Photodetector with improved detection results

Abstract

Photodetector (1-8) for spectrally selective detection of electromagnetic radiation, comprising a first optoelectronic component (100-106, 108) for detection of a first wavelength of the electromagnetic radiation: - a first optical cavity formed by two spaced-apart parallel mirror layers (11, 11a, 11', 12, 12a), wherein the length (L, L a ) the first optical cavity is designed such that for the first wavelength a corresponding resonance wave of order (13, 13a) is formed in the first optical cavity, and - at least one detection cell (21, 21a, 22, 22a, 23) arranged in the first optical cavity, wherein each detection cell (21, 21a, 22, 22a, 23) contains a photoactive layer (210, 220, 230), wherein the photoactive layer (210, 220, 230) is arranged within the first optical cavity such that exactly one vibration maximum of the resonance wave (13, 13a) lies within the photoactive layer (210, 220, 230), wherein the order of the resonance wave (13, 13a) of the first optoelectronic device (100-106, 108) is greater than 1, characterized in that at least one optically absorbing intermediate layer (30, 31) is arranged in the first optical cavity such that a vibration node of the Resonance wave (13) lies in the absorbing intermediate layer (30, 31), wherein the absorbing intermediate layer (30, 31) is suitable to absorb so much energy of a specific electromagnetic wave within the first optical cavity,that it is canceled out, whereby the specific electromagnetic wave has a wavelength different from the resonant wavelength assigned to the first wavelength.

Description

[0001] The invention relates to a photodetector for the spectrally selective detection of electromagnetic radiation, which comprises an optoelectronic component with an optical cavity and at least one detection cell arranged therein, and enables an improved detection result.

[0002] Photodetectors for the spectrally selective detection of electromagnetic radiation are used for the qualitative and quantitative detection of electromagnetic radiation, hereinafter also referred to as light, of a specific wavelength in an incident radiation. The incident radiation is broadband radiation containing light of many different wavelengths. Such photodetectors often have filters or an optical cavity that allows resonance only of specific wavelengths of the incident radiation within the cavity. The optical cavity is created by mirrors, at least one of which is semi-transparent and which are arranged at a distance L from each other.Within the optical cavity, the radiations (electromagnetic waves) of the resonant wavelengths are reflected and amplified multiple times between the mirrors, passing through a photoactive layer that converts the electromagnetic radiation into electrical power. Such a photodetector is described, for example, in WO 2017 / 029223 A1. Each of the resonant waves exhibits a natural number of oscillation maxima within the optical cavity and is referred to as a first-order resonant wave, where i corresponds to the number of oscillation maxima. All developed first- to nth-order resonant waves contribute to the electrical signal of the photodetector. Therefore, detection of a specific wavelength of the resonant waves is only possible within a limited range for the wavelength to be detected or with considerable external effort, e.g., through upstream filters or complex evaluation of the measured electrical signal.

[0003] Another crucial factor for the accuracy of detecting a specific wavelength in the optical cavity is the width of the wavelength range amplified by the optical cavity. Although individual resonance wavelengths were mentioned above, ideally only forming standing waves at these wavelengths, in reality a certain wavelength range around each resonance wavelength is amplified in the optical cavity, thus forming standing waves. The gain of the optical cavity, which determines the external quantum efficiency (EQE) for a given wavelength, is approximately a sequence of super-Gaussian or Lorentzian distributions, with the maximum value at each resonance wavelength. The resonance wavelengths are spectrally plotted, i.e., they appear as peaks in the representation of the photodetector gain versus wavelength.Peak width is defined as the width of the wavelength range in which the peak lies and at whose limits the gain reaches half its maximum. The larger the peak width, the less accurate the detection becomes, as wavelengths within the amplified wavelength range can no longer be distinguished from one another. This is described by the cavity quality factor Q, which is approximately calculated as the quotient of the peak wavelength and the peak width.

[0004] Zynek et al. describe a resonant chamber-gain photodiode operating at 1.9 µm. Detection is based on interband absorption in a thin pseudomorphic InGaAs layer located in a resonant chamber that amplifies an optical field. The photodiode structure comprises an InP pin junction with a thin strained InGaAs layer between two parallel Bragg mirrors. x Ga 1-x As layer in an undoped area.

