A material work function measurement method and device based on emission probe technology

Abstract

The invention belongs to the technical field of cathode electronics for measuring work function of materials, and provides a material work function measurement method and device based on an emission probe technology, comprising an emission probe, a vacuum chamber and a sample support platform, wherein the emission probe is fixed inside the vacuum chamber through a three-dimensional driver; the sample support platform is fixed inside the vacuum chamber; the emission probe is located on one side of the sample support platform, and is used to detect a sample to be measured placed on the sample support platform; when measuring the work function of a solid material, it is not necessary to heat the material to be measured or to apply an external electric field to it, and there are no special requirements for the shape and size of the material to be measured, and the work function measurement result of the solid material is given by the displacement difference of two emission probe volt-ampere characteristic curves measured successively at different positions of the emission probe filament, and the obtained work function measurement result can truly reflect the actual situation of the material surface.

Description

Technical Field

[0001] The invention belongs to the technical field of material work function measurement, and in particular relates to a material work function measurement method and device based on emission probe technology. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The work function of a material is one of the important parameters for describing the properties of a material, especially for solid cathode materials, where the size of the work function directly characterizes the level of its electron emission capability. Studies have shown that the size of the work function of a material is not only directly related to the external electric field and material temperature, but is also closely related to the structure and surface condition of the material. Therefore, accurate measurement of the work function can not only reveal the electron emission mechanism of solid cathode materials, but also has very important significance for the study of physical processes and surface phenomena on the surface of solid materials.

[0004] So far, common material work function measurement methods include: Richardson linear method, calorimetry, Fowler isotherm curve method, DuBridge isochromatic curve method, contact potential difference method and field electron emission method, etc. When using these methods to measure the work function of solid materials, it is usually necessary to heat the material to be tested or apply a very strong external electric field to it, so that it can generate thermal electron emission current or field electron emission current, thereby obtaining the work function parameters of the material. However, this operation usually obtains the electron emission performance of the entire material to be tested, that is, the work function measurement result obtained is the work function average value of the entire material surface, rather than the work function distribution change on the material surface. In addition, heating the entire material to be tested or applying a strong electric field to it often causes inevitable and irreparable damage to the material surface, which is not conducive to the study of surface physical phenomena of the solid material to be tested. In addition, currently known work function measurement methods often have specific requirements for the shape and size of the solid material to be measured. Therefore, before measuring the work function, it is usually necessary to first process the material to be measured. However, the processing of the material to be measured will inevitably change the surface condition of the material to be measured, thereby affecting the final work function measurement result.

[0005] In short, using the current work function measurement method, it is impossible to obtain the high-precision work function size of the material and the work function distribution on the material surface without changing the original surface condition of the material. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a material work function measurement method and device based on emission probe technology. When measuring the work function of solid materials, the present invention does not need to heat the material to be measured or apply an external electric field to it, and has no special requirements on the shape and size of the material to be measured. The work function measurement result of the solid material is given by the difference in displacement of two emission probe volt-ampere characteristic curves measured successively at different positions of the emission probe filament. The obtained work function measurement result can truly reflect the actual situation of the material surface.

[0007] According to some embodiments, a first solution of the present invention provides a material work function measurement device based on emission probe technology, which adopts the following technical solution:

[0008] A material work function measurement device based on emission probe technology, comprising an emission probe, a vacuum chamber and a sample support platform, wherein the emission probe is fixed inside the vacuum chamber through a three-dimensional driver; the sample support platform is fixed inside the vacuum chamber;

[0009] The emission probe is located on one side of the sample supporting platform and is used to detect the sample to be tested placed on the sample supporting platform.

[0010] Further, the transmitting probe is fixed in a three-dimensional actuator, and the three-dimensional actuator is fixed on the vacuum chamber through a vacuum flange;

[0011] Two electrodes are fixed on one side of the vacuum flange extending outside the vacuum chamber, and the electrodes are connected to the transmitting probe heating circuit outside the vacuum chamber; the transmitting probe heating circuit is connected to the transmitting probe through the two electrodes.

