Detector for measuring thermoelectric, rectification and Hall effects of micro-nano material and preparation method thereof

Abstract

The invention relates to the technical field of thermoelectric material testing, and discloses a detector for measuring thermoelectric, rectification and Hall effects of a micro-nano material and a preparation method of the detector. The first microelectrode group comprises a first microelectrode and a second microelectrode which are oppositely arranged on the two sides of the detection area in the first direction; the second microelectrode group comprises a third microelectrode and a fourth microelectrode which are oppositely arranged on the two sides of the detection area in the second direction, and a preset angle is formed between the first direction and the second direction; gaps are formed between the first microelectrode group and the second microelectrode group and the sample to be detected; the third microelectrode group comprises four microelectrodes which are respectively arranged between the microelectrodes of the first microelectrode group and the microelectrodes of the adjacent second microelectrode group and are suitable for being connected with a sample to be detected. The detector can realize in-situ integrated measurement of thermoelectric, rectification and Hall effects of a thermoelectric material, facilitates analysis of a thermal-electric-magnetic coupling transport mechanism, and ensures the accuracy of a measurement result.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric material testing, and in particular to a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials and a preparation method thereof. Background Art

[0002] Thermal energy and electrical energy are the most common forms of energy used in our daily lives. Thermoelectric functional devices can directly convert the two to achieve temperature difference power generation or pressure difference refrigeration. They are ideal "zero-carbon" power supplies and refrigerators without vibration, noise, leakage, and environmental friendliness. The performance of thermoelectric functional devices is restricted by thermoelectric materials. Thermoelectric materials use temperature difference to generate electricity without mechanical parts and chemical reactions. They use voltage difference to cool without compressors or refrigerants such as Freon. They are pollution-free green energy materials. The measurement of the properties of thermoelectric materials is an important foundation for the development of thermoelectric functional devices. The accurate measurement of material properties has a good driving effect on the development of thermoelectric devices.

[0003] The thermal Hall effect refers to the phenomenon that when an external magnetic field perpendicular to the temperature gradient is applied to a material with a temperature gradient, hot carriers are deflected, resulting in a heat flow perpendicular to the temperature gradient in the material, thereby generating a lateral temperature difference. In the actual measurement of the thermal Hall effect, since the effective signal of the thermal Hall effect is relatively small compared to the background noise signal, the experimental measurement of the thermal Hall effect is relatively difficult. At present, the measurement of the thermal Hall effect is mainly focused on macroscopic materials, whose size is at the mm level. In the related art, the detector for realizing the thermal Hall effect of macroscopic thermoelectric materials usually includes: a substrate, a thermocouple or a detection probe arranged on both sides of the substrate, the substrate includes a heating end and a heated end, the sample is placed between the heating end and the heated end and kept suspended, and then the lateral temperature difference is measured by the thermocouple or the detection probe to obtain the parameters of the thermal Hall effect.

[0004] As the research on micro-nano thermoelectric materials gradually deepens, the above-mentioned detectors are not suitable for measuring the thermal Hall effect of micro-nano materials due to the small size of micro-nano thermoelectric materials and the difficulty in preparing suspended samples. In current related research, there is still a gap in the in-situ integrated measurement of the thermoelectric effect, rectification effect and Hall effect of thermoelectric materials. If different detectors are used to measure different physical properties of the same sample to be tested, it will cause the transmission of errors, further increase the measurement error, and lead to low measurement accuracy of sample properties. In summary, due to the limitations of micro-nano technology, existing detectors cannot guarantee the consistency of sample preparation, and measurement errors may occur when measuring different properties of samples through multiple sample preparations. Summary of the invention

[0005] In view of this, the present invention provides a detector and a preparation method for measuring the thermoelectric, rectification and Hall effects of micro-nano materials, so as to solve the problem that the existing detectors cannot ensure the consistency of sample preparation, and measurement errors may be caused when measuring different properties of samples through multiple sample preparations, and to realize the study of the thermal electromagnetic coupling transport mechanism of materials.

[0006] In a first aspect, the present invention provides a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials, comprising:

[0007] A substrate layer, wherein the substrate layer has a detection area suitable for placing a sample to be detected;

[0008] A first microelectrode group includes a first microelectrode and a second microelectrode arranged opposite to each other on both sides of the detection area on the substrate layer in a first direction;

[0009] The second microelectrode group includes a third microelectrode and a fourth microelectrode arranged on both sides of the detection area on the substrate layer in a second direction, the first direction and the second direction are arranged at a preset angle; there is a gap between the first microelectrode group and the second microelectrode group and the sample to be tested;

[0010] The third microelectrode group includes a fifth microelectrode, a sixth microelectrode, a seventh microelectrode and an eighth microelectrode, which are respectively arranged between the microelectrode of the first microelectrode group and the adjacent microelectrode of the second microelectrode group, and one end extends toward the detection area to connect with the sample to be tested.

[0011] Beneficial effects: The present invention uses the four microelectrodes in the first microelectrode group and the second microelectrode group for heating or temperature measurement to measure the thermal properties of the sample to be tested; the four microelectrodes in the third microelectrode group are used to directly connect with the sample to be tested to ensure the ohmic contact between the microelectrode and the sample to be tested, and the standard four-wire method is used for measurement to achieve accurate measurement of the voltage and current signals of the thermoelectric material. Finally, the in-situ integrated measurement of ten related parameters of the thermoelectric performance, rectification effect and Hall effect of the thermoelectric material is achieved. It only needs to place the sample to be tested in the detection area of ​​the detector to achieve the in-situ integrated measurement of multiple data, which is convenient for analyzing the coupled transport mechanism of heat, electricity and magnetism. The various parameters do not affect each other, which is conducive to mass production; compared with the traditional probe method, which requires multiple adjustments of the probe head and the sample to be tested by relying on the atomic force microscope, the detector of this scheme is simpler and faster when placing the sample, and can measure samples of different shapes without adjusting the detector itself, avoiding measurement errors or even wrong results caused by multiple sample preparations, multiple measurements and calculations, and ensuring the accuracy of the measurement results.

