CN107228957B - The system that AFM signal is measured using the current signal of STM - Google Patents
The system that AFM signal is measured using the current signal of STM Download PDFInfo
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- CN107228957B CN107228957B CN201610178483.3A CN201610178483A CN107228957B CN 107228957 B CN107228957 B CN 107228957B CN 201610178483 A CN201610178483 A CN 201610178483A CN 107228957 B CN107228957 B CN 107228957B
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
- G01Q60/02—Multiple-type SPM, i.e. involving more than one SPM techniques
- G01Q60/04—STM [Scanning Tunnelling Microscopy] combined with AFM [Atomic Force Microscopy]
Abstract
The present invention discloses a kind of system that the current signal using STM measures AFM signal, can be measured using the current signal of STM to AFM signal.The system specifically includes that mechanics sensor, high bandwidth current amplifier, non-sine periodic signal processing module, AFM amplitude collector, AFM frequency collection device, current collector, multiplier, low-pass filter, PI control module, voltage controlled oscillator, amplitude control module, difference frequency output module and z control module.In Figure of abstract using tuning-fork-type micro-cantilever as mechanics sensor for provide technical schematic diagram: make micro-cantilever with frequency f first with voltage controlled oscillator0Concussion.Sample making alive, guide line obtains the tunnel current between tip-sample on needle point, obtains real-time tunnel current through high bandwidth current amplifier, is inputted non-sine periodic signal processing module, subsequent analysis obtains AFM amplitude A1, frequency fsample, STM tunnel current；And then tunnel current or Δ f is used to realize scanning as feedback.
Description
Technical field
The present invention relates to Scanning probe technique fields, and in particular to a kind of current signal using STM carries out AFM signal
The system of measurement.
Background technique
Scanning probe technique (SPM) is the general name of a kind of microscopy, is grown up on the basis of STM, main point
For STM and AFM.First scanning tunneling microscope came out in 1981, its appearance is so that people for the first time can be with direct detection object
The atomic arrangement and its electronic behavior in body surface face, for physics, materialogy, Surface Science, microelectronic processing technique, chemistry and
Life science etc. has great significance.The basic principle of STM is quantum tunnel caused by the duality principle due to particle
It is V that the particle that channel effect, i.e. energy are E, quality is m, which is incident to height,0Potential barrier when, in particle energy E < V0In the case where, grain
The transmission probability of son is not zero.Due to tunnel-effect, when probe and sample to be tested surface spacing z very little (< 1nm), in addition voltage V
Afterwards, there will be electric current generation, here it is tunnel currents.
STM has the advantages that many surface analysis instruments cannot compare, but it is limited only to semiconductor and metal sample
It measures.In order to make up STM, this is insufficient, and AFM is born within 1985.AFM is by between detection sample and the atom of needle point
Interaction force obtains the technology of sample surface information.The research object of AFM includes conductor, semiconductor and insulator；Molten
It also can measure in liquid.According to needle point-sample interval when scanning from difference, AFM operating mode is divided into following three kinds: contact mould
Formula (contact), amplitude modulation AFM (AM-AFM, or make tapping mode), warbled AFM (FM-AFM) or
NC-AFM)。
Determine that the component of resolution ratio is force snesor in AFM.After AFM invention shortly useful quartz tuning-fork as power
The research of sensor.The quartz tuning-fork probe system of early stage is all fixed tuning fork base portion, and two-arm is hanging, and tuning fork two-arm is when vibration
Symmetrical reversal of vibrations state, has very high quality factor, but its imaging signal can not go to explain with theory.In order to solve
One whole arm of quartz tuning-fork is fixed on sapphire pedestal by above-mentioned technical problem, F.J.Giessibl proposition in 1998, and
Another arm sling is empty, is equivalent to the micro-cantilever of conventional atom force microscope probe system, i.e. qPlus technology.Then by the tungsten of corrosion
Needle is vertically bonded in hanging prong front end for scanning sample by insulating cement.
