CN113204047A - Semiconductor radiation detector - Google Patents

Abstract

The invention belongs to the field of semiconductor radiation detection, and discloses a semiconductor radiation detector which comprises at least 2 groups of electrode pairs, semiconductor materials positioned in a radiation response area and a plurality of thickness areas divided according to different distances from an incident end face of a radiation ray; each group of electrode pairs corresponds to a certain thickness area, and different groups of electrode pairs correspond to different thickness areas; the semiconductor radiation detector can collect radiation response signals of different target energy particles through different groups of electrode pairs by utilizing different attenuation degrees of different energy particles in a semiconductor material, thereby realizing energy spectrum distinguishing and realizing multi-energy spectrum detection. The invention can detect detection signals at different depths by adopting an energy spectrum distinguishing scheme different from the existing energy spectrum distinguishing scheme in the prior art and utilizing the characteristic that high-energy radiation particles with different energies have different penetrating abilities to materials and arranging the electrode pairs at different positions, thereby realizing energy spectrum distinguishing and being applied to multi-energy spectrum detection.

Description

A semiconductor radiation detector

technical field

The invention belongs to the field of semiconductor radiation detection, and more particularly relates to a semiconductor radiation detector, which is a new type of semiconductor radiation detector that can be applied to energy spectrum division, and is widely applicable to semiconductor radiation detectors composed of various semiconductor materials.

Background technique

Radiation detection refers to a detection method that obtains information by detecting radioactive high-energy particles (including X, γ photons, α, β particles, etc.) Common and important diagnostic, detection and monitoring techniques in society. One of the applications of radiation detectors is to perform multispectral discrimination. Traditional high-energy radiation detectors that do not have the ability to distinguish energy spectrum use continuous radiation sources, and the attenuation capabilities of particles in each energy segment are different in matter (for example, low-energy spectrum is often more easily absorbed, and high-energy spectrum is less absorbed and more easily penetrated. over), the misjudgment phenomenon of "foreign body co-image" will occur; when irradiating substances with stronger absorption capacity, hardening artifacts will also occur due to the "high-energy shift" of the ray energy distribution.

With the further development of related technologies, several different solutions have emerged for high-energy ray detection technology for energy spectrum discrimination. The following takes "X-ray detection with dual energy spectrum discrimination" as an example to list the existing methods to solve this problem. In addition, other high-energy particles have similar solutions in the field of energy spectrum discrimination:

①Adjust the radiation source, such as dual-source detection, light source filtering, dual-kVp fast switching, etc. Dual-source technology uses two different ray sources for detection, filtering is to process a single continuous light source through two filter materials to obtain two energy spectrum distributions, and dual-kVp fast switching is to change the energy by switching the working voltage of a single ray source. The spectral shape yields two different energy spectra. The above adjustment scheme for the incident source may result in low energy spectral discrimination due to the overlapping phenomenon of low-energy spectral segments; it may also inevitably double the radiation dose due to multiple exposures.

②Adjust the detector structure, such as photon counter, double-layer scintillator. Photon-counting radiation detectors are currently the mainstream solution in the field of energy spectrum discrimination. They capture high-energy photons through the photoelectric effect. The captured high-energy photons have different energies (the photon energy is mostly in the order of keV and MeV). Different electrons (the activation energy of the carrier is in the order of eV), so the number of charges collected is different; at the same time, the detector and the coupling circuit are integrated, and the different numbers of charges collected by the circuit will be converted into voltages of different sizes in the chip The signal falls into the analyzers with different channel numbers after being judged by the threshold value, thereby distinguishing the energy of the multi-energy spectrum. Photon counters represented by silicon (Si), cadmium telluride (CdTe) and cadmium zinc telluride (CZT) have high count rates, free threshold division, and high energy spectrum discrimination; however, photon counting detectors have high cost and require material performance. Harsh, unable to do anything about the bremsstrahlung continuum of most X-rays, suitable for application in other fields. The double-layer scintillator detector can express the low-energy and high-energy information of the continuous energy spectrum by absorbing the low-energy and high-energy rays of the upper and lower scintillator materials respectively, and then emitting fluorescence of different wavelengths respectively. More layers of scintillator composite structures can be built for higher-resolution spectral discrimination, but factors such as optical crosstalk, broad emission peaks, and the material integration of multiple high-efficiency scintillators limit their further development.

