Radiation detection element and radiation detector

Abstract

To provide a radiation detection element and radiation detector, which offer reduced noise in wave-height spectrum measurement.SOLUTION: The challenge is overcome by employing a radiation detection element comprising a specific coating layer in addition to a substrate containing a semiconductor and electrodes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation detection element containing a specific compound. [Background technology]

[0002] In recent years, there has been a demand for higher resolution in medical diagnostic imaging. Photon-counting CT, which converts light into an electric charge and calculates a pulse signal, is attracting attention. A major feature of photon counting CT is that it records the energy information of the incident radiation. It is easy to obtain data and is superior to energy discrimination CT, which separates data in multiple energy bands. It is expected that imaging diagnostics with a high amount of information will be realized. The energy resolution of the energy discrimination CT is , which is determined from the half-width of the photoelectric absorption peak, in order to obtain excellent energy resolution, Therefore, it is important to obtain clear peaks. However, if the radiation detection element contains a defect, the defect may cause a leakage current. This causes the peak to become unclear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Table 2018-503060 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a radiation detection element with reduced leakage current. [Means for solving the problem]

[0005] The present inventors have conducted extensive research to solve the above-mentioned problems. The above-mentioned problems can be solved by using a radiation detection element that has a specific coating layer between the electrode and the substrate. This has led to the completion of the present invention.

[0006] That is, the present invention provides the following.

[0007] [1] A radiation detection element comprising a substrate, a first electrode, and a second electrode, the substrate being a semiconductor a conductor between the first electrode and the substrate or between the second electrode and the substrate; and a coating layer is provided on at least one of the surfaces between the surface and the substrate, and the coating layer contains a compound having an ionic functional group. A radiation detection element comprising: [2] The radiation detector according to [1], wherein the thickness of the coating layer is 0.01 nm or more and 3 nm or less. Line detector. [3] The semiconductor contains a compound having a composition represented by the following formula (1): [1] or The radiation detection element according to [2]. AB v X w ···(1) (In the above formula (1), A, B, and X represent elements constituting the compound, and A represents a compound containing a monovalent cation.) B contains one or more metal elements selected from the 4th to 6th periodic metal elements, and C contains an anion. v and w respectively represent the molar ratios of B and C when the molar ratio of A is 1.0, and v and w and w each independently satisfy 0.5≦v≦1.5 and 2.5≦w≦3.5. [4] The substrate according to any one of [1] to [3], wherein the thickness of the substrate is 0.2 to 500 mm. The radiation detection element. [5] The ionic functional group has at least one quaternary ammonium ion, [1 The radiation detection element according to any one of [1] to [4]. [6] The compound according to any one of [1] to [5], wherein the ionic functional group has at least one zwitterion. The radiation detection element according to any one of the preceding claims. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a radiation detection element with reduced leakage current. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an example of a method of using a radiation detection element. [Figure 2A] 1 is a photograph of a cross section of Comparative Example 1 taken with a transmission electron microscope. [Figure 2B] 1 is a transmission electron microscope photograph of the cross section of Example 1, with supplementary notation indicating the thickness of the coating layer. [Figure 2C] 1 is a transmission electron microscope photograph of the cross section of Example 2, with supplementary notation indicating the thickness of the coating layer. [Figure 3] FIG. 1 is a schematic diagram of an apparatus used for measuring pulse height spectra in the examples. [Figure 4] FIG. 1 is a conceptual diagram of a pulse height spectrum measurement system used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. stomach.

[0011] [Radiation detection element] In one embodiment, the present invention provides a radiation detection element, comprising: a substrate, a first electrode, and a second electrode; the substrate comprises a semiconductor; Furthermore, at least one of the first electrode and the substrate and the second electrode and the substrate may be a coating layer on at least one side, In the radiation detection element, the coating layer contains a compound having an ionic functional group. Details are explained below.

