CN113109595B - Atomic force microscopy method and system for analyzing electrostatic and force-electricity coupling response - Google Patents
Atomic force microscopy method and system for analyzing electrostatic and force-electricity coupling response Download PDFInfo
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Abstract
The embodiment of the invention discloses an atomic force microscopy method and an atomic force microscopy system for analyzing electrostatic and force-electricity coupling response. An atomic force microscopy method for resolving an electrostatic and force-electric coupling response, comprising: synthesizing the sub-waveforms with different characteristic parameters in the two frequency bands into excitation signals according to a preset splicing sequence; applying the excitation signal to a target to be detected to obtain amplitude images corresponding to different characteristic parameters of the target to be detected; and decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected to generate a strain image and an electrostatic image of the target to be detected. The problems that the force-electricity coupling strain measurement is easily affected by static electricity and the result is inaccurate are solved, and the effect that a force-electricity coupling strain image and an electrostatic response image of a target to be measured are accurately obtained through the quantitative analysis of the target decoupling model bimodal data is achieved.
Description
Technical Field
The embodiment of the invention relates to a microscopic imaging technology, in particular to an atomic force microscopic method and system for analyzing electrostatic and force-electric coupling response.
Background
In the last decade, the advent of a dynamic excitation measurement mode based on an Atomic Force Microscope (AFM), represented by piezoelectric response force microscopy (PFM) and Electrochemical Strain Microscopy (ESM), has greatly promoted the mechanization and performance optimization of a series of materials. In practical measurements, however, the response is not limited to the expected electrostrictive strain, but is also disturbed by electrostatic forces.
In the prior art, different probes, high-order modes of the probes and AFM hardware improvement modes are adopted in measurement to qualitatively eliminate interference of electrostatic force, however, the actual effect cannot be effectively verified, and the electro-strain response strength of different sample materials is difficult.
Disclosure of Invention
The invention provides an atomic force microscopy method and system for analyzing electrostatic and force-electricity coupling response, which aim to achieve the effects of obtaining bimodal test result data through one-time scanning, obtaining the test results of strain and electrostatic force through quantitative analysis, reducing the requirement on a specific probe and improving the applicability.
In a first aspect, an embodiment of the present invention provides an atomic force microscopy method for analyzing electrostatic and force-electric coupling responses, including:
synthesizing a plurality of sub-waveforms with different characteristic parameters in two frequency bands into an excitation signal according to a preset splicing sequence;
applying the excitation signal to a target to be detected to obtain bimodal amplitude images corresponding to different characteristic parameters of the target to be detected;
decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected, and generating a force-electricity coupling strain image and an electrostatic response image of the target to be detected.
Optionally, before the synthesizing the excitation signal by the plurality of sub-waveforms with different characteristic parameters according to the preset splicing order, the method further includes: constructing a decoupling model; the constructing of the decoupling model comprises:
calibrating vibration parameters of a probe of the atomic force microscope;
constructing an initial decoupling model based on the vibration parameters of the probe;
and verifying the reliability of the initial decoupling model based on the measurement data of the atomic force microscope to obtain a target decoupling model.
Optionally, the vibration parameters of the probe include bimodal stiffness and optical lever conversion coefficient of coupling resonance between the probe and the sample to be measured.
Optionally, the frequency spectrum range of the excitation signal covers the frequency corresponding to the bimodal mode.
Optionally, the applying the excitation signal to the target to be measured to obtain amplitude images corresponding to different characteristic parameters of the target to be measured includes:
sequentially applying the excitation signal to a target to be detected through a probe of an atomic force microscope to obtain a corresponding response signal;
and separating amplitude images corresponding to different characteristic parameters in the response signals.
Optionally, the separating the amplitude images corresponding to different characteristic parameters in the response signal includes:
demodulating the full-time-domain vibration response signals under the different characteristic parameters to obtain characteristic information of the target to be measured under the different characteristic parameters and the different modes;
and obtaining bimodal amplitude images correspondingly contained in the target to be detected under different characteristic parameters according to the characteristic information and a preset fitting algorithm.
Optionally, the decoupling and reconstructing according to the target decoupling model and the amplitude image of the target to be detected to generate the strain image and the electrostatic image of the target to be detected includes:
demodulating the full-time-domain amplitude response data of the target to be detected to obtain the intrinsic amplitude and the phase of the target to be detected under the condition that the probe applies an excitation signal;
and reconstructing the decoupled data by the target decoupling model according to the intrinsic amplitude and the intrinsic phase to obtain a force-electricity coupling strain image and an electrostatic response image of the target to be tested.
