Ultrahigh vacuum surface defect detection method and system based on scanning tunneling microscope

Abstract

The invention belongs to the technical field of semiconductor material surface engineering and defect analysis, and provides an ultrahigh vacuum surface defect detection method and system based on a scanning tunneling microscope, and the method comprises the following steps: carrying out mechanical stripping on a bulk single crystal gallium oxide sample based on the cleavage property of a crystal, and obtaining a gallium oxide single crystal wafer with a micron thickness; placing the stripped single crystal gallium oxide sample in an ultrahigh vacuum environment, and removing atmospheric adsorbates on the surface through vacuum high-temperature annealing treatment; performing sputtering annealing cycle treatment on the surface of the preliminary annealing sample in an ultrahigh vacuum environment to generate an oxygen vacancy defect on the surface so as to obtain a post-treatment sample; the oxygen vacancy concentration, the surface cleanliness and the surface atom orderliness are verified through auxiliary characterization means (XPS, LEED); performing scanning imaging on the surface of the post-treatment sample through a scanning tunneling microscope (STM), and performing oxygen vacancy defect identification by combining with an oxygen vacancy defect STM image simulated by DFT calculation; according to the method, the atomic-scale resolution of the surface of the single crystal gallium oxide sample is detected through the scanning tunneling microscope, the oxygen vacancy defect and other various surface defects are accurately recognized, and the surface state of the sample is comprehensively evaluated.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material surface engineering and defect analysis, and specifically relates to a method and system for ultra-high vacuum surface defect detection based on a scanning tunneling microscope. Background Art

[0002] In the field of semiconductor materials, single-crystalline gallium oxide has become an ideal material for fabricating high-performance power devices, deep ultraviolet detectors, etc. due to its excellent properties such as a wide bandgap, high breakdown electric field, and high thermal conductivity. However, in terms of surface chemistry, oxygen vacancies, as active sites, directly affect surface adsorption and catalytic properties, which is crucial for the development of high-performance gas sensors. In terms of device applications, the concentration and distribution of oxygen vacancies will significantly affect the interface state density and Schottky barrier characteristics of power devices, which are related to the threshold stability of MOS devices and the response performance of ultraviolet detectors.

[0003] In terms of defect detection accuracy, early optical microscopes could only observe defects at the micron level due to resolution limitations, and could not meet the atomic-scale detection requirements for oxygen vacancy defects and other microscopic defects. An atomic force microscope (AFM) generates images by detecting the interaction force between the tip and the sample atoms and does not depend on the conductivity of the sample. However, the resolution of AFM is usually lower than that of STM. The ultra-wide bandgap of gallium oxide gives it low conductivity, and the high-resistance surface makes it difficult to generate and maintain a tunneling current, resulting in difficult STM needle insertion and image distortion, making it difficult to accurately identify tiny defects such as oxygen vacancies and impossible to precisely control the defect density.

[0004] In the surface treatment process, conventional surface cleaning methods such as simple chemical cleaning are difficult to completely remove surface-segregated impurities and deep-seated adsorbed pollutants. Some high-temperature annealing treatments, due to the lack of precise control of parameters such as temperature and vacuum degree, not only cannot stably generate oxygen vacancy defects with a specific density, but may also cause surface atomic structure disorder due to over-annealing and cannot provide an ideal surface state for subsequent detection. In argon ion sputtering treatment, if the parameters are set unreasonably, it is easy to cause excessive damage to the sample surface, affect surface atomic reconstruction, and thus cannot effectively improve surface cleanliness and structural stability.

[0005] Therefore, those skilled in the art have proposed a method and system for ultra-high vacuum surface defect detection based on a scanning tunneling microscope, aiming to achieve the purposes of effectively purifying the surface, precisely controlling defect generation, atomic-level resolution detection, and mutual verification by multiple means, providing a research means with atomic-level accuracy for surface property characterization and defect precise identification of wide-bandgap semiconductors, and solving the technical problem that the scanning tunneling microscope cannot characterize wide-bandgap semiconductors at present. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a method and system for detecting surface defects in ultra-high vacuum based on a scanning tunneling microscope to solve the problems raised in the background art.

