X-ray radiation detector and operating procedures

Abstract

Radiation detector (1) for X-rays (X) with - a semiconductor body (2) for detecting X-ray radiation (X) with a radiation entrance side (20), - an electrically conductive window layer (3) which is applied flatly to the radiation entrance side (20), comprising boron and / or carbon and having a thickness (T) of at most 20 nm, and - an electrically conductive web structure (4) on the window layer (3) and in electrical contact with the window layer (3), wherein - the semiconductor body (2) comprises a p-doped layer (22) on the window layer (3) and an n-doped layer (21) on a side of the p-doped layer (22) facing away from the window layer (3), - the window layer (3) and the ridge structure (4) form an additional electrode (43) and the radiation detector (1) further comprises a first electrode (61) on the n-doped layer (21) and a second electrode (62) on the p-doped layer (22), - the web structure (4) is electrically connected independently of the semiconductor body (2), and - the first and second electrodes (61, 62), but not the additional electrode (43), are designed to read out a signal from the radiation detector (1).

Description

[0001] A radiation detector for X-rays is specified. Furthermore, an operating method for such a radiation detector is specified.

[0002] The document DE 10 2012 012 296 B4 concerns a radiation detector for X-rays.

[0003] Radiation transmission windows for X-rays are known from the publications DE 10 2014 103 546 A1 and DE 10 2012 107 342 B4.

[0004] The publication US 2019 / 0 214 217 A1 concerns radiation windows for X-rays containing boron.

[0005] The publications CN 1 04 062 676 A and Ji P. et al., “High-performance photodetector based on an interface engineering-assisted graphene / silicon Schottky junction” in Microsystems & Nanoengineering, Vol. 8, 2022, pages 1 to 9, and H.-A. Guo et al., “Silicon- and oxygen-codoped graphene from polycarbosilane and its application in graphene / n-type silicon photodetectors”, in: Applied Surface Science, Vol. 64, 2019, pages 125 to 130, concern radiation detectors with a graphene layer.

[0006] One challenge is to provide a radiation detector that is radiation-hard and has high sensitivity in the low-energy range. Another challenge is to provide a corresponding operating procedure.

[0007] These objects are achieved by a radiation detector and an operating method having the features of the independent patent claims. Preferred developments are the subject of the dependent claims.

[0008] The radiation detector comprises a semiconductor body. The semiconductor body is configured to detect X-rays. In particular, the semiconductor body comprises a semiconductor region designed to absorb the X-rays to be detected. For example, the semiconductor body is based on silicon, Si, or Ge.

[0009] The semiconductor body comprises a radiation entrance side. The radiation entrance side is preferably a main side and a boundary surface of the semiconductor body. The X-ray radiation to be detected enters the semiconductor body at the radiation entrance side. The semiconductor region intended to absorb the X-ray radiation to be detected can be located directly or close to the radiation entrance side. "Close" means, for example, that the distance between the radiation entrance side and the aforementioned semiconductor region is at most 100 nm or at most 30 nm.

[0010] The radiation detector comprises one or more electrically conductive window layers. The at least one, or preferably exactly one, window layer is applied in particular flatly to the radiation entrance side.

[0011] The at least one window layer comprises boron, B, and / or carbon, C. In particular, the at least one window layer consists of either B or C.

[0012] The at least one window layer has a thickness of at most 50 nm, or at most 20 nm, or at most 10 nm, or at most 5 nm, or at most 2 nm. The thickness of the at least one window layer is one atomic layer, two atomic layers, or more than two atomic layers.

[0013] The radiation detector comprises one or more electrically conductive ridge structures. The at least one, and preferably exactly one, ridge structure is located directly or indirectly on the window layer. Furthermore, the at least one ridge structure is in electrical contact with the window layer.

[0014] Thus, the radiation detector, which is designed to detect X-ray radiation, comprises - a semiconductor body for detecting X-rays with a radiation entrance side, - an electrically conductive window layer, which is applied flatly to the radiation entrance side, comprising boron and / or carbon and with a thickness of at most 20 nm, and - an electrically conductive web structure on the window layer and in electrical contact with the window layer.