[0012] Furthermore, the emission probe is composed of a filament, an insulating bracket and a filament wire;

[0013] The insulating bracket is composed of two single-hole capillary insulating tubes and one double-hole insulating tube, and the two single-hole capillary insulating tubes are inserted into the two holes of the double-hole insulating tube and fixed;

[0014] A filament lead wire is extended out of each of the two single-hole capillary insulating tubes and connected to the filament, and the filament is fixed at the tube openings on the same side of the two single-hole capillary insulating tubes.

[0015] Furthermore, the two filament wires extend from one end of the single-hole capillary insulating tube away from the filament and are connected to two electrodes on the vacuum flange.

[0016] Furthermore, two identical sampling resistors are arranged on the first branch of the transmitting probe heating circuit, and a voltmeter is connected in parallel at both ends of the branch;

[0017] An emission probe scanning bias circuit is connected between the two sampling resistors; the emission probe scanning bias circuit is also connected to the ground electrode of the vacuum chamber.

[0018] Further, the sample support platform comprises a sample table, a sample table bracket and a base, and the sample table is fixed on the base through the sample table bracket;

[0019] The sample table is provided with a plurality of grooves for placing insulating clamps.

[0020] Furthermore, two screw holes are symmetrically arranged on the base, and the sample support table is fixed to the bottom of the vacuum chamber by two fixing screws.

[0021] According to some embodiments, a second solution of the present invention provides a material work function measurement method based on emission probe technology, which adopts the following technical solution:

[0022] A material work function measurement method based on emission probe technology, comprising:

[0023] Step S1: The sample to be tested is brought into contact with the standard part, and fixed on the sample table with an insulating clamp, and the sample support table on which the sample to be tested and the standard part are placed is fixed on the bottom of the vacuum chamber;

[0024] Step S2: installing the emission probe on the three-dimensional driver, the three-dimensional driver is fixed on the vacuum chamber through a vacuum flange, and the emission probe filament is placed vertically and parallel to the surface of the standard part;

[0025] Step S3: Move the emission probe by a three-dimensional driver so that the filament of the emission probe moves to the vicinity of the standard part with a spacing of no more than 1 mm, apply a fixed heating current to the filament of the emission probe by a emitting probe heating circuit, and apply a set of sequentially changing scanning biases to the filament of the emission probe by a emitting probe scanning bias circuit, and obtain a volt-ampere characteristic curve of the emission probe collected near the standard part;

[0026] Step S4: Move the emission probe through a three-dimensional driver so that the filament of the emission probe moves to different positions on the surface of the sample to be tested, keep the heating current unchanged, and use the emission probe scanning bias circuit to apply a set of scanning bias voltages that are exactly the same as step S3 to the filament of the emission probe to obtain the emission probe volt-ampere characteristic curve at different positions on the surface of the sample to be tested, compare the emission probe volt-ampere characteristic curve collected at different positions on the surface of the sample to be tested with the emission probe volt-ampere characteristic curve collected near the standard part, and obtain the work function corresponding to different surface positions of the sample to be tested, that is, obtain the surface work function distribution of the sample to be tested.

[0027] Furthermore, the detection process of step S4 is specifically as follows:

[0028] The emitting probe is moved by a three-dimensional driver so that the filament of the emitting probe is moved to the vicinity of the first position of the sample to be tested, with a spacing of no more than 1 mm, and the heating current is kept unchanged. At the same time, a set of scanning bias voltages identical to those in step S3 are applied to the filament of the emitting probe by a scanning bias circuit of the emitting probe to obtain a volt-ampere characteristic curve of the emitting probe at the first position of the sample;

[0029] The emission probe is moved by a three-dimensional driver so that the filament of the emission probe moves to different positions near the sample to be tested, and the above process is repeated to obtain the emission probe volt-ampere characteristic curve at different positions on the surface of the sample to be tested.