[0007] According to the first aspect of the present disclosure, a method for detecting surface defects in ultra-high vacuum based on a scanning tunneling microscope is proposed, including the following steps:

[0008] S1. Mechanically exfoliate a single-crystal gallium oxide sample based on the maximum cleavage plane to obtain a pretreated single-crystal gallium oxide sample;

[0009] S2. After ultrasonic cleaning the pretreated sample, place it in an environment with a vacuum degree of 1×10 -9 mbar and heat it at 700 °C for 40 minutes to remove surface atmospheric adsorbents and obtain a preliminary annealed sample;

[0010] S3. In the above ultra-high vacuum environment, perform argon ion sputtering treatment on the surface of the preliminary annealed sample to remove segregation impurities, and perform vacuum high-temperature annealing treatment at 750 °C - 850 °C. The sputtering annealing cycle is carried out to generate oxygen vacancy defects on the sample surface and obtain a post-treated sample;

[0011] S4. Verify the surface oxygen vacancy concentration, surface cleanliness, and surface atomic order through auxiliary characterization means;

[0012] S5. Scan and image the surface of the post-treated sample through a scanning tunneling microscope, use DFT calculation to obtain an oxygen vacancy STM simulation image, and qualitatively analyze oxygen vacancy defects and surface defects in combination with the STM image.

[0013] Preferably, the mechanical exfoliation and ultrasonic cleaning of the single-crystal gallium oxide sample to obtain a single-crystal gallium oxide sample with a micron thickness include:

[0014] Separate a single-crystal wafer with a micron thickness along the maximum cleavage plane of the single-crystal gallium oxide using a blade;

[0015] Ultrasonically clean the single-crystal gallium oxide sample with acetone and ethanol for 15 minutes each in sequence, rinse it with deionized water, and dry it with nitrogen;

[0016] Under a vacuum degree of 1×10 -9 mbar, heat it at 700 °C for 40 minutes to remove surface atmospheric adsorbents.

[0017] Preferably, the ultra-high vacuum environment includes:

[0018] A vacuum chamber equipped with a mechanical pump, a molecular pump, an ion pump, and a titanium sublimation pump, with a real-time monitoring accuracy of the vacuum degree of 10 - 10 mbar;

[0019] An argon ion sputtering device with adjustable acceleration voltage, equipped with an argon gas source with a purity ≥ 99.9999%.

[0020] Preferably, in the ultra-high vacuum environment, the surface of the preliminary annealed sample is subjected to argon ion sputtering treatment to remove segregation impurities, and through vacuum high-temperature annealing treatment at 750 °C - 850 °C, oxygen vacancy defects are generated on the sample surface, including:

[0021] The parameters of the argon ion sputtering treatment are as follows: Argon gas is introduced to maintain the vacuum degree at 1×10 -6 mbar - 5×10 - 5 mbar; the ion beam energy is 1 KeV - 3 KeV, and the sputtering time is 10 - 20 minutes;

[0022] The parameters of the high-temperature annealing are: annealing at a temperature of 750 °C - 850 °C for 30 - 60 minutes to form a sputtering annealing cycle treatment to obtain a post-treatment sample, and the heating rate is controlled at 50 °C / min - 70 °C / min. During the heat preservation period, the vacuum degree is maintained at 5×10 - 9 mbar - 1×10 -8 mbar.

[0023] Preferably, the combined auxiliary characterization means is used to monitor the surface oxygen vacancy defect concentration and surface cleanliness, including:

[0024] The auxiliary characterization means includes: X-ray photoelectron spectroscopy to detect the O1s characteristic peak of gallium oxide and the split peak caused by oxygen vacancies, and analyze the peak area to determine the surface oxygen vacancy defect concentration; low-energy electron diffraction pattern to characterize the surface atomic order;

[0025] The surface oxygen vacancy defect concentration > 1.4% to meet the STM needle insertion requirements;

[0026] Preferably, the surface of the post-treatment sample is scanned and imaged by a scanning tunneling microscope to obtain an STM image, and the oxygen vacancy defects are detected through the STM image, including:

[0027] The detection parameters of the scanning tunneling microscope are as follows: The probe uses tungsten metal; in the constant current mode, the bias voltage range is -10 V to +10 V, and the tunneling current is 0.001 - 10 nA or 0.001 - 50 nA;

[0028] The identification of the oxygen vacancy defects is to calculate and simulate the STM image of the oxygen vacancy defects through density functional theory, and analyze and identify the oxygen vacancy defects in combination with the experimental STM image;

[0029] According to the second aspect of the present disclosure, a scanning tunneling microscope-based ultra-high vacuum surface defect detection system is proposed, including:

[0030] A sample pretreatment unit for mechanically peeling, physically cleaning, and preliminarily removing impurities from a single-crystal gallium oxide sample;

[0031] A sputtering annealing cycle treatment unit for removing surface impurities and promoting atomic reconstruction through cyclic treatment of argon ion sputtering and high-temperature annealing, making the surface defect characteristics of the sample obvious; inducing oxygen vacancy defects on the surface of single-crystal gallium oxide through high-temperature treatment in an ultra-high vacuum environment and optimizing the surface atomic structure;

[0032] An auxiliary characterization unit for monitoring the concentration of surface oxygen vacancy defects and surface cleanliness through XPS characterization, and characterizing the surface atomic order through LEED;

[0033] An STM imaging unit for imaging the surface of the single-crystal gallium oxide sample at the atomic scale resolution through a scanning tunneling microscope to obtain an STM image and observe the surface atomic structure and oxygen vacancy defects;

[0034] A defect analysis module that calculates and simulates the STM image of oxygen vacancy defects through DFT, performs noise reduction processing on the STM image, and extracts and identifies defect characteristics by combining the simulated and experimental STM images.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. Through the detection of the surface of the single-crystal gallium oxide sample at the atomic scale resolution, the present invention accurately identifies oxygen vacancy defects, and by precisely controlling the vacuum high-temperature annealing parameters, it can stably generate a specific concentration of surface oxygen vacancy defects, which is beneficial to studying the influence law of defects on the material properties.

[0037] 2. By combining argon ion sputtering and annealing cycle treatment, the present invention effectively removes surface impurities, realizes surface atomic rearrangement, improves surface cleanliness and structural stability, and creates good conditions for STM detection.

[0038] 3. By combining simulated STM images, experimental STM images, and XPS characterization means, the present invention mutually verifies the detection results, greatly improves the accuracy and reliability of the detection, and comprehensively evaluates the surface state of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0040] Figure 1Flow chart of the ultra-high vacuum surface defect detection method of the present invention;

[0041] Figure 2 Block diagram of the ultra-high vacuum surface defect detection system of the present invention;

[0042] Figure 3 Schematic diagram of mechanical exfoliation of a gallium oxide single crystal wafer in Example 1 of the present invention;

[0043] Figure 4 Cross-sectional SEM image of the mechanically exfoliated gallium oxide single crystal wafer in Example 1 of the present invention;

[0044] Figure 5 Surface AFM 2D and 3D images of the mechanically exfoliated gallium oxide single crystal wafer in Example 1 of the present invention;

[0045] Figure 6 XPS O 1s fine spectrum after sputtering annealing cycle of the mechanically exfoliated gallium oxide single crystal wafer in Example 1 of the present invention;

[0046] Figure 7 LEED image of the mechanically exfoliated gallium oxide single crystal wafer after sputtering annealing cycle in Example 1 of the present invention;

[0047] Figure 8 Surface oxygen vacancy atomic structure model (top view) and atomic resolution oxygen vacancy defect STM image of the mechanically exfoliated gallium oxide single crystal wafer in Example 1 of the present invention; Detailed implementation manners

[0048] The following further describes in detail the implementation manners of the present invention with reference to the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0049] As shown in the attached Figure 1 figures:

[0050] Example 1: The present invention provides an ultra-high vacuum surface defect detection method based on a scanning tunneling microscope, including the following steps:

[0051] S1. Based on the cleavage property of the crystal, mechanically exfoliate the single crystal gallium oxide sample to obtain a single crystal gallium oxide sample with a thickness of 20.58 μm;

[0052] Mechanical exfoliation aims to separate a micron-thick single crystal wafer by using a blade along the maximum cleavage plane of the single crystal gallium oxide, which can effectively remove macroscopic scratches, damaged layers, etc. on the surface of the bulk single crystal gallium oxide sample, making the surface of the sample reach a certain flatness and laying a foundation for subsequent fine processing.

[0053] S2. Ultrasonically clean the single-crystalline gallium oxide sample with acetone and ethanol for 15 minutes each in turn. After rinsing with deionized water and drying with nitrogen, place it in an ultra-high vacuum environment and heat the sample at 700 °C for 40 minutes to degas and remove the atmospheric adsorbates on the surface, obtaining a preliminarily annealed sample;

[0054] Ultrasonic cleaning utilizes the cavitation effect of ultrasonic waves, combined with organic solvents such as acetone and ethanol, to efficiently remove the oil stains, dust, and other organic pollutants on the surface. After ultrasonic cleaning, the organic pollutants on the sample surface are basically removed. Rinsing with deionized water and drying with nitrogen avoid water stain residues and prepare for entering the ultra-high vacuum environment.

