WO2023197297A1 - Spectromètre de réflectance à modulation de lumière dans l'ultraviolet lointain et son application - Google Patents

Spectromètre de réflectance à modulation de lumière dans l'ultraviolet lointain et son application Download PDF

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WO2023197297A1
WO2023197297A1 PCT/CN2022/087066 CN2022087066W WO2023197297A1 WO 2023197297 A1 WO2023197297 A1 WO 2023197297A1 CN 2022087066 W CN2022087066 W CN 2022087066W WO 2023197297 A1 WO2023197297 A1 WO 2023197297A1
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laser
light
module
deep ultraviolet
pump
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PCT/CN2022/087066
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English (en)
Chinese (zh)
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谭平恒
刘雪璐
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中国科学院半导体研究所
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Priority to PCT/CN2022/087066 priority Critical patent/WO2023197297A1/fr
Publication of WO2023197297A1 publication Critical patent/WO2023197297A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence

Definitions

  • the present disclosure relates to the field of spectrum detection technology, and specifically to a deep ultraviolet light modulated reflection spectrometer and its application.
  • Ultra-wide bandgap semiconductors represented by gallium oxide and diamond are used in new generation deep ultraviolet optoelectronic devices, high-voltage and high-power electronic devices, quantum communications and extreme environments due to their higher bandgap width, thermal conductivity and material stability. Important fields have significant advantages and huge application prospects. Research on the energy band structure and physical properties of ultra-wide bandgap semiconductors will provide a useful reference for exploring their application and development directions. In the field of spectral analysis technology, light modulated reflection spectroscopy technology is non-destructive to samples and has no special preparation requirements, and has the advantages of high sensitivity and resolution. It is used in electronic band structure research, structural component determination, growth processing and device structure manufacturing processes. In-situ real-time monitoring in China has been widely used.
  • Light modulated reflectance spectroscopy is a spectral analysis technology that measures relative changes in material surface reflectance by periodically changing the irradiation of a pump light source on the sample.
  • the change in reflection signal intensity caused by pump laser modulation is most effectively displayed near the joint density of states singular point in the energy band structure, suppressing the contribution of other extensive regions in the Brillouin zone.
  • Light-modulated reflection spectroscopy technology It is used to study the interband transition, surface electric field, alloy composition, defect energy level and other parameter characteristics in semiconductor materials.
  • the energy of the laser source that provides pump modulation often needs to be greater than the bandgap width of the material under study to excite electron-hole pairs to affect its built-in electric field and achieve modulation of the material's dielectric function and reflection. rate changes.
  • Conventional visible light lasers and ultraviolet lasers cannot meet the requirements for research on the electronic band structure of ultra-wide bandgap semiconductor materials.
  • the present disclosure provides a deep ultraviolet light modulated reflection spectrometer and its application to solve the problem that traditional light modulated reflection spectrometers are difficult to achieve light modulated reflection spectrum detection of ultra-wide bandgap semiconductors.
  • the present disclosure provides a deep ultraviolet light modulated reflection spectrometer, which includes: a laser pump module, which at least includes a first laser with an output wavelength in the deep ultraviolet band; a search light module, which sequentially includes a wide-spectrum light source, an incident single light source, and an incident light source along the optical path direction.
  • the colorimeter and the search light chopper are used to emit search light;
  • the vacuum sample cavity module includes the first laser incident window, the pump light chopper, the lens group, and the sample to be measured along the direction of the pump light path.
  • the path direction includes the search light incident window, the first plane reflector, the first parabolic reflector, the sample to be measured, the second parabolic reflector, the second plane reflector, and the reflected light exit window, which is used to convert the laser pump module
  • the laser and search light are transmitted to the sample to be measured, and the reflected light signal on the surface of the sample to be measured is output;
  • the signal acquisition module includes an exit monochromator, a detector, a lock-in amplifier and a signal processing device in sequence along the optical path direction for Collect reflected light signals and analyze and process them.
  • the laser pump module also includes: a second laser and a second reflecting mirror; a third laser and a third reflecting mirror; the second reflecting mirror is switched between two fixed positions for selecting the second laser or the third reflecting mirror.
  • the laser serves as the pump light source and transmits the corresponding laser light to the vacuum sample cavity module.
  • the vacuum sample cavity module also includes: a first reflector, which is switched between two fixed positions, used to select the first laser, the second laser or the third laser as the pump light source, and transmit the corresponding laser to In the pump optical chopper; the second laser incident window is used to receive the laser output from the second laser or the third laser to the vacuum sample cavity module; the fourth reflector is used to transmit the laser from the second laser incident window to First reflector.
  • a first reflector which is switched between two fixed positions, used to select the first laser, the second laser or the third laser as the pump light source, and transmit the corresponding laser to In the pump optical chopper
  • the second laser incident window is used to receive the laser output from the second laser or the third laser to the vacuum sample cavity module
  • the fourth reflector is used to transmit the laser from the second laser incident window to First reflector.
