CN117705851B - Time-resolved cathode fluorescence and ultrafast scanning electronic imaging system - Google Patents
Time-resolved cathode fluorescence and ultrafast scanning electronic imaging system Download PDFInfo
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- CN117705851B CN117705851B CN202410167283.2A CN202410167283A CN117705851B CN 117705851 B CN117705851 B CN 117705851B CN 202410167283 A CN202410167283 A CN 202410167283A CN 117705851 B CN117705851 B CN 117705851B
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- 238000003384 imaging method Methods 0.000 title claims abstract description 48
- 230000003287 optical effect Effects 0.000 claims abstract description 65
- 238000010894 electron beam technology Methods 0.000 claims abstract description 35
- 238000004458 analytical method Methods 0.000 claims abstract description 12
- 238000005086 pumping Methods 0.000 claims abstract description 11
- 238000012545 processing Methods 0.000 claims abstract description 6
- 239000000523 sample Substances 0.000 claims description 70
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 9
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 9
- 239000003990 capacitor Substances 0.000 claims description 9
- 239000013078 crystal Substances 0.000 claims description 9
- 230000005284 excitation Effects 0.000 claims description 6
- 230000005281 excited state Effects 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 10
- 239000004065 semiconductor Substances 0.000 abstract description 9
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- 239000000463 material Substances 0.000 description 6
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- 238000012512 characterization method Methods 0.000 description 1
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- 238000003271 compound fluorescence assay Methods 0.000 description 1
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- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
- G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
- G01N23/2254—Measuring cathodoluminescence
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Abstract
The application provides a time-resolved cathode fluorescence and ultrafast scanning electron imaging system, which belongs to the technical field of semiconductor measurement, and comprises an electron microscope and an electron imaging system, wherein the electron microscope and the electron imaging system are used for realizing time-resolved ultrafast electron imaging; a femtosecond laser; a wavelength selective optical path for generating a supercontinuum and selecting a specific wavelength; the pumping light path is used for introducing light pulses with target wavelength into a sample chamber of the electron microscope and exciting the sample; the electron beam brake is arranged in the lens barrel of the electron microscope and is positioned at a position far away from the electron cavity of the electron microscope and used for generating pulse electrons; the frequency generator is connected with the electron beam gate and is used for generating an adjustable square wave signal; and the cathode fluorescence collection and analysis device is used for collecting cathode fluorescence generated by the sample and analyzing and processing the fluorescence signal. The time-resolved cathode fluorescence and ultrafast scanning electron imaging system provided by the application can reduce damage to an electron microscope.
Description
Technical Field
The application relates to the technical field of semiconductor measurement, in particular to a time-resolved cathode fluorescence and ultrafast scanning electronic imaging system.
Background
In scanning electron microscopy, time-resolved cathode fluorescence measurement is a key experimental technique to directly evaluate carrier lifetime in semiconductors. The technology not only can provide supplementary data such as secondary electron images, cathode fluorescence images and the like, but also has strong non-contact and non-destructive capability of analyzing the multi-layer semiconductor material. The multimode imaging function of electron microscopes enables the correlation of optical properties with surface morphology on the nanoscale. By time-resolved cathode fluorescence characterization, researchers can directly observe and measure the lifetime of carriers in semiconductors, thereby understanding their kinetic behavior in depth. Furthermore, the non-contact and non-destructive nature of this technique makes it an important tool in the analysis of multi-layer semiconductor materials. By comprehensively utilizing the multimode imaging function of the electron microscope, researchers can comprehensively understand the structure, optical characteristics and carrier dynamics of the semiconductor material on a microscopic level, and provide key information for the design and manufacture of semiconductor devices.
However, most research efforts have focused on qualitative analysis using cathodic fluorescence spectral imaging and depth-resolved cathode techniques. Time-resolved cathode fluorescence analysis work is hampered by the lack of measurement systems with high spectral, spatial and temporal resolution. Since little effort has been made in developing time-resolved cathode fluorescence assay devices that can provide extremely high spatial and temporal resolution, economical, simple and high performance systems are not plentiful. Time resolved cathode fluorescence requires several modifications to the scanning electron microscope to provide time information.
