CN112713240A - Preparation method of anti-symmetric magneto-resistance device based on two-dimensional material - Google Patents
Preparation method of anti-symmetric magneto-resistance device based on two-dimensional material Download PDFInfo
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Abstract
The invention discloses a preparation method of an antisymmetric magnetoresistance device based on a two-dimensional material, which comprises the following steps of firstly preparing a metal electrode; spin-coating PMMA on a silicon substrate by using a spin coater, exposing the silicon substrate by using an electron beam exposure machine, designing a transport measurement structure area on an EBL system, and exposing; placing the exposed silicon substrate in a developing solution for developing operation, and then placing the silicon substrate in isopropanol for fixation; evaporating a Ti/Au metal layer on the silicon substrate after fixation, and stripping in acetone to obtain a metal electrode; then screening out Fe with uneven thickness3GeTe2Nanometer thick slice, using two-dimensional material transfer platform to transfer Fe successively3GeTe2And hBN transfer to metal-bearing electrodesA silicon substrate of the pole; the invention screens out Fe with uneven thickness3GeTe2The self-rotation electronic device prepared by the nano-scale thickness sheet can realize the adjustment of the device in three resistance states of high, medium and low, and solves the problems of complicated device preparation links and low fault tolerance rate in the current multi-resistance state magnetic storage device.
Description
Technical Field
The invention relates to the technical field of two-dimensional material devices, in particular to a preparation method of an anti-symmetric magneto-resistance device based on a two-dimensional material.
Background
Magneto-resistance, as it is commonly said at present, is the change in resistance when a magnetic field is applied to a device of conductive or semiconducting material. In the present study, the giant magnetoresistance effect generated in the magnetic multilayer thin film structure is receiving much attention, and because it has two resistance states, high and low, it is studied to be applied to magnetic storage and magnetic sensor. However, in the conventional method for preparing a magnetic multilayer thin film, the metal thin film is the main material, but is limited by experimental techniques and equipment, and the thin film is easy to generate defects, vacancies and other negative factors, which greatly affect the device performance.
Two-dimensional materials can be cleaved from crystals to atomically thin physical thicknesses by manual exfoliation and have extremely high film quality, which is one of the effective ways to solve this problem. Research on two-dimensional materials has originated from the 2004 discovery of graphene, and over the past decade, two-dimensional materials have become hot research targets in the fields of condensed state physics, material science, semiconductor devices, and the like. Wherein the two-dimensional ferromagnetic material Fe3GeTe2The magnetic memory device is found in 2018 through experiments, and is researched and used for being integrated into device systems such as magnetic storage devices and magnetic sensors due to the existing ferromagnetism, so that a way is provided for the optimized development of magnetic storage devices with higher integration.
The problem today is how to make magnetic memory devices smaller in size, higher in integration and larger in storage. It is noted that the current magnetic memory devices usually achieve information access by the giant magnetoresistance effect or tunneling magnetoresistance effect, but the curves of the giant magnetoresistance effect or tunneling magnetoresistance effect with respect to the magnetic field are even symmetric, so that only two resistance states, i.e., high and low, exist, which means that only two kinds of data can be read in or out in one memory device cell. The anti-symmetric magnetoresistance is firstly found in the magnetic multilayer film with a special wedge-shaped structure, and the curve of the anti-symmetric magnetoresistance about a magnetic field is odd-symmetric, namely, the anti-symmetric magnetoresistance device has three resistance states, namely, the resistance state is higher, middle and lower, which means that compared with the prior magnetic memory device, the anti-symmetric magnetoresistance device is in one resistance stateMore data can be accessed in the memory device cells. Although devices which are prepared based on two-dimensional materials and can realize anti-symmetric magnetoresistance are gradually researched and developed, the devices are all of heterostructure which is formed by stacking a plurality of two-dimensional materials, the preparation method is complicated, and the fault-tolerant rate is low. In order to simplify the structure of the device and achieve the same purpose, the invention is based on a two-dimensional ferromagnetic material Fe3GeTe2A device capable of realizing the anti-symmetric magnetoresistance is prepared, and the anti-symmetric magnetoresistance device can become a powerful competitor in the research and development of next-generation high-density nonvolatile memories.