JP3757266B2 - Method and apparatus for detecting near-field light with a superconducting detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a near-field microscope and a scanning probe microscope.
[0002]
[Prior art]
In a near-field microscope, means for detecting near-field light in the photon energy region (wavelength region) of ultraviolet light from infrared light localized near the boundary surface of a different medium such as a sample surface by irradiation of excitation light such as laser light. , By opening a probe with a tip or scattering probe into the near field and collecting and detecting a part of the scattered light with an optical system, or using an aperture probe such as an optical fiber probe having a minute aperture A method is adopted in which a part of the near field is taken out from the part and detected. When it is necessary to split the scattered light, the spectroscopic spectrum is measured by installing a spectroscope after the condensing system or fiber.
[0003]
[Problems to be solved by the invention]
In the conventional method using a scattering probe, it is necessary to collect scattered light as efficiently as possible in order to increase the detection efficiency of near-field light. Is difficult to raise. That is, at the tip of the scattering probe, since the scattering tip for changing the near field into a propagation field, or the probe itself covers the scattering center with a large solid angle, scattered light entering the converging optical lens was generated. There is a disadvantage that it becomes part of the scattered light and the amount of collected light is extremely insufficient. In the method using the aperture probe, only a part of the near-field light propagates through the fiber, and it is difficult to increase the near-field detection efficiency. In addition, there is a problem that light emission from the optical fiber itself becomes noise in the case of spectroscopy.
[0004]
[Means for Solving the Problems]
The present invention solves these problems by a near-field superconducting integrated probe using a superconducting photodetector having a single-photon spectroscopic ability up to the visible or infrared region.
High near-field detection by integrating a near-field cantilever and a superconducting photodetector to insert a detector directly in the near-field, or by placing a superconducting photodetector near the scattering probe Realize efficiency and near-field photon unit spectroscopy. In addition, by performing surface observation using atomic force and tunnel current, surface morphology, electrical characteristics, and optical characteristics due to the near field can be acquired simultaneously.
[0005]
[Example 1]
In FIG. 1, a support having a sharp tip is provided at the end of a cantilever, and a photodetector having a superconducting tunnel junction structure composed of a superconductor 1, an insulator, and a superconductor 2 is formed on the support. FIG. 3 is a cross-sectional view of a near-field light detection probe that can detect near-field light with high efficiency and also measure photon energy by inserting the photodetector into the near-field.
As the cantilever, a cantilever used in an atomic force microscope or a tunnel microscope manufactured by a micromachining technique or the like, or a cantilever used in a conventional near-field microscope can be used.
In order to produce a superconducting tunnel junction on a conical or polyhedral support with a sharp tip, a superconducting thin film such as Nb is deposited from the side by sputtering while rotating the support. Thereafter, an Al thin film is deposited by the same method, and the surface is oxidized to form an insulating layer. An Al thin film and an Nb thin film are deposited thereon. The superconducting tunnel junction can be produced by a method other than the thin film deposition method other than the sputtering method. Further, the superconducting tunnel junction laminated structure may be other than the above example.
[0006]
[Example 2]
FIG. 2 shows a case where a support body having a sharp tip is provided at the end of the cantilever, a calorimeter photodetector made of superconductor is formed on the support body, and the photodetector is inserted into the near field, It is sectional drawing of the near-field light detection probe which can detect near-field light with high efficiency and can also measure the energy of a photon.
As the cantilever, a cantilever used in an atomic force microscope manufactured by a micromachining technique or the like, or a cantilever used in a conventional near-field microscope can be used.
In order to manufacture a calorimeter photodetector on a conical or polyhedral scattering tip with a sharp tip, for example, a thin W film is deposited from the side surface by sputtering while rotating the scattering tip.
The calorimeter detector can be produced by a method other than the thin film deposition method other than the sputtering method. Further, the calorimeter photodetector may be a single superconductor, a multilayer film composed of different types of superconducting thin films, or a multilayer film composed of a superconducting thin film and a normal metal thin film.
[0007]
[Example 3]
FIG. 3 shows a superconducting tunnel junction structure comprising a superconductor 1, an insulator, and a superconductor 2 on the surface of a near-field cantilever, and a scattering chip for converting near-field light into propagating light on the structure. FIG. 4 is a cross-sectional view of a near-field light detection probe that detects the near-field light and measures the photon energy of the light with high efficiency by placing it and bringing the tip of the scattering chip close to the superconducting tunnel junction photodetector.
As an example of a probe fabrication method, a superconducting tunnel junction photodetector is fabricated on a silicon substrate covered with, for example, silicon nitride, after fabricating the detector by a conventional tunnel junction fabrication method using thin film fabrication and photolithography, Processed into cantilevers using conventional micromachining technology. In order to mount the scattering chip on the photodetector, a method of adhering the scattering chip manufactured by the micromachining technique or a method of mounting a plastic microsphere can be used. The detection efficiency can be further increased by arranging a plurality of detectors instead of only one.
[0008]
[Example 4]
FIG. 4 shows that a calorimeter photodetector made of a superconductor is provided on the surface of a near-field cantilever, and a scattering chip for converting near-field light into propagating light is placed on the detector. It is sectional drawing of the near-field light detection probe which detects a near-field light and measures the photon energy of this light by making a conduction | electrical_connection calorimeter photodetector close.
As an example of a probe fabrication method, a calorimeter photodetector is fabricated on a silicon substrate covered with silicon nitride, for example, by fabricating a detector by a conventional method using thin film fabrication and photolithography, and then a conventional micromachining technology. To make a cantilever.
In order to place the scattering chip on the photodetector, a method of adhering the scattering chip produced by the micromachining technique or a method of placing a plastic microsphere can be used. The detection efficiency can be further increased by arranging a plurality of detectors instead of only one.
[0009]
[Example 5]
FIG. 5 shows a high-efficiency near-field light by arranging a superconducting tunnel junction structure photodetector composed of a superconductor 1, an insulator, and a superconductor 2 on or near a scattering chip of a near-field cantilever. 2 is a cross-sectional view of a near-field light detection probe that detects light and measures the photon energy of the light.
When the detector is above the cantilever, only light in the wavelength range that passes through the cantilever can be detected. The detection efficiency can be further increased by arranging a plurality of detectors instead of only one.
[0010]
[Example 6]
FIG. 6 shows a near-field light that detects a near-field light or measures a photon energy of the light by arranging a calorimeter photodetector made of a superconductor in the vicinity of a scattering tip of a near-field cantilever. It is sectional drawing of a detection probe.
When the detector is above the cantilever, only light in the wavelength range that passes through the cantilever can be detected. The detection efficiency can be further increased by arranging a plurality of detectors instead of only one.
[0011]
【The invention's effect】
The present invention can detect near-field light with high efficiency by integrating a superconducting tunnel junction photodetector or superconducting calorimeter photodetector and a cantilever probe, and can detect the near-field light in photon units. Measurement (spectroscopy) can be performed. Also, by scanning the sample with this probe, two-dimensional information on the surface shape, electrical characteristics, and optical characteristics can be obtained individually or simultaneously.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a near-field light detection probe including a photodetector having a superconducting tunnel junction structure according to the present invention. FIG. 2 includes a calorimeter photodetector made of a superconductor according to the present invention. FIG. 3 is a cross-sectional view of a near-field light detection probe. FIG. 4 is a cross-sectional view of a near-field light detection probe in which a scattering chip is mounted on a light detector having a superconducting tunnel junction structure according to the present invention. FIG. 5 is a cross-sectional view of a near-field light detection probe in which a scattering chip is mounted on a photodetector made of a superconductor. FIG. 5 shows a photodetector having a superconducting tunnel junction structure in the vicinity of the scattering chip according to the present invention. FIG. 6 is a cross-sectional view of a near-field light detection probe in which a calorimeter light detector made of a superconductor is disposed in the vicinity of a scattering chip according to the present invention.