In a second aspect, the present invention also provides an atomic force microscopy system for resolving an electrostatic and force-electrical coupling response, comprising:
the signal generating module is used for synthesizing a plurality of sub-waveforms with different characteristic parameters in two frequency bands into an excitation signal according to a preset splicing sequence;
the image acquisition module is used for applying the excitation signal to a target to be detected and acquiring bimodal amplitude images corresponding to different characteristic parameters of the target to be detected;
and the data processing module is used for decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected, and generating a force-electricity coupling strain image and an electrostatic response image of the target to be detected.
Optionally, the atomic force microscope system for analyzing the electrostatic and force electric coupling response further includes: a decoupled model construction module comprising:
the parameter calibration unit is used for calibrating the vibration parameters of the probe of the atomic force microscope;
an initial model construction unit, which is used for constructing an initial decoupling model based on the vibration parameters of the probe;
and the model verification unit is used for verifying the reliability of the initial decoupling model based on the measurement data of the atomic force microscope to obtain a target decoupling model.
Optionally, the data processing module includes:
the intrinsic characteristic acquisition unit is used for demodulating the full-time-domain amplitude response data of the target to be detected to obtain the intrinsic amplitude and the phase of the target to be detected under the condition that the probe applies an excitation signal;
and the result acquisition unit is used for reconstructing the decoupled data by the target decoupling model according to the intrinsic amplitude and the intrinsic phase to obtain a force-electricity coupling strain image and an electrostatic response image of the target to be tested.
According to the invention, a plurality of sub-waveforms with different characteristic parameters in two frequency bands are synthesized into an excitation signal according to a preset splicing sequence; applying the excitation signal to a target to be detected to obtain bimodal amplitude images corresponding to different characteristic parameters of the target to be detected; decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected to generate a force-electricity coupling strain image and an electrostatic response image of the target to be detected; the problems that the force-electricity coupling strain measurement is easily affected by static electricity and the result is inaccurate are solved, and the effect that a force-electricity coupling strain image and an electrostatic response image of a target to be measured are accurately obtained through the quantitative analysis of the target decoupling model bimodal data is achieved.
Drawings
FIG. 1 is a schematic flow chart of an atomic force microscopy method for analyzing electrostatic and force-electric coupling response according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of signal synchronization of an atomic force microscopy method for analyzing electrostatic and force-electric coupling responses according to an embodiment of the present invention;
fig. 3 is a response spectrum diagram corresponding to different vibration modes of an atomic force microscopy method for analyzing electrostatic and force-electric coupling responses according to an embodiment of the present invention;
FIG. 4A is a diagram illustrating the total response amplitude of the excitation signal of an atomic force microscopy method for analyzing the electrostatic and force electrical coupling response according to an embodiment of the present invention;
fig. 4B is a strain-force response diagram of an atomic force microscopy method for analyzing electrostatic and force-electric coupling responses according to an embodiment of the present invention;
FIG. 4C is a schematic diagram illustrating electrostatic force response of an atomic force microscopy method for analyzing electrostatic and force electric coupling responses according to an embodiment of the present invention;
FIG. 5A is a schematic flow chart of another atomic force microscopy method for analyzing electrostatic and force electrical coupling responses according to an embodiment of the present invention;
FIG. 5B is a schematic sub-flow diagram of another atomic force microscopy method for analyzing electrostatic and force electrical coupling responses according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an atomic force microscope system for analyzing electrostatic and force electric coupling responses according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1 is a schematic flowchart of an atomic force microscopy method for analyzing electrostatic and force electrical coupling response according to an embodiment of the present invention, where the present embodiment is applicable to electrostatic and strain tests on a target sample, and the method may be performed by an atomic force microscopy system for analyzing electrostatic and force electrical coupling response, and specifically includes the following steps:
and 110, synthesizing a plurality of sub-waveforms with different characteristic parameters in the two frequency bands into an excitation signal according to a preset splicing sequence.
When an Atomic Force Microscope (AFM) is used to test various properties of a sample, multiple dynamic and/or static scans are required, multiple test result data are correspondingly collected for processing, and switching between different harmonic scans is relatively long. Because the intrinsic amplitude of the target to be measured is usually very weak, the intrinsic amplitude is easily covered by the system noise of the instrument, and the resonance excitation is needed to amplify the response.
In the embodiment, a high-throughput technology is adopted, a plurality of sub-waveforms are synthesized into the excitation signal according to a preset splicing sequence, the sub-waveforms have different characteristic parameters, the sub-waveforms are sine waves, the different characteristic parameters comprise one or more of different frequencies, different periods, different amplitudes and different phases, and the sequentially synthesized excitation signal comprises a plurality of sub-waveforms with different characteristic parameters, so that the sequentially synthesized excitation signal has multiple testing functions. Furthermore, the frequencies of the sub-waveforms of the synthesized excitation signal all belong to two preset frequency bands, that is, the frequency spectrum range of the excitation signal covers the frequencies corresponding to the bimodal states, and the frequencies of the sub-waveforms are discrete states. The excitation signal synthesized by a plurality of discrete sine waves with frequencies is adopted for testing, so that the test result meeting the precision requirement can be obtained, and meanwhile, compared with a method for testing by adopting continuous frequency wavelets, the test speed is improved. The scanning area is excited by the excitation signal waveform to obtain scanning information of electrostatic response and force-electricity coupling strain response, and the effect of simply and efficiently acquiring large data with high physical correlation is achieved. Meanwhile, excitation energy is concentrated on a plurality of key frequencies, so that the signal to noise ratio is improved, and data redundancy is reduced.