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the problems of complicated preparation links and low fault tolerance of the conventional anti-symmetric magneto-resistance device, the invention aims to provide the device, and the core part of the device only needs to be based on a two-dimensional ferromagnetic material Fe3GeTe2, namely a preparation method of a device capable of realizing anti-symmetric magnetoresistance.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:
a preparation method of an anti-symmetric magneto-resistance device based on a two-dimensional material comprises the following steps:
step S1, preparing a metal electrode on the silicon substrate;
s1.1, sequentially placing a silicon substrate in acetone, ethanol and deionized water; cleaning and drying the silicon substrate by an ultrasonic machine; the silicon substrate comprises pure silicon and a top oxide layer;
s1.2, adsorbing the silicon substrate on a spin coater, uniformly spin-coating electron beam glue polymethyl methacrylate (PMMA) and drying;
s1.3, putting the silicon substrate coated with PMMA in a spin mode into an electron beam cavity of an electron beam exposure machine EBL, and vacuumizing the cavity to 10 DEG-6Pa magnitude or less; designing a transportation measurement structure area in the EBL system; bombarding a silicon substrate corresponding to the spin-coated PMMA by adopting an electron beam according to the design drawing, and carrying out exposure operation to obtain an exposed pattern;
s1.4, placing the silicon substrate in a developing solution for developing operation, removing PMMA in an exposed area on the silicon substrate, and exposing the silicon substrate at the bottom; then moving the silicon substrate into isopropanol to stop developing, and finishing the fixing operation; drying the silicon substrate after fixing;
s1.5, placing the blow-dried silicon substrate in an electron beam cavity of an electron beam evaporation system EBE, and vacuumizing the cavity to 10 DEG-6Pa magnitude or less; firstly, evaporating a layer of metal titanium as an adhesion layer on a silicon substrate, and then evaporating a layer of gold;
s1.6, placing the evaporated silicon substrate in acetone for soaking, stripping off a metal part in contact with the unexposed PMMA, and obtaining the prepared metal electrode as the remaining metal electrode in contact with the silicon substrate;
step S2 of preparing two-dimensional material Fe3GeTe2And hexagonal boron nitride hBN nano-scale thickness platelets; screening out Fe with uneven thickness3GeTe2Nano-scale thick flake, sequentially mixing Fe3GeTe2And hBN is transferred to the silicon substrate with the metal electrode prepared in step S1;
s2.1, adhering one surface of a polydimethylsiloxane PDMS film to a glass slide, and adhering Fe to the other surface of the polydimethylsiloxane PDMS film3GeTe2Sample particles;
s2.2, screening Fe with nano-scale thickness on the PDMS film by using an optical microscope3GeTe2Flake and Simultaneous screening for Fe3GeTe2The thickness of the nano-thin sheet ensures Fe on the PDMS film3GeTe2The thickness of the nano thin slice is non-uniformly distributed;
s2.3, placing the screened glass slide at the end of a sample to be transferred of a two-dimensional material transfer platform, and placing the metal electrode prepared in the step S1.6 on a sample stage for fixing; transferring the Fe3GeTe2 nano-scale sheet on the PDMS film to a metal electrode by using a two-dimensional material transfer platform;
and S2.4, transferring the two-dimensional material insulator hBN onto the metal electrode by adopting the method from S2.1 to S2.3.
Further, in the step S1.1, the silicon substrate is sequentially placed in acetone for 2 minutes, placed in ethanol for 2 minutes, and placed in deionized water for 1 minute.
Further, in the step S1.2, the rotation speed of the spin coater is set to 1000 rpm/10S, and the spin coating time is 40S.
Further, in step S1.4, the developing time is 25S and the fixing time is 10S.
Further, the rate of evaporating the metal titanium in the step S1.5 isThe rate of vapor plating isThe thickness of the titanium metal vapor deposition is 10nm, and the thickness of the vapor deposition gold is 40 nm.
Further, the soaking time of the stripping operation in the step S1.6 is 20 min.
