JP2000241555A - Semiconductor radiation detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor radiation detector that has high energy resolution and detection sensitivity and is suited for the energy spectrum analysis of radiation and an image detector such as a gamma camera. SOLUTION: A plurality of units 1000-1 and 1000-2 of a semiconductor radiation detector for achieving relatively high energy resolution are laminated so that cathodes 103 or electric charge collection electrodes 104 are overlapped one another, and at the same time the cathodes 103 and the electric charge collection electrodes 104 of each detector unit are electrically connected in parallel. Detection sensitivity can be increased by increasing thickness by the number of laminations, and the decrease in energy resolution due to the increase in thickness can be minimized. The semiconductor radiation detector can be applied not only to an individual detector but also to a two-dimensional detector where individual detectors are arranged two-dimensionally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor radiation detector for obtaining two-dimensional information of the energy spectrum or radiation intensity of radiation such as X-rays and .gamma.-rays. The present invention relates to a semiconductor radiation detector capable of obtaining sensitivity.

[0002]

2. Description of the Related Art A semiconductor radiation detector utilizes the generation of electric charges in a crystal via ionization due to the interaction between radiation such as X-rays and γ-rays and a semiconductor crystal. By providing electrodes on both surfaces of the semiconductor crystal and applying a bias voltage between these electrodes, the generated charges are collected and taken out as a signal from one of the electrodes (charge collecting electrodes).

In this case, the thickness required to absorb the energy of the incident radiation in the volume of the crystal increases in proportion to the energy of the radiation. For example, the thickness required to detect 80% of incident γ-rays in a CdZnTe crystal is 1.0 mm for an energy of 80 keV, but is 6.0 mm for an energy of 140 keV. Therefore, in order to detect a gamma ray having a relatively high energy, it is necessary to use a crystal having a large thickness.

However, depending on the type of crystal, the energy resolution decreases as the crystal thickness increases. For example, Cd
Te and CdZnTe crystals are characterized in that charge carriers drift in the crystal volume between the cathode and the charge collection electrode, and some of them are trapped by defects inherent in the crystal. This charge carrier trapping phenomenon reduces the charge collection efficiency and also appears stronger for holes than for electrons, so the amount of signal reduction differs depending on where charge carriers are generated in the crystal. Become.

When the energy spectrum of radiation is measured by a detector having such characteristics, a phenomenon in which the energy peak p trails toward the lower energy side (hereinafter referred to as tailing) is caused as shown in FIG. , Which increases the width of the peak and reduces energy resolution. Same figure
(b) shows the relationship between the energy resolution and crystal thickness of CdZnTe and Ge for 140 keV γ-rays, but the curve B for Ge shows almost no decrease in its properties due to the increase in thickness. Whereas the curve A for CdZnTe
Decrease the energy resolution as the thickness increases.

CdTe and CdZnTe which are lower in cost than Ge crystals
In order to widely apply a semiconductor radiation detector using the above method to an energy spectrum analysis of radiation or an image detector such as a gamma camera, it is important to improve the energy resolution of a thick crystal, that is, a crystal having a large volume.

In order to improve the collection efficiency of the charge generated in the crystal, a third voltage is set on the same surface as the charge collection electrode, the voltage being set lower than the charge collection electrode and set higher than the cathode.
A semiconductor detector provided with such an electrode (reference electrode) has been proposed (US Pat. No. 5,677,539). In this semiconductor detector, the charge (electrons) generated in the crystal by the radiation is attracted by the charge collecting electrode and the reference electrode until the charge (electron) approaches the vicinity of the charge collecting electrode, thereby shortening the distance that the charge is guided to the charge collecting electrode. . This improves the effect of the decrease in charge collection efficiency due to capture, suppresses spectrum tailing, and enhances energy resolution.

[0008]

However, in a semiconductor detector having such a reference electrode, a charge collection electrode and a reference electrode are formed on one surface of a crystal, and the pair of electrodes is substantially parallel to the surface. Since an electric field is formed, there is a limit to integration in which a large number of detector units are arranged, and an electrode having a considerably smaller area than the reference electrode is required for the charge collection electrode. Therefore, when applied to a semiconductor detector that detects the intensity distribution of radiation as a two-dimensional radiation image, sufficient charge collection efficiency has not been improved. In addition, there is still a problem of performance improvement from the viewpoint of energy resolution that determines image quality of the two-dimensional detector.