QPlus technology can measure the frequency shift (FS) of the average tunnel current and tuning fork micro-cantilever of sample, energy consumption simultaneously
It dissipates.Its technical schematic diagram is shown in Fig. 1: in tungsten tip, (tip is tungsten tip, U in Fig. 1sFor power supply) on draw conducting wire and obtain needle
Tunnel current (I can be obtained through current amplifier amplification in point-sample room tunnel currentt) average valueIt can useMake
For feedback.At the same time, tuning fork micro-cantilever vibration frequency f is given using voltage controlled oscillator0Pumping signal, micro-cantilever is in sample table
Face is changed by sample-needle point interaction frequency, the voltage signal V acquired on micro-cantileverTSIt can reflect this variation.It will
Ac voltage signal VTSAmplified by voltage amplifier, extracts needle point in the vibration frequency f of sample surfacessample, f can be used0
With fsampleDifference Δ f as feedback.In order to avoid needle point and sample collide, voltage signal is output to amplitude control simultaneously
Molding block is compared with setting value, so that needle point is kept to have certain amplitude in sample surfaces.
Although qPlus technology has while implementing the ability of STM and AFM, in actual application, always by two moulds
Formula separately carries out.Tracing it to its cause is average tunnel currentAnd the frequency shift (FS) Δ f and energy dissipation three of tuning fork micro-cantilever
Between the problems such as crosstalk (Crosstalk) can occur.Several qPlus AFM problems faceds are set forth below:
(1) precise measurement of dissipative force between tip-sample how is realized.It is mostly at present that piezoelectricity is utilized to make pottery to the excitation of needle point
Porcelain mechanical excitation causes the efficiency of excitation very low due to the presence of matrix (base) huge behind cantilever beam.It is shaken similar to exerting oneself
Dynamic bed rearrangement mountain is intended merely to that a bar on mountain top is allowed to vibrate.Which results in the presence of dissipative force, and the size of dissipative force is not
Know.
(2) crosstalk between alternation charge signal and the current signal of STM needed for AFM.Due to signal amplifier totally,
The influence of capacitor and parasitic capacitance between needle point and tuning fork, leads in qPlus technology while implementing STM and AFM has
Signal cross-talk, the method for common reduction crosstalk are to implement STM and AFM respectively, this undoubtedly reduces working efficiency.
(3) selection fed back.In qPlus technology, average tunnel current both can chooseIt does and feeds back, also can choose
Frequency shift (FS) Δ f, which is done, to be fed back, such as Fig. 1.Wherein Δ f reflects sample-needle point interaction force Fts, FtsAs the reduction of z is first
It is quicklyd increase after slowly reducing, there is nonmonotonicity, the damage of needle point is easy to cause as feedback.With monotonicity, but with
The reduction of sample-needle point spacing continue to increase, current amplifier will soon be made to reach saturation.Therefore, the selection of feedback is
One of problem in qPlus technology.The operating mode of qPlus is utilized at STM at presentAfter the pattern for scanning sample,
It is scanned under AFM mode using constant height mode, obtains Δ f with the variation of position, but working efficiency in this way is low, and constant height mode
There is many-sided limitation to research work.
(4) limitation of working environment.Due to the presence of crosstalk, the realization of qPlus technology need successively to carry out AFM and
STM avoids hot drift in order to which the same area to sample surfaces measures, it is desirable that working environment is under liquid helium temperature.The technology is such as
It is a greatly challenge that, which moves towards liquid nitrogen/room temperature even atmospheric environment,.
(5) higher resolution ratio how is realized.How the resolution ratio of qPlus just can be further improved in atom level at present
Resolution ratio obtains the resolution of atomic orbital grade.This needs to further decrease tip vibration amplitude, improves the stability of instrument, reduces noise
Than.