  • the vacuum sample chamber module also includes: an air extraction port, used to evacuate the vacuum sample chamber module to achieve a high vacuum; and an air inlet, used to fill the vacuum sample chamber module with gas to release the vacuum.
  • the vacuum sample chamber module also includes: a camera for imaging the surface of the sample to be tested; a variable temperature sample holder, which is arranged below the sample to be tested and used to regulate its temperature.
  • the operating wavelength range of the optical elements in the vacuum sample cavity module is 180nm ⁇ 1100nm; the wavelength range output by the broad spectrum light source is 180nm ⁇ 1100nm.
  • the incident monochromator and the emergent monochromator are grating spectrometers; the operating wavelength range of the optical elements in the incident monochromator and the emergent monochromator is 180nm ⁇ 1100nm; the entrances of the incident monochromator and the emergent monochromator are narrow.
  • the width of the slit and exit slit are adjustable.
  • the first laser and the vacuum sample chamber module are sealedly connected.
  • the lock-in amplifier contains 2 input channels, which can be used to receive inputs from the chopping frequency f 2 of the pump light chopper and/or the chopping frequency f 1 from the search light chopper as reference signals.
  • Another aspect of the present disclosure provides a use of a deep ultraviolet light modulated reflection spectrometer according to the aforementioned deep ultraviolet light modulated reflection spectrometer, which is used to perform reflection spectrum, dual modulation mode light modulation reflection spectrum, and single modulation mode on ultra-wide bandgap semiconductors. Detection of light modulated reflectance spectrum and fluorescence spectrum.
  • the deep ultraviolet light modulated reflection spectrometer and its application provided by the present disclosure adopt the first laser in the deep ultraviolet band as the pump light source, adopt the optical components in the deep ultraviolet band, and design the vacuum sample cavity, making the light modulated reflection spectrometer applicable.
  • the range extends to the deep ultraviolet band, which can be widely used for research on the electronic band structure of ultra-wide bandgap semiconductor materials. It can also be used for high-order critical point detection of other semiconductor materials in the deep ultraviolet energy range and research on corresponding physical properties; Through the cooperation of multiple lasers, mirrors and other components, switching between reflection spectrum, dual modulation mode light modulated reflection spectrum, single modulation mode light modulated reflection spectrum and fluorescence spectrum testing can be achieved within the same device of the present disclosure. , combining multiple analysis methods to conduct in-situ measurements of samples to obtain more information about the energy band structure of semiconductor materials.
  • Figure 1 schematically shows a structural diagram of a deep ultraviolet light modulated reflection spectrometer according to an embodiment of the present disclosure
  • Figure 2 schematically shows the reflection spectrum of GaAs bulk material in the detection range of 180nm to 1100nm measured by a deep ultraviolet light modulated reflection spectrometer in an embodiment of the present disclosure
  • Figure 3 schematically shows the light modulation reflection spectrum of the GaAs bulk material measured by the deep ultraviolet light modulation reflection spectrometer in the detection range of 200nm to 1000nm with 177nm laser pumping in an embodiment of the present disclosure
  • Figure 4 schematically shows the light modulated reflection spectrum of the GaAs bulk material pumped by the 177nm laser measured at temperatures of 295K and 8.7K by a deep ultraviolet light modulated reflection spectrometer in an embodiment of the present disclosure
  • Figure 5 schematically shows the fluorescence spectrum (a) of the GaAs bulk material under 532nm laser pumping in the detection range of 600nm to 1000nm, and single modulation mode measured according to the deep ultraviolet light modulated reflection spectrometer in the embodiment of the present disclosure.
  • the present disclosure provides a deep ultraviolet light modulated reflection spectrometer, see Figure 1, which includes: a laser pump module 1, including at least a first laser 101 with an output wavelength in the deep ultraviolet band; a search light module 2, along the optical path The direction includes a wide spectrum light source 201, an incident monochromator 202, and a searchlight chopper 203, which are used to emit searchlight; the vacuum sample cavity module 3 includes the first laser incident window 301, the pump light, and the pump light path.
  • the chopper 315, the lens group 312, and the sample to be measured 309 include, along the direction of the search light path, the search light incident window 303, the first plane reflector 304, the first parabolic reflector 305, the sample to be measured 309, and the second parabolic reflector.
  • the mirror 306, the second plane mirror 307, and the reflected light exit window 308 are used to transmit the laser and search light of the laser pump module 1 to the sample to be measured 309, and to output the reflected light signal on the surface of the sample to be measured 309;
  • the signal acquisition module 4 sequentially includes an emission monochromator 401, a detector 402, a lock-in amplifier 403 and a signal processing device 404 along the optical path direction, for collecting reflected light signals and performing analysis and processing.
  • the laser pump module 1 is used to emit laser light to pump the sample 309 to be measured.
  • the first laser 101 is a deep ultraviolet laser source and has the characteristics of good beam quality, high energy resolution and high output power.
  • the first laser 101 emits The laser enters the vacuum sample cavity module 3 through the first laser incident window 301, and sequentially passes through the pump optical chopper 315 and the lens group 312 to reach the sample to be measured 309.
