Detection method and detection apparatus for atomic-scale defects in gallium oxide crystals

Abstract

A detection method and detection apparatus for atomic-scale defects in gallium oxide crystals. In the detection method, a scattering-type scanning near-field optical microscope system and / or a nano-infrared system are used to detect atomic-scale defects in gallium oxide crystals. Aiming at real requirements for the detection of internal structural defects in Ga2O3 materials and devices, a near-field optical microscope system and a nano-infrared system are used to detect structural defects in Ga2O3 crystals, thereby realizing highly sensitive and nondestructive detection of atomic-scale defects in materials.

Description

A method and device for detecting atomic-level defects in gallium oxide crystals

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese invention patent application No. CN 202311398360.7 filed on October 26, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention belongs to the field of optical microscopes, and in particular relates to a method and a device for detecting atomic-level defects in gallium oxide crystals. Background Art

[0004] Wide-bandgap semiconductors possess many unique properties due to their large band gaps. Representative third-generation semiconductor materials, such as gallium nitride (GaN) and silicon carbide (SiC), have been applied in numerous fields, including optoelectronics, power electronics, and high-temperature electronics. With the continuous advancement of cutting-edge science and technologies such as 5G communications, aerospace, and new energy vehicles, semiconductor materials are moving toward wider band gaps, higher breakdown field strengths, and lower energy consumption. Gallium oxide (Ga2O3), a new ultra-wide-bandgap semiconductor material, possesses a range of excellent physical properties, including ultra-high critical breakdown field strength, a short absorption cutoff edge, and exceptionally strong transparent conductivity. It holds broad application prospects in high-power devices, solar-blind detectors, and short-wavelength light-emitting devices. Furthermore, compared to GaN and SiC, Ga2O3 offers lower preparation costs, faster growth rates, lower crystal defect density, and greater stability, making it a highly anticipated next-generation semiconductor material.

[0005] Almost all wide-bandgap semiconductor materials inevitably generate structural defects during the manufacturing process. Even if these defects are very small (nanoscale or even atomic level), they are sufficient to disrupt the continuity and symmetry of the crystal lattice, significantly altering various physical properties of the material, affecting the material's band structure, light absorption and scattering, carrier capture and recombination, and other processes, resulting in material quality and device performance falling short of expectations. For example, defect levels introduced by vacancies and impurities can capture and release charge, increasing leakage current in the device, causing additional power consumption and reducing device efficiency. At the same time, defects can reduce the breakdown voltage of power devices, limiting the maximum voltage they can withstand, thereby reducing the reliability of high-power devices. Furthermore, the carrier scattering and capture processes caused by defects can limit the signal transmission speed within the device, reducing the device's high-frequency performance. Therefore, defect detection technology has important application value in material quality control and traceability analysis of device failure causes during the Ga2O3 device production process.

[0006] Due to the small size of defects and weak signals, defect detection in Ga2O3 crystals remains a technical challenge, and existing detection technologies and methods have their limitations. For example, transmission electron microscopy (TEM) and scanning tunneling microscopy (STM) can resolve atomic-level defects, but both require complex and lossy sample preparation processes. They are suitable for tracing the cause of device failure but not for monitoring device production processes. Electron channel contrast imaging (ECCI) technology has a detection depth of only about 50 nanometers and cannot detect defects below the surface of materials or devices. Various electrical detection technologies are generally qualitative and cannot complete the spatial localization of defects.

[0007] Currently, there is no existing technology that can detect atomic-level defects in gallium oxide using optical microscopy.

[0008] Summary of the Invention

[0009] The present invention aims to overcome the shortcomings of the prior art by providing a method and apparatus for detecting atomic-level defects in gallium oxide crystals. Current methods for detecting atomic-level defects in gallium oxide crystals have not yet utilized a scattering scanning near-field optical microscope system and a nano-infrared system for gallium oxide defect detection. Addressing the practical need for detecting structural defects within Ga2O3 materials and devices, the present invention utilizes a near-field optical microscope system and a nano-infrared system for Ga2O3 crystal structural defect detection, achieving highly sensitive, nondestructive detection of atomic-level defects within the material.