Has the advantages that:
(1) the device has a simple structure, and compared with the traditional magnetic film capable of realizing the anti-symmetric magnetoresistance or the two-dimensional material heterojunction, the device has three, four or more main sample layers, and the sample structure of the invention has only two layers;
(2) the two-layer device structure enables the device preparation process flow to be relatively simple, and greatly improves the fault tolerance rate in the device preparation process;
(3) in the process flow, the process flow of firstly making the metal electrode and then making the sample is adopted, so that the problem that the performance of the device is difficult to achieve the expectation due to the negative influence of the electron beam glue, the organic liquid (acetone, isopropanol and the like) and the deionized water on the sample can be effectively avoided. The traditional process flow is that a sample is made first and then an electrode is made, and Fe is generated in the process of making the electrode3GeTe2The sample contacts electron beam glue, organic liquid (acetone, isopropanol and the like) and deionized water and other pollutants, so that the performance of a final device is influenced;
(4) the two-dimensional material nanometer thickness slice is obtained from the two-dimensional material crystal, the quality of the slice is high, and the slice has no defects and vacancies like the film obtained by the methods of chemical vapor deposition, physical vapor deposition and the like.
(5) Core sample of device Fe3GeTe2The material has good chemical stability, and can be compounded with metals such as gold, silver, copper and the like to prepare more complex devices;
(6) the working current is small, the device can be driven to work by 100 muA current, the power consumption is low, and the potential of integrating the magnetic device is realized.
Drawings
FIG. 1 is a schematic view of a metal electrode structure according to the present invention;
FIG. 2 is a schematic front view of a two-dimensional material transfer platform provided in accordance with the present invention;
FIG. 3 is a schematic diagram of a two-dimensional material device manufacturing process provided by the present invention;
FIG. 4 is a schematic side view of a two-dimensional device structure provided by the present invention;
FIG. 5 is a graph showing the longitudinal resistance R of the measuring device of the present inventionxxAnd a Hall resistor RxyA schematic diagram of (a);
FIG. 6 is a photograph of a two-dimensional material device under an optical microscope in accordance with one embodiment of the present invention;
FIG. 7 is a voltage-current graph of a two-dimensional material device according to an embodiment of the present invention;
FIG. 8 shows a vertical resistance R according to an embodiment of the present inventionxxThe relation with the magnetic field and the fed back antisymmetric reluctance curve graph are obtained;
FIG. 9 is a photograph of a two-dimensional material device under an optical microscope according to a second embodiment of the present invention;
FIG. 10 is a voltage-current graph of a two-dimensional material device according to a second embodiment of the present invention;
FIG. 11 shows the longitudinal resistance R in the second embodiment of the present inventionxxThe relationship with the magnetic field and the fed-back antisymmetric reluctance curve graph.
Description of reference numerals:
1-a silicon substrate; 2-PDMS film; 3-glass slide; 4-CCD image display; 5-optical microscopy; 6-fixing the knob; s1-metal electrode; S2-hBN; S3-Fe3GeTe2(ii) a S4-metal electrode; s5-metal electrode; s6-metal electrode; s7-metal electrode;
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
A preparation method of an anti-symmetric magneto-resistance device based on a two-dimensional material comprises the following steps:
step S1, preparing a metal electrode on the silicon substrate.
S1.1, sequentially placing a silicon substrate in acetone, ethanol and deionized water; and cleaning and drying the silicon substrate by an ultrasonic machine. The silicon substrate comprises pure silicon and a top oxide layer.
The cleaning time of acetone, ethanol and deionized water in an ultrasonic machine is 2min, 2min and 1 min. Acetone is used for removing contaminants such as grease scraps on the silicon wafer, ethanol is used for removing residual acetone, and deionized water is used for removing residual ethanol. The total thickness of the silicon wafer is 500 +/-15 mu m, and the thickness of the oxide layer is 285 nm.
