A method for growing nanoscale two-dimensional materials in amorphous materials using electron beam induction

Abstract

The present invention belongs to the technical field of nanomaterials, and specifically relates to a method for growing nanoscale two-dimensional materials in amorphous by electron beam induction. The present invention uses a focused electron beam to irradiate the boundary between the crystallization region and the amorphous region of a ferroelectric sample and the atomic groups in the amorphous region. The electron beam irradiation of the ferroelectric sample will introduce energy, because the energy at the crystallization and amorphous edges and unstable atomic groups of the ferroelectric sample is high, and the energy introduced by the electron beam irradiation will generate holes and point defects in the crystallization and amorphous edges or unstable atomic groups of the ferroelectric sample, thereby growing a new nanoscale two-dimensional material with the same element but lower energy.

Description

Technical Field

[0001] The invention belongs to the technical field of nano materials, and in particular relates to a method for growing nano-scale two-dimensional materials in amorphous materials by using electron beam induction. Background Art

[0002] Two-dimensional materials are defined as independent sheet-like nanomaterials, in which atoms are bound together by strong chemical bonds such as covalent bonds and ionic bonds within the sheet, the chemical bonds outside the plane are saturated, and the layers are bound together by weak van der Waals forces. This unique structure enables two-dimensional materials to have stable structure and performance even at the single-layer limit. In the past decade, many new two-dimensional materials have been predicted and prepared, and they have also demonstrated different functions, showing great application prospects in electronics, optoelectronics, energy storage and conversion, etc.

[0003] There are many methods for preparing two-dimensional materials. The two most commonly used methods are mechanical exfoliation and CVD (chemical vapor deposition). Both methods can prepare thin layers of two-dimensional materials, but the samples obtained by these two methods are large in size and difficult to control in size. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for growing nanoscale two-dimensional materials in amorphous materials using electron beam induction. This method uses electron beam induction to grow smaller nanoscale two-dimensional materials at the amorphous-crystalline interface of ferroelectric materials and from atomic clusters in the amorphous material, and the size of the nanoscale two-dimensional materials can be controlled by controlling the electron beam.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for growing nanometer-scale two-dimensional materials in amorphous materials by electron beam induction, comprising the following steps:

[0007] Using a focused electron beam-ion beam dual beam electron microscope to cut the layered ferroelectric material to obtain a bulk ferroelectric material;

[0008] The bulk ferroelectric material is thinned overall and in the middle in sequence by using a focused electron beam-ion beam dual beam electron microscope to obtain a nano-scale layered sample; the middle of the nano-scale layered sample is an amorphous region, and the surroundings are crystalline regions;

[0009] The focused electron beam-ion beam dual beam electron microscope includes an electron beam mode and an ion beam mode;

[0010] The electron beam is irradiated on the atomic clusters in the amorphous region and the interface between the amorphous region and the crystalline region of the nano-scale layered sample using the STEM mode in the spherical aberration-corrected transmission electron microscope to obtain a nano-scale two-dimensional material.

[0011] Preferably, the layered ferroelectric material is 2H-α-In2Se3.

[0012] Preferably, the operating voltage of the electron beam mode in the focused electron beam-ion beam dual beam electron microscope is 2 to 30 kV, and the electron beam current is 1 to 25 cps.

[0013] Preferably, the voltage of the ion beam mode in the focused electron beam-ion beam dual beam electron microscope is 2 to 30 kV, and the current is 5 pA to 20 nA.

[0014] Preferably, the thickness of the layered ferroelectric sample obtained by overall thinning is 80 to 120 nm.

[0015] Preferably, the electron beam energy of the electron beam irradiation is 300 kV.

[0016] Preferably, the beam spot size of the electron beam irradiation is 3-10 pm.

[0017] Preferably, the screen current of the electron beam irradiation is 0.1-0.5 nA.

[0018] Preferably, the electron beam irradiation is performed by continuous scanning; the scanning mode of the electron beam irradiation is linear scanning; and the scanning speed of the electron beam irradiation is 10 to 100 nm / s.

[0019] Preferably, the residence time of each electron beam irradiation is 1 to 10 seconds.