One of the most important applications of X-ray detection with dual energy spectrum discrimination is "dual source CT". At present, among the three major CT giants in the world, the double-layer scintillator detector IQon launched by Philips can realize dual-source CT imaging in clinical practice; Simens' dual-source + dual-detector solution, and GE's single-source 80kVp/140kVp fast CT imaging The switching scheme has also been verified.

In the present invention, a new structural design scheme of a semiconductor radiation detector will be introduced. It provides an alternative for the design of spectrally differentiated radiation detectors, and also reduces the performance requirements of photoelectric conversion materials (compared to single-photon counting mode), greatly expanding the variety of materials that can be applied in this field.

SUMMARY OF THE INVENTION

In view of the above defects or improvement requirements of the high-energy particle energy spectrum discrimination technical solutions in the prior art, the purpose of the present invention is to provide a semiconductor radiation detector, which is different from the existing energy spectrum discrimination solutions in the prior art. The high-energy radiation particles of energy have different penetrating abilities to materials. By setting electrode pairs at different positions, the detection signals at different depths can be detected, so that the energy spectrum can be distinguished and applied to multi-energy spectrum detection. Compared with In the prior art, the single photon counting mode greatly reduces the performance requirements of the photoelectric conversion material.

In order to achieve the above object, according to the present invention, a semiconductor radiation detector is provided, characterized in that, the semiconductor radiation detector includes at least two groups of electrode pairs, and the semiconductor material in the semiconductor radiation detector located in the radiation response region is The difference in distance from the incident end face of the radiation ray is divided into a plurality of thickness regions; where,

Each group of electrode pairs corresponds to a certain thickness region, and different groups of electrode pairs correspond to different thickness regions; the positive and negative electrodes in any group of electrode pairs can be electrically connected to each other through the corresponding thickness regions;

The semiconductor radiation detector can utilize the different attenuation degrees of different energy particles in the semiconductor material to collect radiation response signals of different target energy particles through different groups of electrodes, thereby realizing energy spectrum distinction and multi-energy spectrum detection.

As a further preference of the present invention, the semiconductor material is a homogeneous semiconductor material;

Preferably, starting from the incident end face of the radiation ray, the thickness of each group of electrode pairs increases sequentially, and the thickness of the corresponding thickness region also increases sequentially.

As a further preference of the present invention, the semiconductor material is a heterogeneous semiconductor material; these heterogeneous semiconductor materials are sequentially arranged in layers along the direction perpendicular to the incident radiation rays;

Preferably, starting from the incident end face of the radiation ray, the material properties of these hetero semiconductor materials will be able to produce a stronger and stronger attenuation effect on the ray.

As a further preference of the present invention, the semiconductor material is preferably selected from halide perovskite materials, silicon, cadmium zinc telluride, and cadmium telluride.

As a further preference of the present invention, the semiconductor material is preferably a variety of halide perovskite materials, and these halide perovskite materials are sequentially arranged in layers along the direction perpendicular to the incidence of radiation rays;

Starting from the incident end face of the radiation ray, the average atomic number of the halogen site elements in these halide perovskite materials is getting larger and larger.

As a further preference of the present invention, the at least two groups of electrode pairs are at least two groups of strip-shaped electrode pairs.

As a further preference of the present invention, the electrode pair is prepared by wire binding, laser marking or mask evaporation.

As a further preference of the present invention, the electrode pair is also connected with a plurality of opposite electrodes, and these surface electrodes are used to draw out these electrode pairs and apply a voltage.

Through the above technical solutions conceived by the present invention, compared with the prior art, due to the use of the feature that the high-energy radiation particles of different energies have different penetrating abilities to the detector, by collecting the detection signals on the electrodes at different depths, the Detailed distinction of the continuum of plurienergy radiation. The semiconductor radiation detector based on the energy spectrum discrimination obtained by the invention does not need to work under the single photon counting formula, and also has the energy spectrum resolution capability under the integral formula. It can reconstruct the unknown energy spectrum after completing the detection of the known radiation energy spectrum; it can also perform multi-energy information acquisition or imaging at the same time under a single exposure.

