CN112713240B - Preparation method of antisymmetric magnetoresistance device based on two-dimensional material - Google Patents

Preparation method of antisymmetric magnetoresistance device based on two-dimensional material Download PDF

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CN112713240B
CN112713240B CN202110125771.3A CN202110125771A CN112713240B CN 112713240 B CN112713240 B CN 112713240B CN 202110125771 A CN202110125771 A CN 202110125771A CN 112713240 B CN112713240 B CN 112713240B
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普勇
曹志
钮伟
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Nanjing University of Posts and Telecommunications
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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 is transferred to a silicon substrate with a metal electrode; the invention screens out Fe with uneven thickness3GeTe2The self-rotation electronic device prepared by the nano-scale thickness slice 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

Preparation method of antisymmetric magnetoresistance device based on two-dimensional material
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 originated from the 2004 discovery of graphene, and the two-dimensional materials have become condensed physical and material science in the past decadeAnd semiconductor devices, and the like. Wherein the two-dimensional ferromagnetic material Fe3GeTe2The magnetic material is found in 2018 through experiments, and is researched and used for being integrated into device systems such as a magnetic storage device and a magnetic sensor due to the existing ferromagnetism, so that a way is provided for the optimized development of a magnetic storage device with higher integration level.
The problem today is how to make magnetic memory devices with smaller size, higher integration and larger storage capacity. 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 first thing is that in the magnetic multilayer film with a wedge-shaped structure, the curve of the magnetic field is odd symmetrical, i.e. the anti-symmetric magnetoresistive device has three resistance states, namely, high resistance state, medium resistance state and low resistance state, which means that more data can be accessed in one memory cell compared with the existing magnetic memory device. Although devices which are prepared based on two-dimensional materials and can realize anti-symmetric magnetoresistance are gradually researched and developed, heterogeneous structures formed by stacking multiple two-dimensional materials are utilized, the preparation method is complex, 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 the next generation of high-density nonvolatile memories.
Disclosure of Invention
The invention aims to: in order to solve the problems of complicated preparation links and low fault tolerance rate of the conventional anti-symmetric magneto-resistor device, the invention aims to provide a 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 realize 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, placing the silicon substrate coated with PMMA 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 performing 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 taking the residual metal electrode in contact with the silicon substrate as the prepared metal electrode;
step S2 of preparing two-dimensional material Fe3GeTe2And hexagonal boron nitride hBN nano-scale thickness flakes; 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-flake 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, the developing time in said step S1.4 is 25S, and the fixing time is 10S.
Further, the rate of evaporating the metal titanium in the step S1.5 is
Figure BDA0002923970360000031
The rate of vapor plating is
Figure BDA0002923970360000032
The 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 thin 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 final device performance is influenced;
(4) the two-dimensional material nanometer-scale thickness slice is obtained from two-dimensional material crystals, has high quality, and does not have defects and vacancies like films obtained by chemical vapor deposition, physical vapor deposition and other methods.
(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 material device structure provided by the present invention;
FIG. 5 is a diagram 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:
and 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:
Figure BDA0002923970360000051
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 why PMMA is selected is that the bonding structure of PMMA is broken under the bombardment of electron beams and PMMA is easy to dissolve 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:
Figure BDA0002923970360000052
s1.4, placing the silicon substrate in a developing solution for developing operation, and removing PMMA in an exposed area on the silicon substrate to expose the bottom silicon substrate; 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.
Here evaporation of the metallic titanium adhesion layerThe plating thickness is 10nm, and the gold evaporation thickness is 40 nm. The rate of titanium deposition is
Figure BDA0002923970360000053
The rate of vapor plating is
Figure BDA0002923970360000054
The purpose of the titanium adhesion layer of the evaporated metal is to prevent the gold layer from falling off from the silicon substrate due to insufficient adhesion.
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 formed on the surface of the silicon substrate, and a part of the metal is in contact with the exposed SiO2 in step S1.4, and another part of the metal 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, 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 was transferred to the silicon substrate with 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 film3GeTe2And (3) sample particles. The structural formula of the polymer Polydimethylsiloxane (PDMS) is as follows:
Figure BDA0002923970360000061
paste Fe3GeTe2The method of sampling the 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 side of Polydimethylsiloxane (PDMS) film to the glass slide, and attaching the other side of PDMS film to the tenth step, wherein the 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 stage to be transferred and the sample stage 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 may be subject to atmospheric or other potential 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, in which hBN is used as the protective layer covering the Fe3GeTe2Upper surface, 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 antisymmetric magnetoresistance is fed back in 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 and S4-S7 are metal electrodes, S2 is a solid line frame representing hBN covered by the uppermost layer, and S3 is a dashed line frame representing 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 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 10-6Plating below Pa magnitude in sequenceTi, Au metal film, the rate of evaporating Ti is
Figure BDA0002923970360000071
The thickness is 10 nm; the rate of Au deposition is
Figure BDA0002923970360000072
The 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 a piece of adhesive tape with 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 embodiment is based on the longitudinal resistance RxxThe anti-symmetric magnetoresistance is fed back from the relation curve of the magnetic field strength.
The device prepared in this example is shown in FIG. 5, Fe3GeTe2The morphology of the nanoflakes is shown in FIG. 6Dashed line in dashed line.
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 the sizes of three resistance states, namely three lines L1, L2 and L3 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 screened3GeTe2Nanometer-scale thickness flakes, and other steps were the same as in the above example, to prepare a new set of two-dimensional material devices. The resulting device is shown in fig. 9, and the resulting device performance 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, the magnetic field is applied along the vertical direction of the sample, and the high, medium and low resistance states can be seen as the magnetic field scans up and down along the direction vertical to the sample. The values associated with this device are small compared to the values in the previous example, which corresponds to non-uniform Fe3GeTe2The thickness difference in the sample is relevant. The greater the difference in thickness in the heterogeneous Fe3GeTe2 samples, 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 performing 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 taking the residual metal electrode in contact with the silicon substrate as the prepared metal electrode;
step S2 of preparing two-dimensional material Fe3GeTe2And hexagonal boron nitride hBN nano-scale thickness flakes; screening out Fe with uneven thickness3GeTe2Nano-scale thick flake, sequentially adding Fe3GeTe2And hBN transferred to gold bearing article prepared in step S1A silicon substrate of the electrode;
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 microscope3GeTe2Flaking while screening 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 platform 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 as claimed in claim 1, wherein the silicon substrate is placed in acetone, ethanol, and deionized water sequentially for 2 minutes, and 1 minute in sequence in step S1.1.
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 antisymmetric magnetoresistive device based on two-dimensional material as claimed in claim 1, characterized in that the rate of evaporating metal titanium in step S1.5 is
Figure FDA0002923970350000022
The rate of vapor plating is
Figure FDA0002923970350000021
The 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, characterized in that the stripping soaking time in step S1.6 is 20 min.
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