In the related art, it is necessary to open an electron cavity of a scanning electron microscope so that laser light can enter an internal electron gun through an outer wall. However, the working difficulty is relatively high, the manufacturing cost is high, and irreversible damage to the electronic cavity and the lamp filament is easy to cause.
Disclosure of Invention
The application provides a time-resolved cathode fluorescence and ultrafast scanning electron imaging system, which aims to reduce damage to an electron microscope.
The application provides a time-resolved cathode fluorescence and ultrafast scanning electronic imaging system, which comprises:
The electron microscope and the electron imaging system are used for realizing time-resolved secondary electron ultrafast imaging;
the femtosecond laser is used for outputting near infrared femtosecond laser;
A wavelength selective optical path for generating a supercontinuum and selecting an excitation wavelength;
the pumping light path is used for introducing the light pulse selected by the wavelength selection light path into a sample chamber of the electron microscope, and exciting the sample to enable the sample to be in an excited state;
An electron beam shutter for converting a continuous electron beam into a pulsed electron beam to excite a sample or perform ultra-fast scanning imaging, the electron beam shutter being disposed in a barrel of the electron microscope and being located at a position away from an electron cavity of the electron microscope;
The frequency generator is connected with the electron beam gate and is used for changing the voltage of the electron beam gate so as to generate an electron pulse;
And the cathode fluorescence collection and analysis device is used for collecting cathode fluorescence generated by the sample and analyzing and processing the fluorescence signal.
Optionally, the electron beam shutter is composed of a plate capacitor.
Optionally, the wavelength selection optical path includes a delay optical path, a supercontinuum optical path, and a selection optical path;
the delay light path comprises a plurality of first reflectors which are sequentially arranged, and two adjacent first reflectors are oppositely arranged in the plurality of first reflectors;
The supercontinuum light path comprises an attenuation sheet, a first focusing lens and a calcium fluoride crystal which are sequentially arranged;
The selective light path comprises a second reflecting mirror and a filter sheet which are sequentially arranged, and the second reflecting mirror faces the calcium fluoride crystal.
Optionally, the pump light path includes at least two third mirrors, a second beam splitter, a second focusing lens, and a second optical sensor, wherein the second beam splitter reflects part of the light to the second optical sensor; the second optical sensor is used for monitoring the light spot position.
Optionally, the sample chamber includes an optical window, the near infrared femtosecond laser is emitted into the sample chamber from the optical window, and an included angle between the near infrared femtosecond laser and an electron pulse light path generated by the electron microscope is greater than or equal to 45 ° and less than or equal to 50 °.
Optionally, the cathode fluorescence collection and analysis device comprises a telescopic probe and a prism spectrometer, wherein one end of the telescopic probe is positioned above the sample chamber, and the other end of the telescopic probe is connected with the prism spectrometer;
the prism spectrometer comprises a first optical signal outlet and a second optical signal outlet, wherein the first optical signal outlet is connected with the first optical sensor, and the second optical signal outlet is connected with the single photon counter.
Optionally, the system further comprises: the control system is connected with the first optical sensor and the single photon counter;
The control system is used for receiving the time-resolved cathode fluorescence signals acquired by the first optical sensor and the single photon counter and processing and analyzing the time-resolved cathode fluorescence signals.
Optionally, the near infrared femtosecond laser is injected into the sample chamber from the retractable probe.
Optionally, the system further comprises: and the first beam splitter is used for introducing part of the near infrared femtosecond laser into a photodiode connected with the single photon counter.
The beneficial effects are that:
The application provides a time-resolved cathode fluorescence and ultrafast scanning electron imaging system, which can simultaneously provide time-resolved cathode fluorescence measurement and ultrafast scanning electron imaging by arranging an electron microscope and an electron imaging system, a femtosecond laser, a wavelength selection light path, a pumping light path, an electron beam gate, a frequency generator and a cathode fluorescence collection analysis device.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a time-resolved cathode fluorescence and ultra-fast scanning electron imaging system according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a time-resolved cathode fluorescence and near infrared femtosecond laser introduced from a retractable probe in an ultrafast scanning electronic imaging system according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a time-resolved cathode fluorescence and ultrafast scanning electron imaging system according to an embodiment of the present application.