[0015] In particular, due to the window layer serving as a current spreader, the window layer can be used as part of an electrode. Due to the ridge structure, the material of the window layer only needs to have a comparatively low electrical conductivity. Thus, electrical cross-conduction can be primarily achieved through the ridge structure. The ridge structure therefore only needs to cover a comparatively small area of the radiation entrance side. Since the window layer can be made of a material that only weakly absorbs low-energy X-rays, detection behavior for low-energy X-rays can be improved. Low-energy X-rays specifically refer to radiation with photon energies between 50 eV and 2 keV.

[0016] According to at least one embodiment, the area fraction of the radiation entrance side covered by the web structure is at most 30%, or at most 20%, or at most 10%, or at most 5%. Alternatively or additionally, this fraction is at least 0.5%, or at least 2%, or at least 5%.

[0017] According to at least one embodiment, the window layer is made of graphene.

[0018] According to at least one embodiment, the window layer is made of borophene.

[0019] According to at least one embodiment, the ridge structure is attached directly to the window layer. The ridge structure is located, for example, partially or completely on a side of the window layer facing away from the semiconductor body. The ridge structure can then be attached at a distance from the semiconductor body and can contact the window layer. Alternatively or additionally, the ridge structure is located, for example, partially or completely between the semiconductor body and the window layer. The ridge structure can thus contact both the semiconductor body and the window layer.

[0020] According to at least one embodiment, the window layer extends seamlessly over part or all of the radiation entrance side. The window layer or layers, or at least one of the window layers, can be flat.

[0021] According to at least one embodiment, the window layer has an area of at least 1 mm 2 or at least 0.1 cm 2 or at least 1 cm 2 This area of the window layer can be smaller than or equal to the area of the radiation entrance side, which in turn can be larger than or equal to an area of the semiconductor region intended to absorb the X-ray radiation to be detected, in each case viewed in plan view of the radiation entrance side.

[0022] According to at least one embodiment, the web structure comprises one or more metal grids. The at least one metal grid comprises one or more webs. All or some of the webs can be oriented parallel to one another, for example, with a tolerance of at most 30°, of at most 10°, or of at most 2°. Alternatively or additionally, at least some of the webs are oriented perpendicular to one another, as seen in a plan view of the radiation entrance side. This applies, for example, with a tolerance of at most 30°, of at most 10°, or of at most 2°. Thus, the web structure can include webs running transversely to one another and longitudinally to one another.

[0023] A web structure specifically means that at least one web is present. A web is, for example, a straight and / or unbranched metal strip. A web means, for example, that a longitudinal dimension exceeds a transverse dimension by at least a factor of five, by at least a factor of 10, or by at least a factor of 20. Intersecting webs are not considered a branch if the crossing angle is at least 45°, at least 60°, or at least 80°.

[0024] It is possible that the web structure comprises at least 10 or at least 100 or at least 500 of the webs. Alternatively or additionally, a maximum of 10 4 or a maximum of 1000 of the bridges are present.

[0025] According to at least one embodiment, a distance between at least some of the webs is at least 0.1 µm, or at least 1 µm, or at least 10 µm, or at least 30 µm, or at most 1 mm. Alternatively, this distance is at most 1 mm, or at most 0.2 mm, or at most 0.1 mm, or at most 30 µm. This distance applies in particular to webs oriented longitudinally to one another and / or as seen in a plan view of the radiation entrance side.

[0026] According to at least one embodiment, a thickness of the webs (42) is at least 10 nm or at least 20 nm or at least 30 nm. Alternatively or additionally, this thickness is at most 400 nm or at most 200 nm or at most 100 nm.

[0027] According to at least one embodiment, the thickness of the webs is at least twice, at least five times, or at least ten times the thickness of the at least one window layer. Alternatively or additionally, the thickness of the webs is at most 1000 times, at most 200 times, or at most 40 times the thickness of the at least one window layer.

[0028] According to at least one embodiment, a width of the webs is greater than the thickness of the webs by at least a factor of 2 or by at least a factor of 10. Alternatively or additionally, this difference is at most a factor of 200 or at most a factor of 40.