[0012] In one embodiment, the radiation detection element according to the present invention comprises a substrate, a covering layer, a first electrode, and A second electrode is provided. The shapes and positional relationship of the substrate, the covering layer, the first electrode, and the second electrode are such that the effects of the present invention can be obtained. In a typical embodiment, the substrate has a first surface and a and a second electrode facing the first electrode. The radiation detection element is located between the first electrode and the substrate, and The radiation source has a coating layer between the second electrode and the substrate. The line detection element may be located between the substrate and the covering layer, between the covering layer and the electrode, or outside the electrode. , other layers or other components may be included. The radiation detected by the present invention includes, for example, alpha rays, gamma rays, X-rays, and neutron rays. From the viewpoint of utilization in the field of security, X-rays or gamma rays are preferable, and the general application field is From the viewpoint of practicality, X-rays are preferable. The charges to be detected are electrons or holes. For convenience, the following description will be directed to the exemplary embodiment described above as an example of a non-limiting embodiment of the present invention. explain.

[0013] <Substrate> The radiation detection element according to this embodiment includes a substrate. The substrate is not particularly limited as long as it has a first surface and a second surface opposite to the first surface. From the viewpoint that it is preferable that the electric field strength generated when a voltage is applied to the substrate is uniform within the substrate, The distance between the first surface and the second surface is equal at least in the region in contact with the first electrode and the second electrode. In other words, it is preferable that the first surface and the second surface are parallel to each other. The shape is not particularly limited and may be flat or curved, for example, rectangular, square, or the like. From the viewpoint of ease of device manufacturing, a flat surface is preferred. is preferred, and a rectangle is more preferred.

[0014] The area of ​​the first and second surfaces of the substrate is independent, usually 1 mm 2 More than 4m, preferably m 2 More than 16mm, preferably 16mm 2 The upper limits of the areas of the first and second surfaces of the substrate is not particularly limited, but from the viewpoint of the difficulty of manufacturing, it is usually 1000 mm 2 The following is the area: When is equal to or greater than the lower limit, an image of a wider area can be obtained in one image capture. The thickness of the substrate is usually 0.2 mm or more, preferably 0.5 mm or more, and more preferably The thickness is preferably 0.8 mm or more, and more preferably 1.0 mm or more. There is no particular upper limit to the thickness. However, it is usually 500mm or less, and can be 100mm or less, 50mm or less, or 30mm or less. When the thickness of the substrate is within the above range, the radiation absorption rate can be increased.

[0015] The substrate usually contains a semiconductor. When the substrate contains a semiconductor, it generates a charge (charge) when irradiated with radiation. The generated carriers reach the electrodes and are detected, resulting in the detection of radiation. do. From the viewpoint of uniformity of sensitivity, the substrate is preferably crystalline, and more preferably single crystal. The larger the single crystallite and the fewer defects, the more easily the charges generated by radiation are trapped and scattered. The possibility of the charge being disturbed or absorbed is reduced, and the amount of charge reaching the electrode from the single crystallite increases. As a result, the efficiency of converting radiation into electric current is improved. Substrate fabrication methods include coating processes, stacking of microcrystals, and the use of bulk crystals. However, from the viewpoint of ensuring stable physical properties, it is more preferable to utilize bulk crystals. Examples of methods for obtaining crystals include high-temperature melting and solution growth. From the viewpoints of low temperature production and facility costs, the solution growth method is more preferable.

[0016] The material of the substrate is not limited, but in certain embodiments, for reasons described later in the <Covering Layer> section, Therefore, the substrate preferably comprises a compound having a composition represented by the following general formula (1): AB v X w ···(1) (In the above formula (1), A, B, and X represent the elements that constitute the compound, and A represents a monovalent cation. B includes one or more metal elements selected from the metal elements of the fourth to sixth periods, and C includes an anion. v and w respectively represent the molar ratios of B and C when the molar ratio of A is 1.0, 0.5≦v≦1.5, 2.5≦w≦3.5, respectively.)

[0017] The A includes a monovalent cation, preferably a cation of an organic molecule, a group 1 cation of the periodic table, and It contains one or more cations selected from the group consisting of cations of Groups 13 to 16 elements. From the viewpoint of effectively repairing defects, A is preferably a cesium ion or a rubidium ion. ion, potassium ion, ammonium ion which may have a substituent, or ammonium ion which may have a substituent and at least one phosphonium ion selected from the group consisting of phosphonium ions, From the viewpoint of the stability of the crystal structure, A is more preferably methylammonium ion and cesium ions, From the viewpoint of long-term stability, A particularly preferably contains cesium ions. The cations may be of one or more types. The proportion of the monovalent cations in A is usually 50 mol % or more, preferably 70 mol % or more, more preferably 80 mol % or more, and particularly preferably 90 mol % or more, is not particularly limited and may be 100%.

