Scanning probe measuring device for imaging needle point by needle point and control method

Abstract

The invention relates to the technical field of scanning tunneling microscopes, and discloses a scanning probe measuring device and a control method for pinpoint-to-pinpoint imaging, two pinpoints are oppositely arranged, and the pinpoints are accurately controlled and movably positioned based on a basic working mode of a scanning probe microscope. A needle tip-tunnel junction-needle tip working structure is established, after bias voltage is applied externally, electron tunneling between needle tips only relates to a small number of atoms or single atoms at the tail ends of the needle tips, the tunneling effect that the small number of atoms contribute to electrons is achieved, and therefore small number or single atom imaging is achieved. The device can be rapidly transplanted to application scenes of low temperature, strong magnetic field, optical measurement and the like, the double-needle-point structure is regulated and controlled through piezoelectric displacement or an electric field, tunnel junction width and barrier height can be optimized in real time, and research on dynamic construction and dynamic electrical characteristics of nanoscale tunnel junctions is greatly facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of scanning tunneling microscopes, and in particular to a scanning probe measuring device for tip-to-tip imaging and a control method thereof. Background Art

[0002] Since its invention by Binnig and Rohrer in 1981, the scanning tunneling microscope (STM) has revolutionized research in surface science, materials physics, and nanotechnology with its atomic-scale spatial resolution. Its core principle is based on the tunneling effect in quantum mechanics: when the distance between a metal tip and a conductive sample is reduced to the nanometer scale, electrons can tunnel through an energy barrier driven by an applied bias, forming a tunneling current. Using a piezoelectric ceramic-driven three-dimensional nanopositioning system, the tip can scan along the sample surface with atomic-level precision. Real-time feedback of tunneling current changes is processed by algorithms to reconstruct the surface topography and localized density of states (LDOS) distribution (Binnig et al., Physical Review Letters, 1982). However, this classical technical framework has inherent limitations in both physical mechanisms and engineering implementation, severely restricting its ultimate resolution.

[0003] The core contradiction of conventional scanning tunneling microscopy (STM) stems from the mismatch between the nanoscale tip and the macroscopic sample surface. Despite the meticulous machining of the tip's end (a radius of curvature of approximately 5-50 nanometers, equivalent to a microscopic bump composed of dozens of atoms), its detection range covers areas of the sample surface far beyond the atomic scale (typically on the order of square micrometers). This "nanoprobe-macroscopic field of view" physics results in the simultaneous tunneling of dozens of sample atoms within approximately 1-3 nanometers below the tip as it approaches the sample (Chen, CJ, Introduction to Scanning Tunneling Microscopy, 1993).

[0004] Specifically, even though the tip is a signal collector with a single atom at its end, it still forms parallel electron channels with multiple atoms in the corresponding area of the sample surface below it. For example, when imaging a metal surface, the tip may simultaneously cover multiple adjacent atoms on the sample surface. The electron clouds of these atoms jointly emit tunneling electrons toward the tip, resulting in the measured signal being essentially the overall average of the contributions of multiple atoms (Tersoff et al., Phys. Rev. Lett, 1985). More seriously, due to the periodic arrangement of atoms on the sample surface, the tip will periodically trigger the coordinated response of different atomic groups during scanning, resulting in the appearance of "superlattice fringes" in the image that do not exist (Hofer et al., Science, 2003). This signal aliasing caused by the nonlocality of the detection area has become a core obstacle that limits STM from achieving true single-atom resolution.

[0005] Existing attempts generally focus on tip preparation and system architecture. Regarding tip optimization, field ion microscopy (FIM) technology can produce an ideal tip containing only a single atom at its tip through the principle of field evaporation (Nakamura et al., Ultramicroscopy, 2012). However, such tips are easily damaged in practice due to mechanical vibration, thermal drift, or accidental contact. Relying on an ultrahigh vacuum interconnect system, single-atom imaging is only an improvement, as it still relies on the traditional tip-sample configuration and cannot avoid polyatomic interactions between the tip atoms and the sample region. Regarding system architecture modification, the STM-BJ method uses mechanical impact between the tip and the sample to establish contact, lifting the tip to form a metallic atomic wire, which forms a conductive channel between the tip and the sample. This allows for direct measurement of quantum conductivity properties at the single-atom scale, but does not reflect the real-space atomic positions and is currently unsuitable for imaging applications. Summary of the Invention

