CN2392189Y - Scanning channel telscope work function information imaging device - Google Patents
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- CN2392189Y CN2392189Y CN 99250257 CN99250257U CN2392189Y CN 2392189 Y CN2392189 Y CN 2392189Y CN 99250257 CN99250257 CN 99250257 CN 99250257 U CN99250257 U CN 99250257U CN 2392189 Y CN2392189 Y CN 2392189Y
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Abstract
本实用新型涉及一种扫描隧道显微镜的功函数信息成像装置,包括带探针的扫描器、放大器、比例积分器、模数、数模转换器及计算机装置,其中加设一信号发生器和锁相放大器,其锁相放大器的一个输入端接至所述对数放大器A2的输出端,另一个输入端与信号发生器连接,其带有功函数信息的输出信号与模数转换器ADC相连,信号发生器输出端同时与高压放大器HA输入端连接。具有既能获得表面精细结构,也可测量表面元素功函数信息之优点。
The utility model relates to a work function information imaging device of a scanning tunneling microscope, which comprises a scanner with a probe, an amplifier, a proportional integrator, an analog-to-digital, a digital-to-analog converter and a computer device, wherein a signal generator and a lock are added. Phase amplifier, one input terminal of the lock-in amplifier is connected to the output terminal of the logarithmic amplifier A2 , the other input terminal is connected to the signal generator, and the output signal with work function information is connected to the analog-to-digital converter ADC, The output terminal of the signal generator is connected with the input terminal of the high voltage amplifier HA at the same time. It has the advantages of not only obtaining the surface fine structure, but also measuring the work function information of the surface elements.
Description
本实用新型涉及扫描探针成像技术，是基于扫描隧道显微镜建立的功函数信息成像装置。The utility model relates to a scanning probe imaging technology, which is a work function information imaging device based on a scanning tunneling microscope.
在现有技术中，扫描隧道显微镜以其优越的分辨率能够获得样品表面纳米乃至原子尺度的分辨像，可对表面结构进行观察研究，但却不能标定样品表面元素种类及分布，然而根据隧道效应原理可知：探针与样品之间的隧道电流不仅反映样品表面的结构，同时也包含了样品元素的功函数信息。In the existing technology, the scanning tunneling microscope can obtain the resolution image of the sample surface at the nanometer or even the atomic scale with its superior resolution, and can observe and study the surface structure, but it cannot calibrate the type and distribution of the element on the sample surface. However, according to the tunneling effect The principle shows that the tunnel current between the probe and the sample not only reflects the structure of the sample surface, but also contains the work function information of the sample elements.
为了克服上述不足，本实用新型的目的是基于扫描隧道显微镜采用对隧道电流的调制、解调、提取功函数信息等技术，建立了一种既能获得表面精细结构，也可测量表面元素功函数信息的扫描隧道显微镜功函数信息成像装置。In order to overcome the above deficiencies, the purpose of this utility model is based on the technology of modulation, demodulation and extraction of work function information of the tunnel current based on the scanning tunneling microscope, and establishes a method that can not only obtain the surface fine structure, but also measure the work function of the surface elements. Information imaging device for scanning tunneling microscope work function information.