[0010] Before describing the present invention, the terms used in this article are defined as follows:

[0011] The term "s-SNOM" refers to: Scattering Scanning Near-Field Optical Microscopy.

[0012] The term "AFM" refers to: Atomic Force Microscope.

[0013] The term "Nano-FTIR" refers to: Fourier transform nano-infrared spectroscopy technology, abbreviated as nano-infrared.

[0014] The term "FIB" means: Focused Ion Beam.

[0015] The term "ADF-STEM" refers to: Annular Dark Field Scanning Transmission Electron Microscopy.

[0016] The term "HAADF" means: High Angle Annular Dark Field.

[0017] The term "STM" means: Scanning Tunneling Microscope.

[0018] The term "TEM" means: Transmission Electron Microscope.

[0019] The term "ECCI" refers to: Electron Channeling Contrast Imaging.

[0020] The term "STEM" refers to: Scanning Transmission Electron Microscope.

[0021] The term "A-E band" refers to the five test bands of the broad-spectrum laser used in nano-infrared systems: A-band, B-band, C-band, D-band, and E-band. Different bands have different primary light output wavenumbers and intensities. Band A is primarily emitted from 600 to 1300 wavenumbers; band B is primarily emitted from 600 to 1400 wavenumbers; band C is primarily emitted from 750 to 1550 wavenumbers; band D is primarily emitted from 900 to 1800 wavenumbers; and band E is primarily emitted from 1100 to 2200 wavenumbers.

[0022] A first aspect of the present invention provides a method for detecting atomic-level defects in gallium oxide crystals, wherein the method uses a scattering scanning near-field optical microscope system to detect atomic-level defects in gallium oxide crystals;

[0023] The scattering scanning near-field optical microscope system collects optical signals of gallium oxide crystal defects through the scattering enhancement effect of the probe tip for imaging.

[0024] According to the detection method of the first aspect, the scattering scanning near-field optical microscope system includes: an atomic force microscope system and an optical system, wherein:

[0025] The light source of the optical system is a tunable quantum cascade laser and / or a carbon dioxide laser, and is most preferably a tunable quantum cascade laser.

[0026] According to the detection method of the first aspect, the atomic force microscopy system includes a probe and a laser; wherein,

[0027] The tip of the probe in the atomic force microscopy system is a platinum-coated probe tip, and the radius of curvature of the probe tip is 10 to 20 nm, preferably 10 to 15 nm, and most preferably 10 nm; and / or

[0028] The laser in the atomic force microscopy system is a quantum cascade laser, and the tunable wave number range of the quantum cascade laser is preferably 890 to 1805 cm -1 , more preferably 890 to 1550 cm -1 , more preferably 900~1550cm -1 .

[0029] According to the detection method of the first aspect, the detection method further comprises using a nano-infrared system to detect atomic-level defects in gallium oxide crystals to obtain a nano-infrared spectrum of defects in gallium oxide crystals; wherein,

[0030] The nano-infrared system and the scattering scanning near-field optical microscope system are integrated on the same atomic force microscope system, and the nano-infrared system has an independent optical system;

[0031] Preferably, the independent optical system is an asymmetric Michelson interferometer.

[0032] According to the detection method of the first aspect, the laser of the independent optical system in the nano-infrared system is a broadband laser, and the tunable wave number range of the broadband laser is preferably 600 to 2200 cm -1 , more preferably 750 to 1550 cm -1 and / or 1100~2200cm -1 , more preferably 750 to 1550 cm -1

[0033] According to the detection method of the first aspect, the detection method comprises the following steps:

[0034] (1) The optical system introduces the excitation light into the atomic force microscope system and focuses it onto the tip of the near-field platinum-coated probe, while collecting the scattered signal of the near-field platinum-coated probe;

[0035] (2) The atomic force microscope system scans the gallium oxide crystal point by point at different wave numbers to image the same area, and stitches the output of the detector into a two-dimensional near-field optical image. The contrast of the two-dimensional near-field optical image is used to identify and locate atomic-level defects in the gallium oxide crystal.