The invention only needs to improve the structure design of the detector electrode to realize the energy spectrum differentiation of high-energy rays, and provides a new idea for the energy spectrum differentiation of high-energy particles. The principle on which the invention is based is to utilize the feature that high-energy radiation particles with different energies have different penetrating abilities to materials, and to achieve energy spectrum distinction by collecting detection signals of electrodes at different positions at different depths.

The following combines physical models and mathematical analysis for further explanation:

The principle of the present invention is obtained by analyzing the mathematical relationship "representing the relationship between the signals collected by the electrode pairs at different positions and the radiation particles of different energy". This mathematical relationship can be obtained by analyzing the physical model shown in Figure 1:

表示A_i在j层电极的厚度范围内沉积的能量，j为[1,m]内的整数。因此，探测器在探测能谱A(E)时，可在第k层电极收集到的信号大小为i_k，k为[1,m]内的整数，For a detector with m electrode pairs, energetic particles with a radiation spectrum of shape A(E) are incident from the front face. Divide the energy spectrum A(E) into n segments, each segment of the energy spectrum A _i represents the monochromatic-like components of different energies, A _i is absorbed by the detector material and converted into an electrical signal through the photoelectric effect, i is [1 ,n] integer. Known attenuation coefficient α, conversion efficiency γ and collection efficiency ξ, l represents the thickness of the detector, where

Represents the energy deposited by A _i in the thickness range of the j-layer electrode, where j is an integer in [1,m]. Therefore, when the detector detects the energy spectrum A(E), the size of the signal that can be collected at the electrode of the kth layer is i _k , where k is an integer in [1,m],

For the eigenvectors A=A _n×1 =(A ₁ ,A ₂ ,...,A _i ,...,A _n ) ^T representing the energy spectrum information, which is related to the current signal I=I _m×1 =( The relation of i ₁ , i ₂ ,..., _ik ,...,im ) ^T is I _{m ×1} =C _m×n ·A _n×1 . That is, for a radiation detector whose attenuation coefficient α, conversion efficiency γ and collection efficiency ξ are constant values, there is a definite and unique conversion matrix C _m×n that satisfies the above mathematical relationship, which gives the new energy spectrum involved in the present invention Differentiating the realization ideas provides a theoretical basis.

A key parameter for spectral discrimination applications is the resolution n, the number by which the energy spectrum A(E) can be divided. It can be seen from the above mathematical analysis that A _n×1 can be obtained by solving I _m×1 only when C _m×n has an inverse matrix, that is, m=n, C _m×n is a square matrix, that is to say, the number of electrode pairs is determined. Therefore, the semiconductor radiation detector in the present invention needs to use at least 2 electrode pairs to achieve a difference of at least 2 resolutions of a certain energy spectrum, that is, to distinguish the energy spectrum of low-energy and high-energy information; of course, the specific number of electrode pairs can be flexibly adjusted according to actual needs).

The detection/reconstruction of the unknown energy spectrum is to select m points on each of the known multiple energy spectra (the number of energy spectra ≥ m), and detect the signals i _k of m electrode pairs under each energy spectrum A _i , Based on this, the optimal solution information of the conversion matrix C _m×n is obtained, and then the electrical signal I′=I′ _m×1 of the unknown energy spectrum is detected to obtain the unknown energy spectrum information A′=A′ _m×1 . The solution of the transformation matrix is related to the number of training sets (known energy spectrum), the larger the training set, the more accurate the solution to the test set (unknown energy spectrum). The conversion matrix already contains information such as attenuation coefficient α, conversion efficiency γ and collection efficiency ξ, but there is no need to solve these physical parameters specifically.

Based on the present invention, multi-energy detection/imaging, ie, simultaneous detection of electrical signals on different electrodes under a single exposure. The signals of electrodes at different depths represent radiation particles of different energies. For example, the penetrating ability of high-energy radiation particles to different tissues is directly related to the density of the tissues, so it can be obtained that each tissue (bone, muscle, fat, etc.) of different densities has different energies. to better differentiate and identify individual tissues with different densities.