[0005] An et al describe an organic photodetector structure in which the active layers and a thick optical spacer are arranged between two metal electrodes and form a Fabry-Perot resonance chamber.

[0006] Lao et al describe a detector with improved multiband absorption efficiency using a cavity resonance structure with an Au reflector at the bottom and a dual-band Bragg reflector at the top.

[0007] The object of this application is to provide a photodetector for the spectrally selective detection of electromagnetic radiation with an optical cavity, which enables improved detection. Furthermore, a space-saving design of a photodetector for the detection of electromagnetic radiation of several different wavelengths is to be provided, which allows for the miniaturization of the detectors or spectrometers.

[0008] This problem is solved by a photodetector according to one of the independent claims. Advantageous further developments and embodiments are contained in the dependent claims.

[0009] A photodetector for the spectrally selective detection of electromagnetic radiation according to a first aspect of the invention comprises a first optoelectronic component for detecting a first wavelength of the electromagnetic radiation. The mere presence or absence of the first wavelength in the electromagnetic radiation incident on the photodetector (qualitative assessment) and / or the intensity of the radiation of the first wavelength in the incident electromagnetic radiation (quantitative assessment) can be detected. The first optoelectronic component has a first optical cavity and at least one detection cell arranged in the first optical cavity. The first optical cavity is formed by two spaced-apart parallel mirror layers.For all optical cavities of the present application, the distance between the two mirror layers is referred to as the physical length of the optical cavity, hereinafter also referred to simply as the length of the optical cavity. The length of the first optical cavity is designed such that a corresponding first-order resonance wave is formed in the first optical cavity for the first wavelength. The following relationship generally applies to the ratio of a wavelength of the incident radiation fulfilling the resonance criterion to the physical length of the optical cavity: L=i⋅λi⋅cos α2n, where L is the physical length of the optical cavity, λ iThe incident wavelength, α the angle of incidence of the incident radiation with respect to the normal to the surface of the optoelectronic device upon which the incident radiation strikes, n the effective refractive index over the entire optical cavity and any intervening layers, and i the order of the resonance wave resulting from the incident wavelength. Here, i is a natural number. Corresponding to the order i of the resonance wave associated with the first wavelength, the optoelectronic device is also designated as an i-order device.

[0010] When the following description refers to "the resonance wave", it means the resonance wave that corresponds to the wavelength to be detected in the respective optoelectronic component, unless explicitly stated otherwise.

[0011] Each detection cell arranged in the first optical cavity contains a photoactive layer. The photoactive layer preferably extends over the entire cross-sectional area of ​​the first optical cavity, with the cross-sectional area being perpendicular to the length of the first optical cavity. The photoactive layer of each detection cell is positioned within the first optical cavity such that exactly one vibration maximum of the resonance wave lies within the photoactive layer. In other words, the position of the photoactive layer within the optical cavity depends on the order of the resonance wave generated by the first wavelength to be detected.Preferably, the location of the vibration maximum, i.e., the location of the intensity maximum of the electromagnetic field of the resonance wave, lies as centrally as possible within the photoactive layer with respect to the thickness of the photoactive layer, measured along the length of the first optical cavity. The thickness of the photoactive layer is preferably dimensioned such that a node of the resonance wave adjacent to the vibration maximum located within the photoactive layer is no longer within the photoactive layer.

[0012] According to the invention, the order of the resonance wave of the first optoelectronic device is greater than 1. In other words, in the first optoelectronic device, a first wavelength, which forms a resonance wave of 2nd, 3rd, 4th or higher order in the first optical cavity, is detected, since the photoactive layer is arranged in exactly one vibration maximum of this resonance wave.

[0013] Since higher-order resonance waves have significantly smaller peak widths than first-order resonance waves detected in the prior art, a finer distinction between different wavelengths, i.e., a better spectral resolution of the photodetector, can be achieved.