  • the searchlight module 2 is used to emit searchlight.
  • the wide-spectrum light source 201 outputs complex-color light covering the deep ultraviolet to near-infrared bands.
  • the complex-color light is dispersed by the incident monochromator 202 and outputs monochromatic light.
  • the searchlight chopper 203 After modulation, the searchlight enters the vacuum sample chamber module 3 through the search light incident window 303, and passes through the first plane reflector 304 and the first parabolic reflector 305 to reach the sample to be measured 309. The reflected light on the surface of the sample to be measured 309 passes through the second parabola in sequence.
  • the reflector 306, the second plane reflector 307, and the reflected light exit window 308 enter the signal collection module 4.
  • the signal acquisition module 4 is used to collect the reflected light signal from the vacuum sample cavity module 3.
  • the exit monochromator 401 and the incident monochromator 202 perform synchronous wavelength scanning, and the detector 402 provides the collected reflected light signal to the lock-in amplifier 403.
  • the reference signal of the lock-in amplifier 403 is provided by the pump light chopper 315 and/or the search light chopper 203, and the signal processing device 404 is used to perform data processing on the signal of the lock-in amplifier 403.
  • the first plane mirror 304, the first parabolic mirror 305, the second parabolic mirror 306, and the second plane mirror 307 in the vacuum sample chamber module 3 are placed on a two-dimensional adjustment frame.
  • the pitch and yaw angles of the first plane reflector 304 and the first parabolic reflector 305 the position of the search light spot where the monochromatic light from the search light incident window 303 reaches the surface of the sample 309 to be measured can be controlled.
  • the pitch and yaw angles of the second parabolic reflector 306 and the second plane reflector 307 the reflected light from the surface of the sample 309 to be measured can be collected and transmitted to the reflected light exit window 308.
  • the lens group 312 includes two lenses, one lens is placed on the three-dimensional translation adjustment frame, and the other lens is fixed.
  • the pump spot position of the laser beam from the laser pump module 1 irradiated on the sample 309 to be tested can be adjusted so that the pump spot coincides with the search spot position.
  • the distance between the two lenses along the optical axis direction can be adjusted, thereby adjusting the spot size of the laser beam irradiated on the sample 309 to be tested, so that the spot size of the pump laser is larger than that of the search light Spot size.
  • the disclosed deep ultraviolet light modulated reflection spectrometer expands the applicable range of the light modulated reflection spectrometer to deep ultraviolet light by using the first laser in the deep ultraviolet band as the pump light source, using optical elements in the deep ultraviolet band, and designing the vacuum sample cavity.
  • the ultraviolet band can be widely used to study the electronic band structure of ultra-wide bandgap semiconductor materials, and can also be used to detect high-order critical points of other semiconductor materials in the deep ultraviolet energy range and study the corresponding physical properties.
  • the laser pump module 1 also includes: a second laser 102 and a second mirror 104; a third laser 103 and a third mirror 105; the second mirror 104 moves between two fixed positions. Switching is used to select the second laser 102 or the third laser 103 as the pump light source, and transmit the corresponding laser light to the vacuum sample cavity module 3 .
  • the laser pump module 1 can also include multiple lasers and reflecting mirrors, so that the light modulated reflection spectrometer of the present disclosure has more laser wavelengths to choose from and has a wider application range.
  • the first laser 101 is a deep ultraviolet laser source
  • the second laser 102 and the third laser 103 can be visible laser sources or near-infrared laser sources, used for narrow confinement.
  • the semiconductor is used to detect the reflection spectrum, the light-modulated reflection spectrum of the dual modulation mode, the light-modulated reflection spectrum of the single modulation mode, and the fluorescence spectrum.
  • the second laser 102 and the third laser 103 are also equipped with corresponding reflecting mirrors for allowing their laser beams to enter the vacuum sample cavity module 3 .
  • the second reflector 104 corresponding to the second laser 102 has two fixed positions. The first position (the dotted line position in Figure 1) places the second reflector 104 in the optical path for transmitting the light emitted by the third laser 103. The laser beam is transmitted from the third reflecting mirror 105 to the subsequent optical path; the second position (the solid line position in Figure 1) is not in the optical path and is used to transmit the laser beam emitted by the second laser 102 to the subsequent optical path.
  • the second reflecting mirror The position of 104 depends on the choice of laser.
  • the light modulation reflection spectrometer can also include only one group of lasers, namely the first laser 101. In this case, there is no need to use the second reflector 104 and the third reflector 105; in short, the number of lasers in this disclosure can be Flexible settings.
  • the vacuum sample cavity module 3 also includes: a first reflector 314, which is switched between two fixed positions and used to select the first laser 101, the second laser 102 or the third laser 103 as the pump. pump light source, and transmit the corresponding laser light to the pump light chopper 315; the second and third laser incident windows 302 are used to receive the laser light output by the second laser 102 or the third laser 103 to the vacuum sample cavity module 3 ; The fourth reflector 313 is used to transmit the laser light from the second and third laser incident windows 302 to the first reflector 314.