[0030] Furthermore, the volt-ampere characteristic curve of the emission probe at different positions on the surface of the sample to be tested is compared with the volt-ampere characteristic curve of the emission probe collected near the standard part to obtain the corresponding work function at different positions on the surface of the sample to be tested, specifically:

[0031] Taking the emission probe volt-ampere characteristic curve at the first position of the sample to be tested as an example, the scanning voltage of the emission probe volt-ampere characteristic curve collected near the standard part is subtracted from the scanning voltage corresponding to the same electron current in the emission probe volt-ampere characteristic curve at the first position on the surface of the sample to be tested, and the voltage displacement difference between the two is obtained;

[0032] According to the known work function of the standard part, the work function of the sample to be tested at the first position is obtained by using the principle of contact potential difference between metals;

[0033] According to the above process, different positions of the sample to be tested are tested respectively to obtain the work functions corresponding to different surface positions of the sample to be tested.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. When measuring the work function of a solid material, the present invention does not need to heat the material to be measured or apply an external electric field to it. The work function measurement result of the solid material is given by the difference in displacement of two emission probe volt-ampere characteristic curves measured successively at different positions of the emission probe filament. Therefore, the obtained work function measurement result can truly reflect the actual situation of the material surface.

[0036] 2. When measuring the work function of solid materials, the present invention has no special requirements on the shape and size of the material to be tested, and can meet the testing requirements of most solid materials without changing any physical properties (shape, size, surface morphology, etc.) of the material to be tested.

[0037] 3. The present invention adopts a small-sized emission probe, the diameter of the emission probe filament is in the micron level, and the length of the filament is only a few millimeters. The use of a small-sized emission probe and a high-precision displacement driver can realize high-precision (micron level) work function spatial distribution measurement on the surface of solid materials.

[0038] 4. The work function measurement result of the solid material in the present invention is given by the difference in displacement of two emission probe volt-ampere characteristic curves measured successively at different positions of the emission probe filament, and the difference in displacement of the two emission probe volt-ampere characteristic curves is only related to the voltage output accuracy of the emission probe scanning bias voltage. Therefore, compared with other work function measurement methods, the present invention has a very high measurement accuracy; and can simultaneously perform work function measurement on multiple solid materials to be measured.

[0039] 5. The work function measurement of the material in the present invention needs to be completed in a vacuum environment within a metal vacuum chamber. On the one hand, the metal vacuum chamber can shield the interference of the external electric field on the electric field near the surface of the internal material to be measured; on the other hand, the vacuum environment can also reduce the noise signal in the volt-ampere characteristic curve of the emission probe. Therefore, the work function measurement result of the present invention has good reliability.

[0040] Additional aspects and advantages of the present invention will be given in part in the following description, which will become obvious from the following description, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0042] Figure 1 It is an overall structural diagram of a material work function measurement device based on emission probe technology according to an embodiment of the present invention;

[0043] Figure 2 is a structural diagram of a small-size transmitting probe according to an embodiment of the present invention;

[0044] Figure 3 is a structural diagram of a sample support platform according to an embodiment of the present invention;

[0045] Figure 4 It is a comparison diagram of the volt-ampere characteristic curves of the emission probe measured near the surfaces of different materials in two vacuum environments according to the embodiment of the present invention;

[0046] Among them: 1-filament; 2-insulating bracket; 3-filament wire; 4-sample table; 5-insulating clamp; 6-standard parts; 7-sample to be tested; 8-sample table bracket; 9-sample table base; 10-fixing screw; 11-groove; 12-vacuum chamber; 13-three-dimensional drive; 14-vacuum flange; 15-electrode; 16-load resistor; 17-transmitting probe heating circuit; 18-transmitting probe scanning bias circuit; 19-sampling resistor; 20-ground electrode. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0048] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0050] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0051] Embodiment 1

[0052] like Figure 1-Figure 3 As shown, this embodiment provides a material work function measurement device based on the emission probe technology, including an emission probe, a vacuum chamber 12 and a sample support platform, wherein the emission probe is fixed inside the vacuum chamber 12 through a three-dimensional driver 13; the sample support platform is fixed inside the vacuum chamber 12;

[0053] The emission probe is located on one side of the sample support platform and is used to detect the sample 7 to be tested placed on the sample support platform.

[0054] Specifically, the solid material work function measurement device based on the emission probe technology is mainly composed of an emission probe, a sample support platform, a vacuum chamber 12 , a three-dimensional driver 13 , an emission probe heating circuit 17 and an emission probe scanning bias circuit 18 .