[0018] Examples of ammonium ions which may have a substituent include primary ammonium ions. or a secondary ammonium ion. There is no particular limitation on the substituent. Specific examples of the ammonium ion that may be used include alkylammonium ions and arylammonium ions. Specific examples include methylammonium ion, molybdenum ion, and Methylammonium monofluoride ion, methylammonium difluoride ion, methylammonium trifluoride ethylammonium ion, ethylammonium ion, isopropylammonium ion , n-propylammonium ion, isobutylammonium ion, n-butylammonium ammonium ion, t-butylammonium ion, dimethylammonium ion, diethyl Ammonium ion, phenylammonium ion, benzylammonium ion, phenyl Netylammonium ion, guanidinium ion, formamidinium ion, acetone Examples include a midinium ion and an imidazolium ion.

[0019] The B typically contains a divalent cation. The divalent cation is a metal cation or a semi-metal cation. Thione is preferred. Specific examples include cations of elements in Group 14 of the periodic table. B is preferably one selected from Cd, In, Sn, Hg, Tl, Pb, Bi, and Ge. It contains cations of the above metal elements, and more preferably lead cations (Pb 2+ ), Suzukachio Sn 2+ ), germanium cation (Ge 2+ ) one or more cations selected from Including, From the viewpoint of enhancing the stability of the radiation detection element, it is more preferable to use Pb cations (Pb 2 + In certain preferred embodiments, B comprises two or more cations containing lead cations. Contains thione. The proportion of the cations in B is usually 50 mol % or more, preferably 70 mol % or more. , more preferably 80 mol % or more, and particularly preferably 90 mol % or more. It is not limited and may be 100%.

[0020] The above X contains a monovalent anion. Examples of the anion contained in X include a halide ion. , acetate ion, nitrate ion, sulfate ion, borate ion, acetylacetonate ion, Carbonate ion, citrate ion, sulfur ion, tellurium ion, thiocyanate ion, titanium acid ion, zirconate ion, 2,4-pentanedionate ion, or silicofluoride ion, etc. Examples include: From the viewpoint of crystal stability, X preferably contains one or more of Cl, Br and I, More preferably, X contains Br. X may be one kind of anion or two or more kinds of anions. It may be a combination of ON.

[0021] The proportion of the anion in X is usually 50 mol % or more, preferably 70 mol % or more. , more preferably 80 mol % or more, and particularly preferably 90 mol % or more. It is not limited and may be 100%.

[0022] The above v and w respectively represent the molar ratios of B and X when the molar ratio of A is 1.0. v is usually 0.5 or more, preferably 0.7 or more, more preferably 0.8 or more, and even more preferably or 0.9 or more, usually 1.5 or less, preferably 1.3 or less, more preferably 1.2 or less , and more preferably 1.1 or less. w is usually 2.5 or more, preferably 2.7 or more, more preferably 2.8 or more, and even more preferably or 2.9 or more, usually 3.5 or less, preferably 3.3 or less, more preferably 3.2 or less , and more preferably 3.1 or less. When v and w are within the above ranges, the structure is stabilized and a substrate of uniform quality can be obtained. can. In addition, the compound represented by the above formula (1) contains trace amounts of other components for the purpose of improving stability, etc. may also include:

[0023] In a specific embodiment, the compound represented by the general formula (1) is CsPbB r3, CsPbI3, CsPbCl3, CsPbI 3-x Cl x , CsPbBr 3-x C l x , CsPbBr 3-x I x , CH3NH3PbI3, CH3NH3PbBr3, CH 3NH3PbCl3, CH3NH3SnI3, CH3NH3SnBr3, CH3NH3S nCl3, CH3NH3PbI 3-x Cl x , CH3NH3PbI 3-x Br x , CH3 NH3PbBr 3-x Cl x , CH3NH3Pb 1-y Sn y I3, CH3NH3Pb1 -ySn y Br3, CH3NH3Pb 1-y Sn y Cl3, CH3NH3Pb 1-y Sn y I 3-x Cl x , CH3NH3Pb 1-y Sn y I 3-x Br x , and CH3NH3P b 1-y Sn y Br 3-x Cl x , and in place of CH3NH3 in the above compounds Compounds using CFH2NH3, CF2HNH3, or CF3NH3 can be used. In this embodiment, x represents an arbitrary value of 0 or more and 3 or less, and y represents an arbitrary value of 0 or more and 1 or less. For radiation detection applications, CH3NH3PbBr3 and CsPbBr3 are more preferred. From the viewpoint of long-term stability, CsPbBr3 is particularly preferred.