Accordingly, an object of the present invention is to provide a semiconductor detector which realizes an effective improvement in energy resolution with a relatively simple detector structure. Another object of the present invention is to provide a semiconductor radiation detector in which the detection sensitivity and the energy resolution are increased by increasing the thickness of the crystal to have a substantially large crystal volume. Still another object of the present invention is to provide a two-dimensional detector capable of detecting a high-quality radiation image.

[0010]

According to the present invention, there is provided a semiconductor radiation detector according to the present invention, comprising: a semiconductor crystal which generates electric charge by irradiation of radiation; a cathode provided on a first surface of the crystal; A semiconductor radiation detector unit (hereinafter simply referred to as a detector unit) including a charge collection electrode provided on the second surface of the crystal and a means for applying a bias voltage between the electrodes.
Are laminated, and each cathode and charge collecting electrode are electrically connected in parallel.

In such a semiconductor radiation detector of the present invention, by stacking a plurality of n detector units, the volume can be substantially increased by the number of layers, and the detection sensitivity can be increased. In addition, since each detector unit is electrically connected in parallel and collects electric charges generated in the crystal for each unit, it is possible to avoid a decrease in energy resolution due to an increase in thickness. That is, in a CdTe or CdZnTe crystal or the like, the energy resolution decreases as the crystal thickness increases, but in the semiconductor radiation detector of the present invention,
The decrease in energy resolution is limited to the decrease due to the leakage current of one crystal in the unit of detector added by the number of layers n, which is lower than the decrease in energy resolution when crystals having the same thickness as the stacked layers are used. Is also small enough. Thereby, a radiation detector having high detection sensitivity and high energy resolution can be realized.

In the present invention, the first surface and the second surface of each detector unit are parallel, and are stacked in a direction in which these surfaces are overlapped. Thereby, the effect of increasing the thickness by the lamination can be obtained. Preferably, one of the surfaces is a radiation incident surface. This enables two-dimensional radiation image detection.

Further, in the semiconductor radiation detector of the present invention, it is preferable that each detector unit is stacked so that cathodes or charge collection electrodes face each other. This facilitates parallel connection of each cathode and charge collection electrode. Further, it is preferable to provide connection means between the electrodes in order to ensure and facilitate electrical connection between the electrodes.

The semiconductor radiation detector of the present invention may be a single detector in which each detector unit generates a single output signal, or may be a two-dimensional detector.

That is, the two-dimensional semiconductor radiation detector of the present invention comprises: a semiconductor crystal which generates electric charges by irradiation with radiation;
A semiconductor radiation detector unit comprising a cathode provided on a first face of a crystal, a charge collecting electrode provided on a second face of the crystal, and means for applying a bias voltage between the electrodes (simply referred to as a semiconductor radiation detector unit); A plurality of cathodes and charge collecting electrodes are electrically connected in parallel, and at least one of the cathode and the charge collecting electrodes has a plurality of electrodes. With
It detects two-dimensional information of radiation intensity.

As one mode of such a two-dimensional semiconductor radiation detector, in each detector unit, the charge collecting electrodes are composed of a plurality of charge collecting electrodes arranged in a matrix. According to another aspect of the two-dimensional semiconductor radiation detector, in each detector unit, the cathode includes a plurality of rectangular electrodes arranged in rows, and the charge collection electrode includes a plurality of rectangular electrodes arranged in columns. . The semiconductor radiation detector generates an output signal for each position determined by the matrix.