Reference numerals illustrate: 1. an electron microscope and an electron imaging system; 11. an electronic cavity; 12. a sample chamber; 121. an optical window; 2. a femtosecond laser; 3. a wavelength selective optical path; 31. a first mirror; 32. an attenuation sheet; 33. a first focusing lens; 34. calcium fluoride crystals; 35. a second mirror; 36. a filter; 4. a pump light path; 41. a third mirror; 42. a second beam splitter; 43. a second focusing lens; 44. a second optical sensor; 5. an electron beam shutter; 6. a frequency generator; 7. a cathode fluorescence collection and analysis device; 71. a retractable probe; 711. a semi-elliptical spherical mirror; 72. a prism spectrometer; 73. a first optical sensor; 74. a single photon counter; 741. a photodiode; 8. a first beam splitter; 9. and a control system.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Referring to fig. 1, a time-resolved cathode fluorescence and ultrafast scanning electron imaging system according to an embodiment of the present application is disclosed, and the system includes an electron microscope and electron imaging system 1, a femtosecond laser 2, a wavelength selection light path 3, a pumping light path 4, an electron beam shutter 5, a frequency generator 6, and a cathode fluorescence collection analysis device 7.
Specifically, the electron microscope and the electron imaging system 1 are used for realizing time-resolved secondary electron ultrafast imaging. The electron microscope comprises an electron chamber 11, a barrel, a sample chamber 12, etc., wherein the electron chamber 11 is capable of generating a continuous electron beam towards the sample chamber 12, and the sample chamber 12 is mainly used for placing a sample.
Referring to fig. 1, the femtosecond laser 2 is used to output a fundamental near infrared femtosecond laser. In the embodiment of the application, the femtosecond laser 2 is a high-power high-frequency femtosecond laser 2, wherein the high power refers to that the average power of fundamental frequency light is more than 20W, and the high frequency refers to that the pulse repetition frequency of near infrared femtosecond laser is not lower than the scanning frequency during electron beam scanning imaging of an electron microscope.
The wavelength selective optical path 3 is used to generate a supercontinuum and select the excitation wavelength. The excitation wavelength refers to near-infrared femtosecond laser with characteristic wavelength for exciting the sample.
Referring to fig. 1, the wavelength selection optical path 3 includes a delay optical path, a supercontinuum optical path, and a selection optical path. The delay optical path includes a plurality of first mirrors 31 sequentially disposed, and two adjacent first mirrors 31 among the plurality of first mirrors 31 are disposed opposite to each other. The first reflecting mirrors 31 can be arranged on an electric control displacement table capable of precisely moving, and the specific time for the near infrared femtosecond laser to reach the sample can be regulated and controlled by regulating and controlling the relative optical path difference between the first reflecting mirrors 31.
Referring to fig. 1, the supercontinuum optical path includes an attenuation sheet 32, a first focusing lens 33, and a calcium fluoride crystal 34, which are disposed in this order. Wherein the attenuation sheet 32 is disposed at a side close to the delay light path, near infrared femtosecond laser enters the attenuation sheet 32 after passing through the delay light path and then is focused on the calcium fluoride crystal 34 by the first focusing lens 33, so that a super-continuum spectrum of visible light wave band can be generated, and the width and intensity of the super-continuum spectrum can be modulated by the attenuation sheet 32.
Referring to fig. 1, the selection light path includes a second reflecting mirror 35 and a filter 36 disposed in this order, the second reflecting mirror 35 facing the calcium fluoride crystal 34. The supercontinuum can enter the filter 36 via the second mirror 35, and the particular pump wavelength required can be selected by means of the filter 36 for pumping the sample.
The calcium fluoride crystal 34 can convert light with a single wavelength into super-continuous light (wide spectrum), and then the filter 36 can be used for selecting a required excitation wavelength, so that when light with a specific wavelength is required, the selection of the wavelength can be realized by only selecting different filters, the wavelength selection range is increased, and devices required by the wavelength selection optical path 3 are reduced.