[0055] Among them, when conducting work function measurement, the emitting probe and the sample support platform must be placed inside the vacuum chamber 12. The vacuum chamber 12 is a cylindrical vacuum chamber made of stainless steel metal material. The emitting probe is installed in a three-dimensional driver 13. The three-dimensional driver 13 controlled by a power supply can realize the three-dimensional movement of the emitting probe, and its movement accuracy is required to be no less than 0.5 mm.

[0056] The transmitting probe is fixed in the three-dimensional driver 13, and the three-dimensional driver 13 is fixed on the vacuum chamber through the vacuum flange 14; two electrodes are fixed on the side of the vacuum flange 14 extending outside the vacuum chamber 12, and the electrodes are connected to the transmitting probe heating circuit 17 outside the vacuum chamber 12; the transmitting probe heating circuit 17 is connected to the transmitting probe through the two electrodes.

[0057] Two identical sampling resistors 19 are arranged on the first branch of the transmitting probe heating circuit 17, and a voltmeter is connected in parallel at both ends of the branch;

[0058] A load resistor 16 is connected to the second branch of the transmitting probe heating circuit;

[0059] An emission probe scanning bias circuit 18 is connected between two identical sampling resistors 19; the emission probe scanning bias circuit 18 is also connected to a ground electrode 20 of the vacuum chamber.

[0060] Specifically, the three-dimensional driver 13 is mounted and fixed on the vacuum chamber 12 through the vacuum flange 14, and the transmitting probe is connected to the external transmitting probe heating circuit 17 through two electrodes 15 on the vacuum flange 14. The two electrodes 15 must be insulated from each other, and the electrodes 15 and the vacuum flange must be insulated from each other. The transmitting probe heating circuit 17 heats the transmitting probe filament 1 through the two electrodes 15, and the circuit system includes a load resistor 16. The transmitting probe scanning bias circuit 18 applies a scanning bias between the transmitting probe filament 1 and the ground electrode 20 of the vacuum chamber 12 through two identical sampling resistors 19.

[0061] Specifically, Figure 2 As shown, the small-sized emission probe is mainly composed of a filament 1, an insulating bracket 2 and a filament wire 3. The filament 1 can emit thermal electrons when heated, and its material can be tungsten, molybdenum, rhenium, thorium, thorium dioxide, barium oxide, lanthanum hexaboride and other common metals, metal oxides, alkaline earth metal oxides and other hot cathode materials; its shape and size are filamentous, with a diameter of micrometers and a length of no more than 5 mm.

[0062] The emission probe is composed of a filament 1, an insulating bracket 2 and a filament wire 3;

[0063] The insulating support 2 is composed of two single-hole capillary insulating tubes and one double-hole insulating tube, and the two single-hole capillary insulating tubes are inserted into the two holes of the double-hole insulating tube and fixed;

[0064] A filament lead 3 extends out of each of the two single-hole capillary insulating tubes and is connected to the filament 1, and the filament 1 is fixed at the tube openings on the same side of the two single-hole capillary insulating tubes;

[0065] The two filament wires 3 extend from one end of the single-hole capillary insulating tube away from the filament 1 and are connected to two electrodes on the vacuum flange 14 .

[0066] In addition, the filament 1 is required to be in a straight line shape, not an arc shape. The insulating bracket 2 is composed of two single-hole capillary insulating tubes and a double-hole insulating tube. The single-hole capillary insulating tube can be inserted into the double-hole insulating tube and connected and fixed thereto. The materials of the single-hole capillary insulating tube and the double-hole insulating tube are common high-temperature resistant insulating materials such as ceramics and glass, and the inner diameter of the single-hole capillary insulating tube is just enough to allow the filament wire 3 to pass through. The filament wire 3 is made of refractory metal materials such as tungsten, molybdenum, and thorium, and its diameter is required to be no more than 0.5 mm.

[0067] In this embodiment, Figure 3 As shown, the sample support platform is mainly composed of a sample table 4, an insulating clamp 5, a standard part 6, a sample table bracket 8 and a base 9.

[0068] The sample table 4 is fixed on the base 9 via a sample table bracket 8 , and a plurality of grooves 11 for placing the insulating clamps 5 are provided on the sample table 4 .

