JPS61221689A - Detector for radial rays - Google Patents

Abstract

PURPOSE:To improve detecting sensitivity of X-rays by providing the detection parts of X-rays and rays of light made of amorphous silicon on both faces of an Al base. CONSTITUTION:The titled detector is provided with the detection parts 10a and 10b, the Al base 11, a W collimator 21 and a scintillator 25, etc. Then, the X-rays are first made incident on the detection part 10 b and the X-rays are detected there. Then, the X-rays are made incident on the detection part 10a through the base 11 and the X-rays re also detected there. Further, the X-rays passed through the detection parts 10b and 10a are made incident on the scintillator 25 to emit the scintillator 25. Most of these rays of light are incident on the detection part 10a and the partial rays of light are reflected by the collimator 21 and made incident from the sides of the detection parts 10a and 10b. These rays of light are again detected with the detection parts, 10a and 10b and further, the rays of light incident on the surface of the base 11 of the detection part 10a are reflected and again detected with the detection part 10a. Then, since most of the rays of light by the emission of the scintillator are directly incident on the detection part 10a, the utilizing efficiency of the rays of light is improved especially.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radiation detection device, and more particularly to a radiation detection device that has the function of a photodetection element to improve radiation detection sensitivity.

[Technical background of the invention and its problems]

Conventionally, various radiation detection devices made of semiconductors have been used to detect radiation such as X-rays. FIG. 4 shows an example of a semiconductor radiation detection device. In the figure, 41 is a W collimator, 42 is a /l electrode, 43 is N-8r, and 44 is an A
The LI electrode, 45 is a NaI (T2) scintillator, and 46 is a current amplifier. A multichannel radiation detection device is one in which this device is configured in multiple stages in a direction perpendicular to the X-rays, and is mainly applied to an X-ray CT (computed tomography) device.

This not only directly detects X-rays with a detection section consisting of N-8i 43 and electrodes 42, 44, but also roughly utilizes the X-rays that have passed through the detection section to cause the NaI (TI> scintillator 45 to emit light). This light (indicated by the broken line arrow in the figure) is received again by the detection section to increase the sensitivity.Therefore, the detection section has two roles: X-ray detection and photodetection.

The problems with this semiconductor radiation detection device are as follows.

That is, the depletion layer', which is a part sensitive to light, is formed only on the ALJ electrode 44 side, and AEi! There is almost no sensitivity to light incident on the pole 42 side, and the light utilization efficiency is low.

FIG. 5 is a sectional view showing an example of a semiconductor radiation detection device that has improved the above-mentioned problems (Japanese Patent Laid-Open No. 58-1181
Publication No. 63). This device has an Afi electrode 4 of the detection section.
N′″a-3i :t-1 (N-type amorphous silicon layer) 51.a-3i :@(non-doped amorphous silicon layer) 52 and Au electrode 53 are laminated on top of 2. In this structure, The point where the N-3i 43 detects the line and receives the light (indicated by the broken line in the figure) from the NaI (1° C.) scintillator 45 by the depletion layer formed under the Au electrode 44 is shown in FIG. However, the amorphous silicon layer 51,52 deposited on the electrode 42 operates as a Schottky-type amorphous photodetector and roughly detects the light from the NaI (TI) scintillator 45. Therefore, it has sensitivity characteristics superior to the semiconductor radiation detection device shown in FIG.

However, even this type of device has the following problems. That is, NaI (Tl) scintillator 45
emits light upon receiving X-rays, but the emission peak is at 410 [nm]
If the emission intensity at this wavelength is 100 [%], even at a wavelength of 500 [nml], it will be 30 to 40 [%].
]The luminous intensity is approximately the same as the diameter. On the other hand, the sensitivity of the Schottky type amorphous photodetecting element to light is 500~
600 [nml]. Therefore, the light emitted from the scintillator 45 with a wavelength of 500 nm or more can be fully utilized. On the other hand, N-
The sensitivity to light in the depletion layer due to the Au electrode 44 formed in the 8i 43 is generally 700 to 800 [nm
Since it has its peak at a wavelength around l, 700
It is known that the sensitivity tends to decrease significantly when the wavelength becomes less than [nml], and the sensitivity near 500 [nml is extremely low. Therefore, the degree of utilization of the light emitted by the scintillator is extremely small. Further, there are problems in that the N-s+ used in the detection section is expensive and cannot produce a crystal with a large diameter, so the device inevitably becomes smaller. Furthermore, the Au used for the Schottky electrode is expensive and the manufacturing cost is high.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and its purpose is to have extremely high detection sensitivity when used in combination with a scintillator, and to realize a device of any size at a low cost. The object of the present invention is to provide a radiation detection device capable of detecting radiation.