[0029] According to at least one embodiment, a dielectric insulation layer is located directly between the semiconductor body and the window layer, either in some regions or over the entire surface. "Directly between" means, in particular, that the insulation layer touches both the semiconductor body and the window layer, in particular over the entire surface. For example, the insulation layer is made of an electrically insulating oxide or nitride such as SiO2, Si3N4, or BN, boron nitride.

[0030] According to at least one embodiment, the window layer is located directly on the radiation entrance side, either partially or over its entire surface. This means that the window layer can directly cover the radiation entrance side.

[0031] The semiconductor body comprises a p-doped layer at the window layer and an n-doped layer on a side of the p-doped layer facing away from the window layer. It is possible that a space charge zone forms between the p-doped layer and the n-doped layer during operation of the radiation detector.

[0032] According to at least one embodiment, the p-doped layer is a Si layer.

[0033] According to at least one embodiment, the n-doped layer is a Si layer.

[0034] According to at least one embodiment, the p-doped layer is thinner than the n-doped layer.

[0035] The ridge structure can be electrically connected independently of the semiconductor body, i.e., independently of the p-doped layer and the n-doped layer. The window layer and the ridge structure form at least part of an additional electrode.

[0036] The radiation detector further comprises a first electrode on the n-doped layer and a second electrode on the p-doped layer. A signal from the radiation detector is read out via the first and second electrodes.

[0037] Furthermore, an operating method for a radiation detector as described in connection with one or more of the above-mentioned embodiments is provided. Features of the radiation detector are therefore also disclosed for the operating method, and vice versa.

[0038] The operating method operates a radiation detector. A voltage V2 at a second electrode is smaller than a voltage V1 at a first electrode, and the following applies to a voltage V3 at an additional electrode: 1.1 · V2 ≤ V3 or 1.03 · V2 ≤ V3 and V3 < V2 or V3 < V2 or V3 < 1.005 · V2. At least low-energy X-rays are detected.

[0039] For example, ΔV = |V1 - V2| is at least 5 V or at least 20 V and / or at most 200 V or at most 500 V. For example, V1 = 0 V and -60 V ≤ V2 ≤ -120 V. δV = |V2 - V3| is, for example, at least 0 V or at least 0.3 V and / or at most 3 V or at most 10 V, where V3 is more negative than V2.

[0040] The sign of the applied voltages depends on the doping in the semiconductor. For the case of a weakly n-doped substrate with a p + -contact on the entrance window side, a so-called p-on-n structure, the previous voltage specifications apply. For the case of a weakly p-doped substrate with an n + - contact, a so-called n-on-p structure, the signs of the voltages are reversed.

[0041] A numerical example to illustrate: p-on-n: V3 = 0 V, V2 = -100 V and V3 = -101 V, respectively n-on-p: V3 = 0V, V2 = +100V and V3 = +101V.

[0042] According to at least one embodiment, the radiation detector is configured to detect X-ray radiation with a photon energy of at least 0.1 keV and / or of at most 25 keV. In particular, the radiation detector is configured for photon energies in the low-energy range of at least 50 eV or of at least 100 eV and up to at least 2 keV.

[0043] A radiation detector and an operating method described herein are explained in more detail below with reference to the drawings using exemplary embodiments. Like reference numerals indicate like elements in the individual figures. However, they are not drawn to scale; rather, individual elements may be exaggerated for clarity.

[0044] They show: Fig. 1 and Fig. 2 schematic sectional views of variations of radiation detectors, Fig. 3 a schematic sectional view of an embodiment of a radiation detector described here, Fig. 4 to 6 schematic plan views of embodiments of radiation detectors described here, Fig. 7 to 11 are schematic sectional views of embodiments of radiation detectors described here, Fig. 12 a schematic representation of the penetration depth of X-rays into various materials as a function of the photon energy, and Fig. 13 a schematic representation of the transmission of radiation entrance windows of radiation detectors for X-ray radiation as a function of the photon energy.