[0024] <Coating layer> Generally, the substrate or the compound that constitutes the semiconductor contained in the substrate contains various defects. point defects in which cations are missing (hereinafter, sometimes referred to as anionic defects), and Point defects where anions are missing (hereinafter sometimes referred to as cationic defects) are examples. In particular, defects located on the surface can cause leakage current through the defects, which can lead to the accumulation of charge. This can cause noise during detection. These defects become the starting points for carrier recombination and are one of the factors that hinder the extraction of charges. Therefore, defects contained in the substrate, especially defects present on the surface of the substrate, must be repaired by some means. It is preferable.

[0025] The radiation detection element includes a coating layer, the coating layer being located between the substrate and the electrode. The coating layer contains a compound having an ionic functional group (hereinafter referred to as a specific compound). It contains (sometimes called). The coating layer contains a compound having an ionic functional group, which repairs defects in the substrate and This can reduce leakage current caused by defects. In addition, the repair of defects prevents the recombination of carriers generated when radiation is detected. This reduces noise comprehensively, obtains a clear peak in the wave height spectrum, and It is expected that a radiation detection element and a radiation detector with good energy resolution can be provided.

[0026] In one embodiment, the ionic functional group has one or more cationic moieties. The functional group having a cationic moiety can effectively repair anionic defects. The type of sulfonium ion is not particularly limited as long as the effects of the present invention can be obtained. ions, quaternary phosphonium ions, quaternary ammonium ions, etc. can be used, and preferably A quaternary ammonium ion can be used.

[0027] In one embodiment, the ionic functional group has one or more anionic moieties. The functional group having an anionic moiety can effectively repair cationic defects. The type of group is not particularly limited as long as the effects of the present invention can be obtained. For example, group), [-O-PO3 - ], ate Group), [-COO - ], the anionic carboxyl group (Cca rboxy group) can be used.

[0028] In a preferred embodiment, the ionic functional group comprises one or more anionic moieties and one or more In a more preferred embodiment, the ionic functional group has one or more cationic moieties. The ionic functional group satisfies the above structure, and the cationic vacancies and The anionic moiety in the ionic functional group and the anionic defect can be effectively repaired. The type of the cation part, or the anion part and cation part in the zwitterion, is The cation moiety and the cation moiety can be the same.

[0029] In certain embodiments, the zwitterion species may be, for example, betaines. Examples of the betaine include sulfobetaine, phosphobetaine, and carboxybetaine. The types of the anion moiety, cation moiety, and zwitterion are selected appropriately depending on the material of the substrate. can be selected.

[0030] The specific compound preferably has a polymer structural unit from the viewpoint of suppressing ion diffusion. In one embodiment, the specific compound has a structure represented by the following chemical formula [1]: A unit and a structure represented by at least one of the following chemical formula [2] or the following chemical formula [3] It has a manufacturing unit.

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] In the chemical formula [1], R1 represents either a hydrogen atom or an alkyl group. R2 represents It represents an alkyl group, an aryl group, a carboxylic acid ester group, or a carboxylic acid amide group, and at least Preferably, the compound has at least one ionic substituent, and at least one zwitterionic substituent. It is more preferable that In chemical formulas [1] to [3], * indicates a bond to the polymer chain. 3) is an example of a structural unit having a zwitterion, where Y is a monovalent anion and Phosphate or sulfonate ions are preferred.

[0035] In the chemical formulas [2] and [3], R3, R4, R9-R11 are each independently It represents either an alkyl group or an aryl group. Therefore, an alkyl group having 1 to 8 carbon atoms is preferred, and an alkyl group having 1 to 4 carbon atoms is more preferred. Methyl groups are particularly preferred. In the chemical formulas [2] and [3], R5 to R8 are preferably alkylene having 1 to 4 carbon atoms. Preferably, they may be branched. Furthermore, any of R1 to R11 may have a substituent. stomach.