[0055] Heat at 700 °C for 40 minutes under a vacuum of 1×10 -9 mbar to desorb the water molecules and adsorbates on the sample surface, further purify the sample surface, and reduce the interference of impurities on subsequent experiments.

[0056] S3. Place the preliminarily annealed single-crystalline gallium oxide sample in an ultra-high vacuum environment, perform argon ion sputtering treatment on the sample surface to remove segregation impurities, and perform vacuum high-temperature annealing treatment at 750 °C - 850 °C. The sputtering and annealing are carried out in cycles to generate oxygen vacancy defects on the sample surface, obtaining a post-treated sample;

[0057] The ultra-high vacuum environment includes: a vacuum chamber equipped with a mechanical pump, a molecular pump, an ion pump, and a titanium sublimation pump, with a real-time monitoring accuracy of the vacuum degree of 10 -10 mbar; an argon ion sputtering device with an adjustable acceleration voltage, equipped with an argon gas source with a purity ≥ 99.9999%.

[0058] The parameters of the argon ion sputtering treatment are: introduce argon gas to maintain the vacuum degree at 1×10 -6 mbar - 5×10 -5 mbar; the ion beam energy is 1 KeV - 3 KeV, and the sputtering time is 10 - 20 minutes;

[0059] During the argon ion sputtering treatment, under specific parameters, the bombardment of argon ions is used to remove the segregated impurities and adsorbed pollutants on the sample surface. Subsequently, annealing treatment is carried out at 750 °C - 850 °C to provide energy for the surface atoms, enabling them to rearrange and reconstruct, repair the damage generated during the sputtering process, and further stabilize the oxygen vacancy defects. Multiple cycles of treatment are to ensure the complete removal of surface impurities and the surface atomic structure reaches an ideal state.

[0060] During the vacuum high-temperature annealing treatment, the heating rate is controlled at 50 °C / min - 70 °C / min, and the vacuum degree is maintained at 5×10 -9 mbar - 1×10 -8 mbar during the holding period.

[0061] Under high temperature and ultra-high vacuum environment, sufficient energy is provided to the single crystal gallium oxide sample to cause the oxygen atoms on its surface to detach from the crystal lattice, thereby generating oxygen vacancy defects. By controlling the heating rate and holding time, it helps to stably form oxygen vacancy defects. By generating oxygen vacancy defects of the expected density on the sample surface, the atoms on the sample surface are reconstructed through a high-temperature annealing process to optimize the surface structure.

[0062] S4. Verify the surface oxygen vacancy concentration and surface cleanliness through auxiliary characterization methods; auxiliary characterization methods include: X-ray photoelectron spectroscopy (XPS) to detect the characteristic peak of gallium oxide O1s and the peak caused by oxygen vacancies, and analyze the peak area to determine the surface oxygen vacancy defect concentration; low energy electron diffraction (LEED) pattern to characterize the surface atomic order.

[0063] The O 1s fine spectrum shows that when the surface oxygen vacancy defect concentration is greater than 1.4%, it basically meets the STM needle insertion requirements; the bright focus of the diffraction spot in the LEED image indicates that the atomic order of the sample surface is good.

[0064] S5, scanning and imaging the surface of the post-processed sample by scanning tunneling microscopy to obtain an atomic resolution STM image of the single crystal sample, using density functional theory (DFT) calculation to obtain an oxygen vacancy STM simulation image, and qualitatively analyzing oxygen vacancy defects and surface defects in combination with the STM image;

[0065] The scanning tunneling microscope detection parameters are as follows: the probe is made of tungsten metal; in constant current mode, the bias range is -10V to +10V, and the tunneling current is 0.001-10nA or 0.001-50nA (with the current signal amplifier turned on);

[0066] Using a scanning tunneling microscope, by controlling the distance between the probe and the sample surface and scanning in constant current mode, the atomic-level STM image of the sample surface is acquired, and the atomic arrangement on the sample surface can be clearly observed.

[0067] The oxygen vacancy defect identification is performed by DFT calculation to simulate the oxygen vacancy defect STM image, and the oxygen vacancy defect is manifested as a characteristic bright spot between two rows of gallium atoms outside the surface gallium atom chain arrangement. The STM image is subjected to denoising (simple-flatten) processing, and combined with the above DFT simulated oxygen vacancy defect image and its characteristics, accurate identification of oxygen vacancy defects is achieved.