  • the first reflector 314 also has two fixed positions.
  • the first position (the dotted line position in Figure 1) makes the first reflector 314 located in the optical path, and can enter from the second and third laser incident windows 302 and pass through the fourth laser incident window 302.
  • the laser beam reflected by the mirror 313 is transmitted to the subsequent optical path.
  • the second position (the solid line position in Figure 1) is not in the optical path, and the laser beam entering from the first laser incident window 301 can be transmitted to the subsequent optical path.
  • the position of the first reflector 314 is also determined according to the selection of the laser.
  • This disclosure uses the cooperation of multiple lasers, mirrors and other components to switch lasers, so that within the same device of this disclosure, lasers of different wavelengths can be used to pump samples, and more information about the energy band structure of semiconductor materials can be obtained. .
  • the vacuum sample chamber module 3 also includes: an air extraction port 316, used to evacuate the vacuum sample chamber module 3 to achieve a high vacuum; an air inlet 317, used to evacuate the vacuum sample chamber module 3 Fill with gas to release the vacuum.
  • the air extraction port 316 is connected to the molecular pump and the mechanical pump.
  • the mechanical pump first evacuates the vacuum sample chamber module 3. When the ultimate vacuum that can turn on the molecular pump is reached, the molecular pump is then turned on to perform high vacuum extraction and reach the required vacuum degree. ;
  • the air inlet 317 can fill the vacuum sample chamber module 3 with gas at a certain flow rate to release the vacuum.
  • the vacuum sample cavity module 3 is used to create a high vacuum environment, while transmitting the laser beam from the laser pump module 1 to the sample to be measured 309, and transmitting the search light from the search light module 2 to the sample to be measured 309, and collecting it.
  • the reflected light signal from the surface of the sample 309 to be measured is transmitted to the signal acquisition module 4 .
  • the vacuum sample chamber module 3 also includes: a camera 311 for imaging the surface of the sample to be tested 309; a variable temperature sample holder 310 that is disposed below the sample to be tested 309 and used to regulate its temperature.
  • the camera 311 is disposed around the sample 309 to be tested, and is used to image the surface of the sample 309 to be tested, so as to obtain the position on which the pump laser and search light are irradiated.
  • the temperature of the variable temperature sample holder 310 is controllable, and the temperature of the sample to be measured 309 installed thereon can be adjusted.
  • the temperature control range is, for example, 8K to 325K.
  • the operating wavelength range of the optical elements in the vacuum sample cavity module 3 is 180nm ⁇ 1100nm; the wavelength range output by the broad spectrum light source 201 is 180nm ⁇ 1100nm.
  • the working wavelength range of each optical element in the deep ultraviolet light modulated reflection spectrometer of the present disclosure includes the deep ultraviolet band, the measurement wavelength range of the detector 402, the working wavelength range of the optical elements in the incident monochromator 202 and the exit monochromator 401 etc. also need to include the deep ultraviolet band, which is used to detect the reflection spectrum, dual modulation mode light modulation reflection spectrum, single modulation mode light modulation reflection spectrum and fluorescence spectrum of ultra-wide bandgap semiconductors.
  • the incident monochromator 202 and the exit monochromator 401 are grating spectrometers; the operating wavelength range of the optical elements in the incident monochromator 202 and the exit monochromator 401 is 180nm ⁇ 1100nm; the incident monochromator The width of the entrance slit and the exit slit of the instrument 202 and the exit monochromator 401 are adjustable.
  • the incident monochromator 202 is used to disperse the polychromatic light from the wide-spectrum light source 201 and output monochromatic light.
  • the exit monochromator 401 is used to disperse the reflected light signal from the reflected light exit window 308 and detect it by the detector 402. detection.
  • the incident monochromator 202 and the exit monochromator 401 of the present disclosure adopt grating spectrometers.
  • the grating spectrometer can adapt to different spectral bandwidth requirements, and is especially suitable for use in the deep ultraviolet band.
  • the width of the entrance slit and exit slit of the incident monochromator 202 is adjustable, and is used to adjust the size of the search light spot irradiated on the sample 309 to be measured.
  • the width of the entrance slit and exit slit of the exit monochromator 401 is adjustable, which is used to suppress the collection of stray light and improve the spectral resolution.
  • the incident monochromator 202 and the exit monochromator 401 can be filled with high-purity nitrogen. Nitrogen is an inert gas and does not absorb deep ultraviolet band light to ensure the transmission distance of deep ultraviolet band light.
  • the first laser 101 and the vacuum sample chamber module 3 are sealedly connected.
  • a laser 101 is sealed and connected to the vacuum sample chamber module 3. By pumping the vacuum sample chamber module 3, both of them reach a high vacuum. If the second laser 102 and the third laser 103 are visible laser sources or near-infrared laser sources, they do not need to be sealed together with the vacuum sample cavity module 3, and can directly enter the vacuum sample cavity module 3 through the second and third laser incident windows 302. .