Also in such a two-dimensional detector, it is preferable to stack the two-dimensional detectors such that the cathodes or the charge collection electrodes face each other. Further, it is preferable to provide a connection means for electrically connecting these electrodes. Means for connecting the electrodes include, for example, fine electronic components such as facing electrodes to be connected, interposing a spacer electrode between the electrodes, and bonding with a conductive epoxy material having both conductivity and adhesiveness. In the manufacturing field, general techniques can be adopted.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor radiation detector according to the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 1 shows a semiconductor radiation detector 1000 according to the present invention.
FIG. 3 is a diagram showing a first embodiment of the present invention,
00 has a structure in which two detector units 1000-1 and 1000-2 are stacked via a spacer electrode 105 as a connecting means. The detector units 1000-1 and 1000-2 have the same configuration, each having a cathode 103 formed on a first surface of a plate-like semiconductor crystal 100, and a cathode 103 formed on a second surface parallel to the first surface. Charge collection electrode 10
4 are formed, and the charge collecting electrodes 104 are stacked so as to face (oppose) each other. In the figure, "-1" and "-2" attached after the three- or four-digit code are codes for distinguishing a plurality of equivalent elements from each other (hereinafter the same). .

The spacer electrode 105 is made of a conductive material such as copper, and is provided with a lead 107 for extracting an output signal. The two detector units 1000-1 and 1000-2 and the spacer electrode 105 are mechanically connected to each other by a conductive material 106 such as a conductive epoxy material applied in advance to both surfaces of the spacer electrode 105 or two charge collecting electrodes 104 facing each other. Electrically and electrically. The lead 107 of the spacer electrode 105 is a signal line 108
Is connected to a detection circuit (not shown).

On the other hand, the cathodes 103 of the two detector units 1000-1 and 1000-2 are electrically connected by a lead wire 109 as shown in FIG. 1B, whereby the two detector units are electrically connected. Are connected in parallel. A bias Vg is applied between the cathode 103 and the charge collecting electrode 104, that is, the spacer electrode 105 by a bias power supply 110.

In such a configuration, when a charge is generated in the volume of the two crystals 100-1 and 100-2 by the radiation 200, electrons and holes in the individual detector units are respectively charged and collected by the charge collection electrode and the cathode. The signal as the sum of the two detector units is extracted from the signal line 108 as a radiation signal.

The incident direction of the radiation 200 is not limited to the direction crossing the surface on which the electrodes are formed as shown in the figure, and may be the direction parallel to the surface on which the electrodes are formed. In this case, the effect of stacking the detector units in the thickness direction can be obtained. This is shown in FIG.
This will be described below.

FIG. 2 shows crystals 100-1 and 100-2 by radiation 200.
It shows the state of the movement of the charge composed of the electrons e- and holes h + generated in the radiation 200-1 and 200-2 in the detector unit 10
The case where the light enters from the cathode 103-1 of 00-1 is shown. First, when the relatively low-energy radiation 200-1 is incident, most of the energy of the radiation is converted by ionization in the volume of the crystal 100-1 in the upper layer, whereby the crystal 100-1 is converted.
Of the charges generated in the volume, the holes h + move toward the cathode 103-1 and the electrons e- move toward the charge collecting electrode 104-1 to finally collect each of the cathode 103-1 and the charge. Electrode 104
-1 and is extracted from the signal line 108 as a radiation signal. Radiation 200-
1 can be detected only in the crystal 100-1. For example, 80
For keV gamma rays, a 1 mm thick CdZn crystal satisfies the purpose of the detector.

On the other hand, radiation 200-
In the case of 2, part of the energy is converted by ionization within the volume of the crystal 100-1 and electrons e- generated in the volume of the crystal 100-1 are collected by the charge collection electrode 104-2, Some energy is not converted. That is, the radiation 200-2 having relatively high energy cannot be detected only by the crystal 100-1. However, the remaining radiation energy that has not been converted is converted to charge via ionization in the volume of the second crystal 100-2 provided on an extension of the incident direction. This crystal
Electrons e- generated in the volume of 100-2 are collected by the charge collection electrode 104-2, and the charge collection electrode 1 provided on the first crystal 100-1.
The electron e- collected in 04-1 is collected and extracted from the signal line 108 as a signal of the radiation 200-2. For example, 140keV
Since the crystal thickness required to detect 80% of the γ-rays is about 6 mm, the detection capability of 140 keV γ-rays can be increased by stacking two detector units consisting of 3 mm crystals. %
Can be increased.

