JPS6341183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single tube color image pickup tube. It consists of an electron impact target having an amorphous silicon film formed on a silicon substrate, a striped color filter, and an image intensifier.
This image pickup tube can achieve high sensitivity with low blooming. Conventionally, for color imaging, imaging methods using multiple image pickup tubes, frequency separation methods, phase separation methods,
A three-electrode method and a combination thereof are known. Currently, commercially available image pickup tubes have visible light (Red, Green,
Low sensitivity with blue light). Furthermore, in frequency separation, phase separation, three-electrode systems, etc., a decrease in sensitivity is inevitable due to a decrease in transmittance of filters, electrodes, etc. As described above, commercially available image pickup tubes have difficulty in color reproduction due to insufficient illuminance even when used at low illuminances, such as home lighting. There is a consensus that the main reason for this is that current image pickup tubes lack sensitivity. If it is about 10 times the current sensitivity, that is, the surface illuminance is 1 lux.
It is necessary to raise the sensitivity of the image pickup tube to a point where you can obtain images with good color reproduction at about the same time. An object of the present invention is to provide a high-sensitivity single-tube color image pickup tube that can improve the sensitivity, which is the biggest drawback mentioned above. FIG. 1 shows an explanatory diagram of a high-sensitivity single-tube color image pickup tube according to the present invention. 1 is a focusing electrode, 2 is an electron impact target using an amorphous silicon film, 3 is an electron gun, 4 is an anode, 5 is a stripe filter, 6 is a photocathode, and 7 is an outer container. Of course, the inside of the outer container is kept in a vacuum. The photocathode may be of a generally known type. For example, there are a Cs-Sb vapor deposited film, a Cs-K-Sb vapor deposited film, a Cs-Na-K-Sb vapor deposited film, etc., and it may be selected depending on the purpose. FIG. 2 shows an example of the configuration of a stripe filter. 21 is yellow (Y=R+G), 22 is green (G), 23 is white (W), 24 is cyan (C=B
+G) and are arranged in a grid. The electrical signals are B (Blue) signal, G (green) signal, W
(white) signal and R (red) signal. In addition,
25 is a dotted line indicating scanning of the electron beam. Next, an electron impact target using amorphous silicon, which is an important component of the present invention, will be explained. FIG. 3 shows a cross-sectional view of the electron impact target.
An ohmic electrode 16 is provided on a part of a silicon single crystal substrate or a polycrystalline substrate 11. In this specification, both substrates are simply referred to as a silicon crystal substrate. This electrode may be provided on the entire surface of the incident side of the silicon crystal plate if necessary, but in order to prevent radiation such as light or electron beams from being absorbed by this electrode layer,
It is desirable to provide a ring shape around the silicon crystal substrate. On the back side of the incident surface of the silicon crystal substrate 11, an amorphous silicon layer 12 containing hydrogen is formed. An amorphous silicon layer containing hydrogen usually has a higher electrical resistance than a silicon crystal substrate and is suitable as a charge storage layer of an accumulation mode light receiving element. In the present electron impact target, electron energy is absorbed by the silicon crystal substrate 11 to generate conductive carriers, which are injected into the amorphous silicon layer 12 and accumulated on its surface, forming a charge pattern. This charge pattern can be extracted as an electrical signal by a charge reading means such as an electron beam scanning device such as an image pickup tube. In most cases, the thickness of the light-receiving part of the silicon crystal plate is 5~
Use 200 μm. When the incident radiation is light, it is possible to form a silicon crystal substrate on a transparent support plate, but when the incident radiation is an electron beam, a silicon crystal substrate can be formed on a transparent support plate to avoid reducing the transmittance due to the support plate. The substrate must be self-supporting, and it is necessary to increase the mechanical strength of the substrate by providing a ring-shaped thick portion as shown in FIG. Generally, the appropriate thickness of this thick portion is 200 to 300 μm. The thickness of the amorphous silicon layer 12 containing hydrogen is preferably set to 1 to 10 μm. It is desirable that this layer be thick in order to reduce capacitive afterimages, but if it is too thick, it becomes difficult for the injection carrier to travel, and the required electric field increases, making the layer more difficult to use. Further, it is particularly appropriate for the thickness of the amorphous silicon film to be in the range of 1 to 3 .mu.m; if the thickness is thinner than this, the dark current increases and the S/N ratio decreases. At thicker areas, the current gain decreases significantly. Also, in terms of resistivity
A value of 10 ¹⁰ to 10 ¹⁴ Ωcm is appropriate; a resistivity lower than this range does not provide sufficient resolution, and a resistivity higher than this range significantly reduces the current gain. The hydrogen content in amorphous silicon is preferably 5 to 40 at%. According to the present inventors, an amorphous material containing silicon and hydrogen at the same time can be easily made to have a high resistivity of 10 ¹⁰ Ω・cm or more by controlling the hydrogen content, and is also highly resistant to light. It has been found that since there are fewer traps that impede the movement of the carrier, there is less burn-in phenomenon and good afterimage characteristics, making it extremely preferable for use as a photoconductive surface for imaging.