[0036] According to the detection method of the first aspect, wherein, in step (1):

[0037] After collecting the scattered signal, the method further comprises: improving the signal-to-noise ratio of the signal by interfering with the reference light; and / or

[0038] The platinum-coated probe is prepared by depositing platinum on the tip of the probe.

[0039] According to the detection method of the first aspect, wherein, in step (2):

[0040] The point-by-point scanning mode is: tapping mode or contact mode, and the tapping mode is most preferred; and / or

[0041] The atomic-level defects of the gallium oxide crystal are selected from one or more of the following: irregular lattice distortion, lattice constant change, atomic position dislocation, and incomplete crystal structure.

[0042] According to the detection method described in the first aspect, when the scattered scanning near-field optical microscope system is used for detection, in the step (2), the point-by-point scanning rate is 1 to 12 um / s, preferably 2 to 10 um / s, and more preferably 3 to 5 um / s.

[0043] According to the detection method described in the first aspect, when the nano-infrared system is used for detection, in the step (2), the point-by-point scanning rate is 10 to 40 um / s, preferably 15 to 35 um / s, and more preferably 20 to 32 um / s.

[0044] The second aspect of the present invention provides a gallium oxide crystal atomic level defect detection device for implementing the detection method described in the first aspect, the gallium oxide crystal atomic level defect detection device comprising: a scattering scanning near-field optical microscope system and a nano-infrared system; wherein,

[0045] The scattering scanning near-field optical microscope system includes: an atomic force microscope system and an optical system;

[0046] The atomic force microscopy system includes a probe and a displacement control system;

[0047] The optical system includes a light source, a focusing element and a detector.

[0048] According to the gallium oxide crystal atomic level defect detection device of the second aspect, wherein,

[0049] The light source of the optical system is a tunable quantum cascade laser and / or a carbon dioxide laser, and most preferably a tunable quantum cascade laser;

[0050] The focusing element of the optical system forms a light path, preferably a zinc selenide lens and / or an off-axis parabolic reflector, most preferably an off-axis parabolic reflector; and / or

[0051] The detector of the optical system is a mercury cadmium telluride infrared detector, and the detection light wavelength range of the mercury cadmium telluride infrared detector is preferably 2 to 11.5 μm, more preferably 4 to 11.5 μm, and further preferably 5 to 11.5 μm;

[0052] Preferably, the wave number range of the tunable quantum cascade laser is 890 to 1805 cm -1 , more preferably 890 to 1550 cm -1 , more preferably 900~1550cm -1 .

[0053] According to the gallium oxide crystal atomic level defect detection device of the second aspect, wherein,

[0054] The tip of the probe in the atomic force microscopy system is a platinum-coated probe tip, and the radius of curvature of the probe tip is 10 to 20 nm, preferably 10 to 15 nm, and most preferably 10 nm; and / or

[0055] The displacement control system includes a three-axis displacement stage, and the three-axis displacement stage is preferably an XYZ three-axis displacement stage;

[0056] Preferably, the XYZ three-axis translation stage is a piezoelectric scanning translation stage;

[0057] More preferably, the scanning range of the piezoelectric scanning stage in the XY direction is within 100 μm, and the scanning range in the Z direction is within 2 μm.

[0058] The gallium oxide crystal atomic-level defect detection device according to the second aspect, wherein the nano-infrared system and the scattered scanning near-field optical microscope system are integrated on the same atomic force microscope system, and the nano-infrared system has an independent optical system;

[0059] Preferably, the independent optical system is an asymmetric Michelson interferometer.

[0060] According to the gallium oxide crystal atomic-level defect detection device of the second aspect, the laser of the independent optical system in the nano-infrared system is a broadband laser, and the tunable wave number range of the broadband laser is preferably 600 to 2200 cm -1 , more preferably 750 to 1550 cm -1 and / or 1100~2200cm -1 , more preferably 750 to 1550 cm -1 .