[0014] Preferably, at least one of the detection cells has a first charge transport layer and a second charge transport layer, with the photoactive layer arranged between the first and the second charge transport layer. The individual layers are arranged one above the other along the length of the first optical cavity. The first and the second charge transport layer also preferably extend over the entire cross-sectional area of ​​the first optical cavity, with the first charge transport layer adjoining a first surface of the photoactive layer and the second charge transport layer adjoining a second surface of the photoactive layer, and the second surface being opposite the first surface.Charge transport layers serve to improve charge extraction from the photoactive layer and its conduction to electrical contacts, also called electrodes, which transmit the electrical signals generated in the detection cell to an evaluation unit capable of processing them. These charge transport layers are particularly advantageous for very thin photoactive layers with thicknesses of less than 10 nm, and are then designed with a thickness greater than or equal to 10 nm. In thicker photoactive layers, the charge transport layers can also be very thin, e.g., with a thickness in the range of 1 nm to 5 nm, in which case they can also be referred to as injection or extraction layers. In both cases, the charge transport layers do not necessarily have to be doped layers.

[0015] The mirror layers can be designed as highly reflective metallic layers, e.g., made of silver (Ag) or gold (Au), semi-transparent metallic composite layers, e.g., made of Ag:Ca, or as dielectric mirrors (DBR - distributed Bragg reflector). At least one of the mirror layers is semi-transparent to allow the incident light to enter the optical cavity, while the other mirror layer can be opaque. This property can be adjusted, for example, by the thickness of the mirror layer and / or the materials and mixing ratios of the components of the mirror layers, a process known to those skilled in the art. If the mirror layers consist of a highly electrically conductive material, such as a conductive oxide, a conductive organic compound, or a metal, they can serve as electrodes for transmitting the electrical signals generated in the detection cell to an evaluation unit capable of processing them.The evaluation unit is not necessarily part of the photodetector, but it can be rigidly connected to it and be located on or embedded in the same substrate on which the photodetector is formed. In the case of a dielectric mirror, a thin layer of a highly conductive material, e.g., a thin metal layer, can be arranged on the last dielectric layer of the mirror layer facing the detection cell, so that in this case, too, the mirror layer can serve as an electrode. Further possibilities for electrically contacting the detection cells will be explained later.

[0016] Photoactive layers are used, especially for the detection of wavelengths in the near-infrared (NIR) range with 800 nm ≤ λ. i≤ 10 µm, the following materials are suitable: fullerenes, e.g., C60 or C70, mixed with donors such as materials from the phthalocyanine group (such as zinc phthalocyanine or iron phthalocyanine), the pyrans, e.g., bispyranilides (abbreviated TPDP), the fulvalenes, e.g., tetrathiofulvalene (abbreviated OMTTF), and the aromatic amines (e.g., N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine (abbreviated MeO-TPD), 2,7-bis[N,N-bis(4-methoxyphenyl)amino]9,9-spiro-bifluorene (abbreviated Spiro-MeO-TPD), or 4,4',4''-tris(3-methylphenylphenylamino)triphenylamine (abbreviated m-MTDATA)). Bisthiopyranilidenes, bipyridinylidenes, or diketopyrrolopyrroles. Substances such as HatCN:BFDPB, HATCN:4P-TPD, and HATCN:a-NPB would also be possible. Of course, any other photoactive materials can also be used, for example, polymers produced by liquid processing, such as those from the polythiophene group (e.g.,...).poly(2,5-bis(3-alkylthiophene-2-yl) thieno[3,2-b]thiophene (abbreviated pBTTT).

[0017] In this context, a photoactive layer preferably has a thickness in the range of 0.1 nm to 1 µm, the thickness of which depends on both the material of the photoactive layer and the overall structure of the optoelectronic device. Particularly preferably, the thickness of the photoactive layer for charge transfer photodiodes (CTPDs) that utilize the direct interchromophoric charge transfer state, e.g., C60:TPDP, is in the range of 10 nm to 1000 nm, while for photodiodes that utilize direct material absorption and separate the charge carriers in bulk or flat heterojunctions (BHJ, FHJ), e.g., C60:ZnPc, it is in the range of 0.1 nm to 100 nm.