Summary of the invention
For the defects in the prior art, the embodiment of the present invention provide a kind of current signal using STM to AFM signal into
The system of row measurement, specifically includes that
Mechanics sensor, high bandwidth current amplifier, non-sine periodic signal processing module, AFM amplitude collector, AFM
Frequency collection device, current collector, multiplier, low-pass filter, PI control module, voltage controlled oscillator, phase regulator, Gain
Controller, amplitude control module, frequency difference output module and z control module；
Wherein, by the tunneling current signal collected at mechanics sensor input the high bandwidth current amplifier into
Amplified tunnel current is then inputted the non-sine periodic signal processing module analysis and handled by row amplification；
First output end of the non-sine periodic signal processing module connects the AFM amplitude collector, after analysis
The amplitude A of AFM signal can be obtained1, the A that will collect1It is input to the amplitude control module, amplitude control module is for controlling
A processed1Size and setting value AsetIt is consistent, the output of the amplitude control module connects the Gain controller,
The second output terminal of the non-sine periodic signal processing module connects the AFM frequency collection device, after analysis
Afm tip is obtained in the vibration frequency signal f of sample surfacessample, the AFM frequency collection device connects the of the multiplier
One input terminal, the second input terminal of the multiplier connect the output end of the voltage controlled oscillator, and multiplier is used for the AFM
The output signal of frequency collection device and the output signal of the voltage controlled oscillator do multiplying, after be successively transferred to the low pass
Filter, the PI control module, signal is divided into two-way here, and signal is used to motivate the control of ceramics all the way, specifically: it is described
PI control module connects the voltage controlled oscillator, and the voltage controlled oscillator output connects the input terminal of the phase regulator, institute
The output end for stating phase regulator connects the input terminal of the Gain controller, and the output end of the Gain controller connects excitation
Ceramics.The voltage controlled oscillator exports the high-frequency signal for motivating piezoelectric ceramic oscillator, by phase regulator and described
The adjusting of Gain controller, ultimately generates pumping signal, wherein the phase regulator is for adjusting voltage controlled oscillator output letter
Number phase；The excitation ceramics of the Gain controller connection AFM mechanics sensor, for adjusting the phase regulator output
The gain of signal, and the signal after gain adjustment is transmitted to the excitation ceramics, another way signal is for obtaining frequency shift (FS)
Δ f, the specially signal of PI control module and voltage controlled oscillator input the difference frequency output module jointly, and it is defeated to obtain frequency shift (FS)
Enter to z control module,
The third output end of the non-sine periodic signal processing module connects the current collector, obtains after analysis
Tunneling current signal of STM, such as maximum value, minimum value, the average current of tunnel current etc., the current collector connect z
Control, using tunneling current signal as value of feedback, the z control module connects the direction AFM z piezoelectric ceramics, for according to difference frequency
Output module and the signal of current collector output, which generate, controls the control signal that the piezoelectric ceramics moves in the direction z,
And it is transmitted to the piezoelectric ceramics, for controlling needle point and sample interval.
1. beneficial effect
The system that current signal provided in an embodiment of the present invention using STM measures AFM signal, passes through high bandwidth
Current amplifier obtain real-time tunnel current.Since probe does sinusoidal motion, tip-sample gap periods in sample surfaces
Variation, real-time tunnel current is non-sinusoidal periodicity signal, therefrom can extract vibration frequency of the needle point in sample surfaces, amplitude
With phase etc..It uses needle point frequency signal or tunnel current as feedback quantity, can be realized the scanning of long-time closed loop.Due to can be with
The signal of AFM is obtained by the tunnel current of STM, the extraction of data can be completed with single sweep operation, this makes it possible to need not
It works under liquid helium environment, while can be improved scan efficiency compared to the prior art.And due to not needing under constant height mode
Scanning, because without having excessive limitation to research work；The present invention, can be using electricity due to not needing detection charge signal
Energisation mode/electro-detection mode, so as to realize higher spatial resolution and energy consumption with the work of smaller detection amplitude
Scattered signal accurately detecting.
2. principle summary
The quasi- detection that AFM signal is realized based on STM current signal of this patent.The basic principle is that: by conductive pinpoint with absolutely
Edge is adhesive on AFM mechanics sensor, to constant bias is applied between needle point and sample, with alternating voltage driving micro-cantilever vibration
It is dynamic, tunnel current I is measured using needle pointt(t,z).By non-sinusoidal periodicity It(t, z) is by high bandwidth current amplifier input week
Phase waveform analyzer (PWA), analysis obtain tunneling current signal (average current, peak point current etc.) or vibration signal (frequency, vibration
Width etc.) it is used as feedback quantity, to realize that long-time closed loop scans.
For ease of description, we are illustrated using the tuning fork micro-cantilever in qPlus as mechanics sensitive detection parts below.To micro- outstanding
One, arm excitation, makes it with frequency f0Concussion.To constant bias is applied between needle point and sample, when its spacing z enters tunnel
Distance has tunnel current.The size and z exponent function relation of tunnel current:
WhereinM is mass particle, and Φ is work function,For Planck's constant, I0It is needle point and sample
The density of states function.Real-time tunnel current I is obtained by the galvo-preamplifier of high bandwidtht(t,z).By It(t, z) at any time
Between be averaged, available average tunnel current is used as feedback.Simultaneously because probe does sinusoidal motion in sample surfaces,
It is measured in the same position, It(t, z) will have the period since tip-sample gap periods change, and therefrom can extract
Vibration frequency f of the needle point in sample surfaces outsample.According to the difference of tunnel current and minimum tunnel current maximum in a cycle
Not, the amplitude of needle point can be obtained.Therefore, all information under AFM mode be can be obtained by only by tunnel current.