[0061] According to a specific embodiment, a scattering scanning near-field optical microscope (s-SNOM) consists of an optical system and an atomic force microscope (AFM). The optical system introduces the excitation light into the AFM and focuses it on the tip of the near-field probe, while collecting the scattered signal of the near-field probe and improving the signal-to-noise ratio of the signal by interfering with the reference light. The AFM is responsible for scanning the sample point by point and stitching the output of the detector into a two-dimensional image. The near-field probe is a key component of the s-SNOM and acts as an optical antenna. First, under the irradiation of the focused light beam, the probe induces a strong electromagnetic field near its tip and elastically scatters the excitation light. Secondly, when the probe and the sample approach each other and enter the range of the optical near field, the sample changes the electromagnetic field at the tip of the probe, so that the elastic scattering of the excitation light by the probe-sample combination carries the optical property information of the sample. By scanning the sample point by point, if the sample has different optical properties at different positions, the characteristics (amplitude, phase, etc.) of the elastically scattered light received by the detector will also change accordingly. This is the source of the imaging contrast of the s-SNOM. Structural defects in Ga2O3 crystals can lead to irregular distortions in the crystal lattice, causing changes in the lattice constant, dislocation of atomic positions, and incomplete crystal structure. This can cause localized phonons to be generated at the defects, affecting the material's light absorption and scattering. This in turn causes the detector to detect changes in the elastically scattered light properties of the sample surface, ultimately locating the defect through the contrast of the near-field optical image.

[0062] The scattering scanning near-field optical microscope includes a quantum cascade laser (QCL) with a wavenumber range of 890-1805, an optical path, a detector, and a lock-in amplifier. The optical signal from defects in the gallium oxide crystal is collected and imaged through the scattering enhancement effect of the needle tip.

[0063] The nano-infrared system includes a broadband laser with a wavenumber range of 660-2200, an optical path, an asymmetric Michelson interferometer, a detector, and a lock-in amplifier. The nano-infrared spectrum obtained using the nano-infrared system is Yang Huajia's nano-infrared spectrum.

[0064] The detection method of this invention uses a scattering scanning near-field optical microscope system and a nano-infrared system to detect gallium oxide defects. This method is unprecedented in existing methods for detecting atomic-level defects in gallium oxide crystals. Compared to other detection technologies, this method offers advantages in non-destructive testing, sensitivity, and depth of detection.

[0065] Traditional optical microscopy is limited by the diffraction effect of light, achieving a maximum spatial resolution of half a wavelength. In the visible light band, this limit corresponds to 200-300 nm; in the infrared band, this limit corresponds to a spatial resolution of micrometers, both of which far exceed the ultra-high spatial resolution required for characterizing defects at the nanometer or even atomic level in gallium oxide crystal structures. However, with the development of scanning near-field optical microscopy, its spatial resolution is determined solely by the radius of curvature of the probe tip and is independent of the operating wavelength. The spatial resolution of optical imaging can reach the order of 10 nm, significantly surpassing the optical diffraction limit. Furthermore, scanning near-field optical microscopy boasts high detection sensitivity due to the enhanced scattering of optical signals by the near-field probe tip. Therefore, scanning near-field optical microscopy can simultaneously meet the requirements for both high spatial resolution and high detection sensitivity for atomic-level defects in gallium oxide crystals.

[0066] Compared with the prior art, the detection method of the present invention may have but is not limited to the following beneficial effects:

[0067] 1. The detection method of the present invention realizes highly sensitive non-destructive detection of atomic-level defects inside materials.

[0068] 2. Compared with TEM technology, the detection method of the present invention can realize non-destructive detection and positioning of defects in large-area gallium oxide crystals.

[0069] 3. Compared with the electron channeling contrast imaging (ECCI) technique, the detection method of the present invention can achieve highly sensitive detection of defects in large-area gallium oxide crystals, and has a detection sensitivity of hundreds of nanometers deeper than ECCI (~50nm).