[0069] Among them, the sample table 4 is rectangular or circular, and is made of insulating materials such as glass, ceramics, polytetrafluoroethylene, etc., and many grooves 11 of different widths and non-uniform distribution are engraved on the sample table; the insulating clamp 5 is a flat plate of different thicknesses, which can be inserted into different grooves 11 according to actual needs, and is made of insulating materials such as glass, ceramics, polytetrafluoroethylene, etc.; the standard part 6 is a metal material with a clean surface and known work function, such as tungsten, molybdenum, rhenium, etc., and its shape is flat or cubic; the sample table bracket 8 is tubular, and its material is stainless steel metal material; the sample table base 9 is a rectangular or circular flat plate, and its material is stainless steel metal material. Two left-right symmetrical screw holes are designed on the base 9, and the entire sample support platform can be fixed to the bottom of the vacuum chamber 12 by two fixing screws 10.

[0070] When the sample support platform is used to measure the work function of solid materials, the sample to be tested 7 and the standard part 6 are first brought into contact with each other, and then the insulating clamps 5 are used at the left and right ends to be inserted into appropriate grooves 11 to firmly fix the sample to be tested 7 and the standard part 6 on the sample table 4. In addition, when measuring the work function, multiple samples to be tested can be fixed on the sample table in a mutually contacting manner according to actual needs, and the testing requirements for samples of different shapes can be met, as long as the contact between the sample to be tested 7 and the standard part 6 is good.

[0071] Embodiment 2

[0072] like Figure 1-Figure 3 As shown, this embodiment provides a material work function measurement method based on emission probe technology, including:

[0073] Step S1: The sample to be tested is brought into contact with the standard part, and fixed on the sample table with an insulating clamp, and the sample support table on which the sample to be tested and the standard part are placed is fixed on the bottom of the vacuum chamber;

[0074] Step S2: installing the emission probe on the three-dimensional driver, the three-dimensional driver is fixed on the vacuum chamber through a vacuum flange, and the emission probe filament is placed vertically and parallel to the surface of the standard part;

[0075] Step S3: Move the emission probe by a three-dimensional driver so that the filament of the emission probe moves to the vicinity of the surface of the standard part, with the distance between the two not exceeding 1 mm, apply a fixed heating current to the filament of the emission probe by the emission probe heating circuit, and apply a set of sequentially changing scanning biases to the filament of the emission probe by the emission probe scanning bias circuit, and obtain the emission probe volt-ampere characteristic curve collected near the standard part;

[0076] Step S4: Move the emission probe through a three-dimensional driver so that the filament of the emission probe moves to different positions on the surface of the sample to be tested, keep the heating current unchanged, and use the emission probe scanning bias circuit to apply a set of scanning bias voltages that are exactly the same as those in step S3 to the filament of the emission probe to obtain the emission probe volt-ampere characteristic curves at different positions on the surface of the sample to be tested, compare the emission probe volt-ampere characteristic curves at different positions on the surface of the sample to be tested with the emission probe volt-ampere characteristic curves collected near the standard part, and obtain the work functions corresponding to different surface positions of the sample to be tested, that is, obtain the surface work function distribution of the sample to be tested.

[0077] The detection process of step S4 is specifically as follows:

[0078] The emitting probe is moved by a three-dimensional driver so that the filament of the emitting probe is moved to the vicinity of the first position of the sample to be tested, with a spacing of no more than 1 mm, and the heating current is kept unchanged. At the same time, a set of scanning bias voltages identical to those in step S3 is applied to the filament of the emitting probe by a scanning bias circuit of the emitting probe to obtain a volt-ampere characteristic curve of the emitting probe at the first position of the sample;

[0079] The emission probe is moved by a three-dimensional driver so that the filament of the emission probe moves to different positions near the sample to be tested, and the above process is repeated to obtain the emission probe volt-ampere characteristic curve at different positions on the surface of the sample to be tested.

[0080] The volt-ampere characteristic curve of the emission probe at different positions on the surface of the sample to be tested is compared with the volt-ampere characteristic curve of the emission probe collected near the standard part to obtain the corresponding work function at different positions on the surface of the sample to be tested, specifically:

[0081] Taking the emission probe volt-ampere characteristic curve at the first position of the sample to be tested as an example, the scanning voltage of the emission probe volt-ampere characteristic curve collected near the standard part is subtracted from the scanning voltage corresponding to the same electron current in the emission probe volt-ampere characteristic curve at the first position on the surface of the sample to be tested, and the voltage displacement difference between the two is obtained;

[0082] According to the known work function of the standard part, the work function of the sample to be tested at the first position is obtained by using the principle of contact potential difference between metals;

[0083] According to the above process, different positions of the sample to be tested are tested respectively to obtain the work functions corresponding to different surface positions of the sample to be tested.