3. the core technology of current core limitation and this patent:
Core technology limitation at present essentially consists in the real-time acquisition and subsequent analysis of tunnel current.Due to tip-sample
Between tunnel current usually need the band of preamplifier in 1pA-100nA magnitude to guarantee to obtain tunnel current in real time
It is wide bigger.But the maximum bandwidth of current current amplifier is 1.1kHz, our demand is far not achieved.
To solve the above problems, we intend the current amplifier of oneself design research and development high bandwidth, early period, we put in electric current
International most advanced level is had reached in the research and development of big device and charge amplifier, the research and development of the current amplifier of more high bandwidth are
Progress in.It will be carried out the real-time of non-sinusoidal periodicity tunneling current signal using the current amplifier of high bandwidth directly to mention
It takes.It after signal extraction, needs further to analyze, can just obtain average tunnel current, maximum tunnel current, minimum tunnel current
And the frequency of tunnel current, we will be realized using non-sine periodic signal analysis module.The tunneling current signal that will be obtained
(average current, peak point current etc.) or vibration signal (frequency, amplitude etc.) are used as feedback quantity, can be realized long-time closed loop and sweep
It retouches.
In addition, above-mentioned technology dissipates and believes with measurement in spatial resolution compared to current existing qPlus-STM/AFM
There is big advantage on number.QPlus-STM/AFM uses mechanical excitation/charge detection mode at present, rather than uses electric shock
Encourage/electro-detection mode, the mainly cross-interference issue to avoid electric excitation signal and charge signal.In this patent, due to not needing
Charge signal is detected, therefore electric excitation mode/electro-detection mode can be used, so as to be worked with smaller detection amplitude,
Realize higher spatial resolution and energy dissipation signals accurately detecting.
4. theory analysis
It is motivated to micro-cantilever one, makes it in a free state with frequency f0Concussion, when needle point is close to sample, needle point
Vibration mode are as follows:
A1=A1sinω1t (2)
Wherein ω1=2 π fsample。A1It is Oscillation Amplitude of the needle point in sample surfaces.At this point, even if needle point is in constant current mode
The interval z of lower work, tip-sample can also be changed over time:
Z=z0+A1sinω1t (3)
Wherein z0It is mean place of the needle point apart from sample.To constant bias is applied between needle point and sample, when therebetween
Away from tunnel distance is entered, tunnel current is had.Formula 3 is substituted into formula 1, obtains tunnel current:
The schematic diagram of the above triadic relation such as Fig. 3.By It(t,z0) do the average tunnel current averagely obtained at any time and can make
It is used for feedback.Or by It(t,z0) in the part that does not change over timeIt takes out, maximum tunnel current It(t,
z)maxIt takes out, can be used as feedback and use.From It(t,z0) in can be easy to extract needle point in the vibration frequency of sample surfaces
fsample, frequency shift (FS) Δ f=f then can be obtainedsample-f0。
We discuss the method for obtaining afm tip amplitude below: measuring in the same position, i.e., by z0It remains unchanged, It
The maximum value and minimum value of (t, z) will be respectively as follows:
It is hereby achieved that the amplitude A of needle point1And z0It is respectively as follows:
I.e. by It(t, z) does the tunnel current that can must averagely be averaged at any time, by ItThe ratio between the maximum value and minimum value of (t, z)
Take logarithm that can obtain amplitude of the needle point near sample.
5. further technology extension:
The scalability of technology based on STM current signal measurement AFM signal in the present invention is very strong, subsequent to be expected to following
Several directions further expand:
(1) imaging of second differential conductance.Technology Roadmap according to fig. 2, may be implemented differential conductance (dI/dV) at
Picture.The imaging of second differential conductance can be realized using Phase Lock Technique, thus obtain the vibration information of chemical bond.
(2) scanning potential imaging.Add exchange (AC) bias again between tip-sample, adjusts the direct current (DC) on needle point
Voltage realizes compensation, the imaging of scanning potential can be achieved at the same time, it is hereby achieved that the work function information of sample.