Specifically, the excitation signal for the test is customized according to the resonant frequency interval of the scanned region of the target material, and in the experiment, the "AFM" software is usually used to find the region to be scanned and confirm the resonant frequency interval of the material. Before the excitation signal is synthesized, parameters such as a starting frequency, an ending frequency, a driving voltage, an instrument sampling rate, a fitting point number and the like need to be set in advance to customize the signal, a series of sub-waveforms with equal difference frequency are generated through conversion according to the parameters, and then the generated sub-waveforms with various frequencies are spliced to generate the excitation signal. The intermediate parameters needed in the conversion process are frequency difference interval, cycle number per frequency, phase lag, etc. The excitation signal covers two frequency bands, for example a signal containing first order frequencies and a wavelet signal containing second order frequencies. Because the response intensity is larger when the resonance effect is closer to the eigenfrequency of the sample, the technical scheme provided by the embodiment can better cover each formant frequency section than the traditional other technologies, and therefore more reliable response information can be obtained. Illustratively, the first order frequency bin of the scan region is 330kHZ-360kHZ, and typically 15 frequency bins are used to cover this bin, so the frequency bin is 2kHZ.
And step 120, applying the excitation signal to the target to be detected to obtain bimodal amplitude images of different characteristic parameters of the target to be detected.
The scanning probe applies an excitation signal to a target to be detected to generate a very weak interatomic interaction force, and the cantilever connected with the scanning probe is deformed or the motion state of the cantilever is changed by the interaction force. When a sample is scanned, the sensor is used for detecting the changes, so that the distribution information of the acting force can be obtained, and the surface appearance structure information and the physical information such as current, deformation and the like can be obtained with the nanometer resolution. In this embodiment, the bimodal amplitude image obtained by applying the excitation signal specifically includes: and the response amplitude image of the target to be detected under the action of the probe electric field excitation signal, wherein the contribution is derived from the sum of the electrostatic force response between the target to be detected and the probe and the electric strain response of the target.
Wherein, step 120 specifically includes:
s1, applying the excitation signals to a target to be detected through a probe of an atomic force microscope in sequence to obtain corresponding response signals.
And S2, separating amplitude images corresponding to different characteristic parameters in the response signal.
The random waveform generator converts the generated excitation signal into an analog signal with a preset sampling frequency and sends the analog signal to the scanning microscope probe, and when the excitation signal is converted into the analog signal with the preset sampling frequency, the random waveform generator marks the analog signal, distinguishes different frequency signals at intervals, ensures that the signals do not interfere with each other during excitation and post-processing, and particularly distinguishes and marks different sub-waveforms by blank values with fixed lengths reserved in the middle of the sub-waveforms. The scanning probe sequentially applies the analog signals to the target to be tested, so that the target sample can be scanned once to obtain various test result signals. The test result signals are collected sample response signals, the test result signals respectively generate a plurality of test results according to a preset splicing sequence of the synthesized excitation signals, the type number of the test result signals corresponds to the number of the sub-waveforms with different characteristic parameters, the test results are vibration responses of the probe, and the decoupling results are static and strain attributes of the target sample.
Exemplarily, as shown in fig. 2, the excitation signal is formed by connecting a plurality of discrete sine waves with different frequencies in a time sequence manner within a preset time span, and blank values with fixed lengths are reserved at the junctions of the sub-waveforms with different frequencies constituting the excitation signal for marking, so as to identify response signals generated by different sub-waveforms during post-processing, and ensure that the sub-waveforms with different frequencies do not crosstalk with each other during excitation and post-processing; exciting a sample by a scanning probe according to a plurality of different frequency signals, scanning a target to be detected by the scanning probe in a line sequence, collecting response signals and transmitting the response signals to a post processor, performing segmented cutting and analysis on the collected response signals in different modes by MATLAB software in the post processor, performing reverse solution to obtain corresponding amplitudes and phases, fitting, and finally obtaining amplitude maps and phase maps in different modes.
And step 130, decoupling and reconstructing according to a target decoupling model and the amplitude image of the target to be measured to generate a force-electricity coupling strain image and an electrostatic response image of the target to be measured.
Optionally, step 130 specifically includes:
and 131, demodulating the full-time-domain amplitude response data of the target to be detected to obtain the intrinsic amplitude and the phase of the target to be detected under the condition that the probe applies the excitation signal.