[0020] The invention provides a method for growing nanometer-scale two-dimensional materials in amorphous materials by electron beam induction, comprising the following steps: using a focused electron beam-ion beam dual-beam electron microscope to cut a layered ferroelectric material to obtain a bulk ferroelectric material; using a focused electron beam-ion beam dual-beam electron microscope to sequentially perform overall thinning and middle thinning on the bulk ferroelectric material to obtain a nanometer-scale layered sample; the middle of the nanometer-scale layered sample is an amorphous region, and the surroundings are crystalline regions; the focused electron beam-ion beam dual-beam electron microscope includes an electron beam mode and an ion beam mode; using the STEM mode in a spherical aberration corrected transmission electron microscope to perform electron beam irradiation on atomic groups in the amorphous region of the nanometer-scale layered sample and the interface between the amorphous region and the crystalline region to obtain a nanometer-scale two-dimensional material.

[0021] The present invention utilizes a focused electron beam to irradiate the boundary between the crystalline region and the amorphous region of a ferroelectric sample and the atomic clusters in the amorphous region. The electron beam irradiation of the ferroelectric sample will introduce energy. Since the crystalline and amorphous edges and unstable atomic clusters of the ferroelectric sample have higher energy, the energy introduced by the electron beam irradiation will generate holes and point defects in the crystalline and amorphous edges or unstable atomic clusters of the ferroelectric sample, thereby growing a new nanoscale two-dimensional material of the same element but with lower energy. The growth direction and width of the newly formed nanoscale two-dimensional material can be regulated by controlling the electron beam, thereby controlling its size. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a diagram of the bulk ferroelectric sample transfer and thinning process in Example 1 of the present invention;

[0023] Figure 2 The diffraction patterns of the nano-scale layered sample before and after further thinning in Example 1 of the present invention;

[0024] Figure 3 This is an atomic image representation diagram of the original 2H-α-In2Se3 in Example 1 of the present invention;

[0025] Figure 4 A growth diagram of a nanoscale two-dimensional material during electron beam irradiation in Example 1 of the present invention;

[0026] Figure 5 This is an electron microscope image of the nanoscale two-dimensional material InSe in Example 1 of the present invention;

[0027] Figure 6 The atomic image representation and atomic model diagram of the nanoscale two-dimensional material InSe in Example 1 of the present invention;

[0028] Figure 7 This is a growth diagram of nanoscale two-dimensional materials during electron beam irradiation in Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The present invention provides a method for growing nanometer-scale two-dimensional materials in amorphous materials by electron beam induction, comprising the following steps:

[0030] Using a focused electron beam-ion beam dual beam electron microscope to cut the layered ferroelectric material to obtain a bulk ferroelectric material;

[0031] The bulk ferroelectric material is thinned overall and in the middle in sequence by using a focused electron beam-ion beam dual beam electron microscope to obtain a nano-scale layered sample; the middle of the nano-scale layered sample is an amorphous region, and the surroundings are crystalline regions;

[0032] The focused electron beam-ion beam dual beam electron microscope includes an electron beam mode and an ion beam mode;

[0033] The electron beam is irradiated on the atomic clusters in the amorphous region and the interface between the amorphous region and the crystalline region of the nano-scale layered sample using the STEM mode in the spherical aberration-corrected transmission electron microscope to obtain a nano-scale two-dimensional material.

[0034] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used in the preparation, and commercially available products known to those skilled in the art can be used.

[0035] The present invention utilizes a focused electron beam-ion beam double beam electron microscope to cut the layered ferroelectric material to obtain a block ferroelectric sample.

[0036] In the present invention, the layered ferroelectric material is preferably 2H-α-In2Se3.

[0037] In the present invention, the focused electron beam-ion beam dual beam electron microscope includes an electron beam mode and an ion beam mode.

[0038] In the present invention, the working voltage of the electron beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 2-30 kV, more preferably 5-12 kV; the electron beam current of the electron beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 1-25 cps, more preferably 10-18 cps.

[0039] In the present invention, the operating voltage of the ion beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 2-30 kV, more preferably 5-30 kV; the current of the ion beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 5 pA-20 nA, more preferably 0.1-5 nA.

[0040] In the present invention, the ion beam in the focused electron beam-ion beam dual beam electron microscope is preferably a gallium ion beam.

[0041] Before the cutting, the present invention preferably uses a focused electron beam-ion beam dual beam electron microscope to deposit protection on the layered ferroelectric material to form a deposition protection layer. In the present invention, the material used for the deposition protection is preferably SiO2; the voltage of the deposition protection is preferably 30kV; the beam current of the deposition protection is 100pA; and the deposition protection preferably uses an ion beam mode.

[0042] The present invention preferably uses the ion beam mode in a focused electron beam-ion beam dual beam electron microscope to cut the layered ferroelectric material, and simultaneously uses the electron beam mode in a focused electron beam-ion beam dual beam electron microscope to observe the layered ferroelectric material.