(3) this technology can be in the measurement of lower constant current source module.Traditional qPlus is that it is inclined to obtain frequency under constant height mode
It moves；In technology proposed by the invention, it can be measured under constant current mode and (maintain electric current constant, between detection tip-sample
The variation of voltage), therefore some new functions may be implemented.
Detailed description of the invention
Fig. 1 is the signal functional block diagram of existing q-plus AFM；
Fig. 2 is that the present invention is based on the technology signal functional block diagrams that STM current signal realizes AFM signal measurement；
Fig. 3 is that needle point amplitude, sample and needle point spacing and tunnel current change with time figure in the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical solution in the embodiment of the present invention is explicitly described, it is clear that described embodiment is the present invention
A part of the embodiment, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art are not having
Every other embodiment obtained under the premise of creative work is made, shall fall within the protection scope of the present invention.
Referring to Fig. 2, the present embodiment discloses a kind of system that the current signal using STM measures AFM signal, packet
It includes:
Mechanics sensor, high bandwidth current amplifier, non-sine periodic signal processing module, AFM amplitude collector, AFM
Frequency collection device, current collector, multiplier, low-pass filter, PI control module, voltage controlled oscillator, phase regulator, Gain
Controller, amplitude control module, frequency difference output module and z control module,
Wherein, by the tunneling current signal collected at mechanics sensor input the high bandwidth current amplifier into
Amplified tunnel current is then inputted the non-sine periodic signal processing module analysis and handled by row amplification,
First output end of the non-sine periodic signal processing module connects the AFM amplitude collector, after analysis
The amplitude A of AFM signal can be obtained1, the A that will collect1It is input to the amplitude control module, amplitude control module is for controlling
A processed1Size and setting value AsetIt is consistent, the output of the amplitude control module connects the Gain controller,
The second output terminal of the non-sine periodic signal processing module connects the AFM frequency collection device, after analysis
Afm tip is obtained in the vibration frequency signal f of sample surfacessample, the AFM frequency collection device connects the of the multiplier
One input terminal, the second input terminal of the multiplier connect the output end of the voltage controlled oscillator, and multiplier is used for the AFM
The output signal of frequency collection device and the output signal of the voltage controlled oscillator do multiplying, after be successively transferred to the low pass
Filter, the PI control module, signal is divided into two-way here, and signal is used to motivate the control of ceramics all the way, specifically: it is described
PI control module connects the voltage controlled oscillator, and the voltage controlled oscillator output connects the input terminal of the phase regulator, institute
The output end for stating phase regulator connects the input terminal of the Gain controller, and the output end of the Gain controller connects excitation
Ceramics.The voltage controlled oscillator exports the high-frequency signal for motivating piezoelectric ceramic oscillator, by phase regulator and described
The adjusting of Gain controller, ultimately generates pumping signal, wherein the phase regulator is for adjusting voltage controlled oscillator output letter
Number phase；The excitation ceramics of the Gain controller connection AFM mechanics sensor, for adjusting the phase regulator output
The gain of signal, and the signal after gain adjustment is transmitted to the excitation ceramics.Another way signal is for obtaining frequency shift (FS)
Δ f, the specially signal of PI control module and voltage controlled oscillator input the difference frequency output module jointly, and it is defeated to obtain frequency shift (FS)
Enter to z control module,
The third output end of the non-sine periodic signal processing module connects the current collector, obtains after analysis
Tunneling current signal of STM, such as maximum value, minimum value, the average current of tunnel current etc., the current collector connect z
Control, using tunneling current signal as value of feedback, the direction the z piezoelectric ceramics of the z control module connection AFM, for according to difference
Frequency output module and the signal of current collector output, which generate, controls the control letter that the piezoelectric ceramics moves in the direction z
Number, and it is transmitted to the piezoelectric ceramics, for controlling needle point and sample interval.
According to the difference of tunnel current and minimum tunnel current maximum in a cycle, the amplitude of needle point can be obtained.It is based on
Non-sine periodic signal processing module, can measure obtain physical quantity have: the vibration frequency of sample surfaces afm tip, amplitude,
Phase；Real-time tunnel current, average current, maximum/minimum electric current and shape of sample etc..These parameters are further divided
Analysis, can be obtained atom level structure, density of electronic states, band structure and differential conductance of sample surfaces etc..Therefore, only by tunnel
Road electric current can be obtained by all information under AFM mode.
