Multilayer device for radiation detection and sublimation deposition method

Abstract

The invention relates to a photodetector structure comprising: a planar absorption structure for converting an incident ray into photogenerated electric charge carriers; a lower electrode for collecting the photogenerated electric charge carriers; an upper electrode; said planar absorption structure being confined between the lower electrode and the upper electrode and comprising: an absorption layer made of a first compound material ABX3; an interface layer made of a second compound material AB2X5 arranged between the absorption layer and the upper electrode or the lower electrode; Figure for abstract: Fig. 2a

Description

Title of the invention: Multi-layer device for radiation detection and sublimation deposition method

[0001] Scope of application

[0002] The present invention relates to the field of optoelectronic devices for the detection of radiation by photoelectric effect. More particularly, the invention relates to multilayer planar structures for absorbing radiation and a method of manufacturing by sublimation.

[0003] Problem raised

[0004] Optoelectronic devices are generally constituted by assembling one or more photodetector structures based on semiconductor layers transforming a flow of incident photons into generated photo charge carriers, and a reading circuit for processing the electrical signal from the photodetector structures of the optoelectronic device.

[0005] The response time of an optoelectronic device consists of the speed of establishment of the electrical reading signal from the photo charge carriers generated following its illumination by an incident ray. This is a fundamental technical characteristic which determines the performance of the optoelectronic device. In this context, the response time depends directly on the absorption factor of the photodetector structure but also on the mobility of the charges in the volume of the absorption zone and more particularly at its interfaces.

[0006] The invention proposes to solve a technical problem in this field consisting of designing a photodetector structure for an optoelectronic device while improving the response time and the mobility of the charges compared to state-of-the-art solutions.

[0007] To better understand the problem raised by the invention, we will begin by describing the structure of a radiation detection device according to the state of the art. [Fig.l] illustrates a sectional view of an example of a pixel belonging to an optoelectronic radiation detector device D0 by way of non-limiting example.

[0008] The radiation detection device D0 is a hybrid optoelectronic system, comprising: on the one hand, an optical part formed by a plurality of photodetector structures Pxl0 arranged in rows and columns and on the other hand an electronic part consisting of an integrated reading circuit 12. This reading circuit can constitute the substrate of the device D0 or be itself produced on a substrate 11. Each pixel comprises a dedicated lower electrode 13 connected to the reading circuit 12 to allow individualized reading of each pixel.

[0009] The integrated reading circuit 12 is made up of a plurality of transistors and thin layers of conductive, semiconductive or dielectric material. It can be produced using CMOS (Complementary Metal-Oxide-Semiconductor) technology and then also serves as substrate 11, or using TFT (Thin Film Transistor based on amorphous silicon) technology, deposited on the substrate 11 or using any other type of technology. The photodetector structure Pxl0 of the device DO is produced by a stack of layers of material on a support Sup. The support Sup comprises the reading circuit 12 and the substrate IL. The axis of the photodetector structure A is the axis perpendicular to the horizontal plane (x,y) formed by the upper surface of the support Sup.The photodetector structure Pxl0 comprises a planar absorption structure SPA0 for converting an incident ray Ro into photogenerated electric charge carriers; a lower electrode 13 for collecting the photogenerated electric charge carriers and an upper electrode 16. The planar absorption structure SPAo and the upper electrode 16 are common between the photodetector structures Pxlo of the DO device. The pixelation is achieved by the lower electrodes 13 being distinct and forming a matrix.

[0010] The planar absorption structure SPA0 converts the flux of incident photons with a wavelength X into negative charge carriers "electrons" in the conduction band of the SPA0 structure and / or positive charge carriers "holes" in the valence band of the SPA0 structure. An electrical voltage VI is applied between the upper electrode 16 and the lower electrode 13 to move the photogenerated charges towards the lower electrode 13. The quantity of photogenerated charge carriers collected by the electrode determines the amplitude of the reading signal associated with the pixel Pxl0 generated by the reading circuit 12.

[0011] The materials used to produce the planar absorption structure SPA0 and the thickness of the planar absorption structure are determined by (or adapted according to) the energy of the radiation used in the intended application. In this context, the planar absorption structure SPAo is made up of an absorption layer 15 made of a first composite material ABX3 with: - A chosen from a first group of inorganic cations comprising cesium Cs, rubidium Rb, potassium K or an alloy of said elements of the first group of inorganic cations; - B chosen from a second group of inorganic cations comprising lead Pb, tin Sn, germanium Ge, silicon Si or an alloy of said elements of the second group of inorganic cations; - X chosen from a group of halogens comprising bromine Br, iodine I, chlorine Cl or an alloy of said elements of the group of cations.

[0012] This choice of compound material for the absorption layer 15 presents a solution emerging. Indeed, the choice of ABX3 type material makes it possible to detect radiation in the X, gamma and visible frequency ranges with good detection sensitivity (for example S>1 pC.mGy '.cm2 for X radiation).

[0013] However, the DO device according to the state of the art has a relatively slow response time (i.e. time for establishment or disappearance of the photocurrent) greater than 50 ms. This drawback reduces the performance of existing solutions in the context of applications requiring short integration times (typically < 50 ms). This slow response time results in the appearance of ghost images when producing successive images, which are the trace of the previous images. These artifacts reduce the readability of the detected images. In addition, the prolonged response time limits the possibility of analyzing the temporal evolution of the images, for example following the injection of a contrast agent (case of fluoroscopy). They are particularly harmful for quantitative applications such as tomosynthesis, for which they result in the appearance of circles on the reconstructed images.

[0014] The disadvantage of the too slow response time in this type of structure is explained by the presence of structural defects at the interface between the ABX3 absorption layer and the electrodes of the Pxl0 photodetector structure.