Referring to fig. 1, the pump light path 4 is used to introduce the light pulse selected by the wavelength selection light path into the sample chamber 12 of the electron microscope, and excite the sample to make the sample in an excited state. The pump light path 4 comprises at least two third mirrors 41, a second beam splitter 42, a second focusing lens 43 and a second optical sensor 44. Wherein at least two third mirrors 41 are used to adjust the position and height of the supercontinuum of the waveplate 36 so that the supercontinuum is incident on the sample at a suitable angle. After being reflected by the third mirror 41, the supercontinuum passes through the second beam splitter 42 and the second focusing lens 43 in order, and then is incident on the sample surface on the sample cell 12 of the electron microscope. The second beam splitter 42 is used to split a part of the light to be incident on the second optical sensor 44, and the second optical sensor 44 can monitor the spot position so as to calibrate the excitation position of the laser.
Referring to fig. 1, an electron beam shutter 5 is used to convert a continuous electron beam into a pulsed electron beam to excite a sample or perform ultra-fast scanning imaging. In the embodiment of the present application, the electron beam shutter 5 is disposed in the barrel of the electron microscope, and the electron beam shutter 5 is located at a position away from the electron cavity 11 of the electron microscope. The beam gate 5 is composed of a plate capacitor. The pulse length and frequency of the electron beam can be varied by the beam shutter 5 to establish a dynamic balance of carrier generation for different samples. And the electron beam shutter 5 does not reduce the maximum usable current of the electron beam, thereby ensuring the performance of the detection sensitivity.
Illustratively, the electron beam shutter 5 is a plate capacitor including two capacitor plates, both of which are disposed in a barrel of the electron microscope, and the electron beam output from the electron cavity 11 of the electron microscope passes through a position between the two capacitor plates. One of the capacitor plates is connected to the frequency generator 6 and the other capacitor plate is grounded.
Referring to fig. 1, a frequency generator 6 is used to vary the voltage of the beam gate 5 to generate an electronic pulse. In an embodiment of the application the system further comprises a control system 9, the control system 9 being connected to the frequency generator 6 by passing the output of the frequency generator 6 through a high voltage transformer and applying to a capacitor plate connected to the frequency generator 6. It will be appreciated that the frequency and pulse width of the frequency generator 6 may be set by the scanning input of the electron microscope to synchronize with the scanning frequency by electron beam pulsing; the frequency and pulse width of the frequency generator 6 may also be set by external inputs of the frequency generator 6.
The cathode fluorescence collection and analysis device 7 is used for collecting cathode fluorescence generated by the sample and analyzing and processing fluorescence signals.
Referring to fig. 1, the cathode fluorescence collection and analysis device 7 includes a retractable probe 71 and a prism spectrometer 72. Wherein one end of the retractable probe 71 is located above the sample chamber 12 and the other end is connected to a prism spectrometer 72. In the embodiment of the application, the retractable probe 71 is fixed on the inner side wall of the sample chamber 12, and retraction is achieved by an electrically controlled mechanical arm, so that the probe can extend to the position right above the sample, and can also be retracted conveniently. In addition, the retractable probe 71 includes a semi-elliptical spherical mirror 711 with an aperture that allows the smooth illumination of the sample by the electrical pulses on the semi-elliptical spherical mirror 711, and the semi-elliptical spherical mirror 711 itself can efficiently collect the fluorescent signals and direct them into the prism spectrometer 72.
Referring to fig. 1, a prism spectrometer 72 may analyze the collected fluorescent signals. Meanwhile, in the embodiment of the application, the connection part of the fluorescence signal input port of the prism spectrometer 72 is provided with a slit with adjustable width, and the image in the focal plane of the photon detector can be obtained by adjusting the width of the slit. The prism spectrometer 72 is further provided with a first optical signal outlet and a second optical signal outlet, the first optical signal outlet is connected with the first optical sensor 73, the second optical signal outlet is connected with the single photon counter 74, and fluorescent signals can be respectively transmitted to the first optical sensor 73 and the single photon counter 74 through the first optical signal outlet and the second optical signal outlet.
Meanwhile, the control system 9 is also connected to a first optical sensor 73 and a single photon counter 74. The control system 9 can receive the time-resolved cathode fluorescence signals collected by the first optical sensor 73 and the single photon counter 74, and process and analyze the time-resolved cathode fluorescence signals, so as to observe multiple charge carriers such as electrons, holes, excitons and the like in the ultra-high space-time resolved material.
In the embodiment of the application, the pump light path 4 comprises two introduction modes.