[Summary of the invention]

The gist of the present invention is to form amorphous semiconductor layers on both sides of a light-transmitting substrate, and to provide the semiconductor layers with a function as a radiation and light detection element.

That is, the present invention provides a radiation detection device that has the function of a photodetection element to improve detection sensitivity, and includes a light-transmitting substrate, an amorphous semiconductor layer formed on both surfaces of this substrate, and a combination of the substrate and the semiconductor layer. A scintillator is disposed on the opposite side to the incident side of the radiation incident on the substrate and emits light when irradiated with the radiation that has passed through the substrate and the semiconductor layer, and the semiconductor layer includes a radiation detection element and a photodetector. It is designed to have both functions.

〔Effect of the invention〕

According to the present invention, in addition to directly detecting X-rays with a detection section made of an amorphous semiconductor layer, the X-rays that have passed through the detection section are roughly utilized to cause a scintillator to emit light, and most of the light is emitted by the scintillator. It is possible to increase the sensitivity by directly receiving the light again at the detection unit. Therefore, very excellent sensitivity characteristics can be obtained. Furthermore, since the amorphous semiconductor device can be very thin and utilizes plasma reaction, it has excellent selectivity in substrate size and can be formed more easily. Therefore, it is also possible to reduce the manufacturing cost of the device.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing a radiation detection apparatus according to an embodiment of the present invention. In the figure, reference numeral 10 denotes a detection section having the functions of both an X-ray detection element and a photodetection detection element, and this detection section 10 is arranged between two W collimators 21. It should be noted that the detection unit 10 has an Afl substrate 11. It is formed of amorphous silicon layers 12, 13, 14, a SnO2 film 15, and the like. A NaI (TJ2) scintillator 25 is arranged on the side opposite to the X-ray incident side of the detection unit 10. The scintillator 25 generates light when X-rays that have passed through the detection section 10 are incident thereon, and the detection section 10 is irradiated with the light. The detection signal of the detection section 10 is outputted via the current amplifier 26.

Now, the detection section 10 is formed as shown in FIGS. 2(a) and 2(b). First, as shown in FIG. 2(a), N
Type a-s+:H (N-type amorphous silicon layer>12a
, 12b, I type a-3i:H (non-doped amorphous silicon layer) 13a, 13b and P type a-3i:i(
P-type amorphous silicon layers 14a and 14b are sequentially deposited by glow discharge decomposition plasma CVD method or the like.

Next, as shown in FIG. 2(b), <SnO2 films 15a, 1
It is formed by depositing 5b by sputtering, vapor deposition, or the like.

Here, the detection unit 10 is a SnO2 film when viewed from the X-ray incident side.
p-1-n (a-3i) /AI/ n-1-p(
a-3i)/5n02 structure, A2 substrate 1
It has a parallel connection structure of PIN diodes via 1. That is, the detection section 10 is divided into a detection section 10b on the X-ray incident side and a detection section 10a on the scintillator side. Note that although the scintillator side of the Ag substrate 11 is particularly mirror-finished, mirror-finishing may be applied to both surfaces without any problem. Furthermore, the inner surface of the W collimator 21 may be coated with Ag or the like to increase the light reflection efficiency.

In this example, the film thicknesses of each of the p, i, and n amorphous silicon layers are 100 [μm] or more, 5 [μm] or more, and
Although the number is 100 [persons] or more, regarding the amorphous silicon layer 13, considering the amount of detected X-rays and the amount of light detected by scintillator emission, the amorphous silicon layer 13b on the X-ray incident side and the amorphous silicon on the scintillator side are Determine the thickness of layer 13a. Considering the absorption characteristics of amorphous silicon for X-rays, the amorphous silicon layer 13b on the X-ray incident side should be thicker than 5 [μm], preferably 10 [μTrL] or more, so that as many X-ray direct detection valves as possible are formed. It's better to do so. Also, AJ2
The substrate 11 is made of various materials depending on the size of the desired radiation detection device.
All you have to do is select its shape and size.

In such a structure, the X-rays first enter the detection section 10b, where they are detected. Next, the detection unit 10
The X-rays that have passed through b pass through the A2 substrate 11 and reach the detection unit 10.
a, and X-rays are detected here as well. Then, the X-rays that have passed through the detection units 10b and 10a are incident on the scintillator 25, causing the scintillator 25 to emit light. The light from the scintillator 25 travels as shown by the dashed arrow in FIG.
Most of the light enters the detection section 10a, and some of the light is reflected by the W collimator 21 and passes through the detection section 10a.

The light enters from the side of 10b. The detection unit 10a detects this light again.
10b detects, and furthermore, the Aj2 substrate 11 of the detection unit 10a
An X-ray detection process is used in which light incident on the surface of the X-ray is reflected and detected again by the detection unit 10a.