[0018] Charge transport layers can include, for example, aromatic amines (such as N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine (abbreviated MeO-TPD), 2,7-bis[N,N-bis(4-methoxyphenyl)amino]9,9-spiro-bifluorene (abbreviated Spiro-MeO-TPD) or N4,N4'-bis(9,9-dimethyl-9H-fluoren-2-yl)-N4,N4'-diphenylbiphenyl-4,4'-diamine (abbreviated BF-DPB) or 9,9-bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene (abbreviated BPAPF)) or polymers such as Po-3,4-ethylenedioxythiophene poly(styrenesulfonate (abbreviated PEDOT:PSS), SpiroTTB, NDP9, F6-TCNNQ, C60F48, BPhen, C60, HatnaCl6, MH250, W2(hpp)4, Cr2(hpp)4, and NDN26 can be used. Of course, other suitable materials or a combination of at least two of the named materials can also be used.The material of the first charge transport layer differs from the material of the second charge transport layer in a detection cell in that one is an electron-conducting material and the other is a hole-conducting material. The material of the charge transport layers can be doped, but it doesn't have to be.

[0019] The electrical conductivity of the charge transport layers is preferably in the range of greater than 10 -5 S / cm. The thickness of the charge carrier transport layers is preferably in the range of 1 nm to 100 nm, with the thickness generally decreasing with an increasing number of detection cells in the first optical cavity. Furthermore, the thickness of the first charge carrier transport layer of a detection cell can differ from the thickness of the second charge carrier transport layer of that detection cell.

[0020] If different detection cells are present in the first optical cavity, the photoactive layers and - if present - the first charge transport layers and the second charge transport layers of the different detection cells can differ from each other in terms of material and thickness.

[0021] It goes without saying that in any case, the sum of all layers present in the first optical cavity, i.e., photoactive layer or layers, possibly charge transport layers and / or further layers, is equal to the length of the first optical cavity.

[0022] In one embodiment, the number of detection cells arranged in the first optical cavity corresponds to the order of the resonance wave. This means that the first optoelectronic device contains exactly two detection cells, whose photoactive layers are each arranged in exactly one oscillation maximum of the resonance wave that is distinct from others, if the first wavelength belonging to the second-order resonance wave is to be detected; it contains exactly three detection cells if the first wavelength belonging to the third-order resonance wave is to be detected, and so on. The detection cells are arranged one above the other along the length of the first optical cavity, but do not necessarily have to be adjacent to each other.

[0023] Alternatively, a smaller number of detection cells than the order of the resonance wave can be arranged in the first optical cavity. For example, to detect a second, third, or higher order resonance wave, a single detection cell is generally sufficient, provided its photoactive layer is positioned within the optical cavity such that exactly one vibration maximum of the resonance wave lies within it. This simplifies the fabrication of the photodetector and reduces manufacturing costs by allowing the use of simpler and less expensive materials instead of the missing detection cells.

[0024] In the first optical cavity, at least one optically absorbing intermediate layer is arranged such that exactly one node of the resonance wave lies within the optically absorbing intermediate layer. For optoelectronic devices designed to detect resonance waves of a higher order than the second order, several optically absorbing intermediate layers are preferably arranged such that each node of the resonance wave lies within exactly one optically absorbing intermediate layer. The at least one optically absorbing intermediate layer serves to absorb resonance waves of a different order than the resonance wave belonging to the first wavelength. In particular, resonance waves adjacent to the resonance wave belonging to the first wavelength are canceled out at the nodes, while the resonance wave belonging to the first wavelength is hardly affected.This ensures that a detected electrical signal can be assigned to the first wavelength for a larger range of the first wavelength, thus increasing the possible applications of such a photodetector.

[0025] In embodiments, at least one of the optically absorbing intermediate layers is directly adjacent to a detection cell, i.e., to the photoactive layer or to one of the charge transport layers, if present, of this detection cell, and consists of an electrically conductive material. It is further suitable for electrically conductive connection to an evaluation unit capable of evaluating the electrical signals generated by the at least one detection cell of the first optoelectronic device. Such an intermediate layer thus serves as an electrical contact for tapping the electrical signals from the detection cell, even if the photoactive layer or a corresponding charge transport layer, if present, of the detection cell in question is not directly adjacent to an electrically conductive mirror layer.