[0045] In Fig. 1 illustrates a variation 9 of a radiation detector. Variation 9 comprises a semiconductor body 2, which is based in particular on Si. On a radiation entrance side 20, the semiconductor body 2 comprises a p-doped layer 22. On a side of the p-doped layer 22 facing away from the radiation entrance side 20, there is an n-doped layer 21. Furthermore, a dielectric insulation layer 5 is applied to the radiation entrance side 20, which is made of SiO2, for example, and has a thickness of, for example, between 20 nm and 200 nm.

[0046] On the layers 21, 22 there are a first electrode 61 and a second electrode 62 to which voltages V1, V2 are applied.

[0047] During operation of variation 9, X-ray radiation X enters the semiconductor body 2 through the radiation entrance side 20.

[0048] Thus, variation 9 according to Fig. 1 has an oxide entrance window 5. The oxide layer 5 saturates surface states on the semiconductor body 5, which is why secondary electrons caused by the X-ray radiation X are absorbed less than on a non-passivated or metal-passivated Si surface. This results in good low-energy performance of variation 9 in combination with high transmission for X-ray radiation X. However, the effect depends heavily on the oxide quality, which is why the performance deteriorates with increasing irradiation. In addition, this variation 9 exhibits relatively low radiation hardness. This means that at high cumulative radiation doses, the sensitivity and / or lifetime of this variation 9 decreases significantly.

[0049] Variation 9 according to Fig. 2 has compared to Fig. 1 additionally has a metal layer 7 on the insulation layer 5, which is connected to a further electrode 73. A voltage V3 is applied to the further electrode 73, which is more negative than the voltage V2.

[0050] This combination of insulation layer 5 and metal layer 7 on the semiconductor body 2 is also referred to as an MOS entrance window, where MOS stands for metal-oxide-semiconductor. The metal layer 7 is made of aluminum, for example, with a thickness of 40 nm. The more negative voltage V3 on the metal layer 7 pushes the electrons generated by the X-ray radiation into the semiconductor body 2, thereby very effectively preventing absorption of these secondary charge carriers. This effect is relatively independent of the oxide quality, which is why this configuration is significantly more radiation-hard. However, the additional metal layer 7 absorbs a comparatively large proportion of the incident X-ray radiation, which leads to poorer low-energy performance. The functioning of such a variation can be found in more detail, for example, in document 10 2012 012 296 B4, in particular paragraphs 11, 12, 15, 30, and 38 to 40.

[0051] One aim of a radiation detector 1 described here is in particular to combine the advantages of both variations 9 of the Fig. 1 and Fig. 2. For this purpose, the transmission of the metal layer 7 in the MOS configuration of the Fig. 2 to increase.

[0052] In the example of radiation detector 1 according to Fig. 3, the metal layer 7 is replaced by a window layer 3 together with a ridge structure 4. The window layer 3 and the ridge structure 4 together form at least part of an additional electrode 43 to which the voltage V3 can be applied.

[0053] The window layer 3 is, for example, a graphene layer or a borophene layer with a thickness T of at most 20 nm, in the case of graphene preferably between 2 nm and 15 nm or between 2 nm and 5 nm; in the case of borophene, few monolayers may be present. The ridge structure 4, which is made of aluminum, for example, and in particular has a thickness S of between 30 nm and 50 nm, is applied directly to the window layer 3. A distance D between adjacent ridges 42 of a metal grid 41, which can form the ridge structure 4, is, for example, between 3 µm and 30 µm. A width W of the ridges 41 is, for example, between 1 µm and 5 µm.

[0054] During operation of the radiation detector 1, the voltage V1 at the first electrode 61 is, for example, 0 V, and the voltage V2 at the second electrode 62 is, for example, between -60 V and -80 V. The voltage V3 at the additional electrode 43 is slightly more negative than the voltage V2. Since the additional electrode 43 is preferably not configured for signal evaluation, no or only low currents flow in the additional electrode 43 as intended.