[0036] The method for coating the substrate is not particularly limited, but from the viewpoint of simplicity, a solvent in which a specific compound is dissolved is used. Immersion in a liquid is preferred. There are no limitations on the solvent as long as the specific compound dissolves in it. For silicon crystals, a non-polar solvent that causes less damage to the substrate is preferred, and toluene is more preferred. It's nice.

[0037] When the specific compound having zwitterions is a polymer, its weight average molecular weight is 3.00 Preferably, it is 0 to 500,000, more preferably 5,000 to 300,000, and more preferably 10,0 From the viewpoint of efficient coordination to the defect sites, the above-mentioned respective lower The above upper limit is preferable, and from the viewpoint of solubility, the above upper limit is preferable. The weight average molecular weight of the polymer can be determined by the method described in the Examples.

[0038] When the specific compound is a polymer, the total structural units of the polymer should contain fewer zwitterions. The ratio of monomer units having one or more of the above is determined from the viewpoint of efficiently repairing crystal defects. is preferably 0.1 mol % or more, more preferably 0.3 mol % or more, and even more preferably 0.5 mol or more, and from the viewpoint of ensuring solubility in a non-polar solution in the coating process, Preferably 20 mol % or less, more preferably 15 mol % or less, and even more preferably 10 mol % or less, and particularly preferably 5 mol % or less.

[0039] The thickness of the coating layer is preferably 3 nm or less, more preferably 2 nm or less, and even more preferably 1 nm or less. It is more preferable that the thickness of the coating layer is 0.5 nm or less, and particularly preferable that the thickness of the coating layer is 0.5 nm or less. The tunnel effect allows carriers to reach the electrode, resulting in radiation detection with excellent detection sensitivity. The thickness of the coating layer is usually 0.01 nm or more. When the thickness of the covering layer is equal to or greater than the lower limit, defects can be efficiently repaired and leakage current can be reduced. It is expected that the flow can be effectively reduced and / or ion diffusion can be suppressed.

[0040] <Electrode> The electrodes (first electrode and second electrode) of the radiation detection element are usually formed on the two main surfaces of the substrate. are located on the surface.

[0041] There is no particular limitation on the material of the electrodes, but metals with high electrical conductivity can usually be used. The first electrode and the second electrode may be made of different materials, or a plurality of electrodes may be stacked. In order to prevent diffusion into the substrate in contact with the electrode, the material preferably has a low diffusion coefficient. It is preferable to use Al, W, Ru, Ni, Pd, Cu, Au, Pt, Pb, B, etc. i, GaIn can be used.

[0042] The absolute value of the work function of the electrode is determined by the conduction band of the substrate from the viewpoint of obtaining a good high-resistivity electrical resistivity. It is preferable that the absolute value of the work function of the valence band of the substrate is larger than that of the work function of the valence band of the substrate. It is preferable that the absolute value is smaller than the absolute value. The work function can be determined by a conventional method.

[0043] The radiation detection element usually applies a voltage to the first electrode, and generates a voltage between the first electrode and the second electrode. When a charge is generated by radiation, the electric field creates a gap between the two electrodes. Usually, when a negative voltage is applied to the first electrode, In this case, holes reach the first electrode and electrons reach the second electrode.

[0044] The radiation detection element may include a guard ring. It attracts and removes noise charges that occur unrelated to radiation detection, such as leakage currents. The sensitivity of radiation detection can be increased. The guard ring may be made of any material that can function as an electrode. good. The guard ring is provided, for example, on the periphery of the radiation detection element in a manner that is disconnected from the electrode. It's good that it's done. In addition, the guard ring attracts the charge that becomes noise, so the opposite side of the guard ring It is preferable that an electric field is generated between the electrode and the guard ring. Good too.

[0045] <Other components> The radiation detection element may include other parts, such as electrodes for applying a voltage. In addition to the coating layer, a hole transport layer or an electron transport layer may be provided between the substrate and the substrate to promote the extraction of charges. It may have a transport layer, or an insulating layer for the purpose of suppressing ion diffusion. In addition, a protective layer for protecting the external elements or devices and an adhesive layer for improving the adhesion of each layer are also provided. The device may also include:

[0046] [Radiation detector] In one embodiment, the present invention provides a radiation detector including one or more of the radiation detection elements. When the radiation detector includes two or more of the radiation detection elements, The combination of the substrate and the electrode is, for example, (A) A structure in which multiple electrodes are arranged in the surface direction of the substrate. (B) A structure in which only one pair of electrodes is arranged on one substrate. etc. can be used. When the structure (A) is used, the area sandwiched between a pair of electrodes is treated as one radiation detection element. It can be considered. When the structure (B) is used, a plurality of substrates can be arranged in the plane direction. In other words, the substrate may be connected between a plurality of radiation detection elements to form one layer. , may be independent for each detection element.