In addition, above-mentioned technology dissipates and believes with measurement in spatial resolution compared to current existing qPlus-STM/AFM
There is big advantage on number.QPlus-STM/AFM uses mechanical excitation/charge detection mode at present, rather than uses electric shock
Encourage/electro-detection mode, the mainly cross-interference issue to avoid electric excitation signal and charge signal.In the present invention, due to not needing
Charge signal is detected, therefore electric excitation mode/electro-detection mode can be used, so as to be worked with smaller detection amplitude,
Realize higher spatial resolution and energy dissipation signals accurately detecting.
The system that current signal provided in an embodiment of the present invention using STM measures AFM signal, passes through high bandwidth
Current amplifier obtain real-time tunnel current, and since probe in sample surfaces does sinusoidal motion, due to tip-sample interval
Cyclically-varying and there is the period, non-sine, which can be obtained, has periodic real-time tunnel current, therefrom can extract needle point and exists
Therefore vibration frequency, amplitude and phase of sample surfaces etc. pass through the frequency information under the available AFM mode of tunnel current；
It uses needle point frequency signal or tunnel current as feedback quantity, can be realized the scanning of long-time closed loop.Due to that can pass through STM's
Tunnel current obtains the signal of AFM, the extraction of data can be completed with single sweep operation, this allows for possibility need not be under liquid helium temperature
Work；It does not need to implement STM and AFM respectively, to can be improved scan efficiency compared to the prior art；And due to not needing
It is scanned under constant height mode, because without having excessive limitation to research work.
Optionally, another embodiment of system AFM signal measured using the current signal of STM in the present invention
In, the electric current is average tunnel current, maximum tunnel current or minimum tunnel current.
Optionally, another embodiment of system AFM signal measured using the current signal of STM in the present invention
In, the non-sine periodic signal processing module determines the amplitude A of AFM signal1Calculation formula beIts
In,M is mass particle, and Φ is work function,For Planck's constant, ImaxFor the maximum value of tunnel current,
IminFor the minimum value of tunnel current.
Optionally, another embodiment of system AFM signal measured using the current signal of STM in the present invention
In, the band of the high bandwidth current amplifier is wider than the vibration frequency of mechanics sensor.
Optionally, another embodiment of system AFM signal measured using the current signal of STM in the present invention
In, the non-sine periodic signal processing module is periodic waveform analyzer.
Although the embodiments of the invention are described in conjunction with the attached drawings, but those skilled in the art can not depart from this hair
Various modifications and variations are made in the case where bright spirit and scope, such modifications and variations are each fallen within by appended claims
Within limited range.
Claims (5)
1. a kind of system that the current signal using STM measures AFM signal, which is characterized in that specifically include that
Mechanics sensor, high bandwidth current amplifier, non-sine periodic signal processing module, AFM amplitude collector, AFM frequency
Collector, current collector, multiplier, low-pass filter, PI control module, voltage controlled oscillator, phase regulator, Gain control
Device, amplitude control module, difference frequency output module and z control module；
Wherein, the tunneling current signal collected at mechanics sensor the high bandwidth current amplifier is inputted to put
Greatly, amplified tunnel current is then inputted the non-sine periodic signal processing module analysis to handle,
First output end of the non-sine periodic signal processing module connects the AFM amplitude collector, can obtain after analysis
To the amplitude A of AFM signal1, the A that will collect1It is input to the amplitude control module, amplitude control module is for controlling A1
Size and setting value AsetIt is consistent, the output of the amplitude control module connects the Gain controller,
The second output terminal of the non-sine periodic signal processing module connects the AFM frequency collection device, obtains after analysis
Vibration frequency signal f of the afm tip in sample surfacessample, it is first defeated to connect the multiplier AFM frequency collection device
Enter end, the second input terminal of the multiplier connects the output end of the voltage controlled oscillator, and multiplier is used for the AFM frequency
The output signal of collector and the output signal of the voltage controlled oscillator do multiplying, after be successively transferred to the low-pass filtering
Device, the PI control module, signal is divided into two-way here, and signal is used to motivate the control of ceramics all the way, specifically: the PI control
Molding block connects the voltage controlled oscillator, and the voltage controlled oscillator output connects the input terminal of the phase regulator, the phase
The output end of position adjuster connects the input terminal of the Gain controller, the output end connection excitation pottery of the Gain controller
Porcelain；The voltage controlled oscillator exports the high-frequency signal for motivating piezoelectric ceramic oscillator, by phase regulator and the Gain
The adjusting of controller, ultimately generates pumping signal, wherein the phase regulator is for adjusting voltage controlled oscillator output signal
Phase；The excitation ceramics of the Gain controller connection AFM mechanics sensor, for adjusting the phase regulator output signal
Gain, and the signal after gain adjustment is transmitted to excitation ceramics；Another way signal is used to obtain frequency shift (FS) Δ f,
Specially the signal of PI control module and voltage controlled oscillator inputs the difference frequency output module jointly, obtains frequency shift (FS) and is input to
Z control module,
The third output end of the non-sine periodic signal processing module connects the current collector, obtains STM after analysis
Tunneling current signal, such as maximum value, minimum value, the average current of tunnel current etc., the current collector connection z control
System, using tunneling current signal as value of feedback, the direction the z piezoelectric ceramics of the z control module connection AFM, for according to difference frequency
Output module and the signal of current collector output, which generate, controls the control signal that the piezoelectric ceramics moves in the direction z,
And it is transmitted to the piezoelectric ceramics, for controlling needle point and sample interval.