[0084] Specifically, when the work function measuring device described in the first embodiment is used, the air pressure in the vacuum chamber is not higher than 0.01 Pa. The general process of using the work function measuring device to measure the work function of solid materials is as follows:

[0085] Ⅰ. Clean the surface of the standard part 6, place the sample 7 to be tested in contact with the standard part 6, and fix them on the sample stage using the insulating clamp 5. The entire sample stage is fixedly installed in the vacuum chamber 12.

[0086] II. The emission probe is mounted on a three-dimensional driver 13, which is fixed on a vacuum flange 14. The emission probe filament 1 is placed vertically and parallel to the surface of the standard part 6. The emission probe filament 1 is moved by the three-dimensional driver 13 to the vicinity of the surface of the standard part 6 or the sample 7 to be tested, with the distance between them not exceeding 1 mm.

[0087] III. Move the emission probe filament 1 to the vicinity of the surface of the standard part 6 through the three-dimensional driver 13, and the distance between the two is no more than 1 mm. Apply a fixed heating current to the emission probe filament 1 through the emission probe heating circuit 17 to obtain significant electron emission. At the same time, use the emission probe scanning bias circuit 18 to apply a set of sequentially changing scanning biases to the emission probe filament 1 to obtain the first emission probe volt-ampere characteristic curve in a vacuum environment, such as Figure 4 As shown in the curve a in the middle.

[0088] IV. Move the emission probe filament 1 to the vicinity of the surface of the sample 7 to be tested by the three-dimensional driver 13, with the distance between the two not exceeding 1 mm. Keep the heating current unchanged, repeat step III, and obtain the second emission probe volt-ampere characteristic curve in a vacuum environment, such as Figure 4 As shown in curve b.

[0089] V. Use the scanning voltage of the emission probe volt-ampere characteristic curve a to subtract the scanning voltage corresponding to the same electron current in curve b to obtain the voltage displacement difference ΔU between the two. The work function of the known standard 6 is Then, using the principle of metal contact potential difference (as shown in the following formula), the work function of the sample to be tested can be obtained:

[0090]

[0091] VI. Move the emission probe filament 1 to different positions on the surface of the sample 7 to be tested by the three-dimensional driver 13, keep the heating current unchanged, repeat step III, obtain the emission probe volt-ampere characteristic curves at different positions on the surface of the sample 7 to be tested, compare these emission probe volt-ampere characteristic curves with the emission probe volt-ampere characteristic curve a, repeat step V, and you can get the work function corresponding to different surface positions of the sample to be tested, that is, obtain the surface work function distribution of the sample to be tested.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0093] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A material work function measurement device based on emission probe technology, characterized in that: It includes an emission probe, a vacuum chamber and a sample support platform, wherein the emission probe is fixed inside the vacuum chamber through a three-dimensional driver, wherein the emission probe is fixed in the three-dimensional driver, and the three-dimensional driver is fixed on the vacuum chamber through a vacuum flange; Two electrodes are fixed on one side of the vacuum flange extending outside the vacuum chamber, and the electrodes are connected to the transmitting probe heating circuit outside the vacuum chamber; the transmitting probe heating circuit is connected to the transmitting probe through the two electrodes; The sample supporting platform is fixed inside the vacuum chamber; Two identical sampling resistors are arranged on the first branch of the transmitting probe heating circuit, and a voltmeter is connected in parallel at both ends of the branch; The two sampling resistors are connected to a transmitting probe scanning bias circuit; the transmitting probe scanning bias circuit is also connected to a ground electrode of the vacuum chamber; The sample stage is made of insulating material; The emission probe is located on one side of the sample supporting platform and is used to detect the sample to be tested placed on the sample supporting platform.