On the other hand, regarding the energy resolution of the semiconductor radiation detector 1000, two detector units 1000-1 and 1000-1
Since 00-2 is in a parallel relationship, it is theoretically equal to the energy resolution of each detector unit. In a real detector,
Since the energy resolution is reduced by the leakage current caused by the crystal itself in the detector unit, when the layers are stacked, the energy resolution reduction due to the leakage current is added to the number of layers.
But energy resolution degradation due to commonly leakage currents, cross-sectional area corresponding to the electrode surface of the crystals is in the range of up to about 10 mm ² or less to about 0.5% (0.6 keV), compared to the effect of improving the energy resolution according to the present invention And small enough.

FIG. 2B shows the same CdZnTee as FIG. 5B.
This figure shows the relationship between the energy resolution for 140 keV gamma rays and the crystal thickness. When the thickness of a crystal unit is 2 mm, the energy resolution is 4.7% (220-1). When the thickness of this crystal is doubled (4 mm), the energy resolution becomes 6.4%. However, in the configuration of the present invention in which 2 mm crystals are stacked, the energy resolution is 5.2% even when the energy resolution decrease due to leakage current is taken into consideration. This means that an improvement effect of 1.2% was obtained. Similarly, taking a detector with a crystal thickness of 5 mm as an example (220-2), its energy resolution is
This is 7.2%, which is reduced to 9.7% when the thickness of the crystal is set to 10 mm. However, when two detectors are stacked, it becomes 7.7%, and an improvement effect of 2.0% can be obtained.

As described above, by stacking a plurality of detector units so as to be connected in parallel, a decrease in energy resolution can be minimized, and the energy detection efficiency can be improved by the number of layers.

Assuming that the incident direction of the radiation is the direction traversing the stack, the cathode 103 except the crystal 100,
The thickness of each layer of the charge collecting electrode 104, the conductive material 106, and the spacer electrode 105 is the minimum value required to fulfill the purpose of each layer in order to minimize the reduction in energy resolution due to unnecessary absorption and scattering of radiation, for example, 100 μm A degree is desirable.

In the illustrated embodiment, the case where two detector units are stacked is shown, but the same effect can be obtained even if the number n of stacked units is two or more. In this case, the effect of lowering the energy resolution due to the leakage current becomes n times, so that the value of the number n of layers is practically in the range of 2 to 4.

The first embodiment is suitable as a semiconductor radiation detector (single detector) for analyzing the energy spectrum of radiation. Further, it is also possible to configure the semiconductor radiation detector of this embodiment as one unit of a two-dimensional array type detector and arrange them in a matrix to form a two-dimensional array type detector.

FIG. 3 is a view showing a semiconductor radiation detector according to a second embodiment of the present invention. This semiconductor radiation detector
The 3000 has the same structure as the embodiment of FIG. 1 in which two detector units 3000-1 and 3000-2 are laminated with a spacer electrode 3003 interposed therebetween. Here, each detector unit has a two-dimensional matrix structure. It is a detector and has a radiation intensity of 2 such as a radiation image.
Used for detecting dimensional information.

The detector unit having the matrix structure is a flat crystal 100 having a size that covers the entire matrix.
A cathode 303 is formed on substantially the entire surface of the substrate, and a plurality of charge collecting electrodes 304 are formed in a matrix on the back surface of the surface. Individual elements constituting the matrix are shown in FIG.
It has the same configuration as one detector unit (1000-1, 1000-2). Although omitted in the drawing, a bias voltage is applied between the cathode and each charge collecting electrode in the same manner as in FIG. 1B. In this two-dimensional detector, each charge collecting electrode 304 has a cathode 3
The geometric volumes projected on 03 become independent detection areas, and correspond to one pixel of the radiation image picked up by the present detector. Therefore, in the entire detector 3000, the volume of these stacked in the stacking direction is the unit of detection.

The detector units 3000-1 and 3000-2 are arranged such that the surfaces having the respective charge collecting electrodes 304 face inside each other.