[0070] BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which:

[0072] Figure 1 shows the AFM morphology image and visible light near-field optical image of the Ga2O3 crystal in Example 1; wherein, Figure 1A shows the atomic force microscope (AFM) image of the Ga2O3 crystal, and Figure 1B shows the corresponding near-field optical image under visible light.

[0073] FIG2 shows the near-field optical image of the Ga2O3 crystal in Example 1; wherein the laser wave number in FIG2A is 900 cm -1 , the laser wave number in Figure 2B is 1550 cm -1 .

[0074] FIG3 shows a nano-infrared spectrum of Ga2O3 crystal in Example 2; FIG3A shows a line scan result of the nano-infrared spectrum of Ga2O3 crystal; and FIG3B shows a spectrum corresponding to two points in FIG3A.

[0075] FIG4 shows an atomic number contrast image of a high angle annular dark field (HAADF) of the Ga2O3 crystal in Comparative Example 1.

[0076] FIG5 shows the near-field optical image and electron channel contrast imaging (ECCI) image of Ga2O3 crystal in Comparative Example 2; FIG5A shows the laser wave number of 900 cm -1 FIG5B shows the electron channel contrast image corresponding to the sample in FIG5A when the angle is 0°; FIG5C shows the laser wave number of 900 cm -1 FIG5D shows the electron channel contrast image of the sample in FIG5C when the angle is 0°. FIG5D shows the electron channel contrast image of the sample in FIG5C when the angle is 0°.

[0077] Best Mode for Carrying Out the Invention

[0078] The present invention is further described below by way of specific examples. However, it should be understood that these examples are merely provided for more detailed and specific description and are not to be construed as limiting the present invention in any form.

[0079] This section provides a general description of the materials and experimental methods used in the experiments of the present invention. Although many of the materials and procedures used to achieve the purposes of the present invention are well known in the art, the present invention is described herein in as much detail as possible. It will be understood by those skilled in the art that, unless otherwise specified, the materials and procedures used in the present invention are well known in the art.

[0080] The following examples will help to further understand the present invention, but are not intended to limit the present invention.

[0081] Example 1

[0082] This embodiment is used to illustrate the method for detecting atomic-level defects in gallium oxide crystals of the present invention.

[0083] A scattering scanning near-field optical microscope (s-SNOM) was used for near-field optical testing. The system mainly consists of two parts: an atomic force microscope (AFM) and an optical system, which are used for morphological characterization and near-field optical imaging of samples. The optical system consists of a set of tunable quantum cascade lasers and optical paths. Its main function is to introduce the excitation light into the AFM and focus it on the near-field probe tip and collect the scattered signal of the near-field probe. The AFM uses a tapping mode to scan the sample point by point and stitch the output of the detector into a two-dimensional image. In near-field optical detection, the platinum-coated AFM tip used is prepared by depositing Pt onto the tip of a silicon probe, and the curvature radius of the probe tip is 10 nm. The tunable band range of the infrared laser used is 890-1805 cm -1In the s-SNOM imaging test, scanning was performed at a speed of 4.8162 μm / s, and AFM morphology and near-field optical images were obtained simultaneously.

[0084] As mentioned above, the same area of ​​the Ga2O3 crystal was imaged at different laser wavenumbers on the same scanning near-field optical microscope, with the wavenumber range of 890-1805 cm -1 , to study the optical response of Ga2O3 crystal structure defects.

[0085] Table 1 Typical parameters of near-field optical testing

[0086] Figure 1 shows the results of near-field optical testing: Figure 1A shows an atomic force microscope (AFM) image of a Ga2O3 crystal, and Figure 1B shows the corresponding near-field optical image under visible light. The AFM image reveals a smooth surface with no structural defects. The dark areas represent the substrate, while the bright areas represent the Ga2O3 crystal. Furthermore, in the visible light near-field optical image in Figure 1B, only waveguide mode signals are observed, with no other specific signals observed.