[0012] In an optional embodiment, the first direction and the second direction are arranged at 90°.

[0013] In the present invention, under the action of a vertical magnetic field perpendicular to the sample to be tested, the third microelectrode and the fourth microelectrode can receive the heat flow flowing from the first microelectrode or the second microelectrode to the greatest extent, thereby ensuring the measurement accuracy of parameters related to the thermal Hall effect, and also facilitating the setting of the third microelectrode and the fourth microelectrode.

[0014] In an optional embodiment, the first microelectrode, the second microelectrode, the third microelectrode and the fourth microelectrode are all formed into a bent serpentine structure at one end close to the sample to be tested;

[0015] The fifth microelectrode, the sixth microelectrode, the seventh microelectrode and the eighth microelectrode are all formed into a linear structure.

[0016] In the present invention, the above-mentioned arrangement can ensure the heat transfer from the heating end microelectrode to the sample to be tested and the heat transfer from the sample to be tested to the heat sink end microelectrode to the greatest extent; in addition, the fifth microelectrode, the sixth microelectrode, the seventh microelectrode and the eighth microelectrode used for voltage and current measurement can be simply formed into a linear structure, which is convenient for forming ohmic contact with the sample to be tested and is simple to manufacture.

[0017] In an optional embodiment, the first microelectrode and the second microelectrode are formed into a bent serpentine structure at one end close to the sample to be tested; the third microelectrode and the fourth microelectrode are gradually reduced in size toward the sample to be tested at one end close to the sample to be tested, or the third microelectrode and the fourth microelectrode are formed into a straight structure;

[0018] The fifth microelectrode, the sixth microelectrode, the seventh microelectrode and the eighth microelectrode are all formed into a linear structure.

[0019] In the present invention, the above-mentioned setting is adopted, and the first microelectrode and the second microelectrode used for thermal performance detection are both formed into a bent serpentine structure at one end close to the sample to be tested in the middle of the detector, which can maximize the heat transfer from the heating end microelectrode to the sample to be tested and the heat transfer from the sample to be tested to the heat sink end microelectrode, especially the heat output of the heating end microelectrode; but the third microelectrode and the fourth microelectrode and the fifth microelectrode, the sixth microelectrode, the seventh microelectrode and the eighth microelectrode used for voltage and current measurement are all formed into a linear structure, and even the third microelectrode and the fourth microelectrode are formed into a structure with a size gradually decreasing toward the sample to be tested, such as a needle-shaped structure. The third microelectrode and the fourth microelectrode only need to meet the temperature monitoring under the action of the magnetic field. Since there is no need to output heat, the Hall effect parameter measurement of a more precise position can be achieved by reducing the size toward the end of the sample to be tested, which helps to avoid accidental contact with the sample to be tested and save costs.

[0020] In an optional embodiment, the width dimension of the first microelectrode and the second microelectrode in the second direction near one end of the sample to be tested is L1, the width dimension of the third microelectrode and the fourth microelectrode in the first direction near one end of the sample to be tested is L2, and L1 and L2 satisfy the following relationship: L1>L2.

[0021] Such a setting can not only ensure that the heat generated by the microelectrode at the heating end is transferred to the sample to be tested as much as possible, ensuring the measurement of the initial heat value, but also help to improve the accuracy of parameters related to the Hall effect, while saving costs and achieving a fool-proof effect.

[0022] In an optional embodiment, the substrate layer is rectangular, and the detection area is located at the center of the rectangular substrate layer; the first microelectrode group and the second microelectrode group are respectively arranged in the middle of two opposite sides of the substrate layer and extend toward the center of the substrate layer; the fifth microelectrode, the sixth microelectrode, the seventh microelectrode and the eighth microelectrode are respectively arranged at the four corners of the substrate layer and extend toward the detection area along the diagonal of the substrate layer.

[0023] The above-mentioned arrangement greatly facilitates the processing and forming of the eight microelectrodes and is convenient for the placement of the samples to be tested.

[0024] In an optional embodiment, the detection area of ​​the substrate layer, the substrate layer area corresponding to the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and the substrate layer area corresponding to the middle of the serpentine structure all form a first groove.

[0025] Except for the substrate layer area directly below the formed microelectrode and the area appropriately extending to support the sample to be tested, other areas can form a first groove of a certain depth to ensure that the sample is suspended while reducing heat loss during measurement and ensuring uniform temperature.

[0026] In an optional embodiment, it further comprises a temperature-averaging layer, and the first microelectrode group, the second microelectrode group and the third microelectrode group are all arranged on the temperature-averaging layer;

[0027] The temperature-averaging layer is laid on the substrate layer, and the temperature-averaging layer has a first hollow structure corresponding to the first groove of the substrate layer; or the substrate layer has a second U-shaped groove in the middle, and the edge of the temperature-averaging layer is overlapped on the edge of the second groove of the substrate layer. The temperature-averaging layer forms a second hollow structure in the detection area in the middle, the area between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and the area in the middle of the serpentine structure, and the second hollow structure is connected to the second groove.