[0026] In further embodiments, at least one optically transparent contact layer is arranged in the first optical cavity. This contact layer is directly adjacent to a detection cell, i.e., the photoactive layer or, if present, to one of the charge transport layers of this detection cell, and is made of an electrically conductive material. This contact layer is suitable for electrically conductive connection to an evaluation unit capable of evaluating the electrical signals generated by the at least one detection cell of the first optoelectronic component. It thus serves as an electrical contact for tapping the electrical signals from the detection cell, even if the photoactive layer or a corresponding charge transport layer, if present, of the detection cell in question is not directly adjacent to an electrically conductive mirror layer or an electrically conductive intermediate layer.It is optically transparent, in particular, for the resonance wavelength corresponding to the first wavelength.

[0027] Materials suitable for an optically absorbing intermediate layer include layers of small organic molecules, organic mixed layers, or polymers, such as highly doped hole-conducting materials like MeO-TPD:F6TCNNQ or PEDOT:PSS with quantum dots (QD). If the optically absorbing intermediate layer is required to be electrically conductive, metals like silver (Ag), metal mixtures like Ag:Ca, or conductive oxides like indium tin oxide (ITO), zinc oxide (ZnO), or aluminum-doped zinc oxide (AZO) can also be used. An optically transparent contact layer can also be made from the same materials. The optical and electrical properties of such an intermediate or contact layer can be adjusted by modifying its thickness and material composition.The thickness of the layers is preferably in the range of 0.1 nm to 40 nm for metals, more preferably in the range of 5 nm to 10 nm, while for polymers or oxides it is in the range of 20 nm to 100 nm, more preferably in the range of 30 nm to 60 nm, with smaller thicknesses being associated with greater optical transparency.

[0028] An optically absorbing layer within the meaning of this application, which is used as an optically absorbing intermediate layer, is understood to be a layer capable of absorbing enough energy of a specific electromagnetic wave to cancel it out. Such a specific electromagnetic wave has a wavelength that differs from the resonant wavelength associated with the first wavelength. Furthermore, the product of the absorption coefficient k of the material at the wavelength of the specific electromagnetic wave and the thickness d of the layer, as well as the energy E of the specific electromagnetic wave in the region of the layer, has a value greater than or equal to 1 · E (k · d · E ≥ 1 · E).This means that a layer made of a material with a very high absorption coefficient k can be very thin, while a layer made of a material with a comparatively low absorption coefficient k must be correspondingly thicker to achieve the cancellation of a specific electromagnetic wave. In contrast, for the purposes of this application, an optically transparent layer, which is used, for example, as a spacer layer or as an optically transparent contact layer, is understood to be a layer that absorbs as little energy as possible of a specific electromagnetic wave and thus hardly affects this wave, or at least less than the photoactive layer. Here, the specific electromagnetic wave is the one that has the resonant wavelength associated with the first wavelength.The product of the absorption coefficient k of the material at the wavelength of the specific electromagnetic wave, the thickness d of the layer, and the energy E of the specific electromagnetic wave in the region of the layer has a value of less than 1 (k · d · E < 1 · E). Therefore, a layer made of a material with a very small absorption coefficient k can be relatively thick, while a layer made of a material with a comparatively higher absorption coefficient k must be correspondingly thinner to minimize its influence on a specific electromagnetic wave. Typical absorption coefficients for metals, for example, are greater than 0.5, while typical materials for photoactive layers have absorption coefficients of less than 0.01. Typical materials for charge transport layers have absorption coefficients of less than 0.1.

[0029] If the electrical contact between the detection cell and the evaluation unit is established via such an intermediate or contact layer, the reflective layer, which is then no longer required for electrical contact, can be optimized for its optical properties, i.e., its reflective or semi-transparent characteristics. Decoupling the optical and electrical elements of the optoelectronic component allows for an improvement in detection performance by enhancing the optical properties of the reflective layers.