(Incidentally, a specific resistance of about 10 ¹⁴ Ω・cm would be the practical upper limit.) This property is due to the presence of some impurities such as carbon, germanium, and boron in the amorphous material that contains silicon and hydrogen at the same time. , phosphorus, etc. can also be found. When containing carbon, the specific resistance of the amorphous material increases, and when containing germanium, the specific resistance decreases. Also. Boron, phosphorus, etc. are used as impurities to change the conductivity of amorphous materials to p-type or n-type, respectively.
It is effective for making it look more like a model. The electron beam scanning side surface of the light-receiving surface of this structure is apt to generate secondary electrons due to the impact of the scanning electron beam or to increase the dark current due to the injection of the scanning electron beam. It is desirable to keep it covered. As such materials,
Sb ₂ S ₃ , CeO ₂ , As ₂ Se ₃ etc. are suitable, especially
A thin film obtained by depositing a bolus film of Sb ₂ S ₃ to a thickness of about 100 nm shows good properties. This amorphous silicon layer 12 can be formed by decomposing silane by glow discharge, sputtering silicon in an atmosphere containing hydrogen, or electron beam evaporation. First, the most typical sputtering method will be explained. The device itself may be a general sputtering device. As a target for sputtering, a cut piece of molten silicon may be used. In the case of an amorphous material containing silicon, germanium, or carbon, a target that is a combination of these three group elements is used. In this case, it is convenient to use, for example, a thin piece of graphite or germanium as a target on a silicon substrate. The composition of the amorphous material can be controlled by appropriately selecting the area ratio of silicon to germanium or carbon. Of course, conversely, for example, a silicon thin piece may be provided on a carbon substrate. Furthermore, both materials may be juxtaposed to form a target, or a melt of the same composition may be used. Furthermore, by using Si containing phosphorus (P), arsenic (As), boron (B), etc. in advance as a target for sputtering, it is possible to introduce these elements as impurity elements. . By this method, an amorphous material of any conductivity type such as n-type or p-type can be obtained. Further, by doping with such impurities, the resistance value of the material can be changed. A high resistance of ~10 ¹³ Ω・cm can also be achieved. Note that such impurity doping can also be carried out by mixing diborane or phosphine into the rare gas. Using targets such as those described above, hydrogen (H ₂ )
A thin layer can be obtained by sputtering Si and graphite by generating a high-frequency discharge in an Ar atmosphere containing various mixture ratios of Si and graphite, and depositing them on a substrate. In this case, the pressure of the Ar atmosphere containing hydrogen may be within any range as long as glow discharge can be maintained, and generally about 10 ^-3 to 1 Torr is used. The pressure of hydrogen ranges from 10 ^-4 to ^{10 -1} Torr;
A good example is a hydrogen partial pressure of 2 to 50%. The temperature of the sample substrate is preferably selected between room temperature and 300°C. 150-250℃ is the most practical. This is because it is difficult to conveniently introduce hydrogen into the amorphous material at too low a temperature, and hydrogen tends to be released from the amorphous material at too high a temperature. The amount of hydrogen contained is controlled by controlling the hydrogen partial pressure in the Ar atmosphere. Note that Ar in the atmosphere can be replaced with other rare gases such as Kr. Furthermore, in order to obtain a film with high resistance, a magnetron-type low-temperature, high-speed sputtering device is preferable. Next, the operation of the single-tube color image pickup tube of the present invention will be explained as follows.