[0015] A technical problem to be solved in this field therefore consists of designing a photodetector structure comprising an absorption layer in ABX3 as defined previously by improving the response time of said structure compared to state-of-the-art solutions.

[0016] Response to the problem and provision of solution

[0017] To overcome the limitations of existing solutions with regard to reducing the response time of a photodetector structure comprising an ABX3 absorption layer, the invention proposes several embodiments of a modified planar absorption structure further comprising an interface layer made of a second compound material AB2X5 arranged between, on the one hand, the absorption layer and, on the other hand, the upper electrode or the lower electrode.

[0018] More specifically, the invention proposes solutions compatible with the targeted applications with a better response time. Indeed, the insertion of an AB2X5 interface layer makes it possible to inhibit the effect of defects at the interface of the ABX3 absorption layer with the adjacent layers and more particularly the electrodes of the photodetector structure. The solution according to the invention then makes it possible to improve the response time of the optoelectronic device.

[0019] The photo-detector structure according to the invention makes it possible to design optoelectronic devices meeting the needs in various application fields such as medical imaging (radiology, mammography, tomography, etc.), non-destructive industrial inspection, the geophysical field (analysis of the nature of the ground for oil research), the field of public security (luggage control, vehicles), the field of fundamental research and photovoltaic energy.

[0020] The invention further proposes several embodiments of a method for manufacturing the photodetector structure according to the invention based on the “close-space sublimation deposition” CSS technique (acronym for the English expression Close-Space Sublimation). The use of the “close-space sublimation deposition” technique is well mastered for producing thin layers in ABX3. Generally speaking, deposition of a layer in a material by sublimation is possible when its solid-liquid binary phase diagram is congruent and the deposition is carried out at thermodynamic equilibrium. In the state-of-the-art solutions, obtaining these specific conditions is mastered for ABX3 layers (for the absorption layer) but not for AB2X5 layers (for at least one interface layer).In response to this additional technical problem, the invention proposes a method for manufacturing a photodetector structure according to the invention by exploiting the transient periods towards thermodynamic equilibrium during a CSS “near space sublimation deposition” from an ABX3 target.

[0021] In the following section, the various characteristics of the invention are set out for an illustrative and non-limiting example in which element A is cesium Cs, element B is lead Pb and element X is bromine Br. We emphasize that the invention is not limited to this combination of chemical elements and that the characteristics and advantages of the photodetector structure according to the invention and those of the method according to the invention remain valid for the various combinations of materials starting from the first group of inorganic cations for A, from the second group of inorganic cations for B and from the group of halogens for X. The choice of materials and thicknesses of the layers is determined by the field of application of the photodetector structure according to the invention.The benefit of improved response time by combining the AB2X5 interface layer with the ABX3 absorption layer is not limited to the illustrative example shown below.

[0022] Abstract / Claims

[0023] The subject of the invention is a photodetector structure comprising: - a planar absorption structure for converting an incident ray into photogenerated electric charge carriers; - a lower electrode for collecting photogenerated electric charge carriers; - an upper electrode; Said planar absorption structure being confined between the lower electrode and the upper electrode and comprising: - an absorption layer made of a first ABX3 compound material; - an interface layer made of a second compound material AB2X5 arranged between, on the one hand, the absorption layer and, on the other hand, the upper electrode or the lower electrode; A being selected from a first group of inorganic cations comprising cesium, rubidium, potassium or an alloy of said elements of the first group of inorganic cations; B being selected from a second group of inorganic cations comprising lead, tin, germanium, silicon or an alloy of said elements of the second group of inorganic cations; X being selected from a group of halogens comprising bromine, iodine, chlorine or an alloy of said elements of the group of cations.

[0024] According to a particular aspect of the invention, the photodetector structure further comprises a protective layer made of a material which is chemically inert with respect to the planar absorption structure and electrically insulating. Said protective layer being confined between the planar absorption structure and the lower electrode.

[0025] The invention also relates to a device for detecting X or Y radiation comprising at least one pixel. The at least one pixel comprises the photo-detector structure according to the invention.

[0026] According to a particular aspect of the invention, the X or y radiation detection device further comprises a reading circuit arranged on a substrate configured to generate a reading signal from the electric charge carriers collected by the lower electrode. Said reading circuit being assembled to the photodetector structure by direct or indirect coupling.

[0027] According to a particular aspect of the invention, the X or y radiation detection device is intended to receive the incident ray from the substrate side. The substrate, the reading circuit and the lower electrode are transparent to the wavelength of the incident ray.

[0028] According to a particular aspect of the invention, the absorption layer has a thickness of between 50 pm and 2000 pm.

[0029] According to a particular aspect of the invention, the interface layer has a thickness of between 10 nm and 50 pm.

[0030] According to a particular aspect of the invention, the absorption layer is made of CsPbBr3 and the interface layer is made of CsPb2Br5.

[0031] The invention also relates to a photovoltaic cell comprising the photodetector structure according to the invention.

[0032] According to a particular aspect of the invention, the absorption layer in the photovoltaic cell has a thickness of between 0.1pm and 1pm.

[0033] According to a particular aspect of the invention, the interface layer has a thickness of between 5 nm and 0.1 pm.

[0034] According to a particular aspect of the invention, the absorption layer is made of CsPb3 and the interface layer is made of CsPb25; with x between 0 and 0.5.

[0035] The invention also relates to a method for manufacturing a photodetector structure according to the invention comprising the following steps: ii) producing a planar absorption structure by the close-space sublimation technique from a source of the first compound material ABX3 on the upper face of a support; the source being preheated to a first temperature between 350°C and 500°C; the support being preheated to a second temperature less than or equal to the first temperature; iii) depositing an upper electrode on the planar absorption structure.