The quantitative decoupling method based on the probe vibration principle and the bimodal big data can accurately reflect the true strain of the material under the induction of the needle tip electric field and the interference of the additional electrostatic force. As shown in fig. 3, the intrinsic amplitude of the material of the target to be measured induced by the electrostatic force of the probe is inversely proportional to the stiffness of the material, and the difference is obvious in different vibration modes, but the intrinsic amplitude caused by the strain is not affected by the intrinsic amplitude. It can also distinguish electrostatic effects due to changes in internal properties of the material, such as those induced by changes in ferroelectric polarization, changes in ion concentration.
And 132, reconstructing the decoupled data by the target decoupling model according to the intrinsic amplitude and the intrinsic phase to obtain a force-electricity coupling strain image and an electrostatic response image of the target to be tested.
Before decoupling, a standard sample periodic lithium niobate (PPLN) is used for calibrating the probe, due to the interference of electrostatic force, domain response in different polarization areas of the PPLN is enhanced, and domain response in some polarization areas is weakened, which is caused by different polarization directions of the different domains, and when the electrostatic force is the same as the polarization direction of the sample, the response is enhanced, and when the directions are opposite, the electrostatic force and the sample polarization directions can be mutually counteracted. The first-order and second-order amplitude distribution is decoupled through a target decoupling model to obtain the amplitude distribution of the piezoelectric response distribution graph, the amplitude distribution accords with the real domain structure distribution, domain areas in different directions have consistent amplitude, and the domain boundary has lower response. And performing decoupling operation on the obtained first-order amplitude and second-order amplitude images according to a target decoupling model to obtain the distribution of the force-electricity coupling strain diagram of the sample. Furthermore, the decoupling according to the target decoupling model can be better used for comparing the electrostatic force response and the force electric coupling strain response of different materials. The amplitudes of the force-electric coupling strain and the electrostatic response in different modes are shown in fig. 4A, 4B and 4C, respectively, and the corresponding amplitudes of the probes in the force-electric coupling strain and the electrostatic force response in different modes are different in proportion to the amplitude of the total response.
The technical scheme of the embodiment of the invention synthesizes a plurality of sub-waveforms with different characteristic parameters in two frequency bands into an excitation signal according to a preset splicing sequence; applying the excitation signal to a target to be detected to obtain bimodal amplitude images corresponding to different characteristic parameters of the target to be detected; decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected to generate a force-electricity coupling strain image and an electrostatic response image of the target to be detected; the problems that the force-electricity coupling strain measurement is easily affected by static electricity and the result is inaccurate are solved, the force-electricity coupling strain image and the static response image of the target to be measured are accurately obtained through the quantitative analysis of the target decoupling model and the bimodal data, the requirement on a specific probe is reduced, and the applicability is improved.
On the basis of the above technical solution, as shown in fig. 5A, before step 110, the method further includes:
and step 100, constructing a decoupling model.
As shown in fig. 5B, the method specifically includes: step 101, calibrating vibration parameters of a probe of the atomic force microscope.
The scanning probe microscope applies an alternating voltage on the conductive probe, the piezoelectric sample generates deformation under the action of an inverse piezoelectric effect under the action of a needle tip electric field, the deformation displacement is enhanced and transmitted to the probe, a signal is enhanced through a resonance amplification effect, and the deformation of the sample is quantified through the displacement change of the laser detector detection probe. While the AFM is measuring, electrostatic interaction is introduced due to the capacitance effect between the probe and the sample, which adds an additional contribution to the probe amplitude. Because the electrostatic effect is obviously influenced by the rigidity of the probe, the vibration parameters of the probe need to be calibrated before the decoupling model is constructed.
Optionally, the vibration parameters include bimodal stiffness and optical lever conversion coefficient of coupling resonance between the probe and the sample to be measured.
According to the probe vibration principle, the rigidity of the probe in different modes under free resonance can be measured through experiments, and then the rigidity in the double modes is obtained through beam theory conversion. The conversion coefficient of the optical lever can be calibrated by measuring the pure electrostatic action or changing the comprehensive position of the laser spot on the cantilever of the AFM probe.
And 102, constructing an initial decoupling model based on the vibration parameters of the probe.
And 103, verifying the reliability of the initial decoupling model based on the measurement data of the atomic force microscope to obtain a target decoupling model.
To verify the effectiveness of the decoupling model, various AFM routine measurements can be used to verify the response magnitude match. The AFM probe is lifted to a plurality of nanometers of the surface of the sample after resonance measurement due to the fact that the electrostatic force is a long-range acting force, and the same excitation signal is applied; at the moment, the probe is in a non-contact state, the vibration of the probe is not influenced by the deformation of the sample, and the amplitude of the vibration is determined by the gradient of pure electrostatic force, so that the electrostatic force can be accurately measured by changing the height of the probe and adding different direct current biases. And finally, the applicability of the decoupling model is tested by adopting probes with different rigidity and different samples, such as lithium iron phosphate, cerium oxide, methylamine lead iodide and the like. And determining the verified decoupling model as a target decoupling model.