Based on the present invention, an electrode pair structure can be prepared for a semiconductor radiation detector, for example, a plurality of electrode pairs (such as strip electrodes, or electrodes facing each other can be prepared in sequence in a direction perpendicular to the high-energy ray incident surface of the semiconductor radiation detector) structure; and may preferably leave a portion for extraction/pinning detection). The plurality of electrodes are sequentially arranged at different positions in the ray propagation direction and perform signal collection. When high-energy rays enter the detector, particles with different energies attenuate to different degrees at different depths, that is, electrodes at different positions can collect radiation signals representing different energies. The information of each energy can be analyzed by mathematical processing.

Based on the present invention, the types of semiconductor materials in the multi-energy spectrum semiconductor radiation detector are effectively expanded, which can be either silicon, cadmium zinc telluride, cadmium telluride and other semiconductor materials that support single-photon detection, or halide perovskite, etc. The semiconductor material working in the integral charge collection mode relieves the limitation on the types of detector semiconductor materials that the prior art can only support single-photon detection. Taking the perovskite material working in the integral charge collection mode as an example, the perovskite material has high sensitivity and strong attenuation ability, but the indicators such as mobility and dark current do not meet the conditions of single photon counting detectors; and based on the present invention, It can complete the energy spectrum discrimination function that only the single photon counting type detector can realize in the original energy spectrum discrimination scheme, which is of great significance.

The present invention also preferably designs the thickness of the electrode pair, so that the electrical signals collected by each level of electrode pair are similar in size, so as to better illustrate the attenuation trend of different energy signals at different depths, so that the first level electrode pair ( (closest to the incident end of the radiation particle) is the narrowest (that is, the thinnest), and the subsequent electrode pairs are wider (that is, thicker). The tendency of this electrode pair to widen can be specifically determined according to the "energy-mass attenuation coefficient" curve of the detector material for the radiated particles. Of course, if the electrode pair adopts the design of equal width (ie equal thickness), it will not affect the realization of the function of high-energy ray energy spectrum differentiation of the present invention.

The present invention can be applied to homogeneous radiation detectors, as well as semiconductor detectors with non-homogeneous, layered stack structures in the depth direction. For example, when halide perovskite is used as the detector material, the electrode is Incident end) to deep (that is, away from the incident end), the corresponding halogen element gradually changes from chlorine to bromine and then to iodine (that is, the average atomic number of the halogen element in the halide perovskite material is getting larger and larger), In this way, the difference in electrode thickness design can also be reduced on the basis of making the electrical signals collected by each electrode pair similar in magnitude.

Description of drawings

Figure 1 is a schematic diagram of the principle of multi-energy X-ray continuum decomposition and detection; in which, low-energy rays penetrate the detector shallowly, high-energy rays penetrate deep, and the signals collected by electrode pairs at different depths represent different energies in the energy spectrum. particle information.

Figure 2 shows the attenuation effect of MAPbBr ₃ material on X-rays, in which, (a) in Figure 2 is the energy-mass attenuation coefficient curve of MAPbBr ₃ on X-rays, and (b) in Figure 2 is a specific energy in the range. The thickness-transmission (attenuation) characteristic curve of X-ray.

Figure 3 shows the relevant data of electrode design according to the results of Figure 2, wherein (a) in Figure 3 is the thickness required for X-rays at different energies to attenuate the same proportion, and (b) in Figure 3 is Schematic diagram of the patterned five-electrode structure with the thickness calculated from (a) in Fig. 3 and designed and processed (the five groups of electrodes are recorded in order from top to bottom and from shallow to deep according to the derived radiation response area. No. 1 electrode, No. 2 electrode, No. 3 electrode, No. 4 electrode, No. 5 electrode, as shown in 1, 2, 3, 4, and 5 in the figure).