[0006] To address the aforementioned technical issues, the present invention provides a scanning probe measurement device and control method for tip-to-tip imaging. This device proposes a tip-tunnel junction-tip structure that achieves precise tunnel junction construction and high repeatability through dynamic dual-tip spacing feedback control and atomic-level precision regulation. Technically, this design combines high controllability, high-efficiency construction, and universal scalability, with simple preparation and control methods and a wide range of tip material options. This detection method and experimental platform for single-atom imaging will facilitate the study of single-atom interactions, the exploration of physical properties under extreme conditions, and the investigation of quantum transport phenomena.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a scanning probe measurement device for tip-to-tip imaging, comprising: a frame, a coarse approximation motor, an XYZ three-dimensional scanner, and a first probe;

[0009] The coarse approximation motor is fixed to the frame, one end of the XYZ three-dimensional scanner is fixed to the free end of the coarse approximation motor and is coaxial with the driving direction of the coarse approximation motor, and the first probe is fixed to the free end of the XYZ scanner, forming a structure in which the coarse approximation motor pushes the first probe forward;

[0010] It is characterized in that it also includes a second probe; the second probe is fixed on the other end of the frame away from the coarse approximation motor, and the tip of the second probe can be aligned with the tip of the first probe.

[0011] In one embodiment, the XYZ three-dimensional scanner is integrated with the coarse approximation motor to form a driving and scanning unit, which is installed on the frame and can drive the first probe to move in a spatial range and perform scanning actions in a plane, so that the distance between the tip of the second probe and the tip of the first probe is small enough to allow the tunneling effect to occur. By applying a bias voltage, a tip-tunnel junction-tip structure is formed, and the geometric parameters and barrier characteristics of the tunnel junction can be controlled in real time, and the dynamic stability of the tunneling effect can be maintained through feedback control.

[0012] In one embodiment, the first probe, the second probe and the driving direction of the coarse approximation motor are coaxially arranged; when the frame is a tubular frame, the tubular frame, the first probe, the second probe and the driving direction of the coarse approximation motor are all coaxially arranged.

[0013] In one embodiment, the invention further comprises a second probe holder and a clamping spring sheet; a slot and an opening are provided in the frame; the second probe holder is placed in the slot; the clamping spring sheet is placed between the second probe holder and the slot wall for clamping the second probe holder; the non-needle tip of the second probe is fixedly connected to the second probe holder and extends out of the slot through the opening.

[0014] In one embodiment, an electrode interface is further included, which is used for signal input and signal readout, transmits the driving signal of the external controller to the driving and scanning unit, transmits the bias voltage to the needle tip-tunnel junction-needle tip structure, and transmits the corresponding tunneling current to the acquisition device.

[0015] In one embodiment, the material of the frame is one or more of titanium, tantalum, sapphire, and zirconium oxide; the material of the second probe and the first probe is one or more of tungsten, gold, silver, platinum-iridium alloy, or one or more of silicon, germanium, and gallium arsenide, or a material modified with a CO single molecule, or a nanoscale film grown on any needle-tip-shaped substrate; the tips of the second probe and the first probe can be modified with carbon nanotubes, or carbon nanotubes can be used directly as needle tips.

[0016] In a second aspect, the present invention provides a method for controlling a scanning probe measurement device for tip-to-tip imaging, specifically comprising:

[0017] Under an optical microscope, the second probe holder is moved so that the second probe and the first probe overlap in the vertical direction, and the distance between the needle tips of the two probes is controlled within a set value; a driving signal is output to the driving and scanning unit through the electrode interface, so that the first probe moves along the axis direction of the second frame and is close to the second probe in the longitudinal direction. An optical microscope is used for observation, and the position of the needle tip of the first probe in the plane is adjusted by the driving signal. The distance between the needle tips of the two probes is close, and a scanning signal is output to make the first probe perform a scanning action. If no tunneling current signal is obtained, the driving signal causes the first probe to move forward axially or adjust its position in the plane. If a tunneling current signal is obtained, the tunnel junction construction process stops.