为了实现上述目的，本实用新型的技术方案：包括携带探针的扫描器、放大器、比例积分器、数模、模数转换器以及计算机装置，其中样品接地，前置放大器A1同相端连至隧道偏压Vb正端，其异相端连接来自探针针尖的电流信号，其输出端信号一路与参考电流Ir经误差信号放大器A3接至比例积分器；另一路接对数放大器A2，隧道偏压Vb负端与样品共地，高压放大器HA的输入端接比例积分器，输出端接至扫描器的Z臂，所述扫描器的X、Y臂输出信号来自计算机装置的扫描控制端数模转换DAC，比例积分器输出端接模数转换器ADC至计算机装置的采集控制端，其特征在于：在对数放大器A2后设一锁相放大器，高压放大器HA前加一信号发生器，锁相放大器的一个输入端接至所述对数放大器A2的输出端，另一个输入端与信号发生器连接，其带有功函数信息的输出信号送至模数转换器ADC，所述信号发生器的调制信号同时与高压放大器HA的输入端连接；In order to achieve the above-mentioned purpose, the technical scheme of the utility model: comprise the scanner that carries probe, amplifier, proportional integrator, digital-to-analog, analog-to-digital converter and computer device, wherein sample is grounded, preamplifier A 1 in-phase terminal is connected to The positive end of the tunnel bias voltage Vb , its out-of-phase end is connected to the current signal from the probe tip, one of its output signals and the reference current Ir are connected to the proportional integrator through the error signal amplifier A 3 ; the other is connected to the logarithmic amplifier A 2 , the negative terminal of the tunnel bias voltage Vb is shared with the sample, the input terminal of the high-voltage amplifier HA is connected to the proportional integrator, and the output terminal is connected to the Z arm of the scanner, and the output signals of the X and Y arms of the scanner come from the scanning of the computer device The digital-to-analog conversion DAC of the control terminal, the output terminal of the proportional integrator is connected to the acquisition control terminal of the analog-to-digital converter ADC to the computer device, and it is characterized in that: a lock-in amplifier is set behind the logarithmic amplifier A2 , and a signal generation is added before the high-voltage amplifier HA One input terminal of the lock-in amplifier is connected to the output terminal of the logarithmic amplifier A 2 , and the other input terminal is connected to the signal generator, and its output signal with work function information is sent to the analog-to-digital converter ADC, and the The modulation signal of the signal generator is simultaneously connected to the input terminal of the high-voltage amplifier HA;
所述对数放大器A2输出信号为锁相放大器中高通滤波器的输入信号，所述来自信号发生器的参考信号接于锁相放大器中移相器的输入端，所述锁相放大器中放大器A5输出端与所述模数转换器ADC相连；来自信号发生器的调制信号和来自比例积分器的反馈信号分别经电阻R1和R2与所述高压放大器HA的异相端连接；所述信号发生器的调制信号频率大于回路的截止频率，小于扫描器响应截止频率，与参考信号的频率相同，其回路的截止频率在1KHz-10KHz范围内可调，扫描器截止频率小于50KHz，参考信号的频率和调制信号的的频率均为5KHz-25KHz范围可调。The logarithmic amplifier A 2 output signal is the input signal of the high-pass filter in the lock-in amplifier, and the reference signal from the signal generator is connected to the input terminal of the phase shifter in the lock-in amplifier, and the amplifier in the lock-in amplifier A 5 output terminal is connected with described analog-to-digital converter ADC; The modulation signal from signal generator and the feedback signal from proportional integrator are respectively connected with the out-of-phase end of described high voltage amplifier HA through resistance R 1 and R 2 ; The modulation signal frequency of the above-mentioned signal generator is greater than the cut-off frequency of the loop, less than the cut-off frequency of the scanner response, which is the same as the frequency of the reference signal. The cut-off frequency of the loop is adjustable in the range of 1KHz-10KHz, and the cut-off frequency of the scanner is less than 50KHz. Both the frequency of the signal and the frequency of the modulating signal are adjustable in the range of 5KHz-25KHz.
本实用新型具有如下优点：The utility model has the following advantages:
本实用新型利用了量子力学中电子隧穿原理以及隧道电流依赖材料功函数的关系I∝Vbexp(-1.025Φ1/2S)，在扫描隧道显微镜的基础上，研制了功函数信息成像的功能，使扫描隧道显微镜具有既可观察表面精细结构，也可测量表面元素及其分布的功能。The utility model utilizes the principle of electron tunneling in quantum mechanics and the relationship I∝V b exp(-1.025Φ 1/2 S) of the tunnel current depending on the material work function, and develops work function information imaging on the basis of a scanning tunneling microscope The function makes the scanning tunneling microscope have the function of not only observing the fine structure of the surface, but also measuring the surface elements and their distribution.
附图说明Description of drawings
图1为本实用新型的结构图。Fig. 1 is a structural diagram of the utility model.