[0068] As attached Figure 2 As shown:

[0069] Embodiment 2: The present invention provides an ultra-high vacuum surface defect detection system based on a scanning tunneling microscope, comprising:

[0070] A sample pretreatment unit for mechanically exfoliating, physically cleaning, and preliminarily removing impurities from a single-crystal gallium oxide sample;

[0071] A sputtering annealing cycle treatment unit for removing surface impurities and promoting atomic reconstruction through cyclic treatment of argon ion sputtering and high-temperature annealing, making the surface defect characteristics of the sample obvious; inducing oxygen vacancy defects on the surface of single-crystal gallium oxide through high-temperature treatment in an ultra-high vacuum environment and optimizing the surface atomic structure;

[0072] An auxiliary characterization unit for monitoring the surface oxygen vacancy defect concentration and surface cleanliness through XPS characterization and characterizing the surface atomic order through LEED;

[0073] An STM imaging unit for imaging the surface of the single-crystal gallium oxide sample at the atomic resolution through a scanning tunneling microscope to obtain an STM image and observe the surface atomic structure and oxygen vacancy defects;

[0074] A defect analysis module that uses DFT calculation to simulate the STM image of oxygen vacancy defects, performs noise reduction (simple-flatten) processing on the STM image, and extracts and identifies defect characteristics by combining the simulated and experimental STM images;

[0075] As can be seen from the above, for single-crystal gallium oxide materials, the parameters of vacuum high-temperature annealing, argon ion sputtering, and annealing cycle treatment have been precisely optimized, realizing the precise generation of defects and the fine treatment of the surface. Compared with traditional methods, the treatment of the material is more refined and controllable. The STM detection is innovatively combined with the auxiliary characterization means of X-ray photoelectron spectroscopy to form a complete and mutually verified detection system, improving the credibility and comprehensiveness of the detection results. A sputtering annealing cycle termination condition based on the judgment of the surface oxygen vacancy concentration level monitored by XPS is proposed, which is more scientific and effective compared with the traditional fixed-number cycle treatment.

[0076] Importantly, it should be noted that the structures and arrangements of the present application shown in multiple different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who refer to this disclosure should easily understand that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in this application. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions, and arrangements of the exemplary embodiments without departing from the scope of the present invention. Therefore, the present invention is not limited to specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0077] In addition, in order to provide a concise description of the exemplary embodiments, all features of the actual embodiments may not be described (i.e., those features that are not relevant to the currently contemplated best mode of carrying out the invention or those features that are not relevant to implementing the invention).

[0078] It should be understood that, in the development of any actual implementation, as in any engineering or design project, numerous specific implementation decisions may be made. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, without undue experimentation, such development efforts would be routine work of design, fabrication, and production.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method and system for detecting surface defects in ultra-high vacuum based on a scanning tunneling microscope, characterized in that, It includes the following steps: S1. Mechanically exfoliate the single-crystal gallium oxide sample based on the largest cleavage plane to obtain a pre-treated single-crystal gallium oxide sample; S2. After ultrasonically cleaning the preprocessed sample, place it in an environment with a vacuum of 1×10 -9 mbar and heat it for 40 minutes at 700 °C to remove outgassing and remove surface atmospheric adsorbates to obtain a preliminary annealed sample; S3. In the above ultra-high vacuum environment, perform argon ion sputtering treatment on the surface of the preliminary annealing sample to remove segregation impurities, and perform vacuum high-temperature annealing treatment at 750 °C - 850 °C. The sputtering annealing cycle is carried out to generate oxygen vacancy defects on the sample surface and obtain a post-treatment sample; S4. Verify the surface oxygen vacancy concentration, surface cleanliness, and surface atomic order through auxiliary characterization means; S5. Scan and image the surface of the post-treatment sample through a scanning tunneling microscope, use DFT calculation to obtain the STM simulation image of oxygen vacancies, and qualitatively analyze oxygen vacancy defects and surface defects in combination with the STM image.