[0018] In one embodiment, the drive signal output is dynamically adjusted to control the tip deflection of the first probe, or the spacing and relative configuration between the tips of the two probes are adjusted to maintain the second probe and the first probe within a distance where the tunneling effect can always occur.

[0019] In one embodiment, the process of obtaining a tunneling current-distance tunnel spectrum is further included, which specifically includes: opening a tunnel junction feedback loop, adjusting the distance between the tips of the second probe and the first probe and stabilizing it at a desired size by setting a bias voltage and a target tunneling current; closing the feedback loop, and linearly changing the distance between the tips of the two probes by controlling a driving and scanning unit under a determined bias voltage, while detecting changes in the tunneling current, so as to obtain a tunneling current-distance tunnel spectrum in which the tunneling current changes with the distance between the tips of the two probes after the tips of the two probes are aligned.

[0020] In one embodiment, the process of obtaining a tunneling current-bias voltage tunnel spectrum is also included, which specifically includes: opening the tunnel junction feedback loop, adjusting the distance between the tips of the second probe and the first probe to stabilize at the set position by setting the initial tunneling current and the initial bias voltage; closing the tunnel junction feedback loop, and under the determined distance between the tips of the second probe and the first probe, an external controller changes the bias voltage of the tunnel junction while detecting the change in tunneling current to obtain a tunneling current-bias voltage tunnel spectrum after the tips of the two probes are aligned.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are:

[0022] (1) The second probe holder is fixed with a clamping spring sheet to provide a long-range elastic force. It can work safely in room temperature and low temperature environments. At the same time, the needle tip position can be pre-adjusted, which is convenient to operate.

[0023] (2) The frame structure is reasonably designed. While maintaining high rigidity, the overall size is small. It can work in a narrow low-temperature and strong magnetic field space. It can also be transplanted to any optical table. It is easy to reserve a function expansion interface and can be placed in a micro-nano processing cavity.

[0024] (3) A scanning probe measurement device for tip-to-tip imaging of the present invention: Based on the working principle of the quantum tunneling effect, a driving and scanning unit is used to dynamically feedback and adjust the distance between the two tips, so as to quickly adjust the tip distance to an appropriate size without damaging the tips. The unit is constructed with atomic-level scanning accuracy and precise tunnel junction area. This process has the characteristics of high repeatability and high efficiency, and has little dependence on the environment.

[0025] (4) A scanning probe measuring device for tip-to-tip imaging of the present invention: The controller system is no different from a basic ordinary scanning tunneling microscope. It requires a preamplifier circuit connected to the tip to amplify the tunneling current into a voltage signal to be collected by the controller. At the software level, it only needs to monitor the tunneling current signal and instruct the drive and scanning units to respond in time. Existing commercial controller equipment can be directly used.

[0026] (5) The present invention is a scanning probe measurement device for tip-to-tip imaging: the overall structure is simple, and it can achieve the purpose of a few atoms participating in the contribution of tunneling electrons to obtain tunneling current, thereby realizing imaging of a few or single atoms. By changing the tip, tunnel junction spacing, and bias voltage, it can be applied to various studies and has guiding significance for people to deeply understand the underlying theory of nanoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A basic structural view of a scanning probe measurement device for tip-to-tip imaging according to the present invention;

[0028] Figure 2A and Figure 2B This is an external view of a scanning probe measurement device for tip-to-tip imaging in Example 1 of the present invention;

[0029] Figure 3A and Figure 3B This is an internal view of a scanning probe measurement device for tip-to-tip imaging in Example 1 of the present invention;

[0030] Figure 4 This is a flowchart of the working process of a scanning probe measurement device for tip-to-tip imaging in Example 1 of the present invention;

[0031] Figure 5 A simplified illustration of a scanning probe measurement device for tip-to-tip imaging according to Example 2 of the present invention;

[0032] Figure 6 This is an overall view of a scanning probe measurement device for tip-to-tip imaging in Example 3 of the present invention.