The spacer electrode 3003 is connected to each charge collecting electrode 304
The electrodes 310-1 and 310-2 are arranged on the surfaces (front and back) in contact with the charge collection electrodes 304 having a matrix structure, respectively, and the electrodes at the corresponding arrangement positions are electrically connected to each other. Have. Such a spacer electrode 30
03, for example, while providing a spacer electrode 310-1 and 310-2 of the same electrode arrangement as the charge collection electrode 304 on both sides of the thin or thin insulating material 305 provided with a lead pattern inside,
Insert through holes 311 between corresponding spacer electrodes.
It is formed by electrically conducting with the above. Spacer electrode
3003 and each of the detector units 3000-1 and 3000-2 are similar to the embodiment of FIG.
The conductive material 320 pre-applied to 310-2 is sandwiched therebetween.
The internal lead pattern is made up of individual spacer electrodes 310-1, 3
10-2 is electrically connected to the corresponding electrode lead 312. Thus, an output signal from each element of the charge collecting electrode 304 can be extracted from each electrode lead 311.

The semiconductor radiation detector having such a configuration is as follows.
Each charge collection electrode of two detector units 3000-1 and 3000-2
Since 304 is electrically coupled in parallel and connected in cascade for radiation detection, the detection sensitivity can be increased for relatively high energy X-rays or γ-rays, and high energy A two-dimensional array detector having a resolution can be obtained.

FIG. 4 is a diagram showing a semiconductor radiation detector 4000 according to a third embodiment of the present invention. In the embodiment shown in FIG. 4, the configuration of each detector unit is the same as that of the detector unit 3000-3000 shown in FIG.
1, a two-dimensional array detector similar to 3000-2, in which a cathode 303 is formed on one surface of a semiconductor crystal 100, and charge collecting electrodes 304 arranged in a matrix are formed on the opposite surface. . In this embodiment, the number of charge collecting electrodes 304 per unit area of the crystals 100-1 and 100-2 is set to be larger than that of the semiconductor radiation detector 3000 in FIG. 3 in order to increase the number of pixels that determine the fineness of the radiation image. Although increasing, the basic configuration of each element is the same as that of the detector of FIG. 3 and FIG. 1 (b), and the elements corresponding to the detector unit of FIG. I have.

The semiconductor radiation detector 4000 of this embodiment is
The cathodes 303 of these detector units are stacked so as to face each other, and the charge collecting electrodes 304 are arranged outward. Since the cathode 303 consists of only one continuous layer,
The spacer electrode as used in the embodiment of FIG. 3 is unnecessary, and the cathodes 303 are simply laminated by bonding with a conductive material.

On the other hand, as a connecting means for electrically connecting these two detector units in parallel, an electrode sheet 405 having the same electrode arrangement as the matrix-like charge collecting electrodes 304 is used. The electrode sheet 405 is formed by forming two sets of space electrodes 310 having the same electrode arrangement as the charge collecting electrodes 304 on one surface of an insulating sheet 406 such as a flexible polyimide resin sheet as shown in FIG. And this electrode sheet 4
05 is arranged such that the sets of space electrodes 310 are respectively arranged outward and connected to the charge collecting electrodes 304. At this time, the corresponding space electrodes 310 of each set are electrically connected so that the front and back charge collection electrodes 304 having the same positional relationship are electrically connected. The connection between the space electrodes can be established by a through hole 311 and a strip 312 made of a conductive material such as copper.

By electrically connecting the space electrode 310 of the electrode sheet 405 and the corresponding charge collecting electrode 304 via a conductive material having both adhesiveness and conductivity, the space electrode 310 and the charge collecting electrode 304 are joined to form an integral structure, thereby enabling semiconductor radiation detection. The vessel 4000 can be formed.

The semiconductor radiation detector 4000 of this embodiment is also
The same effect as the detector 3000 shown in FIG. 3 can be obtained in terms of energy detection sensitivity and energy resolution.
Since the 4000 does not have a protruding portion such as a signal extraction electrode or a lead on the side surface, a plurality of the 4000s can be closely arranged in the side direction, whereby a large-area two-dimensional array detector can be obtained. Alternatively, the laminated structure shown in FIG.
It is also possible to configure a semiconductor radiation detector having a multilayer structure by combining a multilayer structure with the above.

Although the embodiments in which the basic units of the semiconductor detector of the present invention and the semiconductor detector of the present invention are arranged in a matrix have been described, the present invention is not limited to these, and various modifications are possible. For example, in order to simplify the detector circuit configuration in a two-dimensional array, the charge collecting electrodes may be arranged in rows or columns, and the cathodes may be arranged in columns or rows orthogonal thereto. Such an embodiment is shown in FIG.