[0047] FIG. 1 is a schematic diagram of a radiation detector according to an embodiment. The radiation detection element 1 comprises a substrate 3 and electrodes 2 and 4, and is connected to an electrometer via a gold wire 5. When the radiation detection element 1 is irradiated with radiation, an electric charge is generated, and the electrode, Au Radiation is detected by detecting the charge via the wire with an electrometer. , in Figure 1, “e - " and "h + " represent electrons and holes, respectively. The gold wire 5 may be replaced with another material, such as copper or other metals, and the carrier may be connected to the electrometer. There are no particular limitations on the material as long as it can perform the function of transmitting the electric current.

[0048] <Power supply section> The radiation detector includes a power supply unit for applying a voltage to the electrodes. The power supply unit may normally supply a first electrode of each radiation detection element included in the radiation detector. Or it is connected to the second electrode. The power supply unit may be connected to an external power source or may have its own power source. The power source or self-power source can be a commonly used power source, such as a direct current (DC) power source. An alternating current (AC) power source can be used.

[0049] <Voltage converter> The power supply may include a voltage converter for adjusting the applied voltage. The arrangement of the voltage converter is not particularly limited as long as the above-mentioned object is achieved, and usually the power source and the first electrode For example, the voltage converter may be directly connected to the power supply, or may be connected via some circuit. The voltage converter may be a known one, for example, a linear regulator. , a switching regulator can be used.

[0050] <Electrical signal output section> The radiation detector may include an electrical signal output unit. The radiation detector is connected to the first or second electrode of each radiation detection element, and the electrode is charged with the radiation. The accumulated charge is output as an electrical signal. The electrical signal output unit is provided inside the device. Alternatively, an external electrical signal output device may be used. In one embodiment, the electrical signal output unit is configured to secondarily convert the electric charge accumulated in at least the electrode. and one or more charge storage circuits for storing the charges, and converting the charges stored in the charge storage circuits into electrical signals. The charge storage circuit includes an electrical signal output circuit that outputs the electrical signal. This can be done.

[0051] The electric signal output circuit detects when the electric charge accumulated in any one of the electric charge accumulation units reaches a threshold value or more. outputting an electrical signal based on the charge when the charge stored in any of the capacitors is detected; a capacitor connected to the output terminal of the power supply; a capacitor connected to the output terminal of the power supply; The accumulated charge is output as an electrical signal by the operation of an external power source (for example, a transistor). It is preferable to enable at least one of the following operations: , a circuit capable of realizing these can be used. These operations may be performed independently, In addition, some or all of the circuits corresponding to these operations may be provided in multiple locations. By the above operation, each pin of the second electrode The charge accumulated in the cell is sent as an electrical signal at a certain threshold and / or at a certain timing. It can be output as

[0052] The electric signal output unit includes an amplifier circuit (an amplifier, an integrator) that amplifies the electric charge or the electric signal information. amplifier circuits, glitch removal circuits such as sample-and-hold circuits, and circuits that can store electric charge A ground that can be connected and a switch for switching ON / OFF the connection between the ground and the circuit, not A filter circuit (such as a low-pass filter, a high-pass filter, etc.) for removing unnecessary low-frequency and high-frequency noises may be provided. By appropriately providing these circuits, the sensitivity can be improved , noise can be removed, residual charges after electrical signal injection / output can be removed, etc., and the accuracy of the electrical signal can be improved .

[0053] <Radiation imaging apparatus> In one embodiment, the present invention provides a radiation imaging apparatus (Radiation Imagi ng Apparatus) that includes the radiation detector and further includes an information processing device that processes an electrical signal to draw an image. The information processing device acquires the intensity and position information of the radiation incident on each radiation detector / detection element based on the electrical signal output from the radiation detector, and forms an image. Also, in a preferred embodiment, the information processing device has characteristics of an energy discrimination type, a photon counting format, and both of them. With this configuration, the energy information of the incident radiation can be acquired, and an image with a larger amount of information can be provided. The specific method and configuration of the information processing device are not particularly limited. For example, it can be the same as the information processing device employed in existing radiation inspection devices.

