEED;

[0035] Step 9: When the film grows to a certain thickness, stop the growth and anneal the sample at the corresponding temperature. 1-x Al x Component deviation Δx≤0.1.

[0036] The above steps use 10 -8 Torr ultra-high vacuum chamber system, which is equipped with independently controlled Fe and Al source crucible evaporation sources and shutter systems. The purity of the Fe and Al sources is ≥99.999%;

[0037] The above steps are achieved by dynamic feedback control through the combination of RHEED diffraction intensity oscillation, quadrupole mass spectrometer and quartz crystal oscillator. The PID algorithm is used to adjust the crucible source power in real time to keep the Fe / Al beam ratio within the range of (1-x) / x±0.1.

[0038] The above steps implement a three-stage variable temperature growth process, in which a 5 nm transition layer is evaporated at 200-250° C. in the first stage, a main layer is evaporated at 400-450° C. in the second stage, and annealing is performed at 300° C. for 10-30 minutes in the third stage.

[0039] Example 1, a molecular beam epitaxy vacuum evaporation Fe 80 Al 20 The preparation method of the alloy includes the following specific steps:

[0040] Step 1: Place the cleaned MgO substrate into the MBE injection chamber and evacuate the chamber to a vacuum of 1×10 -7 Toor or above;

[0041] Step 2: When the vacuum in the injection chamber matches the vacuum in the growth chamber, transfer the MgO substrate to the growth chamber;

[0042] Step 3: Set the degassing temperature of the MgO substrate to 600°C. Observe the RHEED. When clear diffraction fringes appear, stop the degassing and set the substrate temperature to the first stage temperature of 200°C.

[0043] Step 4: Set the Fe evaporation source temperature to 1250°C and increase the heating rate to the target temperature at 10°C / min;

[0044] Step 5: Set the Al evaporation source temperature to 850°C and increase the temperature at a rate of 5°C / min to the target temperature.

[0045] Step 6: Wait until the vacuum in the growth chamber is higher than 1×10 -7 Toor, open the shutter of the evaporation source; monitor the evaporation rate by a quartz crystal oscillator and adjust the evaporation source temperature to make the Fe atomic growth rate 0.015 ML / s (monolayer / second) and the Al atomic growth rate 0.004 ML / s;

[0046] Step 7: After evaporation for 3 minutes, turn on the mass spectrometer to monitor the elements and content deposited on the substrate and correct the evaporation source temperature;

[0047] Step 8: Set the substrate temperature to the second stage temperature of 400°C and maintain the vacuum in the growth chamber above 1×10 -7 Toor;

[0048] Step 9: Real-time detection of the crystal quality of the sample growth by RHEED;

[0049] Step 10: When the film grows to a certain thickness, stop evaporation, maintain the substrate temperature at 300℃ in the third stage, anneal the sample for 10 minutes, observe RHEED, and the diffraction fringes are clear and slender. Figure 1 shown. Figure 2 The HRXRD of the film is shown, and high-quality Fe 80 Al 20 Alloy coating.

[0050] Example 2 A molecular beam epitaxial vacuum evaporation Fe 75 Al 25 The preparation method of the alloy includes the following specific steps:

[0051] Step 1: Place the cleaned MgO substrate into the MBE injection chamber and evacuate the chamber to a vacuum of 1×10 -7 Toor or above;

[0052] Step 2: When the vacuum in the injection chamber matches the vacuum in the growth chamber, transfer the MgO substrate to the growth chamber;

[0053] Step 3: Set the degassing temperature of the MgO substrate to 600°C. Observe the RHEED. When clear diffraction fringes appear, stop the degassing and set the substrate temperature to 200°C, the temperature of the first stage of epitaxial growth.

[0054] Step 4: Set the Fe evaporation source temperature to 1240°C and increase the heating rate to the target temperature at 10°C / min;

[0055] Step 5: Set the Al evaporation source temperature to 850°C and increase the temperature at a rate of 5°C / min to the target temperature.

[0056] Step 6: Wait until the vacuum in the growth chamber is higher than 1×10 -7 Toor, open the shutter of the evaporation source; monitor the deposition rate through the quartz crystal oscillator and adjust the evaporation source temperature to make the Fe atomic growth rate 0.012ML / s and the Al atomic growth rate 0.004ML / s;

[0057] Step 7: After 3 minutes of evaporation growth, turn on the mass spectrometer to monitor the elements and content deposited on the substrate and correct the evaporation source temperature;

[0058] Step 8: Set the substrate temperature to the second stage temperature of 400°C and maintain the vacuum in the growth chamber above 1×10 -7 Toor;

[0059] Step 9: Real-time detection of the crystal quality of the sample growth by RHEED;

[0060] Step 10: When the film grows to a certain thickness, stop evaporation, maintain the third stage substrate temperature at 300°C, anneal the sample for 10 minutes, and observe RHEED. The diffraction fringes are clear and slender. Figure 3 The HRXRD of the film is shown, and high-quality Fe 75 Al 25 Alloy coating.