And S1.2, adsorbing the silicon substrate on a spin coater, and uniformly spin-coating electron beam glue polymethyl methacrylate (PMMA). The thickness of PMMA depends on the rotation speed, and a suitable PMMA thickness is decisive for the success of the entire device. And then drying the mixture on a heating table to remove excessive moisture. The rotation speed of the spin coater is 1000 r/10 s, and the spin coating is carried out at a constant speed for 40 s. The heating stage temperature is 120 deg.C, and oven drying for 2 min. The structural formula of the adopted polymer polymethyl methacrylate (PMMA) is as follows:
s1.3, putting the silicon substrate coated with PMMA in a spin mode into an electron beam cavity of an electron beam exposure machine EBL, and vacuumizing the cavity to 10 DEG-6Pa magnitude or less; designing a transportation measurement structure area in the EBL system; and bombarding the silicon substrate corresponding to the spin-coated PMMA by adopting an electron beam according to the design drawing, and carrying out exposure operation to obtain an exposed pattern.
The reason for selecting PMMA is that the bonding structure of PMMA is broken under the bombardment of electron beams and is easily dissolved in a developing solution (the solution contains methyl isobutyl ketone and isopropanol, and the corresponding volume ratio is 1: 3). The structural formula of Methyl isobutyl ketone (MIBK) is as follows:
s1.4, placing the silicon substrate in a developing solution for developing operation, removing PMMA in an exposed area on the silicon substrate, and exposing the silicon substrate at the bottom; then moving the silicon substrate into isopropanol to stop developing, and finishing the fixing operation; and drying the fixed silicon substrate by blowing.
The development time in the developer was 25s here, and the fixing was carried out for 10s in isopropanol.
S1.5, placing the blow-dried silicon substrate in an electron beam cavity of an electron beam evaporation system EBE, and vacuumizing the cavity to 10 DEG-6Pa magnitude or less; and firstly evaporating a layer of metal titanium as an adhesion layer on the silicon substrate, and then evaporating a layer of gold.
The deposition thickness of the titanium metal adhesion layer was 10nm and the deposition thickness of gold was 40 nm. The rate of titanium deposition isThe rate of vapor plating isThe purpose of the vapor plating metal titanium adhesion layer is to prevent the gold layer from falling off in the subsequent operation due to insufficient adhesion with the silicon substrate.
And S1.6, placing the evaporated silicon substrate in acetone for soaking for 20min, stripping off the metal part in contact with the unexposed PMMA, and obtaining the prepared metal electrode as the remaining metal electrode in contact with the silicon substrate. The prepared metal electrode is shown in fig. 1.
Since after step S1.5, a layer of metal is on the surface of the silicon substrate, and a part of the metal is in contact with the SiO2 exposed in step S1.4, and another part is in contact with the unexposed PMMA, the part in contact with the unexposed PMMA needs to be stripped, and the remaining metal electrode in contact with the silicon wafer is the required part. The structure of the prepared metal electrode part is shown in figure 1.
Step S2 of preparing two-dimensional material Fe3GeTe2And hexagonal boron nitride hBN nano-scale thickness platelets. Screening out Fe with uneven thickness3GeTe2Nano-scale thick flake, sequentially mixing Fe3GeTe2And hBN is transferred to the silicon substrate with the metal electrode prepared in step S1. Step S2 is completed in the glove box, and the water content of the glove box is less than 1 ppm; the oxygen content is less than 1 ppm.
S2.1, adhering one surface of a polydimethylsiloxane PDMS film to a glass slide, and adhering Fe to the other surface of the polydimethylsiloxane PDMS film3GeTe2Sample particles. The structural formula of the polymer Polydimethylsiloxane (PDMS) is as follows:
paste Fe3GeTe2The method of sample particles was as follows:
from Fe3GeTe2Placing a small single crystal sample on a white adhesive tape, and repeatedly performing double adhesion for several times until a large amount of Fe exists on the adhesive tape3GeTe2Sample particles. Attaching one surface of Polydimethylsiloxane (PDMS) film to the glass slide, and attaching the other surface of the PDMS film to the tenth step, wherein the adhesive tape contains Fe3GeTe2Portions of the sample were conformed. The tape was gently torn off, at which time the presence of Fe on the PDMS was visually observed3GeTe2Sample particles.
S2.2, screening Fe with nano-scale thickness on the PDMS film by using an optical microscope3GeTe2Flake and Simultaneous screening for Fe3GeTe2The thickness of the nano-thin sheet ensures Fe on the PDMS film3GeTe2The thickness of the nano-thin sheet is non-uniformly distributed.