[0043] In the present invention, the thickness of the bulk ferroelectric sample is preferably 2-4 μm, more preferably 2-3 μm. After obtaining the bulk ferroelectric sample, the present invention uses a focused electron beam-ion beam dual beam electron microscope to thin the bulk ferroelectric sample as a whole to obtain a layered ferroelectric sample.

[0044] The present invention preferably uses the ion beam mode in a focused electron beam-ion beam dual beam electron microscope to thin the bulk ferroelectric sample as a whole, and simultaneously uses the electron beam mode in a focused electron beam-ion beam dual beam electron microscope to observe the bulk ferroelectric sample.

[0045] In the present invention, the working voltage of the electron beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 2-30 kV, more preferably 5-12 kV; the electron beam current of the electron beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 1-25 cps, more preferably 10-20 cps.

[0046] In the present invention, the operating voltage of the ion beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 2-30 kV, more preferably 5-30 kV; the current of the ion beam mode in the focused electron beam-ion beam dual beam electron microscope is preferably 5 pA-20 nA, more preferably 0.1-11 nA.

[0047] In the present invention, the ion beam in the focused electron beam-ion beam dual beam electron microscope is preferably a gallium ion beam.

[0048] Before the overall thinning, the present invention preferably uses the mechanical probe of the focused electron beam-ion beam dual beam electron microscope to transfer the bulk ferroelectric sample to a support, and then puts the copper metal support into the sample rod of the focused electron beam-ion beam dual beam electron microscope. In the present invention, the support is preferably a copper metal support (grid).

[0049] In the present invention, the thickness of the layered ferroelectric sample obtained by overall thinning is preferably 80 to 120 nm, more preferably 80 to 100 nm.

[0050] The present invention thins the entire layered ferroelectric sample to a thickness that allows lens observation.

[0051] After obtaining the layered ferroelectric sample, the present invention uses a focused electron beam-ion beam dual beam electron microscope to perform intermediate thinning on the layered ferroelectric sample to obtain a nano-level layered sample.

[0052] In the present invention, the middle of the nano-scale layered sample is an amorphous region, and the surrounding areas are crystalline regions.

[0053] The present invention preferably uses the ion beam mode in a focused electron beam-ion beam dual beam electron microscope to perform intermediate thinning on the layered ferroelectric sample, and simultaneously uses the electron beam mode in a focused electron beam-ion beam dual beam electron microscope to observe the layered ferroelectric sample.

[0054] In the present invention, the parameter settings of the ion beam mode and the electron beam mode in the focused electron beam-ion beam dual beam electron microscope during the intermediate thinning process are as described above for overall thinning, which will not be repeated here.

[0055] In the present invention, the further thinned region in the middle is more transparent when observed under a transmission electron microscope, and has a very clear boundary line with the surrounding amorphous region.

[0056] The present invention preferably uses a spherical aberration corrected transmission electron microscope to perform diffraction analysis on the middle part of the layered ferroelectric sample during the intermediate thinning process, and stops thinning when the diffraction pattern of the middle part changes from a regular lattice to a ring.

[0057] The present invention further thins the middle part of the layered ferroelectric sample until the bulk ferroelectric sample in the middle part becomes amorphous while the surrounding parts are still crystalline.

[0058] After obtaining the nano-scale layered sample, the present invention uses the STEM mode in a spherical aberration-corrected transmission electron microscope to perform electron beam irradiation on the atomic clusters in the amorphous region and the interface between the amorphous region and the crystalline region of the nano-scale layered sample to obtain a nano-scale two-dimensional material.

[0059] In the present invention, the electron beam energy of the electron beam irradiation is preferably 300kV; the beam spot size of the electron beam irradiation is preferably 3-10pm, more preferably 3-5pm; the screen current of the electron beam irradiation is preferably 0.1-0.5nA, more preferably 0.15-0.25nA; the electron beam irradiation is preferably performed continuously; the scanning mode of the electron beam irradiation is preferably linear scanning; the scanning speed of the electron beam irradiation is preferably 10-100nm / s, more preferably 10-50nm / s; each residence time of the electron beam irradiation is preferably 1-10s, more preferably 3-5s.

[0060] The present invention preferably controls the scanning direction of the electron beam irradiation by moving the nano-scale layered sample, thereby controlling the growth direction of the nano-scale two-dimensional material. Without changing the electron beam scanning mode, the nano-scale layered sample is moved from bottom to top by controlling the trackball of the sample stage, and the nano-scale two-dimensional material grows from bottom to top; the nano-scale layered sample is moved from left to right, and the nano-scale two-dimensional material grows from left to right, and so on.