[0061] Comparative Example 1, a molecular beam epitaxial vacuum evaporation Fe 85 Al 15 The preparation method of the alloy includes the following specific steps:

[0062] Step 1: Place the cleaned MgO substrate into the MBE injection chamber and evacuate the chamber to a vacuum of 1×10 -7 Toor or above;

[0063] Step 2: When the vacuum in the injection chamber matches the vacuum in the growth chamber, transfer the MgO substrate to the growth chamber;

[0064] Step 3: Set the degassing temperature of the MgO substrate to 600°C. Observe the RHEED. When clear diffraction fringes appear, stop the degassing and set the substrate temperature to the first stage temperature of 200°C.

[0065] Step 4: Set the Fe evaporation source temperature to 1280°C and increase the heating rate to the target temperature at 10°C / min;

[0066] Step 5: Set the Al evaporation source temperature to 850°C and increase the temperature at a rate of 5°C / min to the target temperature.

[0067] Step 6: Wait until the vacuum in the growth chamber is higher than 1×10 -7 Toor, open the shutter of the evaporation source; monitor the evaporation rate through the quartz crystal oscillator and adjust the evaporation source temperature to make the Fe atomic growth rate 0.02ML / s and the Al atomic growth rate 0.004ML / s;

[0068] Step 7: After evaporation for 3 minutes, the substrate temperature was set to 400°C, the temperature of the second stage of epitaxial growth, and the vacuum in the growth chamber was maintained above 5×10 -7 Toor;

[0069] Step 9: Real-time detection of the crystal quality of the sample growth by RHEED;

[0070] Step 10: When the film grows to a certain thickness, stop the growth, maintain the substrate temperature at 300℃, anneal the sample for 10 minutes, and observe the RHEED. The diffraction stripes of the FeAl film are clear and elongated, but has the FeAl film reached the desired thickness? 85 Al 15 The composition is still unknown.

[0071] The difference between Comparative Example 1 and Examples 1 and 2 is that Comparative Example 1 does not use quartz crystal oscillation and mass spectrometry technology, and cannot achieve real-time control of the Fe / Al atomic ratio.

[0072] Although the present invention has been described in detail through the above embodiments, the above description is not intended to limit the present invention. It is obvious for those skilled in the art to modify the present invention. Therefore, any modifications made within the principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A molecular beam epitaxy vacuum evaporation Fe 1-x Al x The method for preparing the alloy is characterized by: The following steps are involved: Step 1: Clean the substrate and place it in the MBE injection chamber. The injection chamber is vacuumed to 1×10 -7 Torr or above; Step 2: When the vacuum in the injection chamber matches the vacuum in the growth chamber, transfer the substrate to the growth chamber. Step 3: Set the substrate degassing temperature and observe the RHEED. When clear diffraction fringes appear, stop degassing and set the substrate temperature to the substrate temperature for the first stage of epitaxial growth. Step 4: Set the Fe and Al evaporation source temperatures, raise the temperature to the target temperature at a certain heating rate, and open the evaporation source baffles; Step 5: Monitor the deposition rate using a quartz crystal oscillator and correct the evaporation source temperature; Step 6: After a period of evaporation, turn on the mass spectrometer to monitor the elements and content of the evaporated elements on the substrate and correct the evaporation source temperature; Step 7: Set the substrate temperature to the substrate temperature of the second stage of epitaxial growth and maintain the vacuum in the growth chamber; Step 8: Real-time detection of the crystal quality of the sample growth by RHEED; Step 9: When the film grows to a certain thickness, stop the growth and anneal the sample at the corresponding temperature; The above steps use 10 -8 Torr ultra-high vacuum chamber system, which is equipped with independently controlled Fe and Al source crucible evaporation sources and shutter systems. The purity of the Fe and Al sources is ≥99.999%; The above steps are achieved by dynamic feedback control through the combination of RHEED diffraction intensity oscillation, quadrupole mass spectrometer and quartz crystal oscillator. The PID algorithm is used to adjust the crucible source power in real time to keep the Fe / Al beam ratio within the range of (1-x) / x±0.

1. The above steps implement a three-stage variable temperature growth process, in which a 5 nm transition layer is evaporated at 200-250° C. in the first stage, a main layer is evaporated at 400-450° C. in the second stage, and annealing is performed at 300° C. for 10-30 minutes in the third stage.

2. A molecular beam epitaxial vacuum evaporation Fe according to claim 1 1-x Al x The method for preparing the alloy is characterized by: The substrate is a MgO substrate.

3. A molecular beam epitaxial vacuum evaporation Fe according to claim 1 1-x Al x The method for preparing the alloy is characterized by: In step 4, the Fe source was heated to 1250°C at a rate of 10°C / min, and the Al source was heated to 850°C at a rate of 5°C / min.

4. A molecular beam epitaxial vacuum evaporation Fe according to claim 1 1-x Al x The method for preparing the alloy is characterized by: The sample Fe 1-x Al x Component deviation Δx≤0.1.

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