Figure 4 shows the real object of the perovskite MAPbBr ₃ detector, in which, (a) in Figure 4 is a scanning electron microscope photo of part of the laser-marked patterned electrode, and (b) in Figure 4 is the patterned electrode The actual photo, (c) in Figure 4 is the energy dispersive spectrum picture of the electrode metal element in (a) in Figure 4 (from which it can be seen that the laser marking processing effect is good, and there is no metal residue in the channel), Figure 4 In (d) is a schematic diagram of the application of semiconductor radiation detectors.

Figure 5 is the result of detecting/reconstructing the unknown X-ray energy spectrum; the cut-off voltages are 45, 55, and 65kV, respectively, and the dots in the figure are the data values calculated during reconstruction.

Figure 6 shows the multi-energy imaging picture under a single exposure, wherein (a) in Figure 6 is a schematic diagram of a simulated human tissue sample (the inset in the lower left corner is a real photo, and the reading of the vernier caliper is 55.03mm), Figure 6 (b) in Fig. 6 is the imaging picture of the No. 2 electrode, and (c) in Fig. 6 is the imaging picture of the No. 5 electrode.

Figure 7 corresponds to a new type of semiconductor radiation detector after replacing the MAPbBr ₃ material with a non-homogeneous, halogen alloyed perovskite material, wherein (a) in Figure 7 is the structure of the heterogeneous semiconductor radiation detector in Example 4 Schematic diagram, (b) in FIG. 7 is a comparison of the energy-mass attenuation coefficient curves of MAPbCl ₃ , MAPbBr ₃ , and MAPbI ₃ to X-rays.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

The following is a specific embodiment, and the present invention will be described in detail from the aspects of the detection principle, structural design and prototype display of the semiconductor radiation detector (the thickness dimension in the present invention refers to the direction parallel to the incident direction of the radiation ray). Because clinical medical diagnosis has a high degree of commercialization and broad application prospects in the subdivision field of X-rays, the specific implementation cases in the present invention will focus on the multi-energy X-ray continuum band that can be applied in clinical medicine.

Example 1: Electrode structure design of integrating perovskite _MAPbBr radiation detector for multi-energy X-ray continuum

Due to the particularity of high-energy radiation detection, the thickness of the photoelectric conversion layer and the electrode structure should be designed according to the specific energy range of the energy spectrum and the absorption coefficient of the detector material during the preparation of the radiation detector. Here, a certain multi-energy X-ray continuum (30kV-70kV) is used as the band to be detected, and the perovskite MAPbBr ₃ is used as the photoelectric conversion material of the detector to carry out the specific structure design of the radiation detector. Its mass attenuation coefficient is shown in Figure 2. shown in (a). It must be noted that, compared with CZT, Si and other detector materials that can work in both single-photon counting mode and integration mode, MAPbBr ₃ that can only work in integration mode can embody the ingenious design of the present invention, Therefore, MAPbBr ₃ is taken as an example here; the same is true when other materials are structurally designed following the ideas of the present invention.

Considering the absorbing ability of MAPbBr ₃ as a detector photoelectric conversion material to the multi-energy X-ray continuum, and the total absorption thickness of X-rays for each energy in this band (as shown in (b) in Fig. 2), in accordance with this On the basis of the foregoing theoretical derivation of the invention, it is preferable to make the electrical signals collected in the range of the thickness of each electrode under the multi-energy X-ray continuum to be similar in magnitude; in this way, the magnitude of the signal of each electrode can be guaranteed to be the same order of magnitude as possible in actual use. , the results are clearer in the lateral comparison, and there is no order of magnitude difference in the electrical signals when the electrodes are of equal thickness. Further, in order to make the detector suitable for the ray source of the multi-energy X-ray continuum spectrum in this band, and have the universality of detection, the X-ray continuum spectrum is set as the square in the range of 30-70kV (0.017-0.041nm). type spectrum.