The semiconductor radiation detector 6000 shown in FIG. 6 also has a structure in which two detector units 6000-1 and 6000-2 are stacked, and each of the detector units 6000-1 and 6000-2 is a semiconductor. This is a two-dimensional array type radiation detector having a structure in which a cathode 603 and a charge collection electrode 604 are formed on both surfaces of a crystal 100. cathode
Both the 603 and the charge collecting electrode 604 are divided into a plurality of rectangular electrodes, and the plurality of electrodes are arranged in rows or columns. The arrangement direction of the cathode 603 and the charge collection electrode 604 are orthogonal, and when viewed from one detector unit, the geometric volume obtained by projecting one rectangular charge collection electrode 604-1 on the cathode 603-1, The volume of a portion that overlaps with the geometric volume of one charge collection electrode 604-1 projected on the cathode 603-1 is a detector unit, and corresponds to one pixel of a radiation image captured by the detector unit. Therefore, in the entire detector 6000, a volume in which these are overlapped is a detection unit.

In this embodiment, each detector unit 6000-1, 60
00-2 is stacked so that the surfaces on which the cathodes 603-1 and 603-2 are formed face each other and the cathodes having the same positional relationship overlap each other. Charge collection electrode 304 for each detector unit 6000-1 and 6000-2
Are arranged parallel to one another and each facing outward. The cathodes of each detector unit may be simply mechanically and electrically connected by a conductive material, but in the illustrated embodiment, they are opposed to each other by using an electrode sheet 6003 having a space electrode 310 formed on both surfaces. The cathodes 603-1 and 603-2 are electrically and cautiously joined. This electrode sheet 6003
For example, a plurality of space electrodes 310 having the same arrangement as the row (column) arrangement of the cathodes are formed on both the front and back surfaces of the insulating sheet 606, and the corresponding space electrodes 310 on the front and back are electrically connected by the space electrode end portions 310-1. And is integrally joined to the two detector units 6000-1 and 6000-2 via a conductive material having both adhesiveness and conductivity (not shown).

On the other hand, the charge collecting electrodes 604-1 and 604-2 of each of the detector units 6000-1 and 6000-2 are electrically connected by an electrode sheet 6004 as shown in FIG. This electrode sheet
Reference numeral 6004 has the same function as the electrode sheet 405 of the semiconductor radiation detector 400 shown in FIG. 4, and includes an insulating sheet 406, space electrodes 311 having the same arrangement as the charge collecting electrodes 604, and strips 312. The strip 312 is connected to each space electrode 31
This is a conductive material that connects 1 to the charge collection electrode 604 of each detector unit at the corresponding array position.

FIG. 7 shows an equivalent circuit of the semiconductor radiation detector 6000 having this structure. As shown, the cathodes 603-1 and 603-2 of the two detector units are connected by a space electrode 310 and also connected to a circuit for extracting a column signal 702. On the other hand, the charge collecting electrodes 604-1 and 604-2 are connected by a space electrode 311 and a strip 312, respectively, and are also connected to a circuit for extracting a row signal 701.
A bias voltage + Vb is applied to each of the charge collecting electrodes 604-1 and 604-2 from a bias power supply 714 via a resistor Ra712.
A bias is applied to each cathode by grounding via a resistor Rd713.

In the semiconductor radiation detector 7000, when the radiation incident position is where the charge collection electrode on the k-th row intersects with the j-th cathode, the k-th row signal 701 and the j-th column signal By the signal value of 702 being maximum,
The position of incidence of radiation is known. Two-dimensional position information can be obtained from such signal calculation of the row signal and the column signal.

Also in the semiconductor radiation detector 7000 of this embodiment, two detector units are electrically connected in parallel,
Further, since the detection of radiation can be connected to a cascade, the same effects as those of the detectors shown in FIGS. 3 and 4 can be obtained. Moreover, a semiconductor radiation detector having a small number of detector signal readout circuits can be realized.