[0033] In the figure: 1. Frame; 2. Second probe holder; 3. Clamping spring sheet; 4. Second probe; 5. First probe; 6. Coarse approximation motor; 7. Electrode interface; 8. Drive and scanning unit; 9. XYZ three-dimensional scanner. DETAILED DESCRIPTION

[0034] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Any equivalent replacement of the technical features of the technical solution of the present invention and any solution derived by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0036] Example 1

[0037] The scanning probe measuring device for tip-to-tip imaging of the present invention has a basic structure diagram as shown in FIG. Figure 1 , including a frame 1, a coarse approximation motor 6, an XYZ three-dimensional scanner 9, a first probe 5 and a second probe 4, the coarse approximation motor is fixed on the frame, one end of the XYZ three-dimensional scanner is fixed to the free end of the coarse approximation motor and is coaxial with the driving direction of the coarse approximation motor, the first probe is fixed to the free end of the XYZ scanner, forming a structure in which the coarse approximation motor pushes the first probe forward, the XYZ three-dimensional scanner and the coarse approximation motor can be integrated to form a driving and scanning unit, which is installed on the frame, and the second probe is installed on the frame in a horizontally movable manner.

[0038] The scanning probe measuring device for tip-to-tip imaging of the present invention has an external view including an isometric view and a top view, see Figure 2A and Figure 2B ; Its internal view includes a side sectional view and an internal display view without the frame structure, see Figure 3A and Figure 3B The device includes a frame 1, a second probe holder 2, a clamping spring 3, a second probe 4, a first probe 5, an electrode interface 7, a drive and scanning unit 8, and should also include a controller drive module, a controller signal acquisition module, a preamplifier, a host computer, etc. The main innovation of the present invention lies in the device for efficiently constructing a tunnel junction to achieve single-electron tunneling. Therefore, the controller drive module, controller signal acquisition module, preamplifier, host computer, etc. are not drawn in the drawings of the specification.

[0039] The clamping spring sheet 3 is pre-fixed on the frame 1 and has a certain elasticity. Its elastic force is used to clamp the second probe frame 2. The clamping spring sheet 3 can be replaced to adjust the elastic force. The driving and scanning unit 8 is fixed on the frame 1. Its driving motor can carry objects to move over a large range in space, and can also perform scanning actions within a plane. The driving and scanning unit 8 allows for free replacement.

[0040] The needle tips of the second probe 4 and the first probe 5 are free ends, and the non-needle tip is a fixed end. The needle tips of the second probe 4 and the first probe 5 are arranged opposite to each other and are relatively close to each other. The two fixed ends of the needle tips are arranged back to back and are relatively far apart. The second probe 4 is connected to the second probe frame 2 through the fixed end, and the fixed end of the first probe 5 is connected to the driving and scanning unit 8.

[0041] The second probe holder 2 is compressed by elastic force, but the position of the second probe holder 2 relative to the frame 1 can still be adjusted to pre-adjust the positional relationship of the second probe 4 relative to the first probe 5. The electrode interface 7 is used for signal access and signal readout, transmitting the drive signal of the external controller to the drive and scanning unit 8, transmitting the bias voltage to the needle tip-tunnel junction-needle tip structure, and transmitting the current signal of the needle tip-tunnel junction-needle tip structure to the acquisition device. The first probe 5 is accurately positioned and the displacement of the first probe 5 is controlled by the drive and scanning unit 8, so that the distance between the needle tip of the second probe 4 and the needle tip of the first probe 5 is small enough to allow the tunneling effect to occur, forming a needle tip-tunnel junction-needle tip structure.

[0042] The frame 1 , the second probe 4 , the first probe 5 , the driving and scanning unit 8 , and the electrode interface 7 are all coaxially arranged.

[0043] In an optional embodiment, the frame 1 and the frame 1 are made of materials with good thermal conductivity, vacuum compatibility and immunity to magnetic fields, such as titanium, tantalum, sapphire, zirconium oxide, etc., the clamping spring sheet 3 is made of phosphor copper, beryllium copper and other materials, and the electrode interface 7 is made of sapphire, zirconium oxide and other materials with excellent insulation properties and extremely small leakage current.