[0036] According to a particular aspect of the invention, step ii) of producing the planar absorption structure comprises the following sub-steps for producing an interface layer arranged below the absorption layer: ii.a) mounting the support in front of the source of a near-space sublimation deposition device; ii.b) controlling the second temperature at a temperature difference with respect to the first temperature greater than or equal to 200°C to deposit the interface layer in a second material composed of AB2X5 from the source during a transient regime corresponding to a thermodynamic non-equilibrium; the duration of the transient regime being between 1 min and 10 min; ii.c) depositing the absorption layer consisting of the first compound material ABX3 from the source during a steady state corresponding to a thermodynamic equilibrium.

[0037] According to a particular aspect of the invention, step ii) of producing the planar absorption structure comprises the following sub-steps for producing an interface layer arranged below the absorption layer: ii.a') mounting the support in front of the source of a near-space sublimation deposition device; ii.b') controlling the second temperature at a temperature difference with respect to the first temperature greater than or equal to 200°C to deposit the interface layer in a second material composed of AB2X5 from the source during a transient regime corresponding to a thermodynamic non-equilibrium; the duration of the transient regime being between 1 min and 10 min; ii.c') increasing the second temperature to obtain a temperature difference with respect to the first temperature of less than 200°C so as to deposit the absorption layer composed of the first compound material ABX3 from the source.

[0038] According to a particular aspect of the invention, step ii) of producing the planar absorption structure comprises the following sub-steps for producing an interface layer arranged above the absorption layer: ii.a”) mounting the holder opposite the source of a near-space sublimation deposition device; ii.b”) controlling the second temperature to a temperature difference from the first temperature of less than 200°C so as to deposit the absorption layer consisting of the first compound material ABX3 from the source; ii.c”) deactivate the sublimation deposition device in the near space and dismantle the support; ii.d”) following cooling of the source, reassemble the support in front of the source of said sublimation deposition device in the close space; ii.e”) controlling the second temperature at a temperature difference with respect to the first temperature greater than or equal to 200°C to deposit the interface layer in a second material composed of AB2X5 from the source during a transient regime corresponding to a thermodynamic non-equilibrium; the duration of the transient regime being between 1 min and 10 min. Detailed Description

[0039] Other characteristics and advantages of the present invention will appear more clearly on reading the description which follows in relation to the following appended drawings.

[0040] [Fig-1] [Fig.l] illustrates a sectional view of an example of a photodetectorized structure detector according to the state of the art. This figure has already been described.

[0041] [Fig.2a] [Fig.2a] illustrates a sectional view of a photodetector structure according to a first embodiment of the invention belonging to a DI detection device for X or y radiation.

[0042] [Fig.2b] [Fig.2b] illustrates a sectional view of a photodetector structure according to a second embodiment of the invention belonging to a DI detection device for X or y radiation.

[0043] [Fig.2c] [Fig.2c] illustrates a sectional view of a photodetector structure according to a third embodiment of the invention belonging to a DI detection device for X or y radiation.

[0044] [Fig.3] [Fig.3] illustrates the response of the photodetector structure according to the invention compared to that of the state-of-the-art photodetector structure following exposure to a radiation pulse.

[0045] [Fig.4] [Fig.4] illustrates a sectional view of a photodetector structure of a fourth embodiment of the invention belonging to a photovoltaic cell.

[0046] [Fig.5a] [Fig.5a] illustrates a manufacturing method for producing an opto- electronics comprising at least one photodetector structure according to the invention.

[0047] [Fig.5b] [Fig.5b] illustrates a near-space sublimation deposition device configured for manufacturing the photodetector structure according to the invention.

[0048] [Fig.6a] [Fig.6a] illustrates the sub-steps according to a first embodiment of the invention for producing the planar absorption structure according to the invention.

[0049] [Fig.6b] [Fig.6b] illustrates the sub-steps according to a second embodiment of the invention for producing the planar absorption structure according to the invention.

[0050] [Fig.6c] [Fig.6c] illustrates the sub-steps according to a third embodiment of the invention for producing the planar absorption structure according to the invention.

[0051] [Fig.2a] illustrates a sectional view of a photodetector structure Pxli according to a first embodiment of the invention belonging to a device for detecting X or y radiation DI.

[0052] The radiation detection device DI comprises an optical part formed by a photodetector structure Pxli and an electronic part consisting of an integrated reading circuit 12 produced on a substrate 11. The optical part is configured to convert an incident ray Ra to a quantity of photogenerated charge carriers. The electronic part is configured to convert the photogenerated charges to an electronic reading signal. In the example illustrated, the device DI is intended to detect an incident ray Ra on the side of the lower face of the substrate 11. The substrate 11 and the reading circuit 12 form a support Sup on which the optical part formed by one or more pixels is produced.

[0053] The integrated reading circuit 12 is produced by means of a plurality of transistors according to TFT technology (Thin Film Transistor based on amorphous silicon) and thin layers of conductive, semiconductive or dielectric material deposited on the substrate 11. The materials used for producing the components of the integrated reading circuit 12 are transparent to the frequency range of the incident ray Ra. The assembly between the optical part and the electronic part can be carried out by direct coupling or by indirect coupling. Direct coupling consists of a direct deposition of the layers constituting the photodetector structure Pxlis on the electronic part constituting the support Sup.Indirect coupling consists of an assembly of the already manufactured optical part to the already manufactured electronic part by hybridization techniques such as hybrid bonding, flip-chip, wire-bond or any other specific techniques to electrically and optically couple two parts having different functions (for example, the reading circuit 12 and the photodetector structure Pxli).