[0030] In other embodiments, the first optoelectronic component has at least one external contact that adjoins an outer surface of a detection cell, i.e., an outer surface of the photoactive layer or one of the charge transport layers, if present, and is made of an electrically conductive material. This external contact is suitable for being electrically connected to an evaluation unit that is capable of evaluating the electrical signals generated by the at least one detection cell of the first optoelectronic component. Such an external contact thus serves as an electrical contact for tapping the electrical signals from the detection cell in question, even if the photoactive layer or a charge transport layer, if present, of this detection cell does not directly adjoin an electrically conductive mirror layer or an electrically conductive intermediate or contact layer.Materials used for such external contact include metals such as Ag or Au.

[0031] Preferably, the first optoelectronic component has at least two such external contacts arranged on opposite sides of the detection cell. The opposite sides are corresponding sides of the detection cell spaced apart along the length of the optical cavity, for example, a first side of the photoactive layer facing the first mirror layer and a second side of the photoactive layer facing the second mirror layer, or the first charge transport layer and the second charge transport layer. Naturally, electrical isolation between the two external contacts is essential in every case. Therefore, external contacts directly adjacent to the photoactive layer are more suitable for thick photoactive layers and not for very thin ones.Since, in the embodiment with two external contacts in a detection cell, no additional electrically conductive layers that could optically influence the resonance wave are present in the detection cell, and since the electrical contacting of the detection cell is simultaneously decoupled from the mirror layers, the layers present in the optical cavity can be optimized for their optical properties. This allows for a further improvement of the detection result by improving the cavity quality.

[0032] In an optoelectronic component, various of the above-described methods for electrical contacting in a detection cell or for different detection cells can be used.

[0033] In embodiments of the photodetector, at least one optically transparent spacer layer is arranged in the first optical cavity, positioned between one of the mirror layers and a detection cell adjacent to that mirror layer. The optically transparent spacer layer is a layer that, as described above, has a minimal effect on the standing wave with the resonant wavelength associated with the first wavelength. The material and thickness of the spacer layer are selected according to the conditions described above, with the thickness also depending on the thicknesses of the other layers present in the optical cavity and the length of the optical cavity.

[0034] If two or more detection cells are arranged in the first optical cavity, then in embodiments of the photodetector according to the invention an optically transparent spacer layer of the type described above is arranged between two detection cells arranged one above the other in the first optical cavity along the length of the first optical cavity.

[0035] The optically transparent spacer layers are preferably electrically non-conductive, i.e., electrically insulating, and preferably consist of transparent oxides, such as Al₂O₃, SiO₂, TiO₂, or organic compounds, such as those also used for charge transport layers. These layers preferably have a charge carrier mobility of less than 10 -6 cm 2 / Vs and thus only very low electrical conductivity. In this case, the electrical contact between the charge transport layer of a detection cell adjacent to the spacer layer and the evaluation unit is established via an electrically conductive intermediate layer or contact layer, or an external contact, as described above. The mirror layer, which is then no longer required for electrical contact, as well as the other layers within the optical cavity, can thus be optimized independently for their optical or electrical properties. Decoupling the optical and electrical elements of the photodetector allows for an improvement in the detection result.

[0036] In embodiments, the photodetector includes a second optoelectronic component for detecting a second wavelength of electromagnetic radiation. Similar to the first optoelectronic component, the second optoelectronic component has a second optical cavity and at least one detection cell arranged within this second optical cavity. The second optical cavity is also formed by two spaced-apart parallel mirror layers, the length of which is configured such that a j-order resonance wave associated with the second wavelength is generated within the second optical cavity. Each detection cell of the second optoelectronic component contains a photoactive layer. The photoactive layer is arranged within the second optical cavity such that a vibration maximum of the resonance wave lies within the photoactive layer.In such a photodetector, the length of the first optical cavity differs from the length of the second optical cavity and / or the order of the resonance wave associated with the second wavelength differs from the order of the resonance wave associated with the first wavelength.

[0037] The order of the resonance wave of the second optoelectronic component can also be first order. Preferably, at least one detection cell of the second optoelectronic component also contains a first charge transport layer and a second charge transport layer, between which the photoactive layer is arranged. That is, the aforementioned layers are arranged one above the other, i.e., adjacent to each other, along the length of the second optical cavity.