[0055] In the Fig. 4 to 6 show exemplary top views of the web structure 4. According to Fig. 4, the metal grid 41 is present, which has a plurality of webs 42 crossing at right angles. The webs 42 define, for example, square or rectangular meshes, within which the window layer 3 can be exposed. The metal grid 41 can have the same grid constant and / or thickness over the entire radiation entrance side 20. As an alternative to a square grid or rectangular grid, deviating from the illustration in Fig. 4, a particularly regular hexagonal metal grid 41 may also be present. A diameter of the radiation entrance side 20 is, for example, between 1 mm and 10 mm.

[0056] In Fig. 5 illustrates that the metal grid 41 is formed by parallel webs 42. Thus, there are no intersecting webs 42, unlike in Fig. 4.

[0057] According to Fig. 6, only two of the webs 42 are present, which cross each other and form the metal grid 41. Deviating from the illustration in Fig. 6 it is also possible that only a single web 42 is present.

[0058] According to the Fig. 4 to 6, the webs 42 each run straight. Alternatively, curved webs 42 or webs 42 with kinks may also be present.

[0059] Furthermore, according to the Fig. 4 to 6, a frame 44 is optionally present. For example, the frame 44 surrounds the radiation entrance side 20 in a circular shape or, unlike the drawing, also as a polygon. The frame 44 can electrically connect the individual webs 42 to one another. It is possible for the frame 44 to serve as a contact point for the additional electrode 43. For example, the frame 44 is made of the same material as the webs 42 and the frame 44 can have the same thickness S as the webs 42 or even a greater thickness.

[0060] The full-surface metal layer 7 made of aluminum according to Fig. In the radiation detector 1 described here, the lattice 2 is thus replaced by the full-surface, ultra-thin graphene or borophene layer with a thickness T of a few nm and the best possible conductivity. The metal support grid structure 4 is applied to this graphene or borophene layer for improved potential distribution. The lattice constant of the electrical support grid structure 4 is chosen to be as large as possible. The lattice constant results from a sheet resistance and a leakage current between the two potentials.

[0061] In all other respects, the statements regarding the Fig. 1 and Fig. 2 in the same way for the Fig. 3 to 6.

[0062] In the example of Fig. 7 shows that the ridge structure 4 can protrude laterally beyond the insulation layer 5 and can be in contact with the p-doped semiconductor layer 22. In this case, V3 = V2 applies. This configuration is also possible in all other embodiments and already achieves an improvement in terms of the desired functionality. However, the configuration of the Fig. 3, according to which V3 can be adjusted independently of V2.

[0063] The radiation detector 1 of the Fig. 8 comprises an intermediate layer 8 on the radiation entrance side 20. The intermediate layer 8 is made, for example, of electrically insulating SiC. This SiC layer 8 can optionally be formed in situ at an appropriate deposition temperature during the graphene deposition process for the window layer 3.

[0064] According to Fig. 9, no insulation layer 5 is present. The window layer 3, which is made of graphene, for example, thus lies directly on the radiation entrance side 20 of the semiconductor body 2. Surface states are saturated by the window layer 3, or accumulating charge carriers can be additionally transported away via the conductive window layer.

[0065] Optionally, the semiconductor layer 22 on the radiation entrance side 20 comprises several sublayers. The semiconductor layer 22 can thus be composed of several sublayers, each of which can be made of appropriately doped Si, for example. This can ensure that p-type doping in the charge-carrier-depleted silicon decreases successively toward the inside, so that an electric field is always directed into the detector volume and the generated charge carriers are driven toward the anode. This can apply accordingly in all other examples.

[0066] In the example of Fig. 10 shows that the web structure 4 is applied directly to the radiation entrance side 20. The window layer 3 is then applied, for example, over the entire surface of the radiation entrance side 20, so that the window layer 3 can partially or completely cover the web structure 4, see Fig. 10, left side. Alternatively, the window layer 3 can be limited to areas between the webs 42, see Fig. 10, right side.

[0067] According to Fig. 11, a space charge zone 23 is formed between the semiconductor layers 21, 22 during operation, caused by the voltages V1 and V2. The additional electrode 43 can be connected separately from the second electrode 62. The second electrode 62 is, for example, a metallic ring electrode around the radiation entrance side 20. The first electrode 61 can be a flat metal layer on a side of the semiconductor layer 21 facing away from the radiation entrance side 20.