[0054] The substrate 11 is made of a material transparent to the frequency range of the incident ray Ra, more particularly X or γ rays. For example, the substrate 11 is made of glass, or plastic, or polyamide, or a semiconductor or metal or a stack of several layers of the aforementioned materials.

[0055] The photodetector structure Pxli comprises a planar absorption structure SPAi for absorbing the photons of the incident ray and converting them into photogenerated charges and an upper electrode 16 and a lower electrode 13 for collecting said charges and conveying them to the reading circuit 12.

[0056] Advantageously, the photodetector structure Pxli comprises a protective layer 14 confined between the lower electrode 13 and the planar absorption structure SPAp. The protective layer 14 is made of a material that is chemically inert relative to the planar absorption structure SPAp. The insertion of the protective layer 14 makes it possible to prevent chemical reactions inducing degradation of the lower electrode 13 by atoms originating from the planar absorption structure SPAi and vice versa.

[0057] In the case where the device DI comprises a plurality of pixels Pxh forming a matrix, it is possible to use a protective layer 14 common to all the pixels of said matrix. The sharing of the protective layer 14 makes it possible to simplify the manufacturing process. In this case, the protective layer is made of a chemically inert material but also electrically insulating to avoid short-circuiting the pixels together. The protective layer 14 is made of zirconia oxide stabilized with yttrium oxide (ZrO2:Y2O3) which is an oxide chemically inert relative to CsPbBr3 and electrically insulating (or poorly conductive) along the plane (X,Y) parallel to the surface on support Sup. It is noted that the protective layer 14 does not prevent the transfer of charge carriers (electrons and / or holes) from the absorption structure SPAi to the lower electrode 13 along the axis of the pixel A.For example, the protective layer 14 has a thickness of between 10 nm and 1000 nm, preferably 200 nm.

[0058] The planar absorption structure SPAi comprises an absorption layer 15 made of CsPbBr3 capable of absorbing X-ray and / or gamma ray photons and an interface layer 17 made of CsPb2Br5. The interface layer 17 is placed between the absorption layer 15 and the lower electrode 13. In the case of using a protective layer 14 on the lower electrode 13, the interface layer 17 is confined between said protective layer 14 and the absorption layer 15. Generally, the interface layer 17 is placed at the lower interface of the absorption layer 15. The interface layer 17 made of CsPb2Br5 allows a considerable gain in response time of the optoelectronic device DI according to the invention. The interface layer 17 has a thickness significantly less than that of the absorption layer 15. For a DI detection device for X or y radiation, the thickness of the absorption layer 15 in CsPbBr3 is between 50 pm and 2000 pm. The thickness of the interface layer 17 is between 10 nm and 50 pm. The person skilled in the art adapts the dimensioning of the thickness of the absorption layer 15 according to the intended application.

[0059] More particularly, when the detection device DI is intended for mammography, the average value of the absorbed energy spectrum is 20keV. Thus, the absorption layer 15 has a thickness of between 50pm and 200pm, preferably equal to 100pm. Alternatively, when the detection device DI is intended for medical radiology with an average value of the absorbed energy spectrum of 50keV, the absorption layer 15 has a thickness of between 300pm and 1500pm, preferably equal to 1000pm. Alternatively, when the detection device DI is intended for medical radiology with a central value of the absorbed energy spectrum of 90keV, the absorption layer 15 has a thickness of between 800pm and 2500pm, preferably equal to 2000pm.For these three applications, it is mainly dynamic operating modes that are targeted, in particular tomosynthesis for mammography, and fluoroscopy and tomography for radiology.

[0060] The lower electrode 13 is made of an electrically conductive material that is transparent to the frequency range targeted by the detector DI. This is particularly necessary in the case where the device DI is intended to detect an incident ray Ra on the side of the lower face of the substrate 11. For example, the lower electrode 13 is made of indium-tin oxide (ITO). For example, the lower electrode 13 has a thickness of between 50 nm and 1000 nm, preferably 200 nm.

[0061] The upper electrode 16 is made of a metal or a transparent conductive oxide (ITO for example) with a thickness of between 50 nm and 1000 nm (preferably 200 nm). Alternatively, the upper electrode 16 is composed of a stack of metal layers, transparent conductive oxide and dielectric layers (PMMA for example) in order to limit the leakage currents. We recall that an electric voltage VI is applied between the upper electrode 16 and the lower electrode 13 to collect the photogenerated charges towards the lower electrode 13.

[0062] The photodetector structure Pxli thus makes it possible to improve the response time of the optoelectronic device DI intended for the detection of X and / or y type radiation. This is obtained by inserting the interface layer 17 in CsPb2Br5 between the lower electrode 13 (charge collection layer) and the absorption layer 15 (charge generation layer).

[0063] [Fig.2b] illustrates a sectional view of a Pxl2 photodetector structure according to a second embodiment of the invention belonging to a device for detecting X or y radiation DI. The photodetector structure Pxl2 differs from the photodetector structure Pxli (first embodiment) by the integration of a second interface layer 18 in addition to the interface layer 17. The interface layer 18 in CsPb2 Br5 is confined between the upper electrode 16 and the absorption layer 15 in CsPbBr 3. Thus, the photodetector structure Pxl2 comprises a planar absorption structure SPA2 composed of an absorption layer 15 confined between two interface layers 17 and 18. The second interface layer 18 has the same technical characteristics and advantages as the first interface layer 17 applied to the interface between the absorption layer 15 and the upper electrode 16.This embodiment makes it possible to improve the response time of the optoelectronic device DI for an incident ray on the side of the lower electrode 13 but also on the side of the upper electrode 16.