[0054] [Examples] Hereinafter, an example of an embodiment of the present invention will be described in detail by way of examples, but the present invention is not limited to the examples.

[0055] [Example 1] [Synthesis of CsPbBr3 crystal] 9 mmol of lead bromide (Tokyo Chemical Industry), 4.5 mmol of cesium bromide (Tokyo Chemical Industry), Lewis salt 1.4 mmol of a basic compound was dissolved in 8 mL of dimethyl sulfoxide (Sigma-Aldrich) at 90 °C for 0.5 to 1 hour, and then filtered through a 0.45 μm PTFE filter. The filtrate was poured into a vial containing seed crystals, and then heated to 100 °C and left standing for about one week to grow the crystals to about 5 mm square.

[0056] <Processing of CsPbBr3 Crystals> After washing CsPbBr3 with toluene or the like, it was heated at 110 °C for 2 hours in vacuo to remove the solvent. Then, the crystal surface was polished.

[0057] <Synthesis of Compound 1> The compound represented by the following Chemical Formula 4 was synthesized by referring to Angew. Chem. Int. Ed. 2020, 59, 10802 - 10806, and the chemical structure and amphoteric ion concentration were identified using 1H-NMR.

[0058] <Measurement Method of Physical Property Values> (Number-average molecular weight (Mn), weight-average molecular weight (Mw)) A solution prepared by dissolving the polymer to a concentration of 0.1 mass% in N,N-dimethylformamide (DMF) was used as the measurement sample. The number-average molecular weight and weight-average molecular weight were measured by gel permeation chromatography (GPC) using N,N-dimethylformamide (DMF) dissolved with lithium bromide to a concentration of 10 mM as the mobile phase and a differential refractometer as the detector. Monodisperse polystyrene was used as the molecular weight standard substance. · Column; Two TSKgel GMHHR-M (7.8 mm X 30 cm, Tosoh) columns connected in series · Mobile phase; DMF dissolved with 10 mM lithium bromide Standard material: Standard polystyrene kit (PStQuick® Kit-H, Tosoh) -) [ka] Zwitterion concentration: 1.7 mol% Weight average molecular weight: 82,600

[0059] [Coating of CsPbBr3 crystals] Compound 1 was dissolved in toluene at a concentration of 0.5 mg / mL, and the resulting solution was processed. The surface was coated by immersing the sample in CsPbBr3 crystals for 0.5 to 3 hours.

[0060] [Fabrication of radiation detection elements] Electrodes were formed by depositing 80 nm of Au on the top surface of the coated crystal and 80 nm of Bi on the bottom surface. The radiation detector of Example 1 was mounted on a glass substrate and wired with Au wire and conductive paste. An output element was fabricated.

[0061] [Example 2] In the coating process, compound 1 was dissolved in toluene at a concentration of 0.1 mg / mL. In the same manner as in Example 1, a radiation detection element according to Example 2 was obtained.

[0062] [Comparative Example 1] The same procedure as in Example 1 was carried out except that Compound 1 was not added to toluene in the coating step. A radiation detection element according to Comparative Example 1 was obtained.

[0063] <Coating layer thickness measurement> The radiation detection elements according to Examples 1 and 2 and Comparative Example 1 were subjected to FIB (μ-sample) analysis. The specimens were cut into thin sections using the pulling method and then examined under a transmission electron microscope (Hitachi High-Tech H-950 The cross section was observed using a transmission electron microscope (at an acceleration voltage of 200 kV). Cross-sectional images of Comparative Example 1 are shown in FIGS. 2A to 2E. The thickness of the coating layer was calculated from the average value of the three points, and the results are shown in Table 1.

[0064] <Radiation response measurement> Connect the radiation detector to a grounded electrometer and keep the voltage constant in the dark. The dark current value was obtained by sweep measurement while the electric field was -200 kV / m. The values ​​of the current density when applied are shown.

