JPH0640825U - Spectrum analyzer - Google Patents

Abstract

(57) [Abstract] [Purpose] By using an electric field detection type photodetector with MIM tunnel junction in the detector, high sensitivity, high response speed and compact infrared to visible light spectrum without cooling Realize an analyzer. [Structure] In a spectrum analyzer for measuring a spectrum of a light emitting element such as a laser diode or a light emitting diode and performing spectrum analysis in a wavelength region such as an emission wavelength or a half width of wavelength, an MIM is used as a photodetector constituting the apparatus. It is characterized by being an electric field detection type photodetector using a tunnel junction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an infrared to visible light spectrum analyzer using a photodetector that utilizes the optical response of a MIM (Metal-Insulator-Metal) tunnel junction.

[0002]

[Prior art]

 Generally, a spectrum analyzer is roughly divided into three components, a light source, a spectroscope, and a detector. Of these, few detectors have high uniform sensitivity in both infrared and visible light regions. In addition, quantum-type semiconductor sensors and thermal-type pyroelectric elements are used as photodetectors in the infrared region, but the former uses optical energy for excitation between band caps of carriers in semiconductors. However, the sensitivity varies depending on the wavelength region, and when used in the long wavelength (infrared) region, cooling with liquid nitrogen or liquid helium is also necessary. On the other hand, the latter thermal sensor converts the energy generated by light irradiation into heat and outputs it as changes in polarizability, resistivity, etc. Since it has low sensitivity in principle, it is difficult to increase the light receiving area. However, it has the drawback that it takes time to analyze a wide range of spectra due to its slow response speed.

Further, it has been known that conventional point contact diodes and MIM tunnel junctions respond to infrared rays. At present, the structure is unstable and its use is limited to several hours, but similar to the quantum type. Alternatively, a detector with high response speed, high sensitivity, and no cooling can be manufactured with an area (volume) smaller than that.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of the above-mentioned problems of the conventional technology, and by using an electric field detection type photodetector using an MIM tunnel junction in the detection unit, high sensitivity, high response speed without cooling, It is an object of the present invention to provide a compact infrared to visible light spectrum analyzer.

[0005]

[Means for Solving the Problems]

 The configuration of the present invention for solving the above problems is a spectrum analyzer that measures the spectrum of a light emitting element such as a laser diode or a light emitting diode and performs spectrum analysis in the wavelength region such as the emission wavelength or the half-width of the wavelength. In the above, the electric field detection type photodetector using the MIM tunnel junction is used as the photodetector constituting the device.

[0006]

[Action]

 According to the present invention, a spectroscopic analysis is performed by combining a light source and a spectroscopic optical system with a photodetector in the infrared to visible light region using a mechanically stable MIM tunnel junction that is minute and has high dimensional stability. The device is realized.

[0007]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. First, the MIM tunnel junction has a junction area of finally less than 10 nm □, and the electrodes are separated by an extremely thin (1-10 nm) insulating layer (natural oxide film, etc.), which is a mechanically stable structure. It is made by, and if necessary, combine a condenser lens and a condenser mirror above and below to form a photodetector. A spectrum analyzer is constructed by combining this photodetector with a light source, an incident optical system for the sample, a spectroscopic optical system (wavelength selection system), and an output optical system for the photodetector.

FIG. 1 is a block diagram showing an embodiment of a photodetector used in the photodetector of the spectrum analyzer of the present invention. In FIG. 1A, the photodetector is composed of a dielectric film 2, a first conductor 1 formed on one surface of the dielectric film 2, and a dielectric film 2 from the other surface of the dielectric film 2. A conductor hole 3 penetrating through the first conductor 1 and reaching the first conductor 1, a tunnel barrier insulating film 4 formed on the bottom surface of the conductor hole 3, and a metal is inserted into the conductor hole 3 through the tunnel barrier insulating film 4. The second conductor 5 is formed by being embedded.

The first conductor 1 is made of nickel, for example, and at least one of the first conductor 1 and the second conductor 5 functions as an antenna for receiving the light to be measured, and the first conductor 1 and the second conductor 5 have a desired wavelength band. It is patterned into an appropriate shape so as to have detection sensitivity, for example, in a spiral shape as shown in FIG. The dielectric film 2 is, for example, a film of silicon dioxide or silicon nitride, and its thickness is 500 to 1000 angstroms, and the thickness of the tunnel barrier insulating film 4 is several tens angstroms.

Since the conductor hole 3 is formed in vacuum by irradiating the dielectric film 2 with a focused ion beam of gallium, the radius of curvature of the conductor hole 3 is determined by the diameter of the focused ion beam. The first conductor 1, the tunnel barrier insulating film 4 and the second conductor 5 form an MIM junction, and the contact surface area between the tunnel barrier insulating film 4 and the second conductor 5 is the diameter of the conductor hole 3. It is decided to be about 10 ^-11 cm ² . The smaller the contact area between the tunnel barrier insulating film 4 and the second conductor 5, the higher the detection sensitivity and the faster the response speed.

The photodetection operation using the photodetector shown in FIG. 1 will be described with reference to FIGS. 2 and 3. In FIG. 2, a voltage source 11 and an ammeter 12 are connected in series between the first conductor 1 and the second conductor 5. Since the photodetector element has an MIM junction, it exhibits the current-voltage characteristic of a tunnel diode having non-linearity as shown in FIG. Therefore, if a bias voltage is applied between the first conductor 1 and the second conductor 5 in advance and the MIM junction portion or the receiving (antenna) portion is irradiated with light in the infrared to visible region, The amplitude oscillation of the optical field is detected as a change in output current due to the nonlinear IV characteristic of the tunnel diode. In other words, it is possible to detect the photoelectric field due to the light to be measured incident on at least one of the first conductor 1 and the second conductor 5 and output a detection current corresponding to the amplitude of the photoelectric field. This rectified signal is converted into the amount of light. Then, the spectrum analysis can be performed by combining the wavelength information of the wavelength selection system (spectrometer) (or the wavelength information of the light source) and knowing the transmittance, reflectance, absorbance, etc. for each wavelength.

There are various methods of spectrum analysis, such as single-path / double-path, FT method, and time-resolved method. When the present MIM detector is used, normal infrared / ultraviolet / visible spectrum is used. All spectroscopic techniques can be applied. It is also possible to use a micromachining technology to integrate all or part of each element into a single chip.

[0013]

[Effect of device]

 As described above in detail with reference to the embodiments, according to the present invention, by using the MIM tunnel junction as an electric field detection type photodetector, cooling is unnecessary, high response speed, high sensitivity, and a small infrared ray. It is possible to realize a spectrum analyzer in the visible light region.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a photodetector used in a detector of a spectrum analyzer of the present invention.

FIG. 2 is a diagram showing an operation of light detection by an MIM tunnel junction.

FIG. 3 is a diagram showing a current-voltage characteristic of an MIM diode.

[Explanation of symbols]

 1 1st conductor 2 Dielectric film 3 Conductor hole 4 Tunnel barrier insulating film 5 2nd conductor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Naoki Kishi 2-932 Nakamachi 2-chome, Musashino City, Tokyo Yokogawa Electric Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A spectrum analyzer for measuring a spectrum of a light emitting element such as a laser diode or a light emitting diode and performing spectrum analysis in a wavelength region such as an emission wavelength or a half width of wavelength of the light emitting element. An electric field detection type photodetector using a MIM tunnel junction as the above.