[0028] In the present invention, a second square-shaped groove slightly smaller than the horizontal cross-section of the substrate layer is formed in the middle area of ​​the substrate layer, the outer peripheral edge of the temperature-averaging layer is placed on the edge of the substrate layer, and multiple hollows are formed in the middle to form a second hollow structure to be suspended above the second groove. The temperature-averaging layer is made of silicon nitride with a thickness of 100nm-800nm. Silicon nitride can not only play a good supporting role for the microelectrode, so that the suspended sample to be tested will not sink due to gravity, ensuring that the sample to be tested is on the same horizontal plane, but also the temperature-averaging layer of silicon nitride can effectively control the temperature and reduce heat loss.

[0029] In a second aspect, the present invention provides a method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials, comprising the following steps:

[0030] preparing a substrate layer;

[0031] A first microelectrode group, a second microelectrode group and a third microelectrode group are prepared on the substrate layer, wherein the first microelectrode group includes a first microelectrode and a second microelectrode that are relatively spaced apart in a first direction, and the second microelectrode group includes a third microelectrode and a fourth microelectrode that are relatively spaced apart in a second direction, and the first direction and the second direction are arranged at a preset angle; the third microelectrode group includes a fifth microelectrode, a sixth microelectrode, a seventh microelectrode and an eighth microelectrode, which are respectively located between the microelectrode of the first microelectrode group and the adjacent microelectrode of the second microelectrode group, and are suitable for connecting with a sample to be tested;

[0032] A detection area suitable for placing a sample to be detected is formed by etching on the substrate layer. The detection area is located between the first microelectrode and the second microelectrode, and between the third microelectrode and the fourth microelectrode.

[0033] Through the above-mentioned preparation method, a detector can be obtained for in-situ integrated measurement of ten relevant parameters of thermoelectric properties, rectification effect and Hall effect of thermoelectric materials. It is only necessary to place the sample to be tested in the detection area of ​​the detector to realize in-situ integrated measurement of multiple data, which is convenient for analyzing the coupled transport mechanism of heat, electricity and magnetism. The various parameters do not affect each other, which is conducive to mass production. Compared with the traditional probe method, which requires multiple adjustments of the connection between the probe head and the sample to be tested by relying on an atomic force microscope, the detector of this scheme is simpler and faster when placing the sample, and can measure samples of different shapes without adjusting the detector itself, avoiding measurement errors and even erroneous results caused by multiple sample preparations, multiple measurements and calculations, and ensuring the accuracy of the measurement results.

[0034] In an optional embodiment, before preparing the first microelectrode group, the second microelectrode group and the third microelectrode group on the substrate layer, the step of: depositing a temperature-averaging layer on the substrate layer;

[0035] After preparing the first microelectrode group, the second microelectrode group and the third microelectrode group on the substrate layer, the method further includes the steps of: forming a second groove on the substrate layer, and forming a second hollow structure on the temperature-averaging layer, wherein the second hollow structure includes a detection area located in the middle of the temperature-averaging layer, an area between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and an area corresponding to the middle of the serpentine structure, and the second groove is connected to the second hollow structure.

[0036] Setting up a suspended silicon nitride temperature-averaging layer can not only provide good support for the microelectrode, so that the suspended sample to be tested will not sink due to gravity, but also ensure that the sample to be tested is at the same horizontal plane. The silicon nitride temperature-averaging layer can also effectively control the temperature and reduce heat loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a schematic diagram of the structure of a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to an embodiment of the present invention;

[0039] Figure 2 It is a flow chart of a method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to an embodiment of the present invention;

[0040] Figures 3A-3J It is a schematic diagram of each step of a method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to an embodiment of the present invention;

[0041] Description of reference numerals:

[0042] 100, sample to be tested; 200, metal microelectrode;

[0043] 1. substrate layer; 11. detection area; 12. second groove;

[0044] 201, a first microelectrode; 202, a second microelectrode;

[0045] 301, third microelectrode; 302, fourth microelectrode;

[0046] 401, fifth microelectrode; 402, sixth microelectrode; 403, seventh microelectrode; 404, eighth microelectrode;

[0047] 5. Temperature uniformity layer; 51. Second hollow structure;

[0048] 6. Photoresist layer. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0050] Thermoelectric materials are mainly used in thermoelectric performance, rectification effect and Hall effect. The Hall effect in the present invention can be specifically referred to as thermal Hall effect. Thermal Hall effect refers to the phenomenon that when an external magnetic field perpendicular to the temperature gradient is applied to a material with a temperature gradient, hot carriers will be deflected, resulting in a heat flow perpendicular to the temperature gradient in the material, thereby generating a lateral temperature difference. By studying the thermal Hall effect, it is possible to further study the properties of electrically neutral excitations of materials, such as phonons and magnons, and their interactions, and further promote the application of spintronic and magnon devices.