  • the lock-in amplifier 403 includes 2 input channels, which can be used to receive the chopping frequency f 2 from the pump light chopper 315 and/or the chopping frequency f from the search light chopper 203 1 input as the reference signal.
  • the lock-in amplifier 403 also includes multiple demodulators, which can simultaneously demodulate signals with f 1 ⁇ f 2 frequencies and signals with f 1 frequencies.
  • the chopping frequency f 1 of the search light chopper 203 and the chopping frequency f 2 of the pump light chopper 315 are both adjustable.
  • the present disclosure also provides a use of the deep ultraviolet light modulated reflection spectrometer according to the foregoing.
  • the deep ultraviolet light modulated reflection spectrometer is used to perform reflection spectrum, dual modulation mode light modulation reflection spectrum, and single modulation mode reflection spectrum of ultra-wide bandgap semiconductors. Detection of light modulated reflectance spectrum and fluorescence spectrum.
  • the present disclosure can realize switching between reflection spectrum, dual modulation mode light modulation reflection spectrum, single modulation mode light modulation reflection spectrum and fluorescence spectrum testing in the same device.
  • the complex-color light output by the wide-spectrum light source 201 in the search light module 2 is dispersed by the incident monochromator 202 and outputs monochromatic light, which is modulated by the search light chopper 203 and then transmitted to the vacuum sample cavity module 3;
  • the colored light is transmitted to the surface of the sample 309 to be tested through the search light incident window 303, the first plane reflector 304 and the first parabolic reflector 305 in the vacuum sample cavity module 3;
  • the reflected light signal from the sample to be measured 309 is reflected by the second parabola
  • the mirror 306, the second plane mirror 307 and the reflected light exit window 308 are transmitted to the signal acquisition module 4;
  • the reflected light signal is collected by the exit monochromator 401 and the detector 402 in the signal acquisition module 4 and input to the lock-in amplifier 403 ;
  • the chopping frequency f 1 of the searchlight chopper 203 is input to the lock-in amplifier 403 as a reference signal.
  • the complex color light output by the broad spectrum light source 201 in the search light module 2 is dispersed by the incident monochromator 202 and outputs monochromatic light, which is modulated by the search light chopper 203 and then transmitted to the vacuum.
  • Sample cavity module 3; monochromatic light is transmitted to the surface of the sample 309 to be measured through the search light incident window 303, the first plane reflector 304 and the first parabolic reflector 305 in the vacuum sample cavity module 3; the laser output from the laser pump module 1 After being modulated by the pump light chopper 315, it is transmitted to the surface of the sample 309 to be tested.
  • the spot position and spot size of the laser beam irradiated on the surface of the sample 309 to be tested are adjusted through the lens group 312, so that the pump laser spot and the search light spot coincide with each other.
  • the pump laser spot size is larger than the search light spot size;
  • the reflected light signal from the sample to be measured 309 is transmitted to the signal acquisition module 4 through the second parabolic reflector 306, the second plane reflector 307 and the reflected light exit window 308; the reflected light
  • the signal is collected by the exit monochromator 401 and detector 402 in the signal acquisition module 4 and input to the lock-in amplifier 403; the chopping frequency f 1 of the search light chopper 203 and the chopping frequency of the pump light chopper 315
  • the frequency f 2 is simultaneously input to the lock-in amplifier 403 as a reference signal.
  • the lock-in amplifier 403 simultaneously demodulates the reflected light change signal with the frequency f 1 ⁇ f 2 and the reflected light signal with the frequency f 1 and inputs it to the signal processing
  • the device 404 performs division to obtain the light modulated reflection spectrum of the dual modulation mode.
  • the polychromatic light output by the wide-spectrum light source 201 in the search light module 2 is dispersed by the incident monochromator 202 and outputs monochromatic light, and is transmitted to the vacuum sample cavity module 3; monochromatic light
  • the search light incident window 303, the first plane reflector 304 and the first parabolic reflector 305 in the vacuum sample cavity module 3 are transmitted to the surface of the sample 309 to be measured;
  • the laser output by the laser pump module 1 passes through the pump optical chopper 315 After modulation, it is transmitted to the surface of the sample 309 to be tested, and the spot position and spot size of the laser beam irradiated on the surface of the sample 309 to be tested are adjusted through the lens group 312, so that the pump laser spot coincides with the search light spot position and the pump laser spot size is larger than the detector light spot.
  • the reflected light signal from the sample to be measured 309 is transmitted to the signal acquisition module 4 through the second parabolic reflector 306, the second plane reflector 307 and the reflected light exit window 308; the reflected light signal is transmitted through the signal acquisition module 4
  • the output monochromator 401 and detector 402 collect and input to the lock-in amplifier 403; the chopping frequency f 2 of the pump optical chopper 315 is input to the lock-in amplifier 403 as a reference signal, and the lock-in amplifier 403 demodulates the band
  • There is a reflected light change signal with a frequency of f 2 which is input to the signal processing device 404 and divided by the reflected light signal obtained by performing the reflection spectrum test to obtain a single modulation mode light modulated reflection spectrum.