On the basis of the above analysis, the design process of a five-electrode MAPbBr ₃ radiation detector with a 30-70kV square spectrum as the multi-energy X-ray continuum is described. The energy-mass attenuation coefficient curve of the detector material is shown in (a) of Figure 2. For each energy value (monochromatic light) in the continuous spectrum range, there is a different mass attenuation coefficient, that is, in different The attenuation degree of this monochromatic light is different under the depth, but they all attenuate according to the trend of 1-e ^-α(E)l ; taking the energy of 35kV, 40kV, 50kV, 60kV, and 70kV as examples, the attenuation intensity in MAPbBr ₃ - The thickness curve is shown in Fig. 2(b). Because there are five sets of electrode pairs, the thicknesses of X-rays of a certain energy when attenuated by 20%, 40%, 60%, 80% and 99.9% are obtained respectively. By plotting the five thickness values corresponding to each energy in the continuous spectrum range, the thickness required for each monochromatic light to reach the same attenuation degree can be known, as shown in (a) in Figure 3. The difference between two adjacent curves represents the thickness difference of the detector required to attenuate the same proportion of X-rays. By solving the integral average value of the difference in the range of the multi-energy X-ray continuum, five thicknesses can be obtained. Values: 0.114, 0.147, 0.207, 0.354, 1.531mm (Take (a) in Figure 3 as an example, you can first integrate and solve the area between the 99.9% curve and the 80% curve in the range of 30keV ~ 70keV, and then divide by (70- 30)keV, that is, 1.531mm; you can first integrate and solve the area between the 20% curve and the x-axis in the range of 30keV ~ 70keV, and then divide by (70-30)keV, that is, 0.114mm), the thickness of this design is The five-electrode detector, when detecting the X-ray square energy spectrum of 30-70kV, will deposit X-rays with the same energy respectively in the width of the five electrodes. For the convenience of processing, the above thickness is approximated as: 0.10, 0.15, 0.20, 0.35, 1.50 mm, and the patterned electrode is drawn by laser marking, as shown in (b) in Figure 3 (the material used for the electrode can be There are known metal electrode materials in the art, such as commonly used gold, platinum, etc.; of course, in addition to laser marking, other processes known in the art can also be used to prepare electrodes of target thickness). Among them, the areas marked with numbers 1-5 represent the lead-out/pinning areas of the five electrodes, and the actual effective part of the patterned electrodes is still the five strip electrodes in the upper middle.

In summary, a double-sided five-electrode MAPbBr ₃ semiconductor radiation detector can be processed, which can be used for multi-energy X-ray continuum detection in the range of 30-70 kV for energy spectrum discrimination. The specific object is shown in (b) in Figure 4. From the SEM image of (a) in Figure 4 and the energy dispersive spectrum image of (c) in Figure 4, the electrode channel and the five electrodes can be clearly seen pattern area. The test schematic diagram of the semiconductor radiation detector is shown in (d) in 4. During detection, the lead-out area of the electrodes should be shielded, and only five strip electrodes are exposed.

Implementation Case 2: Semiconductor Radiation Detector Detects Unknown X-ray Spectrum

Using the above semiconductor radiation detector to detect a plurality of known multi-energy X-ray continuum, the transformation matrix C _m×p can be calculated to analyze the unknown multi-energy X-ray continuum. For example, after being placed or used for a long time, the bulb is no longer accurate and needs to be calibrated, or the shape of the X-ray continuum spectrum after attenuation by an object needs to be detected. For the five-electrode semiconductor radiation detectors here, Au target tubes operating at 35, 40, 50, 60, and 70 kV were used as light sources, providing a known multi-energy X-ray continuum training set, using working at 45, 50, 60, and 70 kV. Au target bulbs at 55 and 65kV are used as light sources to provide unknown continuum test sets.

First, use the semiconductor radiation detector to detect five known spectra, obtain five detection signals I _5×1 , form a square matrix I _5×5 =(I ₁ ,I ₂ ,...,I ₅ ), and then in its continuous The spectrum is up-sampled to obtain five A _5×1 (the sampling method in the prior art can be directly adopted), and a square matrix A _5×5 =(A ₁ ,A ₂ ,...,A ₅ ) is formed, then The conversion matrix C _5×5 is obtained through matrix operation. At this time, if I' _5×1 is obtained by detecting an unknown spectral signal, the sampling signal of its multi-energy X-ray continuum can be reconstructed by (C _5×5 ) ^-1 ·I' _5×1 =A' _5×1 A' _5×1 .