[0087] The near-field infrared test image is shown in Figure 2: Figure 2A The laser wave number is 900cm -1 , Figure 2B is 1550cm -1 The results showed that at 900-1550cm -1 Within the range (the wavenumber range is limited by the instrument laser, and the results are not limited to this range), bright stripes parallel to the long side of the material can be clearly observed, indicating that the optical properties of the Ga2O3 material at this position have changed, and there may be localized phonons caused by lattice defects, which affect the light absorption and scattering of the material.

[0088] Example 2

[0089] This embodiment is used to illustrate the method for detecting atomic-level defects in gallium oxide crystals of the present invention.

[0090] A nano-infrared (Nano-FTIR) system was used for spectral measurement. This system was integrated with the s-SNOM on the same AFM, but the optical systems of the two were independent of each other. In this embodiment, the optical system of the nano-infrared (Nano-FTIR) system mainly consisted of an asymmetric Michelson interferometer. A broadband laser was used as the light source with a wavenumber range of 660-2200 cm -1 At the same time, the same AFM probe as the near-field optical test was used for line scanning in the nano-infrared test to obtain Nano-FTIR spectrum data.

[0091] Table 2 Typical parameters of nano-infrared testing

[0092] The results of the nano-infrared spectrum test are shown in Figure 3: Figure 3A is the line scan result of the nano-infrared spectrum of Ga2O3 crystal, and Figure 3B is the spectrum of the two points corresponding to Figure 3A. According to the line scan image, it can be clearly seen that the 950-1150cm -1 There are three horizontal bright stripes in the range, located at 1.3μm, 2.5μm and 3.0μm respectively. At the same time, the spacing of the bright stripes will change with the change of wave number. Since the infrared absorption and transmission spectra of Ga2O3 are in the range of 900-1200cm -1 There is no obvious characteristic peak between the two, indicating that there is a structural defect in the tested Ga2O3 crystal where the bright stripes appear. It is precisely because of the existence of this defect that the symmetry of the crystal structure is affected, localized phonons are generated, and the Ga2O3 crystal is at 950-1150cm -1 There is a clear optical response within the range.

[0093] Comparative Example 1

[0094] The present invention is used to illustrate the results of high-resolution scanning transmission electron microscopy (STEM) testing.

[0095] (1) Sample preparation: Ga2O3 crystals were cut using a focused ion beam (FIB) and then thinned to less than 100 nm. The sample was then transferred to a copper mesh using the robotic arm equipped with the instrument.

[0096] (2) STEM testing: Atomic-scale annular dark field scanning transmission electron microscopy (ADF-STEM) imaging of cross sections at defects in the Ga2O3 crystal structure was performed using a spherical aberration-corrected STEM. Imaging was performed at an accelerating voltage of 300 kV to avoid damage to the sample surface. For all experiments, the probe current was set to 30 pA. The angular range of the high-angle annular dark field (HAADF) detector was 49-200 mrad at a camera length of 185 mm. Images and sequences were acquired using a short dwell time (5 μs) of 2048 × 2048 pixels. Each image was taken with an exposure time of < 3 s to minimize beam damage.

[0097] Table 3 Typical parameters of STEM test

[0098] Figure 4 shows the atomic number contrast image of the Ga2O3 crystal in Comparative Example 1 using a high-angle annular dark field (HAADF) technique. As can be seen from Figure 4, the STEM testing method requires a complex sample preparation process and is destructive. Lattice structure distortion caused by atomic-level defects below the surface can be observed in the HAADF image. Comparison of the lattice structure of gallium oxide in the atomic-resolution image shows that the bright streaks in the near-field optical image are indeed caused by atomic-level defects in Ga2O3. This shows that, compared to the STEM testing method in the prior art, the detection method of the present invention has both atomic-level defect detection sensitivity and the ability to non-destructively detect defects within materials and devices at depths up to hundreds of nanometers. This enables non-destructive detection and positioning of atomic-level defects in large-area gallium oxide crystals.

[0099] Comparative Example 2

[0100] The present invention is used to illustrate the results of electron channeling contrast imaging (ECCI) testing.