Illustratively, the total amplitude response of an AFM measurement consists of both piezoelectric and electrostatic responses when electrostatic forces are present, as shown in equation (1):
wherein A is total As the total response amplitude, A p Is the amplitude of the piezoelectric vibration, A e Amplitude of static electricity, d 33 Is the piezoelectric coefficient, V, of the sample ac Is the tip AC voltage, k is the system stiffness of the probe sample, C' is the capacitance gradient between the tip samples, V dc Is a probe DC voltage, V sp Is the sample surface potential.
In order to obtain the real piezoelectric response of the sample, the dynamic stiffness of the probe is increased along with the increase of the resonance mode by utilizing the multi-order resonance mode property of the probe, and the stiffness of the probe is inversely proportional to the magnitude of the electrostatic response without influencing the piezoelectric strain, so that the total amplitude A of the response from different modes is realized by using the bimodal PFM w1 ，A w2 In-phase decoupling of the true piezoelectric response A p And electrostatic response A e The amplitude response contributions in the different modes are as follows, F e As shown in equations (2) and (3) for the electrostatic force:
calibrating the probe by using a standard sample PPLN to obtain a system parameter invOLS 1 ，invOLS 2 ，k 1 ，k 2 . The piezoelectric coefficient of the PPLN standard sample is a known value d 33 =7.5pm/V, sample is polarized up and down strips arranged in a periodic distributionThe amplitude response of the domains with different polarization directions is the same, the phases are opposite, and the amplitude response at the domain boundary is the lowest. Needle point AC voltage V ac The value of (A) is set at the time of experimental measurement w1 ，A w2 The amplitude values of the probe obtained for different orders were measured for experiments. According to the dynamic stiffness k of the probe under different modes 1 ,k 2 The piezoelectric response can be obtained by the following formula (4):
in the SSPFM (Switching resonance imaging for microscopy) mode, a linear varying dc voltage scan of 0-15V is set, the ac amplitude is 1V, and the first and second order resonance responses of the probe in different polarization regions on the PPLN sample are measured respectively.
And performing linear fitting on the intersecting line segments, wherein the intersecting point is the real piezoelectric amplitude value of the sample, and the amplitude value is obtained by conversion of static invOLS, so that the static invOLS is removed to obtain an original signal, the static invOLS =95.99nm/V is obtained by Cypher ES through thermal noise test calibration. Then, invOLS1 and invOLS2 in different resonance modes are recalculated through the piezoelectric coefficient d33 known by the standard sample, as shown in formulas (5) and (6):
from the above formula, invOLS1=51.166nm/V and invOLS2=126.711nm/V are obtained.
And then the ratio β of the dynamic stiffness k2 to k1 can be obtained through the slope b1=5.4264pm/V of the fitting line segment of the first-order mode and the second-order mode, and b2=0.223pm/V, as shown in formula (7):
β =6.5 was obtained.
Therefore, all system parameters are calibrated, amplitude response values in a first-order mode and a second-order mode are obtained only through experimental tests, and the real piezoelectric response contribution can be separated through a decoupling formula.
On the basis of the above technical solution, the substep S2 in the step 120 preferably comprises:
s21, demodulating the full-time-domain vibration response signals under different characteristic parameters to obtain characteristic information of the target to be measured under different characteristic parameters and different modes.
Because the arbitrary waveform generator marks the analog signal and distinguishes the signal intervals corresponding to different characteristic parameters, the obtained full-time-domain vibration response signal under different characteristic parameters can obtain the corresponding characteristic information of the target to be detected under different characteristic parameters and different modes after demodulation. The characteristic information includes one or more of amplitude, phase shift, resonance frequency, quality factor, and the like.
And S22, obtaining bimodal amplitude images correspondingly contained in the target to be detected under different characteristic parameters according to the characteristic information and a preset fitting algorithm.
Respectively drawing the obtained characteristic information corresponding to each pixel point under different characteristic parameters to a complex plane, fitting by using a corresponding physical model to obtain the intrinsic amplitude and the phase of the target to be detected, and reconstructing to generate an amplitude diagram and a phase diagram corresponding to the bimodal mode.
Example two
Fig. 6 is an atomic force microscope system for analyzing electrostatic and force electric coupling responses according to an embodiment of the present invention. As shown in fig. 6, an atomic force microscopy system for resolving an electrostatic and force-electrical coupling response, comprising:
and a signal generating module 510, configured to synthesize multiple sub-waveforms with different characteristic parameters in two frequency bands into an excitation signal according to a preset splicing order.