[0044] In an optional embodiment, the second probe 4 and the first probe 5 can be made of metals such as tungsten, gold, silver, platinum-iridium alloy, or semiconductor materials such as silicon, germanium, gallium arsenide, or needle tips modified with single molecules such as CO, or nanoscale films grown on any needle tip-shaped substrate.

[0045] In an optional embodiment, the tips of the second probe and the first probe may be modified with carbon nanotubes, or carbon nanotubes may be directly used as needle tips.

[0046] In an optional embodiment, the driving and scanning unit 8 can be a multi-zone driven inertial piezoelectric motor device, whose application publication number is CN103986365A, or a dual piezoelectric linear nanopositioning piezoelectric driver, whose application publication number is CN1996737A, or a scanning needle tip microscope body whose coarse approximation motor can be detached from the scanning structure, whose application publication number is CN102866265A. The driving and scanning unit 8 can be capable of pushing the moving part forward and backward along the axial direction of the frame 1 to realize the forward and backward movement of the first probe 5 in the axial direction. The driving and scanning unit 8 can drive the first probe 5 to scan in a plane perpendicular to the axis of the second frame with a resolution of atomic precision.

[0047] In an optional embodiment, the driving and scanning unit 8 can be a multidimensional piezoelectric motor with a single piezoelectric device, whose application publication number is CN119298715A, or an X-electrode split cross multidimensional piezoelectric motor, whose application publication number is CN112290826A. The driving and scanning unit 8 can be capable of realizing the forward and backward movement of the first probe 5 along the axial direction, and can also realize the precise displacement of the first probe 5 in a plane perpendicular to the axial direction. The driving and scanning unit 8 can drive the first probe 5 to scan in a plane perpendicular to the axis of the second frame, with a resolution of atomic precision.

[0048] The workflow of efficiently constructing a tunnel junction in this embodiment is as follows: Figure 4As shown, specifically, its workflow can be, in advance, under an optical microscope, find the second probe 4 and the first probe 5, and move the second probe frame 2 so that the second probe 4 and the first probe 5 basically overlap in the vertical direction. At this time, the distance between the two needle tips in the plane should be less than 10 microns. Subsequently, the controller outputs a drive signal to the drive and scanning unit 8 through the electrode interface 7, so that the first probe 5 moves in the direction of the second frame axis and is close to the longitudinal distance of the second probe 4. Using an optical microscope for observation, the position of the needle tip of the first probe 5 in the plane can be adjusted by the drive signal. The distance between the two needle tips is close, and a scanning signal is output to make the first probe 5 perform a scanning action. If a tunneling current signal is not obtained, the drive signal causes the first probe 5 to move forward, or adjust the position in the plane accordingly. If a tunneling current signal is obtained, the process of constructing the tunnel junction stops.

[0049] In an optional embodiment, the method for maintaining the tip-tunnel junction-tip working structure can be to dynamically adjust the drive signal output through a feedback process set by software, control the tip deflection of the first probe 5, maintain the second probe 4 and the first probe 5 always within the distance where the tunneling effect can occur, and also adjust the spacing between the tips and the relative configuration between the tips.

[0050] Since the tunnel junction scale is much smaller than the mean free path of electron motion, vacuum experimental conditions are not necessarily required. The working environment can be room temperature, atmospheric conditions, low temperature, or a strong magnetic field environment.

[0051] This embodiment also provides an experimental setup applicable to the above-mentioned efficient tip-to-tip imaging scanning probe measurement device:

[0052] Maintaining the distance between the needle tips and the relative configuration between the needle tips, outputting a scanning signal, the first probe scans in a conventional constant current mode or constant height mode of a scanning tunneling microscope, recording the tunneling current signal and corresponding it to the scanning signal to obtain a single-atom scanning imaging pattern.