[0051] Specifically, the physical parameters that can be used to characterize the thermoelectric properties, rectification effect and Hall effect of thermoelectric materials include ten items, namely thermal conductivity, thermal rectification coefficient, Seebeck coefficient, electrical conductivity, electrical rectification coefficient, thermoelectric figure of merit, Hall thermal conductivity, Hall coefficient, carrier concentration and carrier mobility. Thermal conductivity, also known as "thermal conductivity", is a measure of the thermal conductivity of a material. Specifically, it refers to the amount of heat transferred through a unit thermal conductive surface per unit time under a unit temperature gradient (temperature drops by 1K within a length of 1m), usually represented by λ; for anisotropic three-dimensional material samples, it is necessary to measure thermal conductivity and electrical conductivity in different directions, so this embodiment includes the measurement of thermal rectification and electrical rectification in different directions of the material. The thermal rectification coefficient is used to characterize the different heat transfer capabilities in different directions of the same temperature gradient, usually represented by η; the electrical rectification coefficient is used to characterize the electrical conductivity in different conductive directions, usually represented by δ; the Seebeck coefficient is used to measure the thermoelectricity caused by the temperature difference on the material The magnitude of voltage is usually represented by S. Electrical conductivity is a parameter used to describe the ease of charge flow in a substance, usually represented by σ, which is the reciprocal of resistivity ρ, i.e. σ = 1 / ρ. Thermoelectric figure of merit is a dimensionless value used to characterize the overall thermoelectric performance, usually represented by ZT, which is related to the Seebeck coefficient S, electrical conductivity σ, thermal conductivity λ and temperature T. Hall thermal conductivity is used to characterize the lateral thermal conductivity of the sample 100 under the lateral temperature difference caused by the thermal Hall effect due to the effect of the magnetic field when a magnetic field is applied vertically perpendicular to the sample surface, and is represented by λ″. The Hall coefficient is the ability of the material to produce the Hall effect when electricity is applied in a magnetic field, usually represented by R H To express; based on the measured material Hall coefficient, combined with the carrier charge, the carrier concentration n can be obtained; based on the measured material Hall coefficient, combined with the conductivity, the carrier mobility μ can be obtained.

[0052] The following will illustrate how to obtain the above parameters through the detector of the present invention through specific embodiments, thereby ensuring the consistency of the sample and the accuracy of the measurement of various parameters.

[0053] In this embodiment, a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials is provided, which can be used to in situ obtain ten parameters that can characterize the thermoelectric performance, rectification effect and Hall effect of thermoelectric sample materials, including:

[0054] A substrate layer 1, a first microelectrode group, a second microelectrode group and a third microelectrode group, wherein the substrate layer 1 has a detection area 11 suitable for placing a sample 100 to be tested; the first microelectrode group includes a first microelectrode 201 and a second microelectrode 202 which are relatively arranged on both sides of the detection area 11 on the substrate layer 1 in a first direction; the second microelectrode group includes a third microelectrode 301 and a fourth microelectrode 302 which are relatively arranged on both sides of the detection area 11 on the substrate layer 1 in a second direction, the first direction and the second direction are arranged at a preset angle, and there is a gap between the first microelectrode group and the second microelectrode group and the sample 100 to be tested; the third microelectrode group includes a fifth microelectrode 401, a sixth microelectrode 402, a seventh microelectrode 403 and an eighth microelectrode 404, which are respectively arranged between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and one end extends toward the detection area 11 to be connected with the sample 100 to be tested.

[0055] like Figure 1 As shown, the substrate layer 1 is placed horizontally, and the middle position of the substrate layer 1 is correspondingly set as the detection area 11, which is used to place the micrometer or nanometer-level thermoelectric material film sample. The four microelectrodes in the first microelectrode group and the second microelectrode group are used for heating or temperature measurement to measure the thermal properties of the sample 100 to be tested, and then obtain the thermal properties of the thermoelectric material, such as thermal conductivity, thermal rectification coefficient, thermal Hall effect, etc.; the four microelectrodes in the third microelectrode group are used to directly connect with the sample 100 to ensure the ohmic contact between the microelectrode and the sample 100 to be tested, and the standard four-wire method is used for measurement to achieve accurate measurement of the voltage and current signals of the thermoelectric material.

[0056] Specifically, first, one of the first microelectrode 201 and the second microelectrode 202 is connected to a power supply for heating as a heating end, and the other receives heat conducted from one side of the sample 100 to be tested as a heat sink end. The temperature difference between the heating end and the heat sink end is obtained by measuring the temperature from the first microelectrode 201 and the second microelectrode 202 respectively, and the thermal conductivity of the sample 100 to be tested is further calculated. It is worth noting that the input voltage of the first microelectrode 201 and the second microelectrode 202 is affected by the sample 100 to be tested. When measuring the sample 100 at the micro-nano level, the input range of the heating voltage between the two microelectrodes should be less than 1V to prevent the high temperature generated by the large voltage from damaging the sample 100 to be tested. In this embodiment, in order to ensure the accuracy of the temperature data of the sample 100 to be tested, the temperature at the first microelectrode 201 and the second microelectrode 202 is calculated by the formula of the change of resistance with temperature. There are different coefficients of change according to different microelectrode materials, which will not be specifically introduced in this embodiment; in addition, by changing the direction of the heating end and the heat sink end, the thermal conductivity in different directions can be measured, and then the thermal rectification coefficient of the thermoelectric material can be calculated.

[0057] Secondly, while measuring the thermal conductivity, since a temperature difference is formed in the first direction where the first microelectrode 201 and the second microelectrode 202 are located, the Seebeck voltage can be obtained at both ends of the temperature difference according to the Seebeck effect of the thermoelectric material, that is, the voltage at both ends of the sample 100 to be tested in the first direction is measured by a high-resolution voltmeter connected to the fifth microelectrode 401 and the eighth microelectrode 404, or to the sixth microelectrode 402 and the seventh microelectrode 403, and the Seebeck coefficient of the sample is further calculated. The sample 100 to be tested is turned on by connecting a constant current source to the fifth microelectrode 401 and the eighth microelectrode 404, and a high impedance voltmeter is connected to the sixth microelectrode 402 and the seventh microelectrode 403 to connect the sixth microelectrode 402 and the seventh microelectrode 403 to measure the voltage, thereby obtaining the electrical conductivity. In addition, the electrical conductivity of the sample 100 to be tested in different directions is measured by changing the direction of the output current of the constant current source, that is, the positive and negative poles of the constant current source are interchanged between the fifth microelectrode 401 and the eighth microelectrode 404, thereby obtaining the electrical rectification coefficient of the sample 100 to be tested. At this time, the thermoelectric figure of merit can be calculated by combining the obtained thermal conductivity, Seebeck coefficient and electrical conductivity with the measured temperature.