[0061] In the present invention, the width of the nanoscale two-dimensional material is preferably ≤100 nm, more preferably 60 nm, and the thickness is preferably 60 to 200 nm, more preferably 80 nm.

[0062] The present invention uses a focused electron beam to irradiate the boundary between the crystallization region and the amorphous region of a ferroelectric sample to grow a two-dimensional material with a new structure. Scanning the atomic clusters in the amorphous region can also grow a two-dimensional material with the same structure. However, compared with inducing growth at the boundary between the crystallization and the amorphous region, the irradiation growth on the atomic clusters is slower, and the new two-dimensional material grows in a divergent manner. The growth width and direction of the new two-dimensional material can be regulated by controlling the electron beam.

[0063] The present invention uses a focused electron beam to irradiate the boundary between the crystallization region and the amorphous region of the ferroelectric sample and the atomic groups in the amorphous region. The electron beam irradiation of the ferroelectric sample will introduce energy. Since the energy at the crystallization and amorphous edges and unstable atomic groups of the ferroelectric sample is relatively high, the energy introduced by the electron beam irradiation will generate holes and point defects in the crystallization and amorphous edges or unstable atomic groups of the ferroelectric sample, thereby growing a new nanoscale two-dimensional material with the same element but lower energy. The growth direction and width of this material can be regulated by controlling the electron beam. The convergent electron beam in the transmission electron microscope provides a unique tool for the growth of two-dimensional materials. This method is not only suitable for basic research, but also can be applied to the design of microelectronic devices.

[0064] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0065] Example 1

[0066] The ion beam mode of a focused electron beam-ion beam dual-beam electron microscope was used to deposit protection on 2H-α-In2Se3 with a voltage of 30 kV and a beam current of 100 pA. The deposited material was SiO2 to form a deposition protection layer. The ion beam mode was then used for cutting with a voltage of 30 kV and a beam current of 5 nA to obtain a 7 μm × 4 μm × 3 μm bulk ferroelectric sample. The bulk ferroelectric sample was then transferred to a copper metal support (hereinafter referred to as grid) using a mechanical probe and the support was placed in the sample rod. Thinning is performed on the grid using the ion beam mode, only the upper half of the sample is thinned, and the entire upper half is thinned to a thickness of 100 nm. When the sample thickness is greater than 1 μm, the voltage used is 30 kV and the beam current is 100 pA. When the sample thickness is less than 1 μm, the voltage used is 30 kV and the beam current is 30 pA. The middle part is then further thinned, and the voltage and beam current used are still 30 kV and 30 pA. During the thinning process, the middle part is subjected to diffraction analysis using a spherical aberration-corrected transmission electron microscope. When the diffraction pattern changes from the original regular lattice to a ring, the thinning can be stopped to obtain a nano-scale layered sample with an amorphous region in the middle and crystalline regions around.

[0067] The STEM mode in the spherical aberration corrected transmission electron microscope was used to irradiate the junction of the amorphous region and the crystalline region of the nanoscale layered sample with an electron beam. The electron beam energy was 300 kV, the beam spot size was 10 pm, the screen current was 0.25 nA, and the scanning was continuous. The scanning mode was linear scanning, the scanning speed was 20 nm / s, and the scanning direction of the electron beam on the sample was controlled by moving the sample. The dwell time for each time was 3 s. The magnification during irradiation was 360 kx, and the nanoscale two-dimensional material InSe was obtained.

[0068] Example 2

[0069] The difference from Example 1 is that the atomic groups in the amorphous region of the nano-scale layered sample are irradiated with electron beams, and the rest of the contents are consistent with Example 1.

[0070] Performance Testing

[0071] (1) The process of transferring the bulk ferroelectric sample and thinning in Example 1 is shown in FIG. Figure 1 As shown, a and b are transfer schematics, and c and d are thinning schematics.

[0072] Depend on Figure 1 It can be seen that the present invention successfully prepares a transmission electron microscope sample with a thinner middle area and slightly thicker at both ends.

[0073] (2) The diffraction patterns of the nano-scale layered sample before and after further thinning in Example 1 (i.e., the diffraction pattern when the diffraction pattern of the nano-scale layered sample changes from the original regular lattice to a ring-shaped pattern) are as follows: Figure 2As shown, a is the diffraction pattern before further thinning, and b is the diffraction pattern after further thinning.