When an Atomic Force Microscope (AFM) is used to test various properties of a sample, multiple dynamic and/or static scans are required, multiple test result data are correspondingly collected for processing, and switching between different harmonic scans is relatively long. Because the intrinsic amplitude of the target to be measured is usually very weak, it is easily covered by the system noise of the instrument, and the resonance excitation is needed to amplify the response.
In the embodiment, a high-throughput technology is adopted, a plurality of sub-waveforms are synthesized into the excitation signal according to a preset splicing sequence, the sub-waveforms have different characteristic parameters, the sub-waveforms can be sine waves, the different characteristic parameters comprise one or more of different frequencies, different periods, different amplitudes and different phases, and the sequentially synthesized excitation signal comprises a plurality of sub-waveforms with different characteristic parameters, so that the sequentially synthesized excitation signal has multiple testing functions. Furthermore, the frequencies of the sub-waveforms of the synthesized excitation signal all belong to two preset frequency bands, that is, the frequency spectrum range of the excitation signal covers the frequencies corresponding to the bimodal states, and the frequencies of the sub-waveforms are discrete states. The excitation signal synthesized by a plurality of discrete sine waves with frequencies is adopted for testing, so that the test result meeting the precision requirement can be obtained, and meanwhile, compared with a method for testing by adopting continuous frequency wavelets, the test speed is improved. The scanning area is excited by the excitation signal waveform to obtain scanning information of electrostatic response and force-electricity coupling strain response, and the effect of simply and efficiently acquiring large data with high physical correlation is achieved. Meanwhile, excitation energy is concentrated on a plurality of key frequencies, so that the signal to noise ratio is improved, and data redundancy is reduced.
And an image obtaining module 520, configured to apply the excitation signal to the target to be measured, and obtain bimodal amplitude images of different characteristic parameters of the target to be measured.
The scanning probe applies an excitation signal to a target to be detected to generate a very weak interatomic interaction force, and the cantilever connected with the scanning probe is deformed or the motion state of the cantilever is changed by the interaction force. When a sample is scanned, the sensor is used for detecting the changes, so that the distribution information of the acting force can be obtained, and the surface appearance structure information and the physical information such as current, deformation and the like can be obtained with the nanometer resolution. In this embodiment, the bimodal amplitude image obtained by applying the excitation signal specifically includes: and the electrostriction of the target to be detected under the action of the probe excitation signal responds to the amplitude image, and the electrostatic force between the target to be detected and the probe responds to the amplitude image.
The excitation signal is formed by connecting a plurality of discrete sine waves with frequencies in a time sequence mode in a preset time span, blank values with fixed lengths are reserved at the connection positions of the sub-waveforms with different frequencies forming the excitation signal for marking, response signals generated by different sub-waveforms are identified during post-processing, and the fact that the sub-waveforms with different frequencies do not interfere with each other during excitation and post-processing is guaranteed; exciting a sample by a scanning probe according to a plurality of different frequency signals, scanning a target to be detected by the scanning probe in a line sequence, collecting response signals and transmitting the response signals to a post processor, performing segmented cutting and analysis on the collected response signals in different modes by MATLAB software in the post processor, performing reverse solution to obtain corresponding amplitudes and phases, fitting, and finally obtaining amplitude maps and phase maps in different modes.
The data processing module 530 is configured to decouple and reconstruct according to a target decoupling model and the amplitude image of the target to be detected, and generate a force-electricity coupling strain image and an electrostatic response image of the target to be detected.
And continuously measuring first-order and second-order modal responses at the same point by synthesizing an excitation signal, completing the bimodal response amplitude in-situ scanning of the whole region, extracting a first-order amplitude image and a second-order amplitude image from the original data by an MATLAB program, and performing decoupling operation according to a target decoupling model to obtain the piezoelectric response image distribution of a target sample to be tested, namely a test result image of the target to be tested.
Optionally, the atomic force microscopy system for analyzing the electrostatic and force electric coupling response further comprises a decoupling model construction module 500. The decoupling model construction module 500 specifically includes:
and the parameter calibration unit is used for calibrating the vibration parameters of the probe of the atomic force microscope.
While the AFM is measuring, electrostatic interaction is introduced due to the capacitance effect between the probe and the sample, which adds an additional contribution to the probe amplitude. Because the electrostatic effect is obviously influenced by the rigidity of the probe, before a decoupling model is constructed, the vibration parameters of the probe need to be calibrated. Optionally, the vibration parameter includes bimodal stiffness and optical lever conversion coefficient of coupling resonance of the probe and the sample to be measured.
According to the probe vibration principle, the rigidity of the probe in different modes under free resonance can be measured through experiments, and then the rigidity in the double modes can be obtained through beam theory conversion. The conversion coefficient of the optical lever can be calibrated by measuring the pure electrostatic action or changing the comprehensive position of the laser spot on the cantilever of the AFM probe.