Here, most of the light emitted by the scintillator is transmitted to the detection unit 1.
Since the light is directly incident on 0a, the efficiency of using the light is much higher than that of the conventional devices shown in FIGS. 4 and 5. Roughly, Na1 (7℃) scintillator 25
The emission wavelength of has a peak around 410 nm, but
The light emission intensity is sufficient even in the vicinity of 00 nm, and the sensitivity characteristics of the detection unit 10 (the peak is 500 to 600 nm, but it has sensitivity from about 400 nm) makes it possible to fully utilize the light. can.

As described above, according to this embodiment, the X-ray and light detection portions 10a made of amorphous silicon are provided on both sides of the second substrate 11.
, 10b, it is possible to significantly improve the X-ray detection sensitivity. That is, although the sensitivity to X-rays is the same as or slightly lower than that of the conventional device, the sensitivity to light is significantly improved compared to the conventional device, so the sensitivity as a whole is also improved.

Further, since amorphous silicon is deposited using the plasma CVD method, the shape and size of the substrate can be arbitrarily selected. Furthermore, there is no need to use expensive AU electrodes or the like. Therefore, it is possible to relatively easily form a detection section with high selectivity, and there are advantages such as being able to reduce the manufacturing cost of the radiation detection device.

FIG. 3 is a schematic configuration diagram showing a radiation detection device according to another embodiment. Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. The difference between this embodiment and the previously described embodiment is that instead of the two substrates described above,
The reason is that an insulating transparent substrate is used. That is, 5nO2111 as a transparent conductive film is coated on both sides of the quartz glass substrate 31.
32a.

32b are formed respectively. These conductive films 32
Amorphous silicon layers 12a, 12b, . . . , 14a are formed on the layers 12a, 32b.

14b and SnO2 [115a, 15b, which are exactly the same as in the previous example.

Of course, even with such a configuration, the same effects as in the previous embodiment can be obtained.

Note that the present invention is not limited to the embodiments described above. For example, the structure of the radiation and light detection section may be a Schottky type or a PN type instead of a PIN structure. Also, when viewed from the radiation incidence side, n + I)/A
It may be a λ/ptn structure. Furthermore, a tandem structure in which these are laminated is also effective. Further, when viewed from the radiation incident side, the structure may be a Schottky type/AR/ntp type or the opposite structure, or various combinations thereof may be used. Generally, P, B, and C are added to I type a-8t:1-1 (non-doped amorphous silicon layer).

The present invention is effective even if a small amount of Zn, (3e, etc.) is doped.

Further, the transparent conductive film is not limited to SnO2, and ITO, In203 may also be used.

In general, when a Schottky type is used as the detection part structure, it is also effective as a transparent conductive film by thinning a metal with a high work function such as AU, Pt, Ti, Ta, or Pd. Also,
As the conductive substrate, any metal such as Be or C that is stable and transmits radiation may be used instead of the A° C. substrate.

Similarly, the insulating substrate is not limited to a quartz substrate, and may be any substrate that transmits radiation. Further, although the substrate is arranged in a direction perpendicular to the radiation incident side, it is also possible to arrange the substrate in a horizontal direction. In general, the materials and shapes of the scintillator, collimator, etc. can be changed as appropriate depending on the specifications. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

- Fig. 1 is a schematic configuration diagram showing a radiation detection device according to an embodiment of the present invention, Fig. 2 (a) and (b) are sectional views showing the manufacturing process of the detection part used in the above device, and Fig. 3 1 is a schematic configuration diagram showing a radiation detection device according to another embodiment, and FIGS. 4 and 5 are schematic configuration diagrams each showing a conventional device. 10.10a, 10b--detection section, 11/'l substrate (transparent conductive substrate), 12...N-type amorphous silicon layer, 13...non-doped amorphous silicon layer, 14...P Type amorphous silicon layer, 15.3
2...SnO2 film, 2l-Wl remeter, 26...
Current amplifier, 31...quartz substrate (transparent insulating substrate)
. Applicant's agent Patent attorney Takehiko Suzue

Claims (5)

[Claims] (1) A translucent substrate, an amorphous semiconductor layer formed on both surfaces of the substrate, and an amorphous semiconductor layer disposed on the side opposite to the incident side of radiation incident on the substrate and semiconductor layer, 1. A radiation detection device comprising: a scintillator that emits light upon being irradiated with radiation that has passed therethrough; and the semiconductor layer has the functions of both a radiation detection element and a photodetection element. (2) The radiation detection device according to claim 1, wherein the substrate is a conductive substrate. (3) The substrate is an insulating substrate with transparent conductive films formed on both sides.
The radiation detection device described in Section 1. (4) The radiation detection device according to claim 1, wherein the main surface of the substrate is arranged in a direction perpendicular to the incident radiation. (5) The radiation detection device according to claim 1, wherein the semiconductor layer has a PIN structure.