  • the laser output from the laser pump module 1 is modulated by the pump optical chopper 315 and then transmitted to the surface of the sample to be tested 309; the fluorescence signal from the sample to be tested 309 passes through the second parabolic reflector 306 and the second The plane reflector 307 and reflected light exit window 308 are transmitted to the signal collection module 4; the fluorescence signal is collected by the exit monochromator 401 and detector 402 in the signal collection module 4 and input to the lock-in amplifier 403; the pump light is chopped
  • the chopping frequency f 2 of the device 315 is input to the lock-in amplifier 403 as a reference signal.
  • the lock-in amplifier 403 demodulates the fluorescence signal with the frequency f 2 and inputs it to the signal processing device 404 to obtain the fluorescence spectrum.
  • the deep ultraviolet light modulated reflection spectrometer includes a laser pump module 1, a search light module 2, a vacuum sample cavity module 3, and a signal acquisition module 4.
  • the schematic diagram of the device is shown in Figure 1.
  • the laser pump module 1 includes a first laser 101 and a second laser 102 .
  • the laser pump module 1 is used to emit laser light to pump the sample under test.
  • the first laser 101 uses a deep ultraviolet all-solid-state laser source with an emission wavelength of 177 nm as a pump light source
  • the second laser 102 uses a solid-state laser with an emission wavelength of 532 nm
  • the second reflector 104 is located at the second position. (the solid line position in Figure 1), that is, not in the optical path, select the second laser 102 as the pump light source.
  • the searchlight module 2 includes a broad spectrum light source 201, an incident monochromator 202, and a searchlight chopper 203.
  • the searchlight module 2 is used to emit searchlight.
  • the broad-spectrum light source 201 uses the LDLS ultra-high-brightness laser-driven white light source of Energetiq Company, which can produce full-spectrum high-brightness white light in the range from deep ultraviolet to near-infrared light.
  • Figure 2 is the uncorrected reflection spectrum collected after the white light source is reflected by the GaAs bulk material. It has a high-brightness super-continuous wide-spectrum light output from 180nm to 1100nm. It is a light-modulated reflection spectrum in the deep ultraviolet to near-infrared band. measurement is possible.
  • the incident monochromator 202 uses the iHR550 imaging spectrometer of HORIBA Jobin Yvon Company, with a focal length of 550mm and equipped with three gratings of 1200gr/mm, 1800gr/mm and 300gr/mm.
  • the optical elements in it can be between 180nm and 180nm.
  • the width of the entrance slit and exit slit are adjustable, and the back is equipped with a high-purity nitrogen air inlet.
  • the vacuum sample cavity module 3 includes a first laser incident window 301, a second and a third laser incident window 302, a search light incident window 303, a first plane mirror 304, a first parabolic mirror 305, a second parabolic mirror 306, Second plane reflector 307, reflected light exit window 308, sample to be measured 309, variable temperature sample holder 310, camera 311, lens group 312, fourth reflector 313, first reflector 314, pump light chopper 315, Air extraction port 316 and air inlet 317.
  • the vacuum sample cavity module 3 is used to create a high vacuum environment, while transmitting the laser beam from the laser pump module 1 to the sample, transmitting the search light from the search light module 2 to the sample, and collecting the reflected light from the sample surface
  • the signal is transmitted to the signal acquisition module 4.
  • the first reflector 314 when the first laser 101, that is, the 177nm laser is used as the pump light source, the first reflector 314 is in the second position (the solid line position in Figure 1), that is, not in the optical path, and the 177nm laser beam Enter the pump optical chopper 315.
  • the second laser 102 that is, the 532nm laser is used as the pump light source
  • the first reflector 314 is in the first position (the dotted line position in Figure 1), entering from the second and third laser incident windows 302 and passing through the fourth The 532nm laser beam reflected by the mirror 313 is transmitted to the pump optical chopper 315 .
  • variable temperature sample holder 310 uses the CCS-XG-HV/204N low-vibration closed-cycle thermostat of Janis Company, including a cold head, a helium compressor and a temperature controller, which can control the temperature of the sample installed on it.
  • the temperature range is 8K ⁇ 325K.
  • the air extraction port 316 is connected to a molecular pump and a mechanical pump.
  • the mechanical pump first evacuates the vacuum sample chamber module 3.
  • the molecular pump is then turned on to perform high vacuum extraction. and achieve the required vacuum degree.
  • the vacuum degree of the vacuum sample chamber module 3 is as low as 1.9 ⁇ 10 -6 hPa.
  • the air inlet 317 can fill the vacuum sample chamber module 3 with high-purity nitrogen at a certain flow rate to release the vacuum.
  • the first laser entrance window 301, the second and third laser entrance windows 302, the search light entrance window 303 and the reflected light exit window 308 use MgF 2 windows
  • the reflector 305, the second parabolic reflector 306, the second plane reflector 307, the fourth reflector 313, and the first reflector 314 are coated with Al-MgF 2
  • the lens group 312 is a CaF2 lens, all of which can be within the range of 180nm to 1100nm. Work.