And the initial model construction unit is used for constructing an initial decoupling model based on the vibration parameters of the probe.
And the model verification unit is used for verifying the reliability of the initial decoupling model based on the measurement data of the atomic force microscope to obtain a target decoupling model.
To verify the effectiveness of the decoupling model, various AFM routine measurements can be used to verify the response magnitude match. The AFM probe is lifted to a plurality of nanometers of the surface of the sample after resonance measurement due to the fact that the electrostatic force is a long-range acting force, and the same excitation signal is applied; at the moment, the probe is in a non-contact state, the vibration of the probe is not influenced by the deformation of the sample, and the amplitude of the vibration is determined by the gradient of pure electrostatic force, so that the electrostatic force can be accurately measured by changing the height of the probe and adding different direct current biases. And finally, the applicability of the decoupling model is tested by adopting probes with different rigidity and different samples, such as lithium iron phosphate, cerium oxide, methylamine lead iodide and the like. And determining the verified decoupling model as a target decoupling model.
Optionally, the image acquiring module 520 includes:
and the signal testing unit is used for sequentially applying the excitation signals to the target to be tested through a probe of the atomic force microscope to obtain corresponding response signals.
And the image processing unit is used for separating amplitude images corresponding to different characteristic parameters in the response signal.
The scanning probe sequentially applies the sequentially synthesized excitation signals to a plurality of pixel points of a target to be tested, so that a plurality of test result signals can be obtained by one-time scanning of a target sample. The test result signals are collected sample response signals, the test result signals respectively generate a plurality of test results according to a preset splicing sequence of the synthesized excitation signals, the type number of the test result signals corresponds to the number of the sub-waveforms with different characteristic parameters, and the test results are static electricity and strain attributes of the target sample.
Optionally, the image processing unit includes:
and the characteristic information acquisition subunit is used for demodulating the full-time-domain vibration response signals under different characteristic parameters to obtain the characteristic information of the target to be detected under different characteristic parameters and different modes.
The AWG marks the analog signals and distinguishes signal intervals corresponding to different characteristic parameters, so that the obtained full-time-domain vibration response signals under different characteristic parameters can obtain the corresponding characteristic information of the target to be detected under different characteristic parameters and different modes after demodulation. The characteristic information includes one or more of amplitude, phase shift, resonance frequency, quality factor, and the like.
And the amplitude image generating subunit is used for obtaining the bimodal amplitude images corresponding to the target to be detected under different characteristic parameters according to the characteristic information and a preset fitting algorithm.
And respectively drawing the obtained characteristic information corresponding to each pixel point under different characteristic parameters to a complex plane, fitting by using a corresponding physical model to obtain the intrinsic amplitude and phase of the target to be detected, and reconstructing to generate an amplitude diagram and a phase diagram corresponding to different modes.
Optionally, the data processing module 530 includes:
and the intrinsic characteristic acquisition unit is used for demodulating the full-time-domain amplitude response data of the target to be detected to obtain the intrinsic amplitude and the phase of the target to be detected under the condition that the probe applies the excitation signal.
The quantitative decoupling method based on the probe vibration principle and the bimodal big data can accurately reflect the real strain of the material under the induction of the needle tip electric field and the interference of the additional electrostatic force.
And the result acquisition unit is used for reconstructing the decoupled data by the target decoupling model according to the intrinsic amplitude and the intrinsic phase to obtain a force-electricity coupling strain image and an electrostatic response image of the target to be tested.
The first-order and second-order amplitude distribution is decoupled through a target decoupling model to obtain the amplitude distribution of the piezoelectric response distribution graph, the amplitude distribution accords with the real domain structure distribution, domain areas in different directions have consistent amplitude, and the domain boundary has lower response. And performing decoupling operation on the obtained first-order amplitude and second-order amplitude images according to a target decoupling model to obtain the distribution of the force-electricity coupling strain diagram of the sample.
The technical scheme of the embodiment of the invention synthesizes a plurality of sub-waveforms with different characteristic parameters in two frequency bands into an excitation signal according to a preset splicing sequence; applying the excitation signal to a target to be detected to obtain bimodal amplitude images corresponding to different characteristic parameters of the target to be detected; decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected to generate a force-electricity coupling strain image and an electrostatic response image of the target to be detected; the problems that the force-electricity coupling strain measurement is easily affected by static electricity and the result is inaccurate are solved, the force-electricity coupling strain image and the static response image of the target to be measured are accurately obtained through the quantitative analysis of the target decoupling model and the bimodal data, the requirement on a specific probe is reduced, and the applicability is improved.