2. A material work function measurement device based on emission probe technology as claimed in claim 1, characterized in that: The emission probe is composed of a filament, an insulating bracket and a filament wire; The insulating bracket is composed of two single-hole capillary insulating tubes and one double-hole insulating tube, and the two single-hole capillary insulating tubes are inserted into the two holes of the double-hole insulating tube and fixed; A filament lead wire is extended out of each of the two single-hole capillary insulating tubes and connected to the filament, and the filament is fixed at the tube openings on the same side of the two single-hole capillary insulating tubes.

3. A material work function measurement device based on emission probe technology as claimed in claim 2, characterized in that: The two filament wires extend from one end of the single-hole capillary insulating tube away from the filament and are connected to two electrodes on the vacuum flange.

4. A material work function measurement device based on emission probe technology as claimed in claim 1, characterized in that: The sample support platform comprises a sample table, a sample table bracket and a base, and the sample table is fixed on the base through the sample table bracket; The sample table is provided with a plurality of grooves for placing insulating clamps.

5. A material work function measurement device based on emission probe technology as claimed in claim 4, characterized in that: Two screw holes are symmetrically arranged on the base, and the sample support table is fixed to the bottom of the vacuum chamber by two fixing screws.

6. A material work function measurement method based on emission probe technology using the device of claim 1, characterized in that: include: Step S1: The sample to be tested is brought into contact with the standard part, and fixed on the sample table with an insulating clamp, and the sample support table on which the sample to be tested and the standard part are placed is fixed on the bottom of the vacuum chamber; Step S2: installing the emission probe on the three-dimensional driver, the three-dimensional driver is fixed on the vacuum chamber through a vacuum flange, and the emission probe filament is placed vertically and parallel to the surface of the standard part; Step S3: Move the emission probe by a three-dimensional driver so that the filament of the emission probe moves to the vicinity of the surface of the standard part, with the distance between the two not exceeding 1 mm, apply a fixed heating current to the filament of the emission probe by the emission probe heating circuit, and apply a set of sequentially changing scanning biases to the filament of the emission probe by the emission probe scanning bias circuit, and obtain the emission probe volt-ampere characteristic curve collected near the standard part; Step S4: moving the emission probe by a three-dimensional driver so that the filament of the emission probe moves to different positions on the surface of the sample to be tested, keeping the heating current unchanged, and applying a set of scanning bias voltages identical to step S3 to the filament of the emission probe by a scanning bias circuit of the emission probe, obtaining the emission probe volt-ampere characteristic curves at different positions on the surface of the sample to be tested, comparing the emission probe volt-ampere characteristic curves collected at different positions on the surface of the sample to be tested with the emission probe volt-ampere characteristic curves collected near the standard part, obtaining the work functions corresponding to different surface positions of the sample to be tested, that is, obtaining the surface work function distribution of the sample to be tested; The volt-ampere characteristic curve of the emission probe at different positions on the surface of the sample to be tested is compared with the volt-ampere characteristic curve of the emission probe collected near the standard part to obtain the corresponding work function at different positions on the surface of the sample to be tested, specifically: The scanning voltage of the emission probe volt-ampere characteristic curve collected near the standard part is subtracted from the scanning voltage corresponding to the same electron current in the emission probe volt-ampere characteristic curve at the first position on the surface of the sample to be tested, to obtain the voltage displacement difference between the two; According to the known work function of the standard part, the work function of the sample to be tested at the first position is obtained by using the principle of contact potential difference between metals; The sample stage is made of insulating material.

7. A material work function measurement method based on emission probe technology as claimed in claim 6, characterized in that: The detection process of step S4 is specifically as follows: The emitting probe is moved by a three-dimensional driver so that the filament of the emitting probe is moved to the vicinity of the first position of the sample to be tested, with a spacing of no more than 1 mm, and the heating current is kept unchanged. At the same time, a set of scanning bias voltages identical to step S3 is applied to the filament of the emitting probe by a scanning bias circuit of the emitting probe to obtain a volt-ampere characteristic curve of the emitting probe at the first position of the sample; The emission probe is moved by a three-dimensional driver so that the filament of the emission probe moves to different positions near the sample to be tested, and the above process is repeated to obtain the emission probe volt-ampere characteristic curve at different positions on the surface of the sample to be tested.

Images