  • the signal acquisition module 4 includes an exit monochromator 401, a detector 402, a lock-in amplifier 403 and a signal processing device 404.
  • the signal acquisition module 4 is used to collect signals from the vacuum sample chamber module 3, and perform analysis and processing using the lock-in amplifier 403 and the signal processing device 404.
  • the exit monochromator 401 uses the iHR550 imaging spectrometer of HORIBA Jobin Yvon Company, with a focal length of 550 mm and equipped with three gratings of 1200 gr/mm, 1800 gr/mm and 300 gr/mm.
  • the exit monochromator 401 and the incident monochromator The colorimeter 202 performs synchronous wavelength scanning.
  • the optical elements can work from 180nm to 1100nm.
  • the width of the entrance slit and exit slit are adjustable.
  • the back is equipped with a high-purity nitrogen gas inlet.
  • the detector 402 uses a TE cooled single-channel solid-state silicon detector, which can measure the measurement wavelength range from 180nm to 1100nm.
  • the lock-in amplifier 403 uses the HF2LI high-frequency dual-channel lock-in amplifier from Zurich Instruments, which contains 2 input channels, the chopping frequency f 2 from the pump light chopper 315 and the chopping frequency from the search light chopper 315 .
  • the chopping frequency f 1 of the waveform filter 203 is simultaneously input as a reference signal. It contains 6 demodulators and can simultaneously demodulate signals with f 1 ⁇ f 2 frequencies and signals with f 1 frequencies.
  • the signal processing device 404 can perform data processing on the signal of the lock-in amplifier 403 .
  • the present disclosure tested the light modulated reflectance spectrum of GaAs bulk material to verify the performance of the system. At the same time, through the cooperation of components in different functional modules, the present disclosure can realize switching between reflection spectrum, dual modulation mode light modulation reflection spectrum, single modulation mode light modulation reflection spectrum and fluorescence spectrum testing in the same device.
  • Figure 3 is a light modulation reflection spectrum of a GaAs bulk material in a dual modulation mode of 177nm laser pumping in the detection range of 200nm to 1000nm measured by a deep ultraviolet light modulation reflection spectrometer of the present disclosure.
  • the first laser 101 of the pump light source is a 177nm laser
  • the chopping frequency f 2 of the pump light chopper 315 is set to 177Hz
  • the chopping frequency f 1 of the search light chopper 203 is set to 220Hz
  • the detection of the detector 402 The range is 200nm to 1000nm
  • f 1 and f 2 are simultaneously input to the lock-in amplifier 403 as a reference signal
  • the lock-in amplifier 403 demodulates the reflected light change signal with the frequency f 1 + f 2 and the reflected light signal with the frequency f 1 , and input to the signal processing device 404 for division, to obtain the light modulation reflection spectrum of the dual modulation mode.
  • the above embodiments illustrate a deep ultraviolet light modulated reflection spectrometer of the present disclosure, which is equipped with a laser with an output wavelength in the deep ultraviolet band as a pump light source for the light modulated reflection spectrum.
  • the present disclosure extends the applicable scope of the light modulated reflection spectrometer to the deep ultraviolet band. , can be widely used for research on the electronic band structure of ultra-wide bandgap semiconductor materials, and can also be used for high-order critical point detection of other semiconductor materials in the deep ultraviolet energy range and research on corresponding physical properties.
  • Figure 4 is the light modulated reflection spectrum of the GaAs bulk material pumped by the 177nm laser measured by a deep ultraviolet light modulated reflection spectrometer of the present disclosure at temperatures of 295K and 8.7K; the dual modulation mode is used to test the light modulated reflection spectrum.
  • the first laser 101 of the pump light source is a 177nm laser
  • the chopping frequency f 2 of the pump light chopper 315 is set to 177Hz
  • the chopping frequency f 1 of the search light chopper 203 is set to 220Hz
  • the detection of the detector 402 The range is 365nm to 455nm
  • the temperature settings of the variable temperature sample holder 310 are 295K and 8.7K respectively
  • f 1 and f 2 are simultaneously input to the lock-in amplifier 403 as a reference signal
  • the lock-in amplifier 403 demodulates the frequency with f 1 + f 2
  • the reflected light variation signal and the reflected light signal of frequency f 1 are input to the signal processing device 404 for division to obtain a light modulated reflection spectrum of the dual modulation mode.
  • Figure 5 is the fluorescence spectrum (a) of the GaAs bulk material under 532nm laser pumping in the detection range of 600nm to 1000nm, and the light modulated reflection spectrum of the single modulation mode measured by a deep ultraviolet light modulated reflection spectrometer of the present disclosure. (b) and the light modulated reflection spectrum (c) of the dual modulation mode:
  • the second laser 102 of the pump light source is a 532nm laser
  • the chopping frequency f 2 of the pump light chopper 315 is set to 207Hz
  • the detection range of the detector 402 is 600nm to 1000nm
  • f 2 is input to
  • the lock-in amplifier 403 serves as a reference signal.
  • the lock-in amplifier 403 demodulates the fluorescence signal with a frequency of f 2 and inputs it to the signal processing device 404 to obtain the fluorescence spectrum (a).