The atomic force microscope system for analyzing the electrostatic and force-electric coupling response provided by the embodiment of the invention can execute the atomic force microscope method for analyzing the electrostatic and force-electric coupling response provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects of the execution method.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. An atomic force microscopy method for analyzing electrostatic and force-electric coupling responses, comprising:
synthesizing a plurality of sub-waveforms with different frequencies in two frequency bands into an excitation signal according to a preset splicing sequence;
applying the excitation signal to a target to be detected to obtain bimodal amplitude images corresponding to different frequencies of the target to be detected;
decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be measured, and generating a force-electricity coupling strain image and an electrostatic response image of the target to be measured.
2. The atomic force microscopy method for analyzing electrostatic and force-electric coupling response of claim 1, wherein before the step of synthesizing the excitation signal by the plurality of sub-waveforms having different frequencies in two frequency bands according to the predetermined splicing sequence, further comprising: constructing a decoupling model; the constructing of the decoupling model comprises:
calibrating vibration parameters of a probe of the atomic force microscope;
constructing an initial decoupling model based on the vibration parameters of the probe;
and verifying the reliability of the initial decoupling model based on the measurement data of the atomic force microscope to obtain a target decoupling model.
3. The atomic force microscopy method for analyzing electrostatic and force-electric coupling response of claim 2, wherein the vibration parameters of the probe comprise bimodal stiffness and optical lever conversion coefficient of coupling resonance of the probe and the sample to be tested.
4. The atomic force microscopy method of resolving an electrostatic and force electrical coupling response of claim 1, wherein a spectral range of the excitation signal covers frequencies corresponding to the bimorph.
5. The atomic force microscopy method for analyzing electrostatic and force-electric coupling response of claim 1, wherein the step of applying the excitation signal to the object to be measured to obtain bimodal amplitude images corresponding to different characteristic frequencies of the object to be measured comprises:
sequentially applying the excitation signal to a target to be detected through a probe of an atomic force microscope to obtain a corresponding response signal;
and separating amplitude images corresponding to different frequencies in the response signal.
6. The atomic force microscopy method for analyzing electrostatic and force electrical coupling response of claim 5, wherein the separating the amplitude images corresponding to different frequencies in the response signal comprises:
demodulating the full-time-domain vibration response signals under different frequencies to obtain characteristic information of the target to be detected under different frequencies and different modes;
and obtaining bimodal amplitude images correspondingly contained in the target to be detected under different frequencies according to the characteristic information and a preset fitting algorithm.
7. The atomic force microscopy method for analyzing electrostatic and force-electric coupling response of claim 1, wherein the decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be measured to generate the force-electric coupling strain image and the electrostatic response image of the target to be measured comprises:
demodulating the full-time-domain amplitude response data of the target to be detected to obtain the intrinsic amplitude and the phase of the target to be detected under the condition that the probe applies an excitation signal;
and reconstructing the decoupled data by the target decoupling model according to the intrinsic amplitude and the intrinsic phase to obtain a force-electricity coupling strain image and an electrostatic response image of the target to be tested.
8. An atomic force microscopy system for resolving an electrostatic and force-electric coupled response, comprising:
the signal generating module is used for synthesizing a plurality of sub-waveforms with different frequencies in two frequency bands into an excitation signal according to a preset splicing sequence;
the image acquisition module is used for applying the excitation signal to a target to be detected and acquiring bimodal amplitude images corresponding to different frequencies of the target to be detected;
and the data processing module is used for decoupling and reconstructing according to a target decoupling model and the bimodal amplitude image of the target to be detected, and generating a force-electricity coupling strain image and an electrostatic response image of the target to be detected.
9. The atomic force microscopy system for resolving an electrostatic and force electrical coupling response of claim 8, further comprising: a decoupled model construction module comprising:
the parameter calibration unit is used for calibrating the vibration parameters of the probe of the atomic force microscope;
an initial model construction unit, which is used for constructing an initial decoupling model based on the vibration parameters of the probe;
and the model verification unit is used for verifying the reliability of the initial decoupling model based on the measurement data of the atomic force microscope to obtain a target decoupling model.
10. The atomic force microscopy system for resolving electrostatic and force-electric coupling responses of claim 8, wherein the data processing module comprises:
the intrinsic characteristic acquisition unit is used for demodulating the full-time-domain amplitude response data of the target to be detected to obtain the intrinsic amplitude and the phase of the target to be detected under the condition that the probe applies an excitation signal;
and the result acquisition unit is used for reconstructing the decoupled data by the target decoupling model according to the intrinsic amplitude and the intrinsic phase to obtain a force-electricity coupling strain image and an electrostatic response image of the target to be tested.
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Non-Patent Citations (1)
| Title |
|---|
| Spatially Resolved Electrochemical Strain of Solid-State Electrolytes via High Resolution Sequential Excitation and Its Implication on Grain Boundary Impedance;Junxi Yu 等;《Small <ethod》;20200914;全文 * |
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