[0058] Then, a magnetic field is applied in a vertical direction perpendicular to the sample 100 to be tested, and the heat flow generated between the first microelectrode 201 and the second microelectrode 202 is offset under the action of the magnetic field, and a thermal Hall effect is generated in the sample 100 to be tested, and a lateral offset at an angle to the first direction is generated on the plane where the sample 100 to be tested is located, that is, a temperature difference is generated between the third microelectrode 301 and the fourth microelectrode 302, and the Hall thermal conductivity of the sample 100 to be tested can be obtained by measuring the temperature difference between the third microelectrode 301 and the fourth microelectrode 302. At the same time, when a vertical magnetic field is applied perpendicular to the surface of the sample 100 to be tested, a current is connected between the fifth microelectrode 401 and the eighth microelectrode 404, and the Hall voltage of the sample 100 to be tested is measured through the fifth microelectrode 401 and the sixth microelectrode 402, or the seventh microelectrode 403 and the eighth microelectrode 404, and then the Hall coefficient of the sample 100 to be tested is obtained by calculation, and the concentration and mobility of the carriers in the sample 100 to be tested are further calculated. In addition, the voltage range of the Hall effect measured between the fifth microelectrode 401 and the eighth microelectrode 404 is affected by the material of the sample 100 to be tested and the input voltage.

[0059] Ultimately, the in-situ integrated measurement of ten related parameters of the thermoelectric properties, rectification effect and Hall effect of thermoelectric materials is achieved. The in-situ integrated measurement of multiple data can be achieved by simply placing the sample 100 to be tested in the detection area 11 of the detector, which is convenient for analyzing the thermal-electric-magnetic coupling transport mechanism. The various parameters do not affect each other, which is conducive to mass production. Compared with the traditional probe method, which requires multiple adjustments of the probe head and the sample 100 to be tested based on an atomic force microscope, the detector of this scheme is simpler and faster when placing the sample, and can measure samples 100 to be tested in different shapes without adjusting the detector itself, avoiding measurement errors and even erroneous results caused by multiple sample preparations, multiple measurements and calculations, and ensuring the accuracy of the measurement results.

[0060] The thickness of the above-mentioned microelectrode is set to 20nm-100nm, such as 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm; the width of a single microelectrode strip is 1um-5um, such as 2um, 3um, 4um; the microelectrode is a metal microelectrode 200, the material can be gold, platinum or nickel, and the length of the metal microelectrode 200 can be designed according to usage requirements.

[0061] The sample 100 to be tested can be a thin film sample with regular geometry or an irregular thin film sample. The detector of this embodiment can measure both of them, has a wide range of applications, and does not require complicated connection and adjustment.

[0062] The gaps between the first microelectrode 201, the second microelectrode 202, the third microelectrode 301 and the fourth microelectrode 302 and the sample 100 to be tested only need to ensure that they do not contact the sample 100 to be tested. Otherwise, after the sample 100 to be tested contacts these four microelectrodes, the heating / temperature measuring electrodes and the sample 100 to be tested will be conductive, affecting the resistance measurement, and further affecting the heating / temperature measuring process, resulting in errors in the measurement results.

[0063] As a preferred implementation, the first direction and the second direction are arranged at 90 degrees in this embodiment. In this case, under the action of the vertical magnetic field perpendicular to the sample 100 to be tested, the third microelectrode 301 and the fourth microelectrode 302 can receive the heat flow from the first microelectrode 201 or the second microelectrode 202 to the greatest extent, ensuring the measurement accuracy of the parameters related to the thermal Hall effect, and also facilitating the arrangement of the third microelectrode 301 and the fourth microelectrode 302.

[0064] In some optional embodiments, the first microelectrode 201, the second microelectrode 202, the third microelectrode 301 and the fourth microelectrode 302 used for thermal property detection are all formed into a bent serpentine structure at one end close to the sample to be tested 100 in the middle of the detector. Such a configuration can maximize the heat transfer from the heating end microelectrode to the sample to be tested 100 and the heat transfer from the sample to be tested 100 to the heat sink end microelectrode; in addition, the fifth microelectrode 401, the sixth microelectrode 402, the seventh microelectrode 403 and the eighth microelectrode 404 used for voltage and current measurement can be simply formed into a linear structure, which is convenient for forming ohmic contact with the sample to be tested 100 and is simple to manufacture.

[0065] As another optional embodiment, the first microelectrode 201 and the second microelectrode 202 for thermal performance detection are both formed into a bent serpentine structure at one end close to the sample 100 to be tested in the middle of the detector, which can maximize the heat transfer from the heating end microelectrode to the sample 100 to be tested and the heat transfer from the sample 100 to the heat sink end microelectrode, especially the heat output of the heating end microelectrode; but the third microelectrode 301 and the fourth microelectrode 302 and the fifth microelectrode 401, the sixth microelectrode 402, the first microelectrode 403 for voltage and current measurement The seventh microelectrode 403 and the eighth microelectrode 404 are both formed into a linear structure, and even the third microelectrode 301 and the fourth microelectrode 302 are formed into a structure whose size gradually decreases toward the sample 100 to be tested, such as a needle-like structure. The third microelectrode 301 and the fourth microelectrode 302 only need to meet the temperature monitoring under the action of the magnetic field. Since there is no need to output heat, the Hall effect parameter measurement of the end toward the sample 100 to be tested can be achieved by reducing the size, which helps to avoid accidental touch with the sample 100 to save costs.