  • the second laser 102 of the pump light source is a 532 nm laser
  • the chopping frequency f 2 of the pump light chopper 315 is set to 207 Hz
  • the chopping frequency of the search light chopper 203 f 1 is set to 230Hz
  • the detection range of the detector 402 is 600nm to 1000nm.
  • f 1 and f 2 are simultaneously input to the lock-in amplifier 403 as reference signals.
  • the lock-in amplifier 403 first demodulates the reflected light signal with the frequency f 1 and inputs it to the signal processing device 404 to obtain the reflection spectrum.
  • the lock-in amplifier 403 demodulates the reflected light variation signal of frequency f 2 and inputs it into the signal processing device 404 to divide the signal with the reflected light signal to obtain the light modulation reflection spectrum (b) of the single modulation mode.
  • the second laser 102 of the pump light source is a 532nm laser
  • the chopping frequency f2 of the pump light chopper 315 is set to 207Hz
  • the chopping frequency of the search light chopper 203 f 1 is set to 230Hz
  • the detection range of the detector 402 is 600nm to 1000nm.
  • f 1 and f 2 are simultaneously input to the lock-in amplifier 403 as reference signals.
  • the lock-in amplifier 403 simultaneously demodulates the reflected light change signal with the frequency f 1 + f 2 and the reflected light signal at the frequency f 1 and inputs them to
  • the signal processing device 404 performs division to obtain the light modulation reflection spectrum (c) of the dual modulation mode.

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Abstract

La présente invention concerne un spectromètre de réflectance à modulation de lumière dans l'ultraviolet lointain, comprenant : un module de pompage par laser comportant au moins un premier laser ; un module de projecteur comportant séquentiellement une source de lumière à large spectre, un monochromateur incident et un hacheur de projecteur le long d'une direction de chemin optique ; un module de cavité d'échantillonnage sous vide comprenant séquentiellement, le long d'une direction de chemin de lumière de pompage, une première fenêtre d'incidence de laser, un hacheur de lumière de pompage, un ensemble de lentilles et un échantillon à mesurer, et comprenant séquentiellement une fenêtre d'incidence de projecteur, un premier réflecteur plan, un premier réflecteur parabolique, ledit échantillon, un second réflecteur parabolique, un second réflecteur plan et une fenêtre d'émergence de lumière réfléchie le long d'une direction de chemin de lumière de pompage ; et un module d'acquisition de signaux comprenant séquentiellement un monochromateur émergent, un détecteur, un amplificateur synchrone et un appareil de traitement de signaux le long de la direction du chemin optique, et utilisé pour l'acquisition et l'analyse d'un signal de lumière réfléchie. Le spectromètre de réflectance à modulation de lumière selon la présente invention convient à une bande d'ultraviolets lointains et peut être largement appliqué à la recherche d'une structure de bande d'énergie électronique d'un matériau semi-conducteur à bande interdite ultralarge.
PCT/CN2022/087066 2022-04-15 2022-04-15 Spectromètre de réflectance à modulation de lumière dans l'ultraviolet lointain et son application WO2023197297A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040253751A1 (en) * 2003-06-16 2004-12-16 Alex Salnik Photothermal ultra-shallow junction monitoring system with UV pump
US20050213100A1 (en) * 2002-11-27 2005-09-29 Murtagh Martin E Optical measurement apparatus and method
CN204086126U (zh) * 2014-08-15 2015-01-07 中国科学院上海技术物理研究所 基于显微镜的激光双调制反射光谱检测系统
CN104458691A (zh) * 2014-12-25 2015-03-25 合肥知常光电科技有限公司 一种光热-荧光双模态光谱检测装置及其检测方法
CN107192675A (zh) * 2017-06-05 2017-09-22 中国科学院上海技术物理研究所 一种简单有效地抑制荧光干扰的光调制反射光谱检测系统
WO2021117035A1 (fr) * 2019-12-11 2021-06-17 Nova Measuring Instruments Ltd. Procédé et système de spectroscopie de photoréflectance à large bande

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050213100A1 (en) * 2002-11-27 2005-09-29 Murtagh Martin E Optical measurement apparatus and method
US20040253751A1 (en) * 2003-06-16 2004-12-16 Alex Salnik Photothermal ultra-shallow junction monitoring system with UV pump
CN204086126U (zh) * 2014-08-15 2015-01-07 中国科学院上海技术物理研究所 基于显微镜的激光双调制反射光谱检测系统
CN104458691A (zh) * 2014-12-25 2015-03-25 合肥知常光电科技有限公司 一种光热-荧光双模态光谱检测装置及其检测方法
CN107192675A (zh) * 2017-06-05 2017-09-22 中国科学院上海技术物理研究所 一种简单有效地抑制荧光干扰的光调制反射光谱检测系统
WO2021117035A1 (fr) * 2019-12-11 2021-06-17 Nova Measuring Instruments Ltd. Procédé et système de spectroscopie de photoréflectance à large bande

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