[0068] Optionally, the semiconductor body 2 comprises a further n-doped layer 24. The layer 24 is preferably more weakly doped than the layer 21. The space charge zone 23 can be formed in the further layer 24.

[0069] In all other respects, the statements regarding the Fig. 1 to 6 in the same way for the Fig. 7 to 11, and vice versa.

[0070] In another category of examples of the radiation detector 1, no window layer 3 is present. In this case, a ridge structure 41 without a window layer is present, for example, aluminum ridges 42, in particular directly on the semiconductor body 2, specifically directly on p-doped silicon. Such radiation detectors 1 also provide an improvement in transmission. This applies in particular to small distances between adjacent ridges 42 of, for example, at most 0.2 mm or at most 0.1 mm or at most 30 µm. For such radiation detectors 1 without a window layer, the statements regarding the Fig. 1 to 11 in the same way.

[0071] In Fig. Figure 12 shows the penetration depths L, also referred to as attenuation lengths, for various materials as a function of photon energy Ep. In particular, it can be seen that graphene, Gr, and borophene, Bo, exhibit a significantly greater penetration depth L and thus higher transmission for incident radiation in the low-energy range at photon energies Ep around 200 eV than aluminum, Al, and silicon oxide, SiO2. Furthermore, the layers can be formed significantly thinner, which further improves transmission.

[0072] In Fig. 13 shows a transmission Tx of an additional electrode described here with a 10 nm thick graphene window 3 and a 40 nm thick aluminum web structure 4, wherein a metal grid according to Fig. 4 with ridge widths D of 2 µm and ridge spacings D of 10 µm. It can be seen that, compared to a flat metal layer 7 made of 40 nm thick aluminum, the transmission Tx, particularly in the spectral range below 300 eV, is significantly increased by several tens of percentage points in a radiation detector 1 described here, corresponding to a transmission gain ΔT.

[0073] Furthermore, Fig. 13 lists the energies of characteristic X-ray emission lines Kα for several elements E. Within the framework of material analysis based on the characteristic X-ray radiation of elements using methods such as EDX (energy dispersive X-ray spectroscopy), XRF (X-ray fluorescence spectroscopy), or PIXE (particle-induced X-ray emission), the photon energy range from 50 eV to several 10 keV, corresponding to wavelengths from 25 nm to about 10 pm, is of interest. Therefore, the term transmission Tx refers particularly to this energy range and, in particular, to the low-energy portion from 50 eV to 2 keV. The table in Fig. Figure 13 shows the energies of the Kα lines of the lightest elements. These energies are required for elemental determination.

[0074] Since the window 3, 4 described here has an increased transmission Tx in the low-energy spectral range, the detection sensitivity is increased in this spectral range.

[0075] The components shown in the figures preferably follow one another in the specified order, in particular directly one after the other, unless otherwise stated. Components that do not touch in the figures are preferably spaced apart. If lines are drawn parallel to one another, the associated surfaces are preferably also aligned parallel to one another. Furthermore, the relative positions of the drawn components to one another are correctly represented in the figures, unless otherwise stated. List of reference symbols 1 radiation detector 2 semiconductor bodies 20 Radiation entrance side 21 n-doped layer 22 p-doped layer 23 Space charge zone 24 additional n-doped layers 3 window layer 4 Bridge structure 41 metal grilles 42 jetty 43 Additional electrode 44 frames 5 dielectric insulation layer 61 first electrode 62 second electrode 7 metal layer 73 additional electrodes 8 Intermediate layer 9 Variation of a radiation detector D Distance between the webs E element in the periodic table Ep photon energy in eV Kα characteristic X-ray emission line L Penetration depth in nm S Thickness of the webs T Thickness of the window layer ΔT transmission gain Tx transmission in % W Width of the webs X X-rays