[0064] [Fig.2c] illustrates a sectional view of a Pxl3 photodetector structure according to a third embodiment of the invention belonging to a DI detection device for X or y radiation. The photodetector structure Pxl3 differs from the photodetector structure Pxli (first embodiment) by the following: The planar absorption structure SPA3 comprises an interface layer 18 made of CsPb2Br5 is confined between the upper electrode 16 and the absorption layer 15 made of CsPbBr3. Thus, the planar absorption structure SPA3 is composed of an absorption layer 15 made of CsPbBr3 on which rests the interface layer 18 made of CsPb2Br5. The interface layer 18 has the same technical characteristics and advantages as the interface layer 17 described previously. This embodiment makes it possible to improve the response time of the optoelectronic device DI for a ray incident on the side of the upper electrode 16.

[0065] Generally speaking, the improvement in the response time of the DI device is optimal when the interface layer 17, 18 is arranged between the absorption layer 15 and the electrode placed on the radiation incidence side. Advantageously, the insertion of the interface layer 17 between the absorption layer 15 and the electrode where the collection of the photogenerated charges is carried out makes it possible to improve the response time of the optoelectronic device.

[0066] [Fig.3] illustrates the response of the photodetector structure Pxli according to the first embodiment compared to that of the Pxl0 photodetector structure according to the state of the art following exposure to an X-ray type radiation pulse.

[0067] The response of the two photodetector structures Pxl0 and Pxh is evaluated by measuring the photocurrent density (in A.mm2) in the planar absorption structures SPAq and SPAi. Each of the photodetector structures Pxl0 and Pxh is exposed to an X-ray pulse for 100ms with the application of a voltage Vi=5V. first curve CO corresponds to the response of the photodetector structure Pxl0 according to the state of the art. The first curve CO has a response time greater than 50ms on the rising edge (i.e. greater than half the pulse duration). The first curve CO has a response time greater than 75ms on the falling edge (i.e. greater than half the pulse duration). The second curve Cl corresponds to the response of the photodetector structure Pxli according to the first embodiment of the invention. The second curve Cl has a response time less than 5ms on the rising edge. The second curve Cl has a response time less than 5ms on the falling edge. The photodetector structure Pxli thus presents a considerable improvement in response time. More specifically, this improvement is advantageous in the context of real-time detection applications.The Pxl2 and Pxl3 photodetector structures also showed results of improved response time compared to the state-of-the-art Pxlode structure.

[0068] The photodetector structure according to the invention is also compatible with applications in the field of photovoltaic generators in order to improve the collection of photogenerated charges and thus improve the energy efficiency of the photovoltaic generator. [Fig.4] illustrates a sectional view of a PV photodetector structure of a fourth embodiment of the invention belonging to a photovoltaic cell D2. Similar to the embodiments of the invention, the photovoltaic cell D2 comprises a PV photodetector structure mounted on a support Sup. For example, the support is a substrate made of a semiconductor material, preferably silicon, and the solar cell is a silicon heterojunction solar cell.

[0069] The PV photodetector structure comprises an upper electrode 16, a lower electrode 13 and a planar absorption structure SPA4 confined between the two electrodes 13 and 16. The electrodes 13 and 16 are multilayers composed of semiconductors and metals, making it possible to selectively inject electrons or holes. For example, the lower electrode 13 is composed of ITO and the upper electrode 16 is composed of a C6o / PCB / Ag stack. The planar absorption structure SPA4 comprises an absorption layer 15 and an interface layer 17 placed between the absorption layer 15 and the lower electrode 13. Alternatively, the planar absorption structure SPA4 comprises an absorption layer 15 and an interface layer 17 placed between the absorption layer 15 and the upper electrode 16.Alternatively, the planar absorption structure SPA4 comprises an absorption layer 15 confined between, on the one hand, a first interface layer 17 placed on the side of the lower electrode 13 and, on the other hand, a second interface layer 18 placed on the side of the upper electrode 16.

[0070] For compatibility with a photovoltaic application, the layer absorption layer 15 is made of CsPb(Ii xBrx)3 and the interface layer 17, 18 is made of CsPb2(Ii xBrx)5; with x between 0 and 0.5. The absorption layer 15 has a thickness between 0.1pm and 1pm, preferably 0.3pm. An interface layer 17, 18 has a thickness between 0.005pm and 0.1pm, preferably 0.01pm.

[0071] Generally speaking, in a planar absorption structure comprising an ABX3 absorption layer, the insertion of an AB2X5 interface layer arranged between said absorption layer 15 and an electrode 13, 16 makes it possible to improve the response time of the optoelectronic device according to the invention.

[0072] We recall that the materials used to implement the invention are defined as follows according to the intended applications: - A is chosen from a first group of inorganic cations comprising cesium Cs, rubidium Rb, potassium K or an alloy of said elements of the first group of inorganic cations; - B is chosen from a second group of inorganic cations comprising lead Pb, tin Sn, germanium Ge, silicon Si or an alloy of said elements of the second group of inorganic cations; - X is selected from a group of halogens comprising bromine Br, iodine I, chlorine Cl or an alloy of said elements of the cation group.

[0073] The invention further provides a PI method for manufacturing an array of photodetector structures according to the invention. The steps of this method are illustrated in [Fig.5a].

[0074] The first step i) consists of depositing the protective layer 14 on the upper face of the support Sup (reading circuit 12 + substrate 11 for example) comprising a matrix of several distinct lower electrodes 13 previously manufactured. The deposition of the protective layer 14 can be carried out by usual deposition techniques in the field of micro and nanotechnologies. This is an optional step making it possible to prevent chemical reactions inducing degradation of the lower electrode 13.