S2.3, placing the screened glass slide at the end of a sample to be transferred of a two-dimensional material transfer platform, and placing the metal electrode prepared in the step S1.6 on a sample stage for fixing; and transferring the Fe3GeTe2 nano-scale thin sheet on the PDMS film to a metal electrode by using a two-dimensional material transfer platform.
The two-dimensional material transfer platform is shown in fig. 2 and is generally divided into three structures, namely a sample stage to be transferred, a sample stage and a microscopic imaging system consisting of a microscope 5 and a CCD image display device 4; the microscopic imaging system, the sample table to be converted and the sample table are fixed on the same base, and a schematic diagram is not shown; the glass slide is 3, and the fixing knob 6 is used for fixing the glass slide on a sample table to be rotated; the PDMS with the sample is 2, one surface with the sample faces the sample platform, and the other surface is attached to the glass slide 3; the silicon chip with the metal electrode is 1 and is fixed on a sample table, and one surface with the metal electrode faces to the PDMS film 2 with the sample.
And S2.4, transferring the two-dimensional material insulator hBN to the metal electrode by adopting the same method from the step S2.1 to the step S2.3.
Coating a two-dimensional material insulator hBN on Fe with uneven thickness3GeTe2A protective layer is arranged on the nano-sheet and is covered to prevent Fe3GeTe2And is subject to atmospheric or other possible contamination during subsequent transport measurements. Finally, the device based on the two-dimensional material is obtained.
The side view of the final device of the present invention is shown in FIG. 3, with hBN as the protective layer covering the Fe3GeTe2Above, Fe3GeTe2The following are metal electrodes used to test device performance. Both of which are located on a silicon substrate.
Finally, carrying out magnetoelectric transport measurement to obtain the longitudinal resistance R of the devicexxAnd a Hall resistor RxyAnd (4) data. The invention will have a resistance R in the longitudinal directionxxThe anti-symmetric magnetoresistance is fed back from the data.
Longitudinal resistance R of the measuring device according to the inventionxxAnd a Hall resistor RxyThe structure of (1) is shown in FIG. 5, wherein S1, S4-S7 are metal electrodes, S2 is a solid line frame indicating hBN covered by the uppermost layer, and S3 is a dashed line frame indicating Fe as the core two-dimensional material3GeTe2(ii) a The left and right electrodes S1 are electrified by current I, and the electrodes S4-S5 or S6-S7 measure the longitudinal resistance RxxElectrodes S4-S6 or S5-S7 measure Hall resistance Rxy. The magnetic field (B) is applied in a direction perpendicular to the sample, shown in the upper right corner.
The preparation method of the two-dimensional material device provided by the invention is verified by the specific embodiment.
The first stage of the steps: cleaning the silicon wafer in an ultrasonic machine for 2 minutes, 2 minutes and 1 minute by using acetone, ethanol and deionized water in sequence, and drying by using a nitrogen gun every time. And then adsorbing the silicon wafer on a spin coater, spin-coating PMMA glue at the rotating speeds of 1000 rpm/10 s and 4000 rpm/40 s, and placing on a 120 ℃ heating table to dry for two minutes after the spin coating is finished. Placing the silicon wafer with PMMA in an electron beam cavity of an EBL, and pumping the vacuum degree to 10-6And designing a transport measurement structure pattern by using the EBL below the Pa magnitude, starting exposure by using the exposure condition of an EBL self-belt, developing the silicon wafer in a developing solution for 25s after the exposure is finished, and fixing for 10s to obtain the silicon wafer with the designed transport measurement structure pattern. Then, the silicon wafer is placed in a cavity of the EBE, and the vacuum degree is pumped to 10-6Below Pa, sequentially plating Ti and Au metal films, and evaporating Ti at a rate ofThe thickness is 10 nm; the rate of Au deposition isThe thickness was 40 nm. And after the evaporation is finished, soaking the silicon wafer substrate in acetone for about 20min to finish the stripping operation, and finally obtaining the silicon wafer substrate with the metal electrode.