Claims (8)

 In the near-field light detection method, by providing a support with a sharp tip at the end of the cantilever, forming a superconducting light detector on the surface of the support, and inserting the light detector into the near-field, A near-field light detection method characterized by detecting near-field light with high efficiency.  In the near-field light detection probe, a support having a sharp tip is provided at the end of the cantilever, and a superconducting light detector is formed on the support surface.  2. The near-field light detection method according to claim 1, wherein the superconducting photodetector is a photodetector having a superconducting tunnel junction structure.  3. The near-field light detection probe according to claim 2, wherein the superconducting light detector is a light detector having a superconducting tunnel junction structure.  2. The near-field light detection method according to claim 1, wherein the superconducting light detector is a calorimeter light detector made of a superconductor.  3. The near-field light detection probe according to claim 2, wherein the superconducting light detector is a calorimeter light detector made of a superconductor.  In the near-field light detection method, a superconducting tunnel junction structure photodetector or a calorimeter photodetector comprising a superconductor is provided on the end surface of the near-field cantilever, and near-field light is propagated on the photodetector. A near-field light detection method comprising: detecting a near-field light with high efficiency by loading a scattering chip for conversion into a near-field and inserting a tip of the scattering chip into the near-field.  In the near-field light detection probe, a superconducting light detector is provided on the end surface of the near-field cantilever, and a scattering chip for converting the near-field light into propagating light is placed on the detector. Near-field light detection probe.

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