[0053] The tunnel junction feedback loop is opened, and the distance between the second probe 4 and the first probe 5 is temporarily stabilized at the desired value by setting the bias voltage and the target tunneling current. The feedback loop is then closed, and the distance between the two probe tips is linearly changed by controlling the drive and scanning unit 8 at a predetermined bias voltage. The changes in tunneling current are simultaneously detected to obtain a tunneling current-distance tunneling spectrum, showing the tunneling current as the distance between the two probe tips changes after the two probe tips are aligned.

[0054] The feedback loop is closed, and by setting the initial tunneling current and initial bias voltage, the spacing between the two probe tips is adjusted to stabilize at a certain position. The feedback loop is then closed, and at the determined spacing between the tips of the second probe 4 and the first probe 5, an external controller changes the bias voltage applied to the tunnel junction while simultaneously detecting changes in the tunneling current to obtain a tunneling current-bias voltage spectrum after the two probe tips are aligned.

[0055] Under low-temperature conditions, the second probe 4 and the first probe 5 were made of different materials, and the tips were processed using micro-nanofabrication techniques, including single-molecule tip modification, to finely adjust the height, shape, and width of the tunneling barrier, achieving controllable regulation of quantum transport. The experiments were repeated under a magnetic field to analyze the electronic coherence of the quantum transport process.

[0056] Example 2

[0057] The difference between this embodiment and embodiment 1 is that the alignment of the second probe 4 and the first probe 5 is no longer specifically achieved by the driving and scanning unit 8, but can be achieved by the needle tip manufacturing process. Figure 5 , which gives a simplified view of the target structure.

[0058] In an alternative embodiment, a complete metal wire, such as a tungsten wire, can be placed vertically in a sodium hydroxide solution and subjected to AC electrochemical etching until a neck, visible under an optical microscope, is formed at the interface between the solution and the wire, i.e., a sudden decrease in the wire diameter. Focused ion beam machining is then used to further reduce the wire diameter. The machining process can be stopped when an electron microscope image clearly shows a nanometer-scale fracture, or when the electron microscope image still shows a connection with minimum machining accuracy.

[0059] In an optional embodiment, the tip of a silicon cantilever is brought close to the surface of a metal substrate to form a jump-to-contact contact, and then slowly retracted to stretch out a nanowire or atomic chain structure, and apply a local electric field to drive atomic migration to form a smooth tunneling interface.

[0060] Example 3

[0061] like Figure 6 As shown, the difference between this embodiment and embodiment 1 is that, in this embodiment, the second probe 4 and the first probe 5 are not required to be placed in the axial direction, nor are they required to be placed coaxially. The distance between the tips of the second probe 4 and the first probe 5 is kept within the distance required by the quantum tunneling effect, and their relative configurations can be freely changed. Figure 6 An alternative implementation is given.

[0062] In this embodiment, the driving and scanning unit 8 is connected to the external frame, the second probe 4 is connected to the driving and scanning unit 8 or directly connected to the external frame, and the first probe 5 is connected to the driving and scanning unit 8. The working process will not be repeated here.

[0063] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

[0064] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0065] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A scanning probe measurement device for tip-to-tip imaging, comprising: Frame, coarse approximation motor, XYZ 3D scanner and first probe; The coarse approximation motor is fixed to the frame, one end of the XYZ three-dimensional scanner is fixed to the free end of the coarse approximation motor and is coaxial with the driving direction of the coarse approximation motor, and the first probe is fixed to the free end of the XYZ scanner, forming a structure in which the coarse approximation motor pushes the first probe forward; It is characterized in that it also includes a second probe; the second probe is fixed on the other end of the frame away from the coarse approximation motor, and the tip of the second probe can be aligned with the tip of the first probe.

2. The scanning probe measurement device for tip-to-tip imaging according to claim 1, characterized in that: The XYZ three-dimensional scanner is integrated with the coarse approximation motor to form a driving and scanning unit, which is installed on the frame and can drive the first probe to move in a spatial range and perform scanning actions within a plane, so that the distance between the tip of the second probe and the tip of the first probe is small enough to allow the tunneling effect to occur. By applying a bias voltage, a tip-tunnel junction-tip structure is formed, and the geometric parameters and barrier characteristics of the tunnel junction can be controlled in real time, and the dynamic stability of the tunneling effect can be maintained through feedback control.