[0066] Of course, the whole can be defined as follows: Figure 1The first direction shown is the horizontal direction, the second direction is the vertical direction, and when the first direction and the second direction are arranged at 90°, the width dimension of the first microelectrode 201 and the second microelectrode 202 near the end of the sample 100 to be tested in the second direction is L1, and the width dimension of the third microelectrode 301 and the fourth microelectrode 302 near the end of the sample 100 to be tested in the first direction is L2, and L1 and L2 satisfy the following relationship: L1>L2. That is, the dimension of the first microelectrode 201 and the second microelectrode 202 near the end of the sample 100 to be tested in the vertical direction is L1, and the dimension of the third microelectrode 301 and the fourth microelectrode 302 near the end of the sample 100 to be tested in the horizontal direction is L2, and the two satisfy L1>L2, that is, the width of the two sets of microelectrodes arranged horizontally near the end of the sample 100 to be tested is greater than the width of the two sets of microelectrodes arranged vertically near the end of the sample 100 to be tested. Of course, this embodiment also includes the case where the width of each microelectrode is consistent at all places along the length direction. Under this condition, it can ensure that the heat generated by the microelectrode at the heating end is transferred to the sample 100 to be tested as much as possible, ensuring the measurement of the initial heat value, and it is helpful to improve the accuracy of parameters related to the Hall effect, while saving costs and achieving a fool-proof effect.

[0067] In one embodiment, the substrate layer 1 is set to be rectangular, and the detection area 11 is located at the center of the rectangular substrate layer 1, that is, the middle area where the two groups of diagonal lines intersect, and the size of the area can be determined according to the size of the sample 100 to be tested; the first microelectrode group and the second microelectrode group are respectively arranged in the middle of the two groups of opposite sides of the substrate layer 1 and extend toward the center of the substrate layer 1; the fifth microelectrode 401, the sixth microelectrode 402, the seventh microelectrode 403 and the eighth microelectrode 404 are respectively arranged at the four corners of the substrate layer 1 and extend along the diagonal of the substrate layer 1 to the detection area 11. This arrangement greatly facilitates the processing and forming of the eight microelectrodes, and is convenient for the placement of the sample 100 to be tested. Of course, it is not ruled out that the substrate layer 1 is set to other shapes, such as square, circle, etc.

[0068] In one embodiment, the detection area 11 of the substrate layer 1, the area of ​​the substrate layer 1 corresponding to the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and the area of ​​the substrate layer 1 corresponding to the middle of the serpentine structure are all formed with a first groove. That is, except for the area of ​​the substrate layer 1 directly below the formed microelectrode and the area appropriately extending to support the sample 100 to be tested, the other areas can form a first groove of a certain depth to ensure that the sample is suspended while reducing the heat loss during measurement and ensuring uniform temperature.

[0069] As a preferred embodiment, the detector for measuring the thermoelectricity, rectification and Hall effect of micro-nano materials in this embodiment is further provided with a temperature-averaging layer 5, and the first microelectrode group, the second microelectrode group and the third microelectrode group are all arranged on the temperature-averaging layer 5. The substrate layer 1 has a second U-shaped groove 12 in the middle, and the edge of the temperature-averaging layer 5 is laid on the edge of the second groove 12 of the substrate layer 1. The temperature-averaging layer 5 forms a second hollow structure 51 in the detection area 11 in the middle, the area between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and the area in the middle of the serpentine structure. The second hollow structure 51 is connected to the second groove 12. That is, the middle area of ​​the substrate layer 1 forms a second U-shaped groove 12 slightly smaller than the horizontal cross-section size of the substrate layer 1, the outer peripheral edge of the temperature-averaging layer 5 is laid on the edge of the substrate layer 1, and multiple hollows in the middle form the second hollow structure 51 to be suspended above the second groove 12. The temperature-averaging layer 5 is made of silicon nitride with a thickness of 100nm-800nm. Silicon nitride can provide good support for the microelectrode, so that the suspended sample 100 will not sink due to gravity, ensuring that the sample 100 is at the same level, and the silicon nitride temperature-averaging layer 5 can also effectively control the temperature and reduce heat loss.

[0070] Of course, in other embodiments, the temperature-averaging layer 5 may not be provided; or the temperature-averaging layer 5 may be provided and laid on the substrate layer 1, and the temperature-averaging layer 5 has a first hollow structure corresponding to the first groove of the substrate layer 1, that is, the temperature-averaging layer 5 is connected to the substrate layer 1, and is not provided as a suspended structure, as long as the sample 100 to be tested is suspended.

[0071] The embodiment of the present invention also provides a method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials, such as Figure 2 As shown, the following steps are included:

[0072] S201, prepare substrate layer 1. The substrate layer 1 is a horizontally placed rectangular silicon wafer, which has a mature processing technology and is easy to obtain. Compared with other materials, it is easier to deposit or sputter other structures on the silicon wafer.

[0073] S202, prepare a first microelectrode group, a second microelectrode group and a third microelectrode group on the substrate layer 1, the first microelectrode group includes a first microelectrode 201 and a second microelectrode 202 arranged relatively to each other in a first direction, the second microelectrode group includes a third microelectrode 301 and a fourth microelectrode 302 arranged relatively to each other in a second direction, and the first direction and the second direction are arranged at a preset angle; the third microelectrode group includes a fifth microelectrode 401, a sixth microelectrode 402, a seventh microelectrode 403 and an eighth microelectrode 404, which are respectively located between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and are suitable for connecting with the sample 100 to be tested.