Although the embodiment shown in FIG. 6 shows the case where the cathodes are joined together, the same configuration can be applied to the case where the charge collection electrodes are joined together, and the same effect can be obtained. Further, in all the above-described embodiments, the case where the thicknesses of the crystals of the stacked detector units are equal is shown, but the thicknesses of the detector units do not necessarily have to be equal, and the detectors using the crystals of different thicknesses are not necessarily required. Units may be stacked.

[0050]

According to the present invention, a semiconductor radiation detector using a crystal having a relatively small thickness is stacked as a unit, and each detector unit is electrically connected in parallel.
The effect of increasing the thickness, that is, the radiation detection sensitivity, can be increased while maintaining a high level of energy resolution in a thin crystal. This makes it possible to detect radiation having relatively high energy with high sensitivity. In addition, CdTe and Cd exhibit excellent energy resolution in the range where the crystal thickness is small.
Using a ZnTe crystal or the like, it is possible to realize a detector with improved energy resolution and radiation detection sensitivity.

The semiconductor radiation detector of the present invention has a structure in which X-rays and γ-rays are formed by stacking the crystal electrodes so that they face each other and arranging the radiation so as to be perpendicular to the electrode forming surface of the crystal. In an arrangement of semiconductor detectors for detecting radiation intensity distribution two-dimensionally, energy resolution and radiation detection sensitivity can be improved, and as a result, a high-quality image with high resolution can be obtained.

Further, the semiconductor radiation detector of the present invention is a semiconductor radiation detector which is excellent in the range of conventional circuit printing board manufacturing technology and assembly technology generally used in the field of manufacturing equipment having relatively simple semiconductor processing technology and electronic circuits. A radiation detector can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a semiconductor radiation detector according to the present invention, wherein (a) is a perspective view and (b) is a sectional view.

2A and 2B are diagrams illustrating the operation of the semiconductor radiation detector according to the present invention. FIG. 2A is a diagram illustrating ionization by radiation in a crystal volume of the detector and transfer of its charge, and FIG. 6 is a graph illustrating the relationship between energy resolutions and the effect of improving energy resolution during stacking.

FIG. 3 is a diagram showing one embodiment of a two-dimensional array type semiconductor radiation detector of the present invention.

FIG. 4 is a diagram showing another embodiment of the two-dimensional array type semiconductor radiation detector of the present invention.

FIGS. 5A and 5B are diagrams illustrating energy resolution of radiation by a semiconductor radiation detector. FIG. 5A is a diagram illustrating an example of an energy spectrum, and FIG. 5B is a graph illustrating an example of a relationship between the crystal thickness of the detector and the energy resolution. It is.

FIG. 6 is a diagram showing another embodiment of the two-dimensional array type semiconductor radiation detector of the present invention.

FIG. 7 is a diagram showing an equivalent circuit of the semiconductor radiation detector of FIG. 6;

[Description of References] 100: Crystals 103, 303, 603: Cathodes 104, 304, 604: Charge collecting electrodes 105, 310, 3003: Spacer electrodes (connection means) 106, 306: Conductive material 107: Electrode leads 110, 714 ... Bias power supply 200… Radiation 405, 6003, 6004… Electrode sheet (connection means) 1000, 3000, 4000, 6000, 7000… Semiconductor radiation detector

Claims (4)

[Claims] 1. A semiconductor crystal for generating electric charge by irradiation of radiation, a cathode provided on a first surface of the crystal, a charge collecting electrode provided on a second surface of the crystal, and a cathode and an electric charge. A semiconductor radiation detector comprising: a plurality of semiconductor radiation detector units each including a means for applying a bias voltage between collection electrodes; and stacking a plurality of units, and each of the cathodes and the charge collection electrodes are electrically connected in parallel. 2. The semiconductor radiation detector unit according to claim 1, wherein at least one of said cathode and said charge collection electrode includes a plurality of electrodes and detects two-dimensional information of radiation intensity. A semiconductor radiation detector as described in the above. 3. The semiconductor radiation detector according to claim 1, further comprising connection means for electrically connecting the cathodes or the charge collection electrodes. 4. The semiconductor radiation detector according to claim 1, wherein the first surface or the second surface is a radiation incident surface.