Claims

[1] Radiation detector (1) for X-rays (X) with - a semiconductor body (2) for detecting X-ray radiation (X) with a radiation entrance side (20), - an electrically conductive window layer (3) which is applied flatly to the radiation entrance side (20), comprising boron and / or carbon and having a thickness (T) of at most 20 nm, and - an electrically conductive web structure (4) on the window layer (3) and in electrical contact with the window layer (3), wherein - the semiconductor body (2) comprises a p-doped layer (22) on the window layer (3) and an n-doped layer (21) on a side of the p-doped layer (22) facing away from the window layer (3), - the window layer (3) and the ridge structure (4) form an additional electrode (43) and the radiation detector (1) further comprises a first electrode (61) on the n-doped layer (21) and a second electrode (62) on the p-doped layer (22), - the web structure (4) is electrically connected independently of the semiconductor body (2), and - the first and second electrodes (61, 62), but not the additional electrode (43), are designed to read out a signal from the radiation detector (1). [2] Radiation detector (1) according to the preceding claim, wherein - the window layer (3) is made of borophene and the thickness (T) is at most 5 nm, - the web structure (4) is attached directly to the window layer (3), and - the window layer (3) is continuous and has an area of at least 1 mm 2 has. [3] Radiation detector (1) according to claim 1, wherein - the window layer (3) is made of graphene and the thickness (T) is at most 5 nm, - the web structure (4) is attached directly to the window layer (3), and - the window layer (3) is continuous and has an area of at least 1 mm 2 has. [4] Radiation detector (1) according to one of the preceding claims, wherein the web structure (4) is located on a side of the window layer (3) facing away from the semiconductor body (2). [5] Radiation detector (1) according to claim 1, 2 or 3, wherein the ridge structure (4) is located between the semiconductor body (2) and the window layer (3). [6] Radiation detector (1) according to one of the preceding claims, wherein the web structure (4) comprises a metal grid (41), so that the web structure (4) includes webs (42) extending transversely to one another and / or parallel to one another. [7] Radiation detector (1) according to the preceding claim, wherein a distance (D) between at least some of the webs (42) is at least 0.1 µm and at most 1 mm, and wherein a thickness (S) of the webs (42) is at least 20 nm and at most 200 nm and a width (W) of the webs (42) is at least a factor of 2 greater than the thickness (S) of the webs (42). [8] Radiation detector (1) according to one of the preceding claims, wherein a dielectric insulation layer (5) is located directly between the semiconductor body (2) and the window layer (3), at least in some regions. [9] Radiation detector (1) according to one of the preceding claims, which includes exactly one additional electrode (43) on the window layer (3). [10] Radiation detector (1) according to one of the preceding claims, wherein the p-doped layer (22) is a Si layer, wherein the n-doped layer (21) is a Si layer, and wherein the p-doped layer (22) is thinner than the n-doped layer (21). [11] Operating method for operating a radiation detector (1), wherein - X-ray radiation (X) is detected with the radiation detector (1), - the radiation detector (1) comprises a semiconductor body (2) for detecting the X-ray radiation (X) with a radiation entrance side (20), - the radiation detector (1) comprises an electrically conductive window layer (3) which is applied flatly to the radiation entrance side (20), - the window layer (3) comprises boron and / or carbon and has a thickness (T) of at most 20 nm, - the radiation detector (1) comprises an electrically conductive web structure (4) on the window layer (3) and in electrical contact with the window layer (3), - the semiconductor body (2) comprises a p-doped layer (22) on the window layer (3) and an n-doped layer (21) on a side of the p-doped layer (22) facing away from the window layer (3), - the window layer (3) and the ridge structure (4) form an additional electrode (43) and the radiation detector (1) further comprises a first electrode (61) on the n-doped layer (21) and a second electrode (62) on the p-doped layer (22), - the web structure (4) is electrically connected independently of the semiconductor body (2), - the first and second electrodes (61, 62), but not the additional electrode (43), read a signal from the radiation detector (1), - a voltage V2 at the second electrode (62) is smaller than a voltage V1 at the first electrode (61) and for a voltage V3 at the additional electrode (43) the following applies: 1.1⋅V2≤V3 <v2 sowie v2<0 und v3<0, undwhere low-energy X-rays (X) with photon energies between 50 eV and 2 keV are detected.< / v2 sowie v2<0 und v3<0, und

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