图2为本实用新型中的锁相放大器电路原理图。Fig. 2 is the schematic diagram of the lock-in amplifier circuit in the utility model.
图3为本实用新型中调制信号与高压放大HA的连接图。Fig. 3 is a connection diagram of the modulation signal and the high-voltage amplifying HA in the present invention.
下面结合附图及其工作原理对本实用新型作进一步详细说明。Below in conjunction with accompanying drawing and working principle thereof, the utility model is described in further detail.
如图1所示，包括携带探针的压电陶瓷扫描器、放大器、比例积分器、数模、模数转换器及计算机装置。其中样品接地，隧道偏压Vb与样品共地，隧道偏压Vb加在前置放大器A1同相端，来自针尖的电流信号与前置放大器A1异相端连接，前置放大器A1输出信号一路与参考电流Ir一起经误差信号放大器A3接至比例积分器，另一路接对数放大器A2，其比例积分器的输出端经高压放大器HA接至扫描器的Z臂，同时接至计算机装置采集控制端的模数转换器ADC，所述扫描器的X、Y臂输入信号来自计算机装置扫描控制端的数模转换器DAC，所述比例积分器输出端接模数转换器ADC至计算机装置的采集控制端；另外加设一信号发生器和锁相放大器，其信号发生器的输出一路接高压放大器HA的输入端作为调制信号，另一路接锁相放大器，所述对数放大器A2的输出端至锁相放大器。As shown in Figure 1, it includes piezoelectric ceramic scanners with probes, amplifiers, proportional integrators, digital-to-analog, analog-to-digital converters, and computer devices. Among them, the sample is grounded, the tunnel bias voltage V b is shared with the sample, the tunnel bias voltage V b is added to the in-phase end of the preamplifier A1 , the current signal from the needle tip is connected to the out-phase end of the preamplifier A1 , and the preamplifier A1 One output signal and the reference current I r are connected to the proportional integrator through the error signal amplifier A 3 , and the other is connected to the logarithmic amplifier A 2 , and the output terminal of the proportional integrator is connected to the Z arm of the scanner through the high-voltage amplifier HA, at the same time Connect to the analog-to-digital converter ADC of the acquisition control end of the computer device, the X and Y arm input signals of the scanner are from the digital-to-analog converter DAC at the scan control end of the computer device, and the output terminal of the proportional integrator is connected to the analog-to-digital converter ADC to The acquisition control end of computer device; Add a signal generator and lock-in amplifier in addition, the output of its signal generator connects the input end of high voltage amplifier HA one way as modulating signal, another road connects lock-in amplifier, and described logarithmic amplifier A 2 to the lock-in amplifier.
如图2所示，所示锁相放大器包括滤波器、放大器、移相器和相敏检波器。所述对数放大器A2输出信号为锁相放大器的输入信号，经高通滤波器接至选择放大器A4，所述信号发生器输出的参考信号为锁相放大器另一输入信号，接移相器的输入端，移相器和选择放大器A4的输出分别为相敏检波器的输入，相敏检波器的输出信号通过低通滤波器经电阻R接至放大器A5，放大器A5的异相输入与输出端跨接一可调电阻RF1同相端经电阻接地。锁相放大器输出端与所述的模数转换器ADC相连。As shown in Figure 2, the lock-in amplifier shown includes a filter, an amplifier, a phase shifter, and a phase-sensitive detector. The logarithmic amplifier A 2 output signal is the input signal of the lock-in amplifier, which is connected to the selection amplifier A 4 through the high-pass filter, and the reference signal output by the signal generator is another input signal of the lock-in amplifier, which is connected to the phase shifter The input terminal of the phase shifter and the output of the selection amplifier A 4 are respectively the input of the phase-sensitive detector, the output signal of the phase-sensitive detector is connected to the amplifier A 5 through the low-pass filter through the resistor R, and the out-of-phase of the amplifier A 5 The input and output ends are connected across an adjustable resistor R F1 and the same phase end is grounded through the resistor. The output terminal of the lock-in amplifier is connected with the analog-to-digital converter ADC.