[0074] The first microelectrode 201, the second microelectrode 202, the third microelectrode 301, the fourth microelectrode 302, the fifth microelectrode 401, the sixth microelectrode 402, the seventh microelectrode 403 and the eighth microelectrode 404 all use metal microelectrodes 200, and the material can be gold, platinum or nickel; the thickness is set to 20nm-100nm, such as 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm; the width of a single microelectrode strip is 1um-5um, such as 2um, 3um, 4um; the length of the metal microelectrode 200 can be designed according to usage requirements.

[0075] S203 , etching the substrate layer 1 to form a detection area 11 suitable for placing the sample 100 to be detected. The detection area 11 is located between the first microelectrode 201 and the second microelectrode 202 , and between the third microelectrode 301 and the fourth microelectrode 302 .

[0076] A detection area 11 is etched at the intersection of the diagonals of the rectangular substrate layer 1 to allow the sample 100 to be suspended in the air. Eight microelectrodes are evenly distributed around the detection area 11 to facilitate the microelectrodes to measure various parameters of the sample 100.

[0077] The detection area 11 in the middle of the substrate layer 1 is used to place a micrometer or nanometer-level thermoelectric material thin film sample. The four microelectrodes in the first microelectrode group and the second microelectrode group are used for heating or temperature measurement to measure the thermal properties of the sample 100 to be tested; the four microelectrodes in the third microelectrode group are used to directly connect with the sample 100 to ensure ohmic contact between the microelectrodes and the sample 100 to be tested, and the standard four-wire method is used for measurement to achieve accurate measurement of the voltage and current signals of the thermoelectric material.

[0078] Ultimately, the in-situ integrated measurement of ten related parameters of the thermoelectric properties, rectification effect and Hall effect of thermoelectric materials is achieved. It is only necessary to place the sample 100 to be tested in the detection area 11 of the detector to realize the in-situ integrated measurement of multiple data, which is convenient for analyzing the thermal-electric-magnetic coupling transport mechanism. The various parameters do not affect each other, which is conducive to mass production. Compared with the traditional probe method, which requires multiple adjustments of the probe head and the sample 100 to be tested based on an atomic force microscope, the detector of this scheme is simpler and faster when placing the sample, and can measure samples 100 to be tested in different shapes without adjusting the detector itself, avoiding measurement errors and even erroneous results caused by multiple sample preparations, multiple measurements and calculations, and ensuring the accuracy of the measurement results.

[0079] In other embodiments, a temperature-averaging layer 5 may be provided between the substrate layer 1 and the microelectrode. The temperature-averaging layer 5 is made of silicon nitride and has a thickness of 100nm-800nm. It can provide good support for the microelectrode so that the suspended sample 100 will not sink due to gravity, and can ensure that the sample 100 is on the same horizontal plane. The temperature-averaging layer 5 of silicon nitride can also effectively control the temperature and reduce heat loss.

[0080] The following will be combined Figures 3A-3J The method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials in this embodiment is described in detail, and specifically comprises the following steps:

[0081] like Figure 3A As shown, a clean silicon material is prepared as the substrate layer 1.

[0082] like Figure 3B As shown, a layer of low-stress silicon nitride is grown on the upper surface of the substrate layer 1 as a temperature-balancing layer 5, and the thickness of the silicon nitride is 100nm-800nm.

[0083] like Figure 3C As shown, on the upper surface of the temperature-homogenizing layer 5, Figure 1 A photoresist layer 6;

[0084] like Figure 3D As shown, a recessed photolithography pattern is formed on the photoresist layer 6 through a mask;

[0085] like Figure 3E As shown, a layer of metal material is sputtered on the photolithography pattern of the formed photoresist layer 6. The metal material may be gold, platinum or nickel, and the thickness is set to 20nm-100nm, such as 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm;

[0086] like Figure 3F As shown, the photoresist layer 6 is peeled off and the unnecessary metal material is removed to obtain the required metal microelectrode 200, wherein the thickness of the metal microelectrode 200 is set to 20nm-100nm, such as 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm; the width is 1um-5um, such as 2um, 3um, 4um; the length can be designed according to the use requirements;

[0087] like Figure 3G As shown, a layer of photoresist layer 6 is spin-coated again on the surface of the temperature-balancing layer 5 on which the metal microelectrodes 200 are formed. At this time, the photoresist layer 6 covers all the metal microelectrodes 200 and the temperature-balancing layer 5;

[0088] like Figure 3HAs shown, the same mask used previously is used for in-situ overlaying to directly cover the photoresist layer 6 on the temperature-uniform layer 5, and the photoresist layer 6 on the metal microelectrode 200 is retained to protect the metal microelectrode 200;

[0089] like Fig. 3I As shown, the silicon material below the silicon nitride is wet-etched from below the silicon nitride to form a second square-shaped groove 12 so that the silicon nitride temperature-balancing layer 5 is suspended. In this process, the second hollow structure 51 on the silicon nitride temperature-balancing layer 5 is completed by photolithography;

[0090] like Figure 3J As shown, the photoresist layer 6 is stripped off and cleaned, and finally a detector for measuring the thermoelectricity, rectification and Hall effect of micro-nano materials is prepared.