Step two: as shown in fig. 4, the following operations are all performed in the glove box. Mixing two-dimensional material Fe3GeTe2The crystals are placed on a section of adhesive tape and repeatedly adhered until the adhesive tape is provided with a piece of two-dimensional material sample particles. Then adhering one side of PDMS with two-sided viscosity on a glass slide, adhering the other side of PDMS with an adhesive tape with a piece of sample particles, slightly tearing off the adhesive tape, wherein the PDMS is provided with a two-dimensional material sample, placing the two-dimensional material sample/PDMS/glass slide under an optical microscope to find a two-dimensional material slice, and judging Fe according to the contrast3GeTe2Sample thickness, transparent, thinner Fe3GeTe2Sample, whitish yellow and reflective is thicker Fe3GeTe2Samples, therefore in the examples it is necessary to find Fe of non-uniform thickness3GeTe2Nano-scale thickness flakes. The above process can be repeated until a suitable two-dimensional sheet of material is found. In this way, Fe can be found separately3GeTe2And nano-scale thickness flakes of hBN. After finding the appropriate flakes, the Fe on PDMS was sequenced using a two-dimensional material transfer platform as shown in FIG. 23GeTe2And hBN transferred to a silicon substrate with a metal electrode. Finally, the device required by the invention is completed.
And (3) carrying out magnetoelectric transport measurement on the device, wherein a structural measurement method is shown in figure 5. The present embodiment is based on a longitudinal resistance RxxThe anti-symmetric magneto-resistance is fed back from the relation curve of the magnetic field strength.
The device prepared in this example is shown in FIG. 5, Fe3GeTe2The nanoflake morphology of (a) is shown in dashed line box of figure 6.
The performance of the devices obtained in this example is shown in fig. 7 and 8, fig. 7 being the current (I) -voltage (V) curve between the metal electrodes in the devices measured by the two-terminal method, showing Fe3GeTe2The contact with the Ti/Au metal electrode is ohmic contact, which shows that the two-dimensional material Fe3GeTe2The contact property with gold is good. Fig. 8 measures the relationship between the longitudinal resistance Rxx and the magnetic field intensity, a current of 100 μ a is applied to the device, the magnetic field is applied along the vertical direction of the sample, and it can be seen that as the magnetic field is scanned in two directions up and down relative to the vertical direction of the sample, three resistance states of high, medium and low exist in the line of the same color. In addition, the positions and sizes of three resistance states, namely three lines L1, L2 and L3 shown in the figure, can be adjusted by adjusting the external temperature and the direction of the magnetic field.
Next, a group of Fe with uneven thickness was additionally screened3GeTe2The nano-scale thickness of the thin sheet, other steps are the same as the above example, and a new set of two-dimensional material devices are prepared. The resulting device is shown in FIG. 9, resulting inThe device performance of (a) is shown in fig. 10-11. FIG. 10 is a plot of current (I) versus voltage (V) across electrodes in a device, showing Fe3GeTe2The contact with the Ti/Au metal electrode is ohmic contact, which is consistent with the embodiment, and shows that the two-dimensional material Fe3GeTe2The contact property with gold is good. Fig. 11 shows the relationship between the longitudinal resistance Rxx and the magnetic field intensity applied along the vertical direction of the sample, and it can be seen that the upper, middle and lower resistance states can be seen as the magnetic field is scanned up and down relative to the vertical direction of the sample. The device-related values are small compared to the values in the previous example, which corresponds to non-uniform Fe3GeTe2The thickness difference in the sample is relevant. The larger the thickness difference in the inhomogeneous Fe3GeTe2 sample, the more pronounced the anti-symmetric magnetoresistance.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (6)
1. A preparation method of an antisymmetric magnetoresistance device based on a two-dimensional material is characterized by comprising the following steps:
step S1, preparing a metal electrode on the silicon substrate;
s1.1, sequentially placing a silicon substrate in acetone, ethanol and deionized water; cleaning and drying the silicon substrate by an ultrasonic machine; the silicon substrate comprises pure silicon and a top oxide layer;