Referring to fig. 1, in the first introduction mode, the sample chamber 12 includes an optical window 121, the near infrared femtosecond laser is injected into the sample chamber 12 from the optical window 121, and an angle between the near infrared femtosecond laser and an electron pulse optical path generated by the electron microscope is greater than or equal to 45 ° and less than or equal to 50 °. Illustratively, the angle between the near-infrared femtosecond laser and the electron pulse optical path generated by the electron microscope may be 45 °, 46 °, 47 °, 48 °, 49 °, 50 °, and so on.
Referring to fig. 2, in the second introduction mode, near infrared femtosecond laser light is injected into the sample chamber 12 from the retractable probe 71. Specifically, in this introduction mode, near-infrared femtosecond laser light is focused onto the sample surface through the light path system of the cathode fluorescence collection analysis device 7 and then through the semi-elliptical spherical mirror 711.
Meanwhile, in the embodiment of the present application, the system further includes a first beam splitter 8. The first beam splitter 8 is used to introduce a part of the near infrared femtosecond laser into a photodiode 741 connected to the single photon counter 74. It will be appreciated that the first beam splitter 8 may split the near infrared femtosecond laser into two beams at a ratio of power levels (in this embodiment, the ratio is 9:1), wherein a beam of near infrared femtosecond laser with smaller power is used to trigger the photodiode 741 so that the single photon counter 74 can synchronize with the pulse of the near infrared femtosecond laser.
Referring to fig. 3, the measurement mode of the time-resolved cathode fluorescence and ultrafast electronic imaging system according to the embodiment of the present application can be simply and rapidly switched, and the specific switching process is as follows:
When the pumping light path 4 is closed, only pulse electrons generated by the electron beam shutter 5 excite the sample, time-resolved cathode fluorescence can be generated, and after being collected by the cathode fluorescence collecting device and being split by the prism spectrometer 72, the time-resolved cathode fluorescence intensity and spectrum measurement are performed by utilizing the first optical sensor 73 and the single photon counter 74 to resolve detection, so that the ultra-fast carrier dynamics process of the material is studied.
When the pumping light path 4 is opened, after the telescopic probe 71 is retracted from the sample cavity, the electron microscope and the electron imaging system 1 can perform time-resolved ultra-fast scanning electron imaging; there are two generation modes of time-resolved ultrafast scanning electronic imaging, including: when the pump light is controlled to have a certain time delay after passing through the time delay line of the pump light path 4, the pump light is firstly introduced into the sample surface from the optical window 121 in front of the sample chamber 12 for pumping the sample; or after the pump light is controlled to have a certain time delay by the time delay line passing through the pump light path 4, the pump light is introduced to the surface of the sample from the semi-elliptical spherical mirror 711 of the cathode fluorescence collection device for pumping the sample; the electronic pulse then reaches the sample for detection of the sample; the time resolved secondary electrons generated by the sample are collected and imaged by a secondary electron detector.
In summary, compared to the conventional time-resolved cathode fluorescence, the electron cavity 11 of the scanning electron microscope needs to be opened, so that the laser can enter the electron cavity 11 with the outer wall to generate the electron pulse. The application is based on a time-resolved cathode fluorescence and ultrafast scanning electron imaging system of electron beam shutter 5, which is economical and simple and can provide high space and time resolution. Not only can time-resolved cathodofluorescence measurements be provided, but also the imaging mode can be switched very simply, and ultra-fast scanning electron imaging can be performed after withdrawal of the retractable probe 71. The method can systematically study the ultra-fast carrier dynamics process of semiconductor nano materials, quantum dots, metals and other materials by combining time-resolved cathode fluorescence measurement and ultra-fast electron imaging measurement, and provides a powerful measuring tool for exploring photoelectric functional materials.
In addition, the scheme of introducing the laser into the electronic cavity 11 is complicated in technical difficulty, so that on one hand, the problem of insufficient stability exists, and on the other hand, the filament in the electronic cavity 11 is easily damaged; the electron beam shutter 5 is utilized in the embodiment of the application, so that the electron cavity 11 is not transformed, and the damage to the electron microscope is reduced.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.
It should also be noted that, in this document, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. Moreover, relational terms such as "first" and "second" may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions, or order, and without necessarily being construed as indicating or implying any relative importance. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or terminal device that comprises the element.