This will be explained according to the diagram. Light 8 from the outside passes through a stripe filter 5 and is decomposed into lights corresponding to R, B, and W signals. When this decomposed light is irradiated onto a photocathode 6 disposed closely on the filter, photoelectrons corresponding to each color are generated on the photocathode. The photoelectrons are accelerated by an accelerating voltage applied to the photocathode 6 and the anode 4. The basic configuration is the same as that of an image intensifier. Electrode 1 that focuses accelerated electrons
The electrons are focused and collided with an electron impact target 2 made of amorphous silicon. By injecting holes generated by colliding electrons into the amorphous silicon film, a charge distribution is formed on the film. Like the photoconductive image tube used in normal storage mode,
By reading this charge distribution with a slow electron beam, it can be converted into a television signal. In this case, by optimizing the pitch of the stripe filter, R,
B and W light signals are obtained at a certain frequency by scanning an electron beam. For example, the pitch of the stripe filter is selected so that the carrier frequency of the R color component is 3.5 MHz and the carrier frequency of the B color component is 5 MHz. R, B, W separated by frequency in this way
Colorization is achieved by re-adding the light signals. Furthermore, the multiplication rate of electrons in the electron impact target varies depending on the accelerating voltage, but naturally the multiplication rate increases as the accelerating voltage increases. For example, when the accelerating voltage is 10kV, the increase rate (current gain) is 1600,
It is about 500 at 6kV. In this way, high sensitivity can be achieved by combining an electron impact target with an image intensifier having a stripe filter. Furthermore, since the holes generated by electron bombardment do not cause lateral flow within the high-resistance amorphous silicon film, high resolution can be expected. Further, there is no need to create a p-type and n-type mosaic pattern unlike conventional electron impact targets. Therefore, there is no blooming, and the process is simple, making it possible to reduce costs. Note that the present invention is also applicable to a phase separation method. Example A silicon substrate (n-type specific resistance ~100 Ω·cm) having a diameter of 20 mm and a thickness of 0.2 mm is etched to form a thin film as shown in 11 in FIG. The etching ratio is HF:HNO ₃ :CH ₃ COOH=1:4:2.
Sputter deposition on the thin silicon film (for example, deposition conditions discharge pressure PAr + PH ₂ 5 × 10 ^-3 Torr,
PH ₂ 1×10 ^-3 Torr, frequency 13.56MHz, discharge power
300W) to 2μ amorphous silicon film containing hydrogen.
m precipitate. In order to improve the landing characteristics of the electron beam after deposition, Sb ₂ S ₃ is deposited on the amorphous silicon film at Ar gas of 3 to 6×10 ^-2 Torr. The electron impact target produced in this manner is attached to an electron gun. By combining this with an image intensifier having a stripe filter as shown in FIG. 2, a high-sensitivity single-tube color image pickup tube is manufactured. FIG. 4 shows the relationship between the current gain and the cathode acceleration voltage of the high-sensitivity single-tube color image pickup tube manufactured in this manner. This shows that it is easier to achieve higher sensitivity than conventional single-tube color image pickup tubes. The following table shows the performance of the high-sensitivity single-tube color image pickup tube according to the present invention. Especially excellent in resolution and blooming performance. 【table】

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a single-tube color image pickup tube of the present invention, FIG. 2 is an explanatory view showing an example of the arrangement of stripe filters, FIG. The figure is a diagram showing the relationship between current gain and cathode variable voltage. 1... Focusing electrode, 2... Electron impact target using an amorphous silicon film, 3... Electron gun, 4...
Anode, 5...Stripe filter, 6...Photocathode, 7...Outer container, 11...Silicon substrate, 1
2...Amorphous silicon film.

Claims (1)

[Claims] 1. A color filter for color-separating incident light;
A photocathode for photoelectrically converting the light that has passed through this color filter, an electrode for focusing the electrons generated by this photocathode, and a conductive carrier generated and accumulated by receiving the electrons focused by this electrode. The electron impact target has an electron impact target for detecting the conductive carrier, and a charge readout means for extracting the charge pattern formed by the conductive carrier accumulated on the electron impact target as an electric signal. and a hydrogen-containing amorphous silicon layer that is formed directly on the silicon crystal substrate and into which the conductive carriers are injected and accumulated by an applied electric field. A single color image pickup tube. 2. The single-tube color image pickup tube according to claim 1, wherein the silicon crystal substrate is a silicon single-crystal substrate. 3. The single-tube color image pickup tube according to claim 1, wherein the silicon crystal substrate is a polycrystalline substrate. 4 Claims 1, 2, or 3
The single-tube color image pickup tube according to item 1, wherein the hydrogen-containing amorphous silicon layer contains hydrogen at 5 at% or more and 40 at% or less. 5 Claims 1, 2 or 3
3. The single-tube color image pickup tube according to item 1, wherein the hydrogen-containing amorphous silicon layer contains carbon. 6 Claims 1, 2 or 3
3. The single-tube color image pickup tube according to item 1, wherein the hydrogen-containing amorphous silicon layer contains germanium. 7 Claims 1, 2 or 3
3. The single-tube color image pickup tube according to item 1, wherein the hydrogen-containing amorphous silicon layer contains at least one element selected from the group of elements consisting of boron and phosphorus. 8. In the single-tube color image pickup tube according to claim 1, the hydrogen-containing amorphous silicon layer
A single color image pickup tube with a film thickness of 1 μm or more and 10 μm or less. 9. In the single-tube color image pickup tube according to claim 8, the hydrogen-containing amorphous silicon layer
A single-tube color image pickup tube with a film thickness of 1 μm or more and 3 μm or less.