如图3所示，来自信号发生器的调制信号和来自比例积分器的反馈信号分别经电阻R1和R2与所述高压放大器HA的异相端相接，其同相端流电阻R3接地，其同相端与输出端还跨接一可调电阻RF2。As shown in Figure 3, the modulation signal from the signal generator and the feedback signal from the proportional integrator are respectively connected to the out-of-phase terminal of the high-voltage amplifier HA through resistors R1 and R2 , and its non-phase terminal current resistor R3 is grounded , and its non-inverting terminal and output terminal are connected across an adjustable resistor R F2 .
所述信号发生器的调制信号频率大于回路的截止频率，小于扫描器压电陶瓷的响应截止频率，与参考信号的频率相同，本实施例所述回路的截止频率为5KHz，所述扫描器压电陶瓷的响应截止频率为40KHz，参考信号频率和调制信号频率为10KHz。The modulation signal frequency of the signal generator is greater than the cut-off frequency of the loop, and is smaller than the response cut-off frequency of the piezoelectric ceramic of the scanner, which is the same as the frequency of the reference signal. The cut-off frequency of the loop in this embodiment is 5KHz, and the scanner voltage The response cut-off frequency of the electroceramic is 40KHz, and the reference signal frequency and modulation signal frequency are 10KHz.
本实用新型的工作原理是：The working principle of the utility model is:
在恒流扫描模式下，给扫描器Z臂高压上叠加一个固定频率和幅值的正弦调制信号，其频率高于回路截止频率，使针尖依赖隧道间距变化的同时，又受到调制信号的调制，调制电流随大小变化，其频率与调制信号同频，幅值与功函数值的大小有关，利用锁相放大器来提取与功函数信息相关的调制电流信号；由隧穿效应可知，调制电流与功函数信息成指数关系，为使所提取信号与功函数数值成比例关系，调制电流信号必须经对数放大器A2线性化，再送入锁相放大器；信号经高通滤波和选择放大器A4以后作为相敏检波器的输入，相敏检波器相当于一个乘法器，两个输入信号分别为调制信号和调制后的电流信号，相敏检波器输出不但和它的两个输入信号的幅值有关，而且还与两个输入信号之间的相位差有关，当这两个信号的相位差为π/2时，输出值最大并且只与输入信号的幅值成比例，因此，在参考信号的通路上接入一个移相电路，用以调整两个输入信号之间的相位差为π/2，使输出与相位无关，只与输入信号幅值有关，这样，相敏检波器的输出只有直流信号(即差频信号)和频率较高的和频信号；为使采集数据稳定，则把相敏检波器的输出送入低通滤波器滤掉高频信号，这样，锁相放大器的输出便为与功函数信息数值成正比的直流电信号；模数转换器ADC采集锁相放大器的输出信号，通过软件把计算机采集的数据以图像的形式表现出来，这样，就可以利用图像来表示功函数信息。这就是扫描隧道显微镜功函数信息成像原理。In the constant current scanning mode, a sinusoidal modulation signal with a fixed frequency and amplitude is superimposed on the high voltage of the Z arm of the scanner. The modulation current varies with the magnitude, its frequency is the same frequency as the modulation signal, and its amplitude is related to the value of the work function. The lock-in amplifier is used to extract the modulation current signal related to the work function information; it can be known from the tunneling effect that the modulation current and the work function The function information has an exponential relationship. In order to make the extracted signal proportional to the value of the work function, the modulated current signal must be linearized by the logarithmic amplifier A2 , and then sent to the lock-in amplifier; the signal is high-pass filtered and selected as the phase amplifier A4 . The input of the phase-sensitive detector, the phase-sensitive detector is equivalent to a multiplier, the two input signals are the modulation signal and the modulated current signal, the output of the phase-sensitive detector is not only related to the amplitude of its two input signals, but also It is also related to the phase difference between the two input signals. When the phase difference of the two signals is π/2, the output value is the largest and only proportional to the amplitude of the input signal. Therefore, the reference signal is connected to the A phase-shifting circuit is used to adjust the phase difference between the two input signals to π/2, so that the output has nothing to do with the phase, but only with the amplitude of the input signal. In this way, the output of the phase-sensitive detector is only a DC signal (ie difference frequency signal) and the sum frequency signal with higher frequency; in order to stabilize the collected data, the output of the phase-sensitive detector is sent to the low-pass filter to filter out the high-frequency signal, so that the output of the lock-in amplifier is equal to the power The function information value is directly proportional to the DC signal; the analog-to-digital converter ADC collects the output signal of the lock-in amplifier, and the data collected by the computer is displayed in the form of an image through the software, so that the image can be used to represent the work function information. This is the principle of scanning tunneling microscope work function information imaging.