2. the system that the current signal according to claim 1 using STM measures AFM signal, which is characterized in that
The electric current is average tunnel current, maximum tunnel current or minimum tunnel current.
3. the system that the current signal according to claim 1 using STM measures AFM signal, which is characterized in that
The non-sine periodic signal processing module determines the amplitude A of AFM signal1Calculation formula beWherein,M is mass particle, and Φ is work function, and h is Planck's constant, ImaxFor the maximum value of tunnel current, IminFor
The minimum value of tunnel current.
4. the system that the current signal according to claim 1 using STM measures AFM signal, which is characterized in that
The band of the high bandwidth current amplifier is wider than the vibration frequency of mechanics sensor.
5. the system that the current signal according to claim 1 using STM measures AFM signal, which is characterized in that
The non-sine periodic signal processing module is periodic waveform analyzer.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0441311A3 (en) * | 1990-02-05 | 1992-02-12 | Hitachi, Ltd. | Surface microscope and surface microscopy |
| US5338932A (en) * | 1993-01-04 | 1994-08-16 | Motorola, Inc. | Method and apparatus for measuring the topography of a semiconductor device |
| JP2004170281A (en) * | 2002-11-21 | 2004-06-17 | Hitachi Ltd | Scanning type local electric current measuring instrument, and thin film device manufacturing apparatus provided with the same |
| CN101329247A (en) * | 2008-02-19 | 2008-12-24 | 中国科学院物理研究所 | Combined microscope for scanning atomic force and tunnel current under atmosphere |
-
2016
- 2016-03-25 CN CN201610178483.3A patent/CN107228957B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0441311A3 (en) * | 1990-02-05 | 1992-02-12 | Hitachi, Ltd. | Surface microscope and surface microscopy |
| US5338932A (en) * | 1993-01-04 | 1994-08-16 | Motorola, Inc. | Method and apparatus for measuring the topography of a semiconductor device |
| JP2004170281A (en) * | 2002-11-21 | 2004-06-17 | Hitachi Ltd | Scanning type local electric current measuring instrument, and thin film device manufacturing apparatus provided with the same |
| CN101329247A (en) * | 2008-02-19 | 2008-12-24 | 中国科学院物理研究所 | Combined microscope for scanning atomic force and tunnel current under atmosphere |
Non-Patent Citations (5)
| Title |
|---|
| Atomic structures of silicene layers grown on Ag (111)_ scanning tunneling microscopy and noncontact atomic force microscopy observations;Andrea Resta et al.;《nature》;20130809;1-6 * |
| Combined AFM and STM measurements of a silicene sheet grown on the Ag (111) surface;Zsolt Majzik et al.;《journal of physics:condensed matter》;20130514;1-10 * |
| QPlus: atomic force microscopy on single-crystal insulators with small oscillation amplitudes at 5 K;Andreas Bettac et al.;《Nanotechnology》;20090610;1-6 * |
| Simultaneous current, force and dissipation measurements on the Si(111) 7×7 surface with an optimized qPlus AFM_STM technique;Zsolt Majzik et al.;《Beilstein J. Nanotechnol》;20120315;249-259 * |
| 基于qPlus 技术的扫描探针显微学研究进展;陈鹏程 等;《科学通报》;20130831;第58卷(第24期);2360-2366 * |
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