It can be seen from the previous analysis that the resolution of the energy spectrum depends on the number of strip electrodes. Here, a five-electrode radiation detector is used, which can only resolve five sampling points on the continuum, but it can still be obtained from Figure 5. On the reconstructed data of the continuous spectrum, clear cut-off voltages (corresponding to 45, 55, and 65kV of the test set in order from top to bottom) were observed, and the reconstructed data reflected the information of the unknown spectrum. If the number of strip electrodes is increased, the reconstructed energy spectrum can be made clearer and more accurate; theoretically, when the number of strip electrodes is infinite, the multi-energy X-ray continuum in this band can be restored.

Implementation Case 3: Semiconductor Radiation Detector for Multi-Energy Imaging in a Single Exposure

Dual-energy (even multi-energy) imaging has high value in practical applications. Taking dual-source CT imaging as an example, its low-energy imaging results and high-energy imaging results can be subtracted and transformed to help distinguish various tissues in the human body. Here, a sample simulating human tissue is taken as an example to illustrate that the above-mentioned semiconductor radiation detector can be applied in this field.

The schematic diagram of the simulated human tissue shown in (a) in Figure 6, in which the three colors of black, gray and white represent three materials with high, medium and low density, respectively, and their absorption of X-rays in the sample tends to be It is close to three representative human tissues of bone/bone marrow, water/muscle, and fat. The actual image of the simulated human tissue sample is shown in the lower left corner of (a) in FIG. 6 , and the distribution and stacking of the tissue cannot be judged by the naked eye alone. Using the semiconductor radiation detector described above to image a simulated human tissue sample, five images can be obtained from five electrodes in a single exposure. Electrodes with smaller numbers contain more low-energy information, and low-energy X-rays are more sensitive to low-density tissues; electrodes with larger numbers contain more high-energy information, and high-energy X-rays are more sensitive to high-density tissues. (b) in Figure 6 is the image imaged by No. 2 electrode, it can be seen that the long edges of low-density materials and medium-density materials are clear; while (c) in Figure 6 is the image of No. 5 electrode imaging, you can see The rounded edges of medium-density materials and high-density materials are clear; the imaging pictures of electrodes of other serial numbers are omitted.

Example 4: Non-homogeneous semiconductor radiation detector

Considering that the attenuation of X-rays by semiconductor materials is proportional to its atomic number, in order to enhance the discrimination and contrast of the novel semiconductor radiation detector in the present invention for different energy ray particles in depth, the homogeneous MAPbBr ₃ perovskite is now used. The ore material is alloyed with halogen elements.

Using the perovskite system of MAPbX ₃ (X=Cl, Br, I), the growth of seed crystals was performed to obtain heterogeneous crystals as shown in (a) in FIG. 7 . The halogen elements of the crystal are respectively composed of Cl, Cl _0.5 Br _0.5 , Br, Br _0.5 I _0.5 , and I in the direction of the ray incident. The detectors correspond to five pairs of strip electrodes, respectively.

This can reduce the difference in electrode thickness design and improve the performance of the detector. Specifically, in the design of implementation case 1, the attenuation coefficient of MAPbBr ₃ is shown in (a) in Figure 2, maintaining a similar exponential downward trend, that is, the decay of low energy is fast, and the decay of high energy is slow; compared with MAPbCl ₃ , the attenuation coefficients of MAPbBr ₃ and MAPbI ₃ , as shown in (b) in Figure 7, MAPbCl ₃ decays more slowly at low energy, while MAPbI ₃ decays faster at high energy, so MAPbCl ₃ is used as the incident detector When MAPbI ₃ is used as the tail end of the detector, the exponential attenuation trend of the ray in the thickness of the detector is slowed down, which is beneficial to obtain a more evenly distributed signal on each electrode.

This design is beneficial to reduce the difference in detector thickness design and is suitable for detector designs with a very large number of electrode pairs. At this time, due to the extremely large number of electrode pairs of the detector, the thickness of a single electrode is reduced, and the narrow electrode at the incident end is easy to reach the limit size of the processing size and restricts the increase of the number of electrode pairs. Therefore, the introduction of this non-homogeneous design can further realize the Improved performance of multi-electrode pair detectors.