另外，利用两路采集通道分别对表面形貌信息和功函数信息采集，即在扫描某点时，先采集该点形貌信息，再采集功函数信息幅值。采集完毕移至下一点继续采集；采集的形貌信息和功函数信息为两组对应的数据，形貌信息的大小反映表面的起伏，以三维扫描线表示；对应的功函数信息的大小则用颜色表示，最终的图像既反映形貌的起伏，又显示功函数的大小。In addition, two acquisition channels are used to collect surface topography information and work function information respectively, that is, when scanning a certain point, first collect the topography information of the point, and then collect the amplitude of the work function information. After the collection is completed, move to the next point to continue to collect; the collected shape information and work function information are two sets of corresponding data, and the size of the shape information reflects the surface fluctuation, which is represented by a three-dimensional scanning line; the size of the corresponding work function information is represented by The color indicates that the final image not only reflects the ups and downs of the topography, but also shows the size of the work function.
本实施例所述信号发生器采用ORTEC Brookdeal 5012F型，另采用PARTM Model 128锁相放大器，比例积分器和放大器为现有技术。The signal generator described in this embodiment adopts the ORTEC Brookdeal 5012F type, and the PAR TM Model 128 lock-in amplifier is used in addition, and the proportional integrator and the amplifier are prior art.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1303415C (en) * | 2004-12-28 | 2007-03-07 | 中山大学 | Probe scanning microscope for tunneling loss and measuring method therefor |
| CN100477067C (en) * | 2002-07-08 | 2009-04-08 | 马尔蒂普罗布公司 | Software synchronization of multiple scanning probes |
| CN102820858A (en) * | 2012-07-31 | 2012-12-12 | 赵烨梁 | High-frequency signal amplifying circuit for scanning tunnel microscope |
| CN109863408A (en) * | 2016-09-19 | 2019-06-07 | 塞威实验室有限责任公司 | Method, Apparatus and System for Scanning Tunneling Microscope Control System Design |
| CN115078773A (en) * | 2022-05-30 | 2022-09-20 | 华东师范大学 | Ultrafast atomic force microscope system |
-
1999
- 1999-11-10 CN CN 99250257 patent/CN2392189Y/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100477067C (en) * | 2002-07-08 | 2009-04-08 | 马尔蒂普罗布公司 | Software synchronization of multiple scanning probes |
| CN1303415C (en) * | 2004-12-28 | 2007-03-07 | 中山大学 | Probe scanning microscope for tunneling loss and measuring method therefor |
| CN102820858A (en) * | 2012-07-31 | 2012-12-12 | 赵烨梁 | High-frequency signal amplifying circuit for scanning tunnel microscope |
| CN109863408A (en) * | 2016-09-19 | 2019-06-07 | 塞威实验室有限责任公司 | Method, Apparatus and System for Scanning Tunneling Microscope Control System Design |
| CN109863408B (en) * | 2016-09-19 | 2022-07-08 | 塞威实验室有限责任公司 | Method, Apparatus and System for Scanning Tunneling Microscope Control System Design |
| CN115078773A (en) * | 2022-05-30 | 2022-09-20 | 华东师范大学 | Ultrafast atomic force microscope system |
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