The foregoing has outlined rather broadly the more detailed description of the application in order that the detailed description of the application that follows may be better understood, and in order that the present contribution to the art may be better appreciated. While various modifications of the embodiments and applications of the application will occur to those skilled in the art, it is not necessary and not intended to be exhaustive of all embodiments, and obvious modifications or variations of the application are within the scope of the application.
Claims (9)
1. A time-resolved cathode fluorescence and ultrafast scanning electron imaging system, comprising:
The electron microscope and the electron imaging system are used for realizing time-resolved secondary electron ultrafast imaging;
the femtosecond laser is used for outputting near infrared femtosecond laser;
a wavelength selective optical path for generating a supercontinuum and selecting an excitation wavelength;
the pumping light path is used for introducing the light pulse selected by the wavelength selection light path into a sample chamber of the electron microscope, and exciting the sample to enable the sample to be in an excited state;
An electron beam shutter for converting a continuous electron beam into a pulsed electron beam to excite a sample or perform ultra-fast scanning imaging, the electron beam shutter being disposed in a barrel of the electron microscope and being located at a position away from an electron cavity of the electron microscope;
The frequency generator is connected with the electron beam gate and is used for changing the voltage of the electron beam gate so as to generate an electron pulse;
And the cathode fluorescence collection and analysis device is used for collecting cathode fluorescence generated by the sample and analyzing and processing the fluorescence signal.
2. The time-resolved cathode fluorescence and ultrafast scanning electron imaging system, as recited in claim 1, wherein:
The electron beam shutter is composed of a plate capacitor.
3. The time-resolved cathode fluorescence and ultrafast scanning electron imaging system, as recited in claim 1, wherein:
the wavelength selection light path comprises a delay light path, a supercontinuum light path and a selection light path;
the delay light path comprises a plurality of first reflectors which are sequentially arranged, and two adjacent first reflectors are oppositely arranged in the plurality of first reflectors;
The supercontinuum light path comprises an attenuation sheet, a first focusing lens and a calcium fluoride crystal which are sequentially arranged;
The selective light path comprises a second reflecting mirror and a filter sheet which are sequentially arranged, and the second reflecting mirror faces the calcium fluoride crystal.
4. The time resolved cathode fluorescence and ultrafast scanning electron imaging system, as recited in claim 3, wherein:
the pumping light path comprises at least two third reflectors, a second beam splitter, a second focusing lens and a second optical sensor, wherein the second beam splitter reflects part of light to the second optical sensor; the second optical sensor is used for monitoring the light spot position.
5. The time-resolved cathode fluorescence and ultrafast scanning electron imaging system, as recited in claim 1, wherein:
The sample chamber comprises an optical window, the near infrared femtosecond laser is emitted into the sample chamber from the optical window, and an included angle between the near infrared femtosecond laser and an electronic pulse light path generated by the electronic microscope is more than or equal to 45 degrees and less than or equal to 50 degrees.
6. The time-resolved cathode fluorescence and ultrafast scanning electron imaging system, as recited in claim 1, wherein:
The cathode fluorescence collection and analysis device comprises a telescopic probe and a prism spectrometer, wherein one end of the telescopic probe is positioned above the sample chamber, and the other end of the telescopic probe is connected with the prism spectrometer;
the prism spectrometer comprises a first optical signal outlet and a second optical signal outlet, wherein the first optical signal outlet is connected with the first optical sensor, and the second optical signal outlet is connected with the single photon counter.
7. The time resolved cathode fluorescence and ultrafast scanning electron imaging system of claim 6, further comprising:
The control system is connected with the first optical sensor and the single photon counter;
The control system is used for receiving the time-resolved cathode fluorescence signals acquired by the first optical sensor and the single photon counter and processing and analyzing the time-resolved cathode fluorescence signals.
8. The time-resolved cathode fluorescence and ultrafast scanning electron imaging system, as recited in claim 6, wherein:
the near infrared femtosecond laser is emitted into the sample chamber from the telescopic probe.
9. The time resolved cathode fluorescence and ultrafast scanning electron imaging system of claim 6, further comprising:
And the first beam splitter is used for introducing part of the near infrared femtosecond laser into a photodiode connected with the single photon counter.
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Citations (7)
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