[0075] The second step ii) consists of depositing a planar absorption structure SPA according to any one of the different embodiments described above. This step is carried out by the sublimation technique in the close space CSS from a source SI of the first compound material ABX3 on the protective layer 14. [Fig. 5b] illustrates a device for deposition by sublimation in the close space configured for the manufacture of the photodetector structure according to the invention. In general, the support Sup on which at least one layer of ABX3 will be deposited, is placed opposite a source SI in ABX3 at a distance of between 1 mm and 20 mm, preferably equal to 5 mm. The source SI is preheated to a first temperature Tl of between 350°C and 500°C via the thermostat Thl. The Sup support is preheated to a second temperature T2. The assembly is placed in a closed chamber at a pressure between 104Pa and 10 Pa, preferably equal to 1 Pa.

[0076] Generally speaking, in order to deposit a layer of a predetermined material by the sublimation technique in the close space CSS, a source SI in the pure phase of said predetermined material is used. The source can be obtained by mechanical synthesis. The two temperatures T1 and T2 are maintained at close values ​​with a difference between 50°C and 150°C. This “standard” setting is well controlled for ABX3 layers. It is a setting in which the system is placed in a thermodynamic equilibrium or quasi-thermodynamic equilibrium configuration. Thermodynamic equilibrium makes it possible to deposit an ABX3 layer from an ABX3 source by sublimation. Indeed, the difference in temperature setpoint AT between the source SI and the upper support is of the order of 100°C (between 50°C and 150°C).Since the distance between the source SI and the upper support is small, the material transported in vapor phase does not have time to cool and therefore cools slowly on the surface of the upper support. We are therefore close to thermodynamic equilibrium and a deposition of an ABX3 layer from an ABX3 source is carried out. However, it has been demonstrated that the deposition of an AB2X5 layer by a "standard" setting with an AB2X5 source is not possible. In this context, the invention proposes a solution through several embodiments of the third step iii) in order to produce the planar absorption structure according to the invention. The different sub-steps for the execution of the third step iii) according to the invention will be detailed later.

[0077] The third step iii) consists of depositing the upper electrode 16 on the upper face of the previously manufactured planar absorption structure SPA.

[0078] [Fig.6a] illustrates sub-steps ii.a) - ii.c) according to a first embodiment of the invention for producing the planar absorption structure SPA according to the invention. This embodiment makes it possible to produce an interface layer 17 in AB2X5 arranged below the absorption layer 15 in ABX3.

[0079] The first sub-step ii.a) consists of mounting the support sup with regard to the source SI of a sublimation deposition device in the close space CSS. The source SI is a pure phase sample of the ABX3. The source SI is preheated to a first temperature Tl between 350°C and 500°C via the thermostat Thl.

[0080] The second sub-step ii.b) is intended to deposit a layer in AB2X5 from the source SI in ABX3 by placing itself out of thermodynamic equilibrium of the material ABX3. For this, the thermostat T2 is configured to control the second temperature T2 to a value lower than the first temperature T1. The temperature difference AT with respect to the first temperature T1 is greater than or equal to 200°C. This triggers a transient phase during which the assembly is out of thermodynamic equilibrium. This induces a deposition of a layer in AB2X5 from the source SI during the transient regime from the source in ABX3 by sublimation. The layer deposited in AB2X5 corresponds to the interface layer 17 described previously. The duration of the transient regime is between 1 min and 10 min. This technique is explained by the following mechanism: By increasing the temperature setpoint difference AT (>=200°C), the particles undergo sudden cooling when they come into contact with the surface of the upper support. The adhesion of the particles coming from the source SI and deposited on the upper support does not occur at thermodynamic equilibrium and an AB2X5 phase appears under these particular conditions. The general conditions of pressure and distances remain unchanged compared to a “standard” deposition.

[0081] As an illustrative and non-limiting example, the source SI is preheated to T1=475°C and the upper support is preheated to T2=100°C. This makes it possible to deposit an interface layer 17 in AB2X5 for 5 min for a thickness of 2 pm.

[0082] It is emphasized that the support sup is placed a few millimeters from the source SI which allows a heat transfer between the two entities throughout the second sub-step ii.b). In addition, the supply of sublimed material heats the support sup. This heat exchange will increase the actual temperature T2 of the support sup beyond the set temperature. Thus, the temperature difference AT will gradually reduce to reach a value lower than 200°C. This induces a transition to the conditions of a “standard” deposition as described previously, corresponding to a permanent thermodynamic equilibrium regime.

[0083] Thus, the third sub-step ii.c) is triggered spontaneously via the transition from the transient regime to the steady state of thermodynamic equilibrium. The third sub-step ii.c) consists of depositing the absorption layer 17 in ABX3 from the source S1 during said steady state corresponding to a thermodynamic equilibrium. In this case, the support is not heated to a temperature comparable to that of the source SL. Thus, this embodiment has the advantage of avoiding the degradation of the components of the reading circuit 12 (limit temperatures for the transistors for example).

[0084] At the end of sub-steps ii.a) - ii.c) a planar SPA absorption structure is thus obtained comprising the stack in this order: an interface layer 17 in AB2X5 arranged below the absorption layer 15 in ABX3.

[0085] Alternatively, [Fig.6b] illustrates sub-steps ii.a') - ii.c') according to a second embodiment of the invention for producing the planar absorption structure according to the invention. This embodiment also makes it possible to produce an interface layer 17 in AB2X5 arranged below the absorption layer 15 in ABX3.

[0086] The first sub-step ii.a') is identical to the sub-step ii.a) described in the first embodiment. The second sub-step ii.b') is identical to the sub-step ii.b) described in the first embodiment.