2. The method and system for detecting surface defects in ultra-high vacuum based on a scanning tunneling microscope according to claim 1, wherein, The mechanical exfoliation and ultrasonic cleaning of the single-crystal gallium oxide sample based on the crystal cleavage property to obtain a single-crystal gallium oxide sample with a micron thickness includes: Use a blade to separate along the largest cleavage plane of the single-crystal gallium oxide to obtain a single-crystal wafer with a micron thickness; Ultrasonically clean the single-crystal gallium oxide sample with acetone and ethanol for 15 minutes each in sequence, rinse with deionized water, and dry with nitrogen; Heat degas at 700 °C for 40 minutes under a vacuum of 1×10 -9 mbar to remove surface atmospheric adsorbates.

3. The method and system for detecting surface defects in ultra-high vacuum based on a scanning tunneling microscope according to claim 1, characterized in that, The ultra-high vacuum environment includes: A vacuum chamber equipped with a mechanical pump, a molecular pump, an ion pump, and a titanium sublimation pump, with a real-time monitoring accuracy of the vacuum degree of 10 -10 mbar; An argon ion sputtering device with an adjustable acceleration voltage, equipped with an argon gas source with a purity ≥ 99.9999%.

4. The ultra-high vacuum surface defect detection method and system based on a scanning tunneling microscope according to claim 1, wherein In the ultra-high vacuum environment, perform argon ion sputtering treatment on the surface of the preliminary annealing sample to remove segregation impurities, and perform vacuum high-temperature annealing treatment at 750 °C - 850 °C to generate oxygen vacancy defects on the sample surface, including: The argon ion sputtering treatment parameters are as follows: argon gas is introduced to maintain the vacuum degree at 1×10 -6 mbar - 5×10 -5 mbar; the ion beam energy is 1 keV - 3 keV, and the sputtering time is 10 - 20 minutes; The high-temperature annealing parameters: annealing is performed at a temperature of 750°C - 850°C for 30 - 60 minutes to form a sputtering annealing cycle treatment, and a post-treatment sample is obtained. The heating rate is controlled at 50°C / min - 70°C / min, and the vacuum degree is maintained at 5×10 -9 mbar - 1×10 -8 mbar.

5. The method and system for detecting surface defects in ultra-high vacuum based on a scanning tunneling microscope according to claim 1, wherein, The combination of auxiliary characterization means to monitor the surface oxygen vacancy defect concentration and surface cleanliness includes: The auxiliary characterization means includes: X-ray photoelectron spectroscopy to detect the O1s characteristic peak of gallium oxide and the split peak caused by oxygen vacancies, and analyze the peak area to determine the surface oxygen vacancy defect concentration; low-energy electron diffraction pattern to characterize the surface atomic order; The surface oxygen vacancy defect concentration > 1.4% to meet the STM needle insertion requirement.

6. The ultra-high vacuum surface defect detection method and system based on a scanning tunneling microscope according to claim 1, characterized in that The scanning and imaging of the surface of the post-treatment sample through a scanning tunneling microscope to obtain an STM image, and the detection of oxygen vacancy defects through the STM image includes: The detection parameters of the scanning tunneling microscope are: the probe uses tungsten metal; in the constant current mode, the bias voltage range is -10V to +10V, and the tunneling current is 0.001 - 10nA or 0.001 - 50nA; The identification of oxygen vacancy defects is to calculate and simulate the STM image of oxygen vacancy defects through density functional theory, and analyze and identify oxygen vacancy defects in combination with the experimental STM image.

7. A scanning tunneling microscope-based ultra-high vacuum surface defect detection system, characterized in that, It includes: A sample pre-treatment unit for mechanically exfoliating, physically cleaning, and preliminarily removing impurities from the single-crystal gallium oxide sample; A sputtering annealing cycle treatment unit for removing surface impurities and promoting atomic reconstruction through the cyclic treatment of argon ion sputtering and high-temperature annealing, making the surface defect characteristics of the sample obvious; inducing oxygen vacancy defects on the surface of single-crystal gallium oxide through high-temperature treatment in an ultra-high vacuum environment and optimizing the surface atomic structure; An auxiliary characterization unit for monitoring the surface oxygen vacancy defect concentration and surface cleanliness through XPS characterization, and characterizing the surface atomic order through LEED; STM imaging unit, which is used to image the surface of the single-crystal gallium oxide sample with atomic-level resolution through a scanning tunneling microscope to obtain an STM image and observe the surface atomic structure and oxygen vacancy defects; Defect analysis module, which is used to calculate and simulate the STM image of oxygen vacancy defects by DFT, perform noise reduction processing on the STM image, and extract and identify defect features by combining the simulated and experimental STM images.

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