[0065] [Table 1]

[0066] As shown in Table 1, Examples 1 and 2, which have a coating layer between the substrate and the electrode, have a higher resistance than Comparative Example 1. The leakage current was reduced in all cases. In Examples 1 and 2, the ionic functional group of the polymer contained in the coating layer The defect was repaired, and the leakage current caused by the defect was reduced compared to Comparative Example 1. It is thought that...

[0067] Next, the sensitivity is calculated by dividing the ON / OFF ratio of X-ray irradiation by the dose rate at a constant voltage. The X-ray irradiation equipment used a tungsten X-ray target, a tube voltage of 100 kV, and a tube A current of 0.5 mA was used. A dose rate meter was placed at the measurement position to measure the dose rate. The measured sensitivity was 2.3 mGy / s. Table 2 shows the measured sensitivity.

[0068] [Table 2]

[0069] Example 2 exhibits the same detection sensitivity at a lower electric field strength than Comparative Example 1, and the sensitivity is improved. Confirmed.

[0070] [Example 3] <Wave height spectrum measurement> In the process of forming the electrodes, Au was applied to one side and GaIn to the other side. Radiation detection elements according to Comparative Example 2 and Example 3 were produced in the same manner as in Example 1 and Example 2. .

[0071] The pulse height spectrum of the obtained radiation detection element was measured as follows. That is, the distance between the radiation source and the detector is 1 cm, and from the second electrode side of the radiation detection element The radiation source was irradiated and a bias of -200 V was applied to extract holes from the first electrode side. The pulse amplitude is amplified by the preamplifier and main amplifier, and then output to the multi-channel amplifier. The wave height spectrum was obtained by counting with a multi-channel analyzer (MCA). The time was set to 0 to 30 minutes. Schematic diagrams of the device configuration are shown in Figures 3 and 4. The energy resolution value can be further improved by smoothing or optimizing the detector. This can be further improved by

[0072] The radiation source is Am 241 , Na 22 , Cs 137 The irradiated radiation was Energy of gamma rays of radioactive elements (Am 241 , Na 22 and Cs 137 was used as the radiation source In the case of The number of channels of the photoelectric absorption peak in the pulse-height spectrum shifted linearly, indicating that the I was able to confirm that it was detected.

[0073] The obtained photoelectric absorption peak was subjected to Gaussian fitting, and its half-width was adjusted to the center. The energy resolution was calculated by dividing by the median value. The results are shown in Table 3.

[0074] [Table 3]

[0075] As shown in Table 3, in Comparative Example 2, a good photoelectric absorption peak was not obtained, and the energy resolution was not measured. Although it was impossible to measure the photoelectric absorption peak, Example 3 showed a good photoelectric absorption peak.

[0076] As described above, according to the present invention, a radiation detection element and a radiation detector with reduced leakage current are provided. A detection device can be provided. [Explanation of symbols]

[0077] 1. Radiation detection element 2. Foundation 3 Covering layer 4 electrodes 5 gold wire 6 Electrometer 7 Guard Ring 8. Wave height spectrum detection system

Claims

1. A radiation detection element, a substrate, a first electrode, and a second electrode; the substrate comprises a semiconductor; Furthermore, a small amount of a conductive material may be present between the first electrode and the substrate or between the second electrode and the substrate. a coating layer on at least one side, The radiation detection element, wherein the coating layer contains a compound having an ionic functional group.

2. 2. The radiation detector according to claim 1, wherein the thickness of the coating layer is 0.01 nm or more and 3 nm or less. Output element.

3. 3. The semiconductor according to claim 1 or 2, wherein the semiconductor contains a compound having a composition represented by the following formula (1): The radiation detection element described above. AB ｖ X ｗ ・・・(1) (In the above formula (1), A, B, and X represent elements constituting the compound, and A represents a monovalent cation. B contains one or more metal elements selected from the metal elements of the fourth to sixth periods, and C contains an anion. v and w respectively represent the molar ratios of B and C when the molar ratio of A is 1.0; and w each independently satisfy 0.5≦v≦1.5 and 2.5≦w≦3.

5.

4. The substrate according to any one of claims 1 to 3, wherein the thickness of the substrate is 0.2 to 500 mm. Radiation detection element.

5. The ionic functional group has at least one quaternary ammonium ion.

5. The radiation detection element according to any one of claims 4 to 4.

6. Any one of claims 1 to @, wherein the ionic functional group has at least one zwitterion. The radiation detection element according to claim 1.

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