[0087] The third sub-step ii.c') consists of depositing the absorption layer 17 in ABX3 from the source SL Unlike the third sub-step ii.c) of the first embodiment, the thermostat T2 is configured to control the second temperature T2 to a value less than or equal to the first temperature T1 so as to obtain a temperature difference AT with respect to the first temperature T1 strictly less than 200°C, preferably between 50°C and 150°C. This places us in the conditions of a “standard” deposition to deposit the absorption layer 15 in ABX3 from the source SI in ABX3. This embodiment has the advantage of obtaining a more robust crystallographic structure of the absorption layer 15 compared to the low-temperature deposition of the first embodiment.

[0088] At the end of sub-steps ii.a') - ii.c') we thus obtain a planar SPA absorption structure comprising the stack in this order: an interface layer 17 in AB2X5 arranged below the absorption layer 15 in ABX3.

[0089] Alternatively, [Fig.6c] illustrates sub-steps ii.a”) - ii.e”) according to a third embodiment of the invention for producing the planar absorption structure SPA according to the invention. This embodiment makes it possible to produce an interface layer 18 in AB2X5 arranged above the absorption layer 15 in ABX3.

[0090] The first sub-step ii.a”) consists of mounting the sup support with regard to the source SI of a sublimation deposition device in the close space CSS. The source SI is a pure phase sample of the ABX3. The source SI is preheated to a first temperature Tl between 350°C and 500°C via the thermostat Thl.

[0091] The second sub-step ii.b”) consists of controlling the second temperature T2 at a temperature difference AT with respect to the first temperature T) of less than 200°C so as to deposit the absorption layer 15 made of the first compound material ABX3 from the source SL. Advantageously, the temperature difference AT is between 50°C and 150°C to improve the robustness of the crystallographic structure of the absorption layer 15 deposited.

[0092] Then, the third sub-step ii.c”) consists of deactivating the near-space sublimation (CSS) deposition device and disassembling the upper support. This is necessary to cool the upper support but also the SL source. This is a step of resetting the thermodynamic state of the system composed of the support, the source and the chamber of the deposition device. The resetting of the thermodynamic state of the system can be done by significantly lowering the temperature to a value below 200°C and / or by increasing the pressure (in the chamber of the sublimation deposition device to stop sublimation.

[0093] Following the cooling sub-step, the fourth sub-step ii.d”) consists of raising the support sup in front of the source SI of said sublimation deposition device in the close space CSS in order to trigger the deposition of the interface layer 18.

[0094] Finally, sub-step ii.e”) consists of depositing the interface layer 18 in a manner identical to that described by the second sub-step ii.b) of the first embodiment.

[0095] At the end of sub-steps ii.a”) - ii.e”), a planar SPA absorption structure is thus obtained comprising the stack in this order: the absorption layer 15 in ABX3 arranged below the interface layer 17 in AB2X5.

[0096] The planar SPAi absorption structure described in [Fig.2a] can be entirely produced by the first or second embodiment of the manufacturing method.

[0097] The planar absorption structure SPA3 described in [Fig.2c] can be fully realized by the third embodiment of the manufacturing method.

[0098] The planar absorption structure SPA2 described in [Fig.2b] can be entirely produced by the first or second embodiment of the manufacturing method (to produce the interface layer 17) in combination with the third embodiment of the manufacturing method (to produce the interface layer 18).

Claims

Claims

1. Photodetector structure (Pxli, Pxl2, Pxl3, PV) comprising: - a planar absorption structure (SPAb SPA2, SPA3, SPA4) to convert an incident ray into photogenerated electric charge carriers; - a lower electrode (13) for collecting the photogenerated electric charge carriers; - an upper electrode (16); said planar absorption structure (SPAb SPA2, SPA3, SPA4) being confined between the lower electrode and the upper electrode and comprising: - an absorption layer (15) made of a first compound material ABX3; - an interface layer (17, 18) made of a second compound material AB2X5 arranged between on the one hand the absorption layer (15) and on the other hand the upper electrode (16) or the lower electrode (13); A being selected from a first group of inorganic cations comprising cesium (Cs), rubidium (Rb), potassium (K) or an alloy of said elements of the first group of inorganic cations; B being selected from a second group of inorganic cations comprising lead (Pb), tin (Sn), germanium (Ge), silicon (Si) or an alloy of said elements of the second group of inorganic cations; X being selected from a group of halogens comprising bromine (Br), iodine (I), chlorine (Cl) or an alloy of said elements of the group of cations.

2. Photodetector structure (Pxli, Pxl2, Pxl3) comprising: - a planar absorption structure (SPAi, SPA2, SPA3) to convert an incident ray into photogenerated electric charge carriers; - a lower electrode (13) for collecting the photogenerated electric charge carriers; - an upper electrode (16);- a protective layer (14) deposited on the lower electrode (13), the protective layer (14) being made of a material which is chemically inert with respect to the planar absorption structure (SPA) and electrically insulating; said planar absorption structure (SPAb SPA2, SPA3) being arranged between the lower electrode and the upper electrode and comprising: - an absorption layer (15) made of a first compound material ABX3; - an interface layer (17, 18) made of a second compound material AB2X5 confined between on the one hand the absorption layer (15) and on the other hand the protective layer (14); A being chosen from a first group of inorganic cations comprising cesium (Cs), rubidium (Rb), potassium (K) or an alloy of said elements of the first group of inorganic cations;B being selected from a second group of inorganic cations comprising lead (Pb), tin (Sn), germanium (Ge), silicon (Si) or an alloy of said elements of the second group of inorganic cations; X being selected from a group of halogens comprising bromine (Br), iodine (I), chlorine (Cl) or an alloy of said elements of the group of cations.;

3. Device (Dl) for detecting X or y radiation comprising at least one pixel (Pxli, Pxl2, Pxl3), the at least one pixel (Pxli, Pxl2, Pxl3) comprising the photodetector structure (Pxli, Pxl2, Pxl3) according to any one of claims 1 or 2.