[0091] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials, It is characterized in that include: A substrate layer (1), wherein the substrate layer (1) has a detection area (11) suitable for placing a sample to be tested (100); A first microelectrode group, comprising a first microelectrode (201) and a second microelectrode (202) arranged on opposite sides of the detection area (11) on the substrate layer (1) in a first direction; A second microelectrode group, comprising a third microelectrode (301) and a fourth microelectrode (302) arranged on both sides of the detection area (11) on the substrate layer (1) in a second direction, the first direction and the second direction being arranged at a preset angle; and a gap is provided between the first microelectrode group and the second microelectrode group and the sample (100) to be tested; The third microelectrode group includes a fifth microelectrode (401), a sixth microelectrode (402), a seventh microelectrode (403) and an eighth microelectrode (404), which are respectively arranged between the microelectrode of the first microelectrode group and the adjacent microelectrode of the second microelectrode group, and one end extends toward the detection area (11) to be connected to the sample to be tested (100).

2. The detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 1, It is characterized in that The first direction and the second direction are arranged at 90 degrees.

3. The detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 2, It is characterized in that The first microelectrode (201), the second microelectrode (202), the third microelectrode (301) and the fourth microelectrode (302) are all formed into a bent serpentine structure at one end close to the sample to be tested (100); The fifth microelectrode (401), the sixth microelectrode (402), the seventh microelectrode (403) and the eighth microelectrode (404) are all formed into a linear structure.

4. The detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 2, It is characterized in that One end of the first microelectrode (201) and the second microelectrode (202) close to the sample to be tested (100) is formed into a bent serpentine structure; one end of the third microelectrode (301) and the fourth microelectrode (302) close to the sample to be tested (100) gradually decreases in size toward the sample to be tested (100) or the third microelectrode (301) and the fourth microelectrode (302) are formed into a straight line structure; The fifth microelectrode (401), the sixth microelectrode (402), the seventh microelectrode (403) and the eighth microelectrode (404) are all formed into a linear structure.

5. The detector for measuring the thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 3 or 4, It is characterized in that The width dimension of the first microelectrode (201) and the second microelectrode (202) in the second direction at one end close to the sample to be tested (100) is L1, and the width dimension of the third microelectrode (301) and the fourth microelectrode (302) in the first direction at one end close to the sample to be tested (100) is L2, and L1 and L2 satisfy the following relationship: L1>L2.

6. The detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 5, It is characterized in that The substrate layer (1) is rectangular, and the detection area (11) is located at the center of the rectangular substrate layer (1); the first microelectrode group and the second microelectrode group are respectively arranged in the middle of two opposite sides of the substrate layer (1) and extend toward the center of the substrate layer (1); the fifth microelectrode (401), the sixth microelectrode (402), the seventh microelectrode (403) and the eighth microelectrode (404) are respectively arranged at the four corners of the substrate layer (1) and extend along the diagonal of the substrate layer (1) toward the detection area (11).

7. The detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 6, It is characterized in that The detection area (11) of the substrate layer (1), the area of ​​the substrate layer (1) corresponding to the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and the area of ​​the substrate layer (1) corresponding to the middle of the serpentine structure all form a first groove.

8. The detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 7, It is characterized in that Also includes: A temperature-averaging layer (5), wherein the first microelectrode group, the second microelectrode group and the third microelectrode group are all arranged on the temperature-averaging layer (5); The temperature-averaging layer (5) is laid on the substrate layer (1), and the temperature-averaging layer (5) has a first hollow structure corresponding to the first groove of the substrate layer (1); or the substrate layer (1) has a second U-shaped groove (12) in the middle, and the edge of the temperature-averaging layer (5) is laid on the edge of the second groove (12) of the substrate layer (1). The temperature-averaging layer (5) forms a second hollow structure (51) in the detection area (11) in the middle, the area between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and the area in the middle of the serpentine structure, and the second hollow structure (51) is connected to the second groove (12).

9. A method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials. It is characterized in that The steps include: Preparing a substrate layer (1); A first microelectrode group, a second microelectrode group and a third microelectrode group are prepared on the substrate layer (1), wherein the first microelectrode group comprises a first microelectrode (201) and a second microelectrode (202) arranged relatively and spaced apart in a first direction, and the second microelectrode group comprises a third microelectrode (301) and a fourth microelectrode (302) arranged relatively and spaced apart in a second direction, and the first direction and the second direction are arranged at a preset angle; the third microelectrode group comprises a fifth microelectrode (401), a sixth microelectrode (402), a seventh microelectrode (403) and an eighth microelectrode (404), which are respectively located between the microelectrode of the first microelectrode group and the adjacent microelectrode of the second microelectrode group, and are suitable for connecting to a sample (100) to be tested; A detection area (11) suitable for placing a sample to be tested (100) is etched on the substrate layer (1), and the detection area (11) is located between the first microelectrode (201) and the second microelectrode (202), and between the third microelectrode (301) and the fourth microelectrode (302).

10. The method for preparing a detector for measuring thermoelectricity, rectification and Hall effect of micro-nano materials according to claim 9, It is characterized in that Before preparing the first microelectrode group, the second microelectrode group and the third microelectrode group on the substrate layer (1), the method further comprises the steps of: depositing a temperature-averaging layer (5) on the substrate layer (1); After preparing the first microelectrode group, the second microelectrode group and the third microelectrode group on the substrate layer (1), the method further comprises the steps of: forming a second groove (12) on the substrate layer (1), and forming a second hollow structure (51) on the temperature-averaging layer (5), wherein the second hollow structure (51) comprises a detection area (11) located in the middle of the temperature-averaging layer (5), an area between the microelectrode of the first microelectrode group and the microelectrode of the adjacent second microelectrode group, and an area corresponding to the middle of the serpentine structure, and the second groove (12) is connected to the second hollow structure (51).

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