s1.2, adsorbing the silicon substrate on a spin coater, uniformly spin-coating electron beam glue polymethyl methacrylate (PMMA) and drying;
s1.3, putting the silicon substrate coated with PMMA in a spin mode into an electron beam cavity of an electron beam exposure machine EBL, and vacuumizing the cavity to 10 DEG-6Pa magnitude or less; designing a transportation measurement structure area in the EBL system; bombarding a silicon substrate corresponding to the spin-coated PMMA by adopting an electron beam according to the design drawing, and carrying out exposure operation to obtain an exposed pattern;
s1.4, placing the silicon substrate in a developing solution for developing operation, removing PMMA in an exposed area on the silicon substrate, and exposing the silicon substrate at the bottom; then moving the silicon substrate into isopropanol to stop developing, and finishing the fixing operation; drying the silicon substrate after fixing;
s1.5, placing the blow-dried silicon substrate in an electron beam cavity of an electron beam evaporation system EBE, and vacuumizing the cavity to 10 DEG-6Pa magnitude or less; firstly, evaporating a layer of metal titanium as an adhesion layer on a silicon substrate, and then evaporating a layer of gold;
s1.6, placing the evaporated silicon substrate in acetone for soaking, stripping off a metal part in contact with the unexposed PMMA, and obtaining the prepared metal electrode as the remaining metal electrode in contact with the silicon substrate;
step S2 of preparing two-dimensional material Fe3GeTe2And hexagonal boron nitride hBN nano-scale thickness platelets; screening out Fe with uneven thickness3GeTe2Nano-scale thick flake, sequentially mixing Fe3GeTe2And hBN is transferred to the silicon substrate with the metal electrode prepared in step S1;
s2.1, adhering one surface of a polydimethylsiloxane PDMS film to a glass slide, and adhering Fe to the other surface of the polydimethylsiloxane PDMS film3GeTe2Sample particles;
s2.2, screening Fe with nano-scale thickness on the PDMS film by using an optical microscope3GeTe2Flake and Simultaneous screening for Fe3GeTe2The thickness of the nano-thin sheet ensures Fe on the PDMS film3GeTe2The thickness of the nano thin slice is non-uniformly distributed;
s2.3, placing the screened glass slide at the end of a sample to be transferred of a two-dimensional material transfer platform, and placing the metal electrode prepared in the step S1.6 on a sample stage for fixing; transferring the Fe3GeTe2 nano-scale sheet on the PDMS film to a metal electrode by using a two-dimensional material transfer platform;
and S2.4, transferring the two-dimensional material insulator hBN onto the metal electrode by adopting the method from S2.1 to S2.3.
2. The method for preparing a two-dimensional material-based anti-symmetric magnetoresistive device according to claim 1, wherein in step S1.1, the silicon substrate is sequentially placed in acetone for 2 minutes, ethanol for 2 minutes, and deionized water for 1 minute.
3. The method for preparing an antisymmetric magnetoresistive device based on two-dimensional material as claimed in claim 1, wherein the spin coater speed in step S1.2 is set to 1000 rpm/10S, and the spin coating time is 40S.
4. The method of claim 1, wherein the developing time of step S1.4 is 25S and the fixing time is 10S.
5. The method for preparing an anti-symmetric magnetoresistive device based on two-dimensional material as claimed in claim 1, wherein the rate of evaporating metal titanium in step S1.5 isThe rate of vapor plating isThe thickness of the titanium metal vapor deposition is 10nm, and the thickness of the vapor deposition gold is 40 nm.
6. The method for preparing an antisymmetric magnetoresistive device based on two-dimensional material as claimed in claim 1, wherein the soaking time of the stripping operation in step S1.6 is 20 min.
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CN114361289A (en) * | 2022-01-10 | 2022-04-15 | 北京工业大学 | Construction method of self-driven ultrafast photoelectric detector based on van der Waals metal electrode |
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CN113540149B (en) * | 2021-07-12 | 2024-06-04 | 南方科技大学 | Programmable multi-quantum state memory and preparation method |
CN114361289A (en) * | 2022-01-10 | 2022-04-15 | 北京工业大学 | Construction method of self-driven ultrafast photoelectric detector based on van der Waals metal electrode |
CN114361289B (en) * | 2022-01-10 | 2024-03-15 | 北京工业大学 | Construction method of self-driven ultra-fast photoelectric detector based on van der Waals metal electrode |
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