The above embodiments are only examples, and the electrode structure design of the present invention can be flexibly adjusted, and the solution thereof can be applied to single-point detectors, and can also be applied to linear array and area array detectors. In addition, the laser marking processing electrode is only an example. The preparation process of the strip electrode is not limited to various electrode processing processes such as wire bonding, laser marking processing, and ultra-fine mask evaporation processing. The specific process parameters and conditions can directly refer to the relevant existing technology.

The high-energy radiation particles detected by the semiconductor radiation detector in the present invention may be X-rays, γ-rays, neutrons, α-particles, β-particles, and other types of high-energy, certain penetration depths, and difficult to distinguish between energy. particle. The above embodiments only take halide perovskite materials as an example. Since all semiconductor radiation detector materials can work under the integral formula, the present invention is applicable to radiation detectors composed of various semiconductor materials (such as those already known in the prior art). Certain semiconductor radiation detector materials, of course, are also applicable to semiconductor radiation detector materials such as CZT, Si, etc., which can work in the single-photon counting mode).

In addition, according to actual needs, based on the technical solutions of the present invention, technicians can also flexibly adjust the above-mentioned embodiments; The square energy spectrum of 70kV is the X-ray energy spectrum of the Monte Carlo simulation of the target (except for the continuum part of the bremsstrahlung radiation, special attention should be paid to the characteristic spectrum of the target material, such as the characteristic spectrum of the mammary target used in breast detection. The lines are K _α = 0.071 nm, K _β = 0.063 nm); in different application scenarios, the target material of the tube is different, its multi-energy X-ray energy spectrum is different, and the structure design of the detector is also different, which can be flexibly adjusted.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (8)

1. A semiconductor radiation detector is characterized by comprising at least 2 groups of electrode pairs, wherein semiconductor materials in a radiation response area in the semiconductor radiation detector are divided into a plurality of thickness areas according to different distances from a radiation ray incidence end face; wherein,

each group of electrode pairs corresponds to a certain thickness area, and different groups of electrode pairs correspond to different thickness areas; the positive and negative electrodes in any group of electrode pairs can be electrically connected with each other through the corresponding thickness area;

the semiconductor radiation detector can collect radiation response signals of different target energy particles through different groups of electrode pairs by utilizing different attenuation degrees of different energy particles in a semiconductor material, thereby realizing energy spectrum distinguishing and realizing multi-energy spectrum detection.

2. The semiconductor radiation detector of claim 1 wherein said semiconductor material is a homogeneous semiconductor material;

preferably, the thickness of each of the electrode pairs increases in sequence from the radiation incident end face, and the thickness of the corresponding thickness region also increases in sequence.

3. The semiconductor radiation detector of claim 1 wherein said semiconductor material is a hetero-semiconductor material; the heterogeneous semiconductor materials are sequentially arranged in layers along the direction vertical to the incidence direction of the radiation ray;

preferably, starting from the radiation-incident end face, the material properties of these hetero semiconductor materials will be such that they will be able to exert an increasingly stronger attenuation effect on the radiation.

4. A semiconductor radiation detector according to claim 1, characterized in that the semiconductor material is preferably selected from the group consisting of halide perovskite materials, silicon, cadmium zinc telluride, cadmium telluride.

5. A semiconductor radiation detector according to claim 3, characterized in that the semiconductor material is preferably a plurality of halide perovskite materials, which are arranged in layers in sequence in a direction perpendicular to the direction of incidence of the radiation rays;

starting from the radiation ray incidence end face, the average atomic number of halogen potential elements in the halide perovskite materials is larger and larger.

6. The semiconductor radiation detector of claim 1, wherein said at least 2 sets of electrode pairs are at least 2 sets of strip electrode pairs.

7. The semiconductor radiation detector of claim 1, wherein the pair of electrodes is formed by wire bonding, laser marking, or mask evaporation.

8. The semiconductor radiation detector of claim 1, wherein said electrode pairs are further connected to a plurality of opposing electrodes for externally extracting said electrode pairs and applying a voltage.

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