3. The scanning probe measurement device for tip-to-tip imaging according to claim 1, characterized in that: The first probe, the second probe and the driving direction of the coarse approximation motor are coaxially arranged; when the frame is a tubular frame, the tubular frame, the first probe, the second probe and the driving direction of the coarse approximation motor are all coaxially arranged.

4. The scanning probe measurement device for tip-to-tip imaging according to claim 1, characterized in that: It also includes a second probe holder and a clamping spring piece; a card slot and an opening are provided in the frame; the second probe holder is placed in the card slot; the clamping spring piece is placed between the second probe holder and the card slot wall and is used to clamp the second probe holder; the non-needle tip of the second probe is fixedly connected to the second probe holder and extends out of the card slot through the opening.

5. The scanning probe measurement device for tip-to-tip imaging according to claim 1, characterized in that: It also includes an electrode interface, which is used for signal input and signal readout, transmits the driving signal of the external controller to the driving and scanning unit, transmits the bias voltage to the needle tip-tunnel junction-needle tip structure, and transmits the corresponding tunneling current to the acquisition device.

6. The scanning probe measurement device for tip-to-tip imaging according to claim 1, characterized in that: The material of the frame is one or more of titanium, tantalum, sapphire, and zirconium oxide; the material of the second probe and the first probe is one or more of tungsten, gold, silver, platinum-iridium alloy, or one or more of silicon, germanium, and gallium arsenide, or a material modified with a CO single molecule, or a nanoscale film grown on any needle-tip-shaped substrate, and the tips of the second probe and the first probe are modified with carbon nanotubes, or carbon nanotubes are directly used as needle tips.

7. A method for controlling a scanning probe measurement device for tip-to-tip imaging according to any one of claims 1 to 6, comprising: Under an optical microscope, the second probe holder is moved so that the second probe and the first probe overlap in the vertical direction, and the distance between the needle tips of the two probes is controlled within a set value; a driving signal is output to the driving and scanning unit through the electrode interface, so that the first probe moves along the axis direction of the second frame and is close to the second probe in the longitudinal direction. An optical microscope is used for observation, and the position of the needle tip of the first probe in the plane is adjusted by the driving signal. The distance between the needle tips of the two probes is close, and a scanning signal is output to make the first probe perform a scanning action. If no tunneling current signal is obtained, the driving signal causes the first probe to move forward axially or adjust its position in the plane. If a tunneling current signal is obtained, the tunnel junction construction process stops.

8. The control method of the scanning probe measurement device for tip-to-tip imaging according to claim 7, characterized in that: By dynamically adjusting the output of the driving signal, the tip deflection of the first probe is controlled, or the spacing and relative configuration between the tips of the two probes are adjusted, the second probe and the first probe are always maintained within the distance where the tunneling effect can occur.

9. The control method of the scanning probe measurement device for tip-to-tip imaging according to claim 7, characterized in that: It also includes a process for obtaining a tunneling current-distance tunnel spectrum, specifically including: opening the tunnel junction feedback loop, adjusting the distance between the tips of the second probe and the first probe and stabilizing it at a desired size by setting the bias voltage and the target tunneling current; closing the feedback loop, and under a determined bias voltage, linearly changing the distance between the tips of the two probes by controlling the drive and scanning unit, while detecting changes in the tunneling current, to obtain a tunneling current-distance tunnel spectrum in which the tunneling current changes with the distance between the tips of the two probes after the tips of the two probes are aligned.

10. The control method of the scanning probe measurement device for tip-to-tip imaging according to claim 7, characterized in that: It also includes a process for obtaining a tunneling current-bias voltage tunnel spectrum, specifically including: opening the tunnel junction feedback loop, adjusting the distance between the tips of the second probe and the first probe to stabilize at the set position by setting the size of the initial tunneling current and the initial bias voltage; closing the tunnel junction feedback loop, and under the determined distance between the tips of the second probe and the first probe, an external controller changes the bias voltage of the tunnel junction while detecting changes in the tunneling current to obtain a tunneling current-bias voltage tunnel spectrum after the tips of the two probes are aligned.

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