[0101] ECCI testing: Backscattered electrons were received using a CBS detector equipped with a scanning electron microscope. Defective samples were imaged at an accelerating voltage of 20 kV, a current of 0.8 nA, and a working distance of 4.3 mm. The sample stage was tilted at 0°.

[0102] FIG5 shows electron channel contrast imaging (ECCI) images of Ga2O3 crystals in Comparative Examples 1 and 2; FIG5A shows that the laser wave number is 900 cm -1 FIG5B shows the electron channel contrast image corresponding to the sample in FIG5A when the angle is 0°; FIG5C shows the laser wave number of 900 cm -1 FIG5D shows the electron channel contrast image of the sample in FIG5C when the angle is 0°. FIG5D shows the electron channel contrast image of the sample in FIG5C when the angle is 0°.

[0103] As shown in Figure 5, defects at the corresponding position are only observed at an angle of 0° (Figure 5B), but in a thicker sample (Figure 5D), no image changes are observed at the position of the defects characterized by near-field optics at 0°. Therefore, the ECCI test method cannot detect structural defects in gallium oxide crystals with a thickness exceeding 50nm, and its detection sensitivity and detection depth are limited. The detection method of the present invention, as shown in Figures 5A and 5C, has a higher detection depth and sensitivity for atomic-level defects in gallium oxide crystals. It can be seen that compared with the ECCI test method in the prior art, the detection method of the present invention can achieve high-sensitivity detection of defects in large-area gallium oxide crystals, and at the same time has a detection sensitivity of hundreds of nanometers deeper than ECCI (~50nm).

[0104] Although the present invention has been described to a certain extent, it is obvious that appropriate changes in various aspects can be made without departing from the spirit and scope of the present invention. It is understood that the present invention is not limited to the embodiments described, but belongs to the scope of the claims, which includes equivalent replacements of each factor described.

Claims

1. A method for detecting atomic-level defects in gallium oxide crystals, characterized in that: The detection method uses a scattering scanning near-field optical microscope system to detect atomic-level defects in gallium oxide crystals; The scattering scanning near-field optical microscope system collects optical signals of gallium oxide crystal defects through the scattering enhancement effect of the probe tip for imaging.

2. The detection method according to claim 1, characterized in that: The scattering scanning near-field optical microscope system comprises: an atomic force microscope system and an optical system, wherein: The light source of the optical system is a tunable quantum cascade laser and / or a carbon dioxide laser, and most preferably is a tunable quantum cascade laser.

3. The detection method according to claim 1 or 2, characterized in that: The atomic force microscopy system includes a probe and a laser; wherein, The tip of the probe in the atomic force microscopy system is a platinum-coated probe tip, and the radius of curvature of the tip of the probe is 10 to 20 nm, preferably 10 to 15 nm, and most preferably 10 nm; and / or The laser in the atomic force microscopy system is a quantum cascade laser, and the tunable wave number range of the quantum cascade laser is preferably 890 to 1805 cm -1 , more preferably 890 to 1550 cm -1 , more preferably 900 to 1550 cm -1 .

4. The detection method according to any one of claims 1 to 3, characterized in that: The detection method further includes using a nano-infrared system to detect atomic-level defects in gallium oxide crystals to obtain a nano-infrared spectrum of defects in gallium oxide crystals; wherein, The nano-infrared system and the scattering scanning near-field optical microscope system are integrated on the same atomic force microscope system, and the nano-infrared system has an independent optical system; Preferably, the independent optical system is an asymmetric Michelson interferometer.

5. The detection method according to claim 4, characterized in that: The laser of the independent optical system in the nano-infrared system is a broadband laser, and the tunable wave number range of the broadband laser is preferably 600 to 2200 cm -1 , more preferably 750 to 1550 cm -1 and / or 1100~2200cm -1 , more preferably 750 to 1550 cm -1 .

6. The detection method according to any one of claims 1 to 5, characterized in that: The detection method comprises the following steps: (1) The optical system introduces the excitation light into the atomic force microscope system and focuses it onto the tip of the near-field platinum-coated probe, while collecting the scattered signal of the near-field platinum-coated probe; (2) The atomic force microscope system scans the gallium oxide crystal point by point at different wave numbers to image the same area, and stitches the output of the detector into a two-dimensional near-field optical image. The contrast of the two-dimensional near-field optical image is used to identify and locate atomic-level defects in the gallium oxide crystal.