[0038] In such a photodetector, the first and second optoelectronic components can be arranged side by side along a direction perpendicular to the length of the first and second optical cavities. This arrangement is also referred to as a lateral arrangement. They can be spaced apart and physically separated from each other, so that each optoelectronic component can be individually (separately) connected to an evaluation unit. The first and second optoelectronic components can also be arranged adjacent to each other, but this requires electrical separation of the charge transport layers, if present, and / or the layers that conduct the electrical signals to the outside, such as mirror layers, intermediate layers, or contact layers, of the optoelectronic components—that is, pixelation of these layers.A predefined lateral arrangement of various optoelectronic components can also be arranged side-by-side, i.e., laterally, repeating once or several times along a direction perpendicular to the length of the optical cavities. This allows the realization of an image-generating system, a so-called imager system.

[0039] In other embodiments of a photodetector with two optoelectronic components, the first and second optoelectronic components are arranged one above the other, such that the lengths of the first and second optical cavities extend along a common line. This arrangement is also referred to as a vertical arrangement. The first and second optical cavities are connected by a semi-transparent mirror layer; that is, the first and second optical cavities share this semi-transparent mirror layer, which serves as a mirror in each of the two optoelectronic components. This design, which resembles a stacking of optoelectronic components, allows for a reduction in the active area of ​​the photodetector.Furthermore, this setup enables a photodetector that responds selectively to specific angles of incidence of the incident electromagnetic radiation. In this configuration, an optoelectronic component with a long optical cavity detects a defined wavelength or wavelength range in the incident radiation at large angles of incidence, while an optoelectronic component with a shorter optical cavity detects the same defined wavelength or wavelength range at small angles of incidence, provided both optoelectronic components are of the same order. Naturally, the angle-dependent differences in response behavior between the two optoelectronic components can be achieved not only through the length of the optical cavity, but also, or additionally, through different orders of the optoelectronic components.

[0040] A photodetector for the spectrally selective detection of electromagnetic radiation according to a second aspect of the invention comprises a first optoelectronic component for detecting a first wavelength of the electromagnetic radiation. The mere presence or absence of the first wavelength in the electromagnetic radiation incident on the photodetector (qualitative assessment) and / or the intensity of the radiation of the first wavelength in the incident electromagnetic radiation (quantitative assessment) can be detected. The first optoelectronic component has a first optical cavity, a detection cell arranged in the first optical cavity, and at least one optically transparent spacer layer.The first optical cavity is formed by two spaced-apart parallel mirror layers, the length of which is such that a corresponding first-order resonance wave is generated in the first optical cavity for the first wavelength. Formula (1) already stated above applies.

[0041] The detection cell arranged in the first optical cavity contains a photoactive layer that preferably extends over the entire cross-sectional area of ​​the first optical cavity, with the cross-sectional area being perpendicular to the length of the first optical cavity. The photoactive layer of the detection cell is arranged within the first optical cavity such that the vibration maximum of the resonance wave lies within the photoactive layer. Thus, the photoactive layer is preferably positioned centrally within the first optical cavity with respect to its length.

[0042] Preferably, the detection cell further comprises a first charge transport layer and a second charge transport layer, with the photoactive layer arranged between the first and the second charge transport layer. The individual layers are arranged one above the other along the length of the first optical cavity. The first and the second charge transport layer also preferably extend over the entire cross-sectional area of ​​the first optical cavity, with the first charge transport layer adjoining a first surface of the photoactive layer and the second charge transport layer adjoining a second surface of the photoactive layer, and the second surface being opposite the first surface.

[0043] The charge transport layers serve to improve charge extraction from the photoactive layer and its conduction to electrical contacts, also called electrodes, which transmit the electrical signals generated in the detection cell to an evaluation unit capable of processing them. These charge transport layers can be very thin, in which case they can also be referred to as injection or extraction layers. They do not necessarily always have to be doped layers.

[0044] The at least one optically transparent spacer layer is arranged between one of the mirