JPH09213206A - Transmission type photoelectric surface, manufacture thereof and photoelectric transfer tube using the transmission type photoelectric surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission type photoelectric surface coexisting photoelectric sensitivity and time response characteristics and having simple configuration and manufacture thereof. SOLUTION: An active layer 32 consisting of GaAs is thinly formed rather than conventional active layers on one surface of a window layer 31. An electrode consisting of Cr and a very thin surface layer 33 consisting of Cs2 O are formed on the upper surface of the active layer 32 at the extreme end part and the central part. Many fine recessed and projecting parts are formed by regularly arranging generally semisphere recessed parts on the other surface of the window layer 31. A glass face plate 10 is closely interposed through an antireflection film 20 on the fine recessed and projecting parts. A light diffusion surface for diffusion light to be detected in the window layer direction is formed at the interfaces of the glass face plate 10, the window layer 31, and the antireflection film 20. This simple configuration sufficiently absorbs the light to be detected entered from the glass face plate 10 and diffused on the light diffusion surface in the thin active layer 32 to release a photoelectron to an outer part in a short period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive photocathode made of a III-V compound semiconductor, a method for producing the same, and a photoelectric conversion tube using the same.

[0002]

2. Description of the Related Art A conventional transmissive photocathode 30 is formed by laminating a window layer 31 made of AlGaAs and an active layer 32 made of GaAs in this order, as shown in FIG. 10, and reflected on the AlGaAs window layer 31. It is supported by thermocompression bonding to the glass face plate 10 through the prevention film 20. The transmission type photocathode 30 as described above is disclosed in, for example, JP-A-51-73379 and USPAT376.
It is disclosed in Japanese Patent No. 9536. The active layer 32 is formed by selecting at least one substance from each substance group of (Al, Ga, In) and (P, As, Sb).

[0003]

In order for such a transmission type photocathode 30 to absorb the light to be detected in the near infrared region to be detected and to obtain high sensitivity, the active layer 32 for generating photoelectrons is used. It is necessary that the thickness of the film is about 2 μm corresponding to the diffusion length of photoelectrons. On the other hand, since the photoelectrons excited by the light to be detected move in the active layer 32 by diffusion and reach the emission surface, the time response characteristics of the photocathode, that is, the response time and the time spread depend on the thickness of the active layer 32. .
For example, if the thickness of the active layer 32 constituting the transmissive photocathode 30 is about 2 μm, the response time of the transmissive photocathode 30 will be several μs, and the half-width of the time spread will be up to 600 ps. However, it is not always sufficient to measure the fluorescence lifetime by the ultrafast light excitation or the time difference of the light pulse. As described above, the photosensitivity and the time response characteristic are contradictory to each other, and satisfying both of them at the same time has not been realized at present.

By the way, the photoelectric conversion tube disclosed in Japanese Patent Laid-Open No. 63-108658 uses a fiber plate as an incident window of a photocathode, and the optical axis of each fiber plate is inclined with respect to the photocathode. I am setting it up. Also, US
The photocathode disclosed in PAT38738729 is
A prism-shaped block is arranged on the light-incident side of the glass face plate that forms it. Both of them obtain a high sensitivity by bending the optical path of light incident perpendicularly to the photocathode to lengthen the optical path and increase the effective absorption efficiency. However, the structure of the incident window (light incident face plate) that supports the above-described photocathode becomes complicated, and a large amount of cost is required to manufacture it.

Therefore, the present invention provides a transmissive photocathode having a simple structure and capable of improving time response characteristics while maintaining photoelectric sensitivity, a method for producing the same, and a photoelectric conversion tube using the same. The purpose is to do.

[0006]

A transmissive photocathode according to the present invention is a transmissive photocathode provided on a glass face plate so as to be in intimate contact therewith through an antireflection film for the light to be detected which is a detection target. A window layer formed of a III-V group compound semiconductor on the antireflection film and blocking light having a shorter wavelength than the light to be detected, and a III-V group compound having a smaller bandgap energy on the window layer than the window layer. At least an active layer formed of a semiconductor, which absorbs the light to be detected and generates photoelectrons, is provided, and the window layer and the interfaces of the glass face plate and the antireflection film are provided with the light to be detected incident through the glass face plate. The light-diffusing surface has a large number of minute irregularities that can be diffused in the direction of the active layer. With a simple configuration that only provides minute irregularities, the light to be detected can be diffused, and therefore the effective light of the light to be detected inside the active layer can be effectively reduced without thickening the active layer and degrading the time response characteristics. The optical path can be lengthened to increase the photoelectric sensitivity.

The minute irregularities of the light diffusing surface are characterized in that the concave portions or the convex portions are arranged in a dot pattern, a stripe pattern, or a mesh pattern. As a result, the detected light is uniformly diffused regardless of the position of the surface having a large number of minute irregularities.

The thickness of the active layer is 1 μm or less. This shortens the time for which photoelectrons are emitted to the outside.

A method of manufacturing a transmission type photocathode according to the present invention is
On the substrate, at least the window layer and an active layer that absorbs the detected light and generates photoelectrons are laminated so that the window layer that blocks light having a shorter wavelength than the detected light that is the detection target is the uppermost layer. , A III-V compound semiconductor multilayer film, a step of forming a large number of minute irregularities on the upper surface of the window layer, and a step of depositing an antireflection film of the detected light on the window layer to a substantially uniform thickness. A step of softening a glass face plate made of a glass material having a transition temperature lower than that of the constituent material of the antireflection film by heating to bring the semiconductor multilayer film into close contact with the glass face plate via the antireflection film; and a step of etching and removing the substrate With. With a simple configuration, a transmissive photocathode that can obtain high photoelectric sensitivity while improving time response characteristics,
It can be produced on a glass face plate with high yield.

A photoelectric conversion tube using a transmissive photocathode according to the present invention is installed inside a vacuum tube, a transmissive photocathode, a vacuum tube in which a glass face plate is supported at an end portion of a side wall and a vacuum state is maintained inside. And an anode that holds a positive voltage with respect to the transmissive photocathode. Thereby, the photoelectron signal from the photocathode can be converted into an electric signal.

Further, a multiplication means for multiplying secondary electrons of photoelectrons emitted from the transmission type photocathode is provided between the transmission type photocathode and the anode. This allows the emitted photoelectron signal to be multiplied.

The anode is a fluorescent film which emits light by receiving a two-dimensional electron image corresponding to the two-dimensional optical image of the light to be detected. Thus, a two-dimensional optical image of the detected light can be directly observed.

Further, the anode is a solid-state image pickup device which outputs an electric signal corresponding to the optical image by receiving a two-dimensional electronic image corresponding to the two-dimensional optical image of the light to be detected incident on the transmission type photocathode. Is characterized by. by this,
A two-dimensional optical image can be converted into an electric signal.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings and tables.

FIG. 1 shows an embodiment of the transmission type photocathode of the present invention.
That is, it is a cross-sectional view of a transmissive photocathode actually manufactured by an embodiment of the method for manufacturing a transmissive photocathode of the present invention.

On one surface of the window layer 31 made of AlGaAs, an active layer 32 made of GaAs having a band gap energy smaller than that of the window layer 31 and having a thickness of about 1 μm is formed. The surface layer 32 made of Cs ₂ O is uniformly and extremely thinly formed on the central portion of the active layer 32, and the electrode 50 made of Cr is formed on the peripheral portion of the active layer 32 by vapor deposition. The active layer 32 can be electrically connected. The surface layer 33 is not limited to an alkali metal oxide such as Cs ₂ O, but may be an alkali metal or a fluoride thereof.

On the other surface of the window layer 31, substantially hemispherical concave portions having a diameter of about 0.5 μm are regularly arranged at intervals of 1 μm to form a large number of minute irregularities, and the above-mentioned fine irregularities are formed thereon. An antireflection film 20 in which SiO ₂ and Si ₃ N ₄ are sequentially laminated with a film thickness according to the wavelength of the detected light to be detected is formed while maintaining the uneven shape. Then, the glass face plate 10 having an uneven surface is arranged so as to be in close contact with the surface of the antireflection film 20 so as to match the uneven shape of the surface. As a result, the interface between the antireflection film 20 and the glass face plate 10 and the window layer 31 made of materials having different refractive indexes forms a surface having a large number of minute irregularities, which refracts and scatters the detected light. It functions as a light diffusing surface that diffuses toward the active layer 32.

Therefore, when the detected light (hν) enters the glass face plate 10 as shown by the arrow in FIG. 1, the intensity is not attenuated by the light diffusing surface and is diffused in the direction of the window layer 31. Light having a wavelength shorter than that of the light to be detected is blocked within 31. Light to be detected often travels in an oblique direction in the active layer 32, and therefore the effective optical path length becomes long, so that it is efficiently absorbed there to generate photoelectrons. The photoelectrons moving in the active layer 32 by diffusion are emitted from the upper surface of the active layer 32 whose work function is sufficiently lowered by the surface layer 33.

In the present embodiment, since the light to be detected diffused by the light diffusing surface is obliquely incident on the active layer 32, the thickness of the active layer 32, which was about 2 μm in the past, is reduced to about 1 μm. However, the detected light is sufficiently absorbed in the active layer 32 to generate photoelectrons. Then, the active layer 3 is diffused.
Since it moves in the second direction, it moves to the surface layer 33 side in a short time without disappearing due to recombination or the like, and is emitted from the active layer 32 whose work function on the upper surface is sufficiently lowered. Therefore, it is possible to obtain a transmissive photocathode which has a simple structure as compared with the conventional one, but has both photoelectric sensitivity and time response characteristics.

Next, a method of manufacturing a transmission type photocathode according to the present invention will be described with reference to FIGS. FIG.
(A)-(h) shows sectional drawing of the transmissive photoelectric surface shown in FIG. 1 in order of process.

First, a semiconductor substrate 60 made of GaAs is prepared. Next, using an epitaxial growth apparatus (not shown), an etching stop layer 61 of AlGaAs having a thickness of about 2 μm, an active layer 32 of GaAs having a thickness of about 1 μm, and an AlGaAs having a thickness of about 2 μm are used. The window layer 31 is sequentially deposited to produce a semiconductor multilayer film having a hetero structure as shown in FIG. The above-mentioned thickness of the etching stop layer 61 takes into consideration selective etching of the semiconductor substrate 60 described later. The thickness of the active layer 32 is about 1 μm in order to improve the time response characteristic.

Next, a photoresist 80 is applied on the upper surface of the window layer 31 of the semiconductor multilayer film. Then, a mask pattern is formed by using the optical lithography technique, and then, as shown in FIG.
As shown in FIG. 5, the window layer 31 having a diameter of about 0.5 μm is regularly exposed at intervals of about 1 μm.

In this state, when the window layer 31 exposed at the opening of the mask pattern is etched using a sulfuric acid solution while adjusting the surface direction, as shown in FIG. A substantially hemispherical depression corresponding to the above arrangement is formed. After that, as shown in FIG.
The photoresist 80 applied on the upper surface of the window layer 31 is removed.

Then, by using the CVD method, as shown in FIG. 2 (e), Si having a film thickness corresponding to the wavelength of the light to be detected while holding the substantially hemispherical depression on the upper surface of the window layer 31 is used.
₃ N ₄ and SiO ₂ are sequentially deposited to form the antireflection film 20.

Next, the glass face plate 10 is attached to the antireflection film 20.
And thermocompression bond. At this time, the glass face plate 10 is relatively close to the thermal expansion coefficient of the GaAs active layer 32 and has a lower transition temperature than the constituent material of the antireflection film, for example, 7056 glass of Corning (see FIG. The chemical analysis composition (% by weight) is used.

This process will be described in more detail below. First, as a preparation for thermocompression bonding of the glass face plate 10 to the antireflection film 20, they are arranged at a predetermined position in a thermocompression bonding device (not shown). Next, the inside of the thermocompression bonding device
Evacuate to × 10 ^-6 Torr. The thermocompression bonding process is performed according to the temperature control chart shown in FIG. That is, the temperature of the thermocompression bonding apparatus is raised to 450 ° C. over 2 hours, and then the temperature is kept at 450 ° C. for about 1 hour for degassing.

Then, the glass face plate 10 is heated to 550 ° C. which is higher than the transition temperature, and the temperature is kept for 30 minutes to thermocompress the glass face plate 10 to the antireflection film 20. In this state, the antireflection film 20 and the semiconductor multilayer film are not deformed,
Only the lower surface of the glass face plate 10 is deformed to form an uneven interface having substantially hemispherical protrusions. Next, these are gradually cooled to 500 ° C., which is close to the transition temperature of the glass face plate 10, over 1 hour, and then rapidly cooled from 500 ° C. to room temperature.
As shown in (f), the semiconductor multilayer film is brought into close contact with the lower surface of the glass face plate 10 through the antireflection film 20. In this way, bubbles are not generated between the glass face plate 10 and the antireflection film 20, and the glass face plate 10 and the antireflection film 20 are adhered to each other with good yield.

Next, when the semiconductor substrate 60 is selectively etched using an ammonia-based solution, the etching removal is automatically stopped when the AlGaAs etching stop layer 61 is exposed, as shown in FIG. 2 (g). To do.

Next, the exposed etching stop layer 6
When 1 is etched using a hydrochloric acid solution, the etching automatically stops at the active layer 32, and the lower surface of the active layer 32 is exposed. Then, by using a predetermined mask, as shown in FIG. 2H, an electrode 50 made of Cr is vapor-deposited on the exposed glass surface plate 10 and the lower peripheral edge of the active layer 32 and the side surface portions of the window layer 31 and the active layer 32. Let

Finally, the glass face plate 10 having a transmission type photocathode formed in this manner is incorporated as an entrance window material into a vacuum tube or the like which constitutes a photoelectric conversion tube such as a photomultiplier tube or an image intensifying tube, and an active layer is formed. 32 After cleaning the exposed part, Cs and O
₂ is introduced into the photoelectric conversion tube and deposited on the exposed portion of the active layer 32. As a result, the transmission type photocathode shown in FIG. 1 in which the work function of the exposed surface of the active layer 32 is lowered can be obtained.

The minute irregularities may have any size and arrangement pitch that allow the light to be detected to be diffused, and the types and the values thereof are not limited to these values. In particular, regarding the type, the concave portions or the convex portions may be, for example, stripe-shaped arrangement, mesh-shaped arrangement, or the like. The thicknesses of the window layer 31 and the active layer 32 are not limited to those described above, and may be any thickness as long as they have a function of blocking the detected light and a function of generating photoelectrons. Furthermore, the window layer 31 and the active layer 32 are not limited to AlGaAs and GaAs, respectively, and are appropriately selected from III-V group compound semiconductors depending on the wavelength band of the light to be detected and the relationship with the refractive index of the glass face plate. To be done.

Next, a photoelectric conversion tube using the transmission type photocathode of the present invention will be described for each embodiment.

First Embodiment of Photoelectric Conversion Tube FIG. 5 is a side sectional view of a so-called line-focus type photomultiplier tube. In FIG. 5, a glass face plate 10 provided so that the transmission type photocathode 30 is closely adhered to the inner surface through an antireflection film is supported at one end of a cylindrical body forming the main body of the vacuum tube 11. Detected light (hν)
Is incident as shown by the arrow. The other end of the tubular body forming the vacuum tube 11 is also hermetically sealed with glass to keep the inside of the vacuum tube 11 in a vacuum state.

An anode 40 is installed at the other end of the vacuum tube 11, and a pair of focusing electrodes for focusing photoelectrons toward the transmissive photocathode 30 between the transmissive photocathode 30 and the anode 40. 70 is installed, and a dynode section 71 (multiplication means) composed of a plurality of stages of dynodes 71a to 71h for multiplying the photoelectrons emitted from the transmission type photocathode 30 in the vicinity of the anode 40 is curved. The electrodes are installed in multiple stages. Although not shown, the transmission type photocathode 30,
The positive bleeder voltage is distributed to the converging electrode 70, the dynode portion 71, and the anode 40 via the bleeder circuit and the electric leads so that the positive bleeder voltage with respect to the transmissive photocathode 30 increases step by step toward the anode 40. Is being applied.

Therefore, when the light to be detected is incident on the photomultiplier tube, the photoelectrons (e ⁻ ) are emitted from the transmission type photocathode 30 in a shorter time than the conventional one while maintaining the same number as the conventional one. The emitted photoelectrons are accelerated and converged by the converging electrode 70 and are incident on the first dynode 71a. Secondary electrons, which are several times as many as the number of incident photoelectrons, are emitted, and are subsequently accelerated and incident on the second dynode 71b. Similarly to the first dynode 71a, the second dynode 71b also emits secondary electrons several times as many as the number of incident electrons. By repeating this eight times, the transmission type photocathode 3
The photoelectrons emitted from 0 are finally multiplied by about 1,000,000 times as secondary electrons, and the secondary electrons emitted from the eighth dynode h after being multiplied are collected by the anode 40 and taken out as an output signal current. .

Since the transmission type photocathode used in the present embodiment has both the photoelectric sensitivity and the time response characteristic, photoelectrons comparable to the conventional one are emitted in a short time. Therefore, the photoelectrons are multiplied by the photoelectrons. The time required for the secondary electrons to finally reach the anode 40 is also shortened. Therefore, in this embodiment, the sensitivity of the signal current and the time response characteristic are compatible with each other as compared with the conventional line-focus type photomultiplier tube. That is,
By using this photomultiplier tube, a faster weak light phenomenon, for example, fluorescence lifetime measurement by high-speed photoexcitation can be observed with high sensitivity.

Second Embodiment of Photoelectric Conversion Tube FIG. 6 is a side sectional view of a so-called proximity type photomultiplier tube. A glass face plate 10 in which the antireflection film 20 and the transmission type photocathode 30 are the same as in the first embodiment of the photoelectric conversion tube.
Is sealed and supported on the upper end of the cylindrical body that constitutes the main body of the vacuum tube 11 using a sealing member composed of the In seal portion 13 and the In reservoir 14, and the detected light (hν) is indicated by the arrow. Is incident.

The bottom plate 12 is supported at the lower end of the cylinder forming the main body of the vacuum tube 11, and the vacuum tube 11 is hermetically sealed to keep the inside of the vacuum tube 11 in a vacuum state. On the upper surface of the bottom plate portion 12, facing the transmissive photoelectric surface 30,
A photodiode 41 is provided which has a multiplication effect when photoelectrons are driven in. One end of the stem pin 52 connected to the photodiode 41 has a bottom plate 12
A reverse bias voltage is applied to this photodiode 41 through the same, and also through a stem pin 52 and an electrical lead (not shown) connected to the electrode 50. A voltage of several kV is applied between the transmissive photocathode 30 and the photodiode 41.

[0039] When the detected light is incident on the photomultiplier tube, photoelectrons as described in the first embodiment of the photoelectric conversion tube (e ^-) after was released in a short time into the interior space of the vacuum tube 11, photo By being accelerated and driven into the diode 41, it was multiplied by several thousand times for one photoelectron.
Secondary electrons are generated. Then, the secondary electrons generated in the photodiode 41 are taken out as an output signal via the stem pin 52.

Therefore, in this embodiment, many photoelectrons are emitted from the transmissive photocathode in a short time as in the first embodiment, and therefore, a weak light at a higher speed than the conventional electron-implanted photomultiplier tube is emitted. The phenomenon can be observed with high sensitivity. Further, since it does not require a dynode section and further does not require a focusing electrode as compared with an electrostatic focusing photomultiplier tube described later,
Miniaturization is possible.

Third Embodiment of Photoelectric Conversion Tube FIG. 7 is a side sectional view of a so-called electrostatic focusing type photomultiplier tube. This photomultiplier tube differs from the second embodiment in that a pair of focusing electrodes 70 are provided between the transmissive photoelectric surface 30 and the photodiode 41. Then, one end of each electric lead 51a, b connected to the pair of focusing electrodes 70 extends through the side wall of the vacuum tube 30, and a predetermined voltage is applied to the pair of focusing electrodes 70 via the electrical leads 51a, b. I am able to do it.

According to the present embodiment, since the photoelectrons are converged by using the converging electrode 70, the photodiode 41 which is small with respect to the effective area of the transmission type photocathode can be used, so that high speed response is possible. Become.

Fourth Embodiment of Photoelectric Conversion Tube FIG. 8 is a side sectional view of a so-called image intensifying tube. Unlike the second to third embodiments, the present embodiment has a large number of glass holes with a diameter of about 10 μm bundled in the center of the cylinder forming the main body of the vacuum tube 11 so that the two-dimensional electrons can be multiplied by the secondary electrons. That is, a microchannel plate (hereinafter referred to as “MCP”) (multiplier) 72 that is configured is installed. Then, the transmissive photocathode 30 and the MC
+10 between the transmission type photocathode 30 and the MCP 72 via each electric lead (not shown) connected to the P72.
A voltage of 0 V is applied. Further, one end of each of the electric leads 53a and 53b connected to the MCP 72 extends through the side wall of the vacuum tube 11, and the upper surface side of the MCP 72 (hereinafter referred to as "input side") and the lower surface side of the MCP 72 (hereinafter referred to as "input side") are passed through them. A voltage for multiplication is applied between the “output side” and the “output side”.

Further, in the present embodiment, the fiber plate 42 is supported on the lower end of the cylindrical body which constitutes the main body of the vacuum tube 11, and the phosphor 43 (fluorescent film) is arranged on the inner surface thereof, which is described above. Different from the embodiment. And
The electric lead 53c and the MCP 72 connected to the phosphor 43
A voltage of about several kV with respect to the MCP 72 is applied to the phosphor 4 via another electric lead (not shown) connected to the above.
3 is applied.

Therefore, the detected light is shown in FIG.
In this way, the two-dimensional photoelectron image (e ⁻ ) corresponding to the two-dimensional optical image is emitted from the transmission type photocathode 30 into the internal space of the vacuum tube 11, and is accelerated and incident on the input side of the MCP 72. The MCP 72 double-multiplies the two-dimensional photoelectron image by about one million times, and a two-dimensional electron image corresponding to the incident position is emitted from the output side of the MCP 72 and accelerated and enters the phosphor 43. On the phosphor 43, a two-dimensional image corresponding to the two-dimensional electron image is intensified and emitted for display. Two-dimensional image shows fiber plate 42 supporting phosphor 43
It is taken out through and observed.

Since this embodiment uses the above-mentioned transmission type photocathode, many two-dimensional photoelectron images are emitted in a short time. The two-dimensional electrons thus multiplied reach the phosphor 43 in a shorter time than the conventional one and emit light at a level equal to or higher than that of the conventional one, so that it is performed at a higher speed than the conventional image intensifying tube. A two-dimensional weak light phenomenon can be observed with high sensitivity.

Fifth Embodiment of Photoelectric Conversion Tube FIG. 9 is a side sectional view of a so-called proximity type image pickup tube. In this image pickup tube, instead of the photodiode 41 in the second embodiment, a charge storage element (hereinafter referred to as “CCD”) 44 which is an image pickup device is used. Although not shown, a voltage for multiplying the emitted photoelectrons is applied between the transmissive photocathode 30 and the CCD 44, and the accelerated photoelectrons enter the CCD 44 to multiply the photoelectron image. It The charges accumulated in each pixel of the CCD 44 are output to the outside in time series via the stem pin 54.

Also in this embodiment, since the transmission type photocathode as described above is used, each pixel of the CCD 44 accumulates multiplied electrons in the same amount as in the conventional case in a short time. It can be output to the outside in time series with good response.
Therefore, it becomes possible to electrically detect and observe a two-dimensional weak light phenomenon that is faster than before.

In the fifth embodiment of the photoelectric conversion tube, the case where the CCD is used as the image pickup device has been described, but the invention is not limited to this as long as it has a function of electrically detecting the position. Further, the photomultiplier tube, the image intensifying tube and the image pickup tube have been described as the photoelectric conversion tube using the transmission type photocathode of the present invention, but it goes without saying that they can also be applied to other photodetection devices such as a streak tube. Yes.

[0050]

According to the transmission type photocathode of the present invention, the structure is simple because the interface between the glass face plate and the window layer and the antireflection film has minute irregularities so as to diffuse the light to be detected. In addition, it is possible to realize a transmissive photocathode capable of achieving both time response characteristics and photoelectric sensitivity.

Further, according to the above-mentioned method of manufacturing the transmission type photocathode of the present invention, by forming minute irregularities on the interface between the glass face plate and the window layer and the antireflection film so as to diffuse the detected light, A transmissive photocathode capable of obtaining high photosensitivity while improving time response characteristics can be manufactured with high yield.

Further, according to the photoelectric conversion tube using the transmission type photocathode of the present invention, the photoelectric conversion tube using the transmission type photocathode can detect weak light phenomenon which occurs at high speed with higher sensitivity than before.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a transmissive photocathode according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the transmission type photocathode of FIG.

FIG. 3 is a temperature control chart when the antireflection film is thermocompression bonded to a glass face plate.

FIG. 4 is a chart showing thermal characteristics and chemical analysis composition (% by weight) of Corning 7056 glass.

FIG. 5 is a side sectional view of a first embodiment of a photoelectric conversion tube including the photoelectric surface of FIG.

FIG. 6 is a side sectional view of a second embodiment of a photoelectric conversion tube including the photoelectric surface of FIG.

FIG. 7 is a side sectional view of a third embodiment of a photoelectric conversion tube including the photoelectric surface of FIG.

FIG. 8 is a side sectional view of a fourth embodiment of a photoelectric conversion tube including the photoelectric surface of FIG.

FIG. 9 is a side sectional view of a fifth embodiment of a photoelectric conversion tube including the photoelectric surface of FIG.

FIG. 10 is a sectional view of a conventional transmission type photocathode.

[Explanation of symbols]

10 ... Glass face plate, 11 ... Vacuum tube, 12 ...
Bottom plate part, 13 ... In seal part, 14 ... In reservoir, 2
0 ... Antireflection film, 30 ... Transmission type photocathode, 31.
..Window layer, 32 ... Active layer, 33 ... Surface layer, 40
... Anode, 41 ... Photodiode, 42 ...
Fiber plate, 43 ... Phosphor, 44 ... Charge storage element, 50 ... Electrode, 51, 51a, b, c ...
..Electric leads, 52, 52a, b ... Stem pins,
60 ... Semiconductor substrate, 61 ... Etch stop layer,
70 ... Focusing electrode, 71 ... Dynode part, 71a
... first dynode, 71b ... second dynode,
71c ... 3rd dynode, 71d ... 4th dynode, 71e ... 5th dynode, 71f ... 6th
Dynode, 71g ... 7th dynode, 71h ...
8th dynode, 72 ... Micro channel plate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01L 31/10 H01L 31/10 A (72) Inventor Jun Kunun 1126 Nonomachi, Hamamatsu City, Shizuoka Prefecture No. 1 Hamamatsu Photonics Co., Ltd.

Claims (8)

[Claims] 1. A transmissive photocathode provided on a glass face plate so as to be in close contact with it through an antireflection film for the light to be detected, which is a III-V group compound semiconductor on the antireflection film. A window layer formed to block light having a wavelength shorter than that of the light to be detected; and a group III-V compound semiconductor having a bandgap energy smaller than that of the window layer on the window layer. An active layer that absorbs to generate photoelectrons, and at least the interface between the window layer and the glass face plate and the antireflection film is the active layer that receives the detected light incident through the glass face plate. 1. A transmissive photocathode, which is characterized by forming a light diffusing surface having a large number of minute irregularities that can be diffused in the direction of. 2. The minute irregularities of the light diffusing surface are characterized in that concave portions or convex portions are arranged in a dot pattern, a stripe pattern, or a mesh pattern. The transmissive photocathode described in. 3. The transmissive photocathode according to claim 1, wherein the active layer has a thickness of 1 μm or less. 4. A photoelectron is generated by absorbing at least the window layer and the detected light so that the window layer that blocks light having a shorter wavelength than the detected light to be detected is the uppermost layer on the substrate. Forming a III-V group compound semiconductor multilayer film by laminating active layers to be formed, forming a large number of minute irregularities on the upper surface of the window layer, and preventing reflection of the detected light on the window layer. Depositing the film to a substantially uniform thickness, and softening the glass face plate made of a glass material having a transition temperature lower than that of the constituent material of the antireflection film by heating so that the semiconductor multilayer film passes through the antireflection film. A method of manufacturing a transmissive photocathode, comprising: bringing the glass face plate into close contact with the substrate; and removing the substrate by etching. 5. A transmission-type photocathode according to claim 1, a vacuum tube whose inside is maintained in a vacuum state by supporting the glass face plate at a side wall end, and the vacuum tube is installed inside the vacuum tube. A photoelectric conversion tube comprising: an anode that holds a positive voltage with respect to the transmissive photoelectric surface. 6. A multiplication means for multiplying secondary electrons of photoelectrons emitted from the transmission type photocathode is provided between the transmission type photocathode and the anode. 5. The photoelectric conversion tube described in 5. 7. The photoelectric conversion device according to claim 5, wherein the anode is a fluorescent film that emits light by receiving a two-dimensional electronic image corresponding to a two-dimensional optical image of the detected light. tube. 8. The solid-state imaging device, wherein the anode receives a two-dimensional electronic image corresponding to the two-dimensional optical image of the light to be detected incident on the transmission type photocathode and outputs an electric signal corresponding to the optical image. 6. The method according to claim 5, wherein
Alternatively, the photoelectric conversion tube according to item 6.