7. The detection method according to claim 6, characterized in that: In the step (1): After collecting the scattered signal, the method further comprises: improving the signal-to-noise ratio of the signal by interfering with the reference light; and / or The platinum-coated probe is prepared by depositing platinum on the tip of the probe.

8. The detection method according to claim 6 or 7, characterized in that: In the step (2): The point-by-point scanning mode is: a tapping mode or a contact mode, and the tapping mode is most preferred; and / or The atomic-level defects of the gallium oxide crystal are selected from one or more of the following: irregular lattice distortion, lattice constant change, atomic position dislocation, and incomplete crystal structure.

9. The detection method according to any one of claims 6 to 8, characterized in that: When the scattered scanning near-field optical microscope system is used for detection, in the step (2), the point-by-point scanning rate is 1 to 12 um / s, preferably 2 to 10 um / s, and more preferably 3 to 5 um / s.

10. The detection method according to any one of claims 6 to 8, characterized in that: When the nano-infrared system is used for detection, in the step (2), the point-by-point scanning rate is 10 to 40 um / s, preferably 15 to 35 um / s, and more preferably 20 to 32 um / s.

11. A gallium oxide crystal atomic level defect detection device for implementing the detection method according to any one of claims 1 to 10, characterized in that: The gallium oxide crystal atomic level defect detection device comprises: a scattering scanning near-field optical microscope system and a nano-infrared system; wherein, The scattering scanning near-field optical microscope system comprises: an atomic force microscope system and an optical system; The atomic force microscopy system includes a probe and a displacement control system; The optical system includes: a light source, a focusing element and a detector.

12. The device for detecting atomic level defects of gallium oxide crystals according to claim 11, characterized in that: The light source of the optical system is a tunable quantum cascade laser and / or a carbon dioxide laser, and most preferably a tunable quantum cascade laser; The focusing element of the optical system forms a light path, preferably a zinc selenide lens and / or an off-axis parabolic reflector, most preferably an off-axis parabolic reflector; and / or The detector of the optical system is a mercury cadmium telluride infrared detector, and the detection light wavelength range of the mercury cadmium telluride infrared detector is preferably 2 to 11.5 um, more preferably 4 to 11.5 um, and further preferably 5 to 11.5 um; Preferably, the wave number range of the tunable quantum cascade laser is 890-1805 cm -1 , more preferably 890 to 1550 cm -1 , more preferably 900 to 1550 cm -1 .

13. The device for detecting atomic level defects of gallium oxide crystals according to claim 11 or 12, characterized in that: The tip of the probe in the atomic force microscopy system is a platinum-coated probe tip, and the radius of curvature of the tip of the probe is 10 to 20 nm, preferably 10 to 15 nm, and most preferably 10 nm; and / or The displacement control system comprises a three-axis displacement stage, and the three-axis displacement stage is preferably an XYZ three-axis displacement stage; Preferably, the XYZ three-axis translation stage is a piezoelectric scanning translation stage; More preferably, the scanning range of the piezoelectric scanning stage in the XY direction is within 100 um, and the scanning range in the Z direction is within 2 um.

14. The device for detecting atomic level defects in gallium oxide crystals according to any one of claims 11 to 13, characterized in that: The nano-infrared system and the scattering scanning near-field optical microscope system are integrated on the same atomic force microscope system, and the nano-infrared system has an independent optical system; Preferably, the independent optical system is an asymmetric Michelson interferometer.

15. The gallium oxide crystal atomic level defect detection device according to claim 14, characterized in that: The laser of the independent optical system in the nano-infrared system is a broadband laser, and the tunable wave number range of the broadband laser is preferably 600 to 2200 cm -1 , more preferably 750 to 1550 cm -1 and / or 1100~2200cm -1 , more preferably 750 to 1550 cm -1 .

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