[0074] Depend on Figure 2 It can be seen that after further thinning, the middle area changes from crystalline to amorphous, while the samples at both ends are still crystalline.

[0075] (3) Characterize the atomic image of 2H-α-In2Se3. The results are as follows Figure 3 shown.

[0076] Depend on Figure 3 It can be seen that 2H-α-In2Se3 is a two-dimensional material with layers bonded by van der Waals forces.

[0077] (4) The growth of nanoscale two-dimensional materials during electron beam irradiation in Example 1 is as follows Figure 4 As shown, a, b, and c are sample growth images taken every 3 seconds, and the brighter area in the figure is the positive zone axis.

[0078] Depend on Figure 4 It can be seen that under the irradiation of the electron beam, the new two-dimensional material InSe grows at a very fast rate, and the sample on the positive band axis can absorb energy more easily and thus grow faster.

[0079] (5) After the irradiation in Example 1 is completed, the magnification is reduced, and the new nanoscale two-dimensional material InSe grown in the amorphous region is Figure 5 shown.

[0080] Depend on Figure 5 It can be seen that the width of the new nanoscale two-dimensional material InSe grown in the amorphous region in Example 1 is 60 nm.

[0081] (6) The atomic image of the nanoscale two-dimensional material InSe in Example 1 was characterized using the STEM mode in a spherical aberration-corrected transmission electron microscope. The results are as follows: Figure 6 As shown, a is the atomic image and b is the atomic model.

[0082] Depend on Figure 6 It can be seen that the newly grown material is the two-dimensional material InSe.

[0083] The results show that electron beam irradiation at the junction of α-In2Se3 and the amorphous region will quickly grow a new and more stable two-dimensional material InSe. The growth width can be controlled within 100nm, and the growth direction can also be controlled by controlling the electron beam scanning direction.

[0084] (7) The electron beam irradiation process in Example 2 is shown in FIG. Figure 7As shown, a, b, c...g, h, i are sample growth images taken every 3 seconds.

[0085] Depend on Figure 7 It can be seen that the present invention irradiates the atomic clusters in the amorphous region, and the two-dimensional material InSe with the same structure as in Example 1 grows divergently around the atomic clusters.

[0086] The results show that when atomic clusters in amorphous materials are irradiated, if the electron beam scanning direction is not controlled by moving the sample, InSe will grow divergently in all directions.

[0087] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for growing nanoscale two-dimensional materials in amorphous materials using electron beam induction, characterized in that: The following steps are involved: Using a focused electron beam-ion beam dual beam electron microscope to cut the layered ferroelectric material to obtain a bulk ferroelectric material; The bulk ferroelectric material is thinned overall and in the middle in sequence by using a focused electron beam-ion beam dual beam electron microscope to obtain a nano-scale layered sample; the middle of the nano-scale layered sample is an amorphous region, and the surroundings are crystalline regions; The focused electron beam-ion beam dual beam electron microscope includes an electron beam mode and an ion beam mode; The electron beam is irradiated on the atomic clusters in the amorphous region and the interface between the amorphous region and the crystalline region of the nano-scale layered sample using the STEM mode in the spherical aberration-corrected transmission electron microscope to obtain a nano-scale two-dimensional material.

2. The method according to claim 1, characterized in that The layered ferroelectric material is 2H-α-In2Se3.

3. The method according to claim 1, characterized in that The working voltage of the electron beam mode in the focused electron beam-ion beam dual beam electron microscope is 2-30 kV, and the electron beam current is 1-25 cps.

4. The method according to claim 1 or 3, characterized in that: The voltage of the ion beam mode in the focused electron beam-ion beam dual beam electron microscope is 2-30 kV, and the current is 5 pA-20 nA.

5. The method according to claim 1, characterized in that The thickness of the layered ferroelectric sample obtained by overall thinning is 80 to 120 nm.

6. The method according to claim 1, characterized in that The electron beam energy of the electron beam irradiation is 300 kV.

7. The method according to claim 1 or 6, characterized in that: The beam spot size of the electron beam irradiation is 3-10 pm.

8. The method according to claim 1 or 6, characterized in that: The screen current of the electron beam irradiation is 0.1-0.5 nA.

9. The method according to claim 1 or 6, characterized in that: The electron beam irradiation performs continuous scanning; the scanning mode of the electron beam irradiation is linear scanning; the scanning speed of the electron beam irradiation is 10 to 100 nm / s.

10. The method according to claim 1 or 6, characterized in that: The residence time of each electron beam irradiation is 1 to 10 seconds.

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