4. X or y radiation detection device (Dl) according to claim 3 further comprising a reading circuit (12) arranged on a substrate (11) configured to generate a reading signal from the electric charge carriers collected by the lower electrode (13); said reading circuit (12) being assembled to the photodetector structure (Pxli, Pxl2, Pxl3) by direct or indirect coupling.

5. X or y radiation detection device (Dl) according to claim 4 intended to receive the incident ray from the side of the substrate (11) in which the substrate (11), the reading circuit (12) and the electrode in- lower (13) are transparent to the wavelength of the incident ray.

6. Device (Dl) for detecting X or y radiation according to any one of claims 3 to 5 in which the absorption layer (15) has a thickness of between 50 pm and 2000 pm.

7. Device (Dl) for detecting X or y radiation according to any one of claims 3 to 6 in which the interface layer (17, 18) has a thickness of between 10 nm and 50 pm.

8. X or y radiation detection device (Dl) according to any one of claims 3 to 7 in which the absorption layer (15) is made of CsPbBr3 and the interface layer (17, 18) is made of CsPb2Br5.

9. Photovoltaic cell (D2) comprising the photodetector structure (PV) according to any one of claims 1 or 2.

10. Photovoltaic cell (D2) according to claim 9 in which the absorption layer (15) has a thickness between O.lpm and Ipm.

11. Photovoltaic cell (D2) according to any one of claims 9 or 10 in which the interface layer (17) has a thickness of between 5nm and 0.1pm.

12. Photovoltaic cell (D2) according to claim 9 in which the absorption layer (15) is made of CsPb(Ii xBrx)3 and the interface layer (17, 18) is made of CsPb2(Ii xBrx)5; with x between 0 and 0.

5.

13. Manufacturing method (PI) of a photodetector structure (Pxl, PV) according to any one of claims 1 or 2 comprising the following steps: ii) producing a planar absorption structure (SPA) by the close-space sublimation technique (CSS) from a source (SI) of the first compound material ABX3 on the upper face of a support (Sup); the source (SI) being preheated to a first temperature (Tl) between 350°C and 500°C; the support (sup) being preheated to a second temperature (T2) less than or equal to the first temperature (Tl); iii) depositing an upper electrode (16) on the planar absorption structure (SPA); step ii) of producing the planar absorption structure (SPA) comprising the following sub-step for producing an interface layer (17): controlling the second temperature (T2) to a temperature difference (AT) relative to the first temperature (Tl) greater than or equal to 200°C to deposit the interface layer (17) in a second material composed of AB2X5 from the source (SI) during a transient regime corresponding to a thermodynamic non-equilibrium;

14. Manufacturing method (PI) according to claim 13 wherein step ii) of producing the planar absorption structure (SPA) comprises the following substeps for producing an interface layer (17) arranged below the absorption layer (15): ii.a) mounting the support (sup) opposite the source (SI) of a sublimation deposition device in close space (CSS); ii.b) controlling the second temperature (T2) at a temperature difference (AT) with respect to the first temperature (Tl) greater than or equal to 200°C to deposit the interface layer (17) in a second compound material AB2X5 from the source (SI) during a transient regime corresponding to a thermodynamic non-equilibrium; the duration of the transient regime being between 1 min and 10 min; ii.c) depositing the absorption layer (17) made of the first compound material ABX3 from the source (SI) during a steady state corresponding to a thermodynamic equilibrium.

15. Manufacturing method (PI) according to claim 13 wherein step ii) of producing the planar absorption structure (SPA) comprises the following substeps for producing an interface layer (17) arranged below the absorption layer (15): ii.a') mounting the support (sup) opposite the source (SI) of a sublimation deposition device in close space (CSS); ii.b') controlling the second temperature (T2) to a temperature difference (AT) with respect to the first temperature (Tl) greater than or equal to 200°C to deposit the interface layer (17) in a second compound material AB2X5 from the source (SI) during a transient regime corresponding to a thermodynamic non-equilibrium; the duration of the transient regime being between 1 min and 10 min; ii.c') increasing the second temperature (T2) to obtain a temperature difference (AT) with respect to the first temperature (Tl) of less than 200°C so as to deposit the absorption layer (17) composed of the first compound material ABX3 from the source (SI).

16. Manufacturing method (PI) according to claim 13 in which step ii) of producing the planar absorption structure (SPA) comprises the following sub-steps for producing an interface layer (18) arranged above the absorption layer (15): ii.a”) mount the support (sup) in front of the source (SI) of a near-space sublimation (CSS) deposition device; ii.b”) controlling the second temperature (T2) at a temperature difference (AT) with respect to the first temperature (Tl) of less than 200°C so as to deposit the absorption layer (17) made of the first compound material ABX3 from the source (SI); ii.c”) deactivate the close-space sublimation deposition (CSS) device and disassemble the support (sup); ii.d”) following cooling of the source (SI), reassemble the support (sup) in front of the source (SI) of said near-space sublimation deposition device (CSS); ii.e”) controlling the second temperature (T2) at a temperature difference (AT) relative to the first temperature (Tl) greater than or equal to 200°C to deposit the interface layer (17) in a second material composed of AB2X5 from the source (SI) during a transient regime corresponding to a thermodynamic non-equilibrium; the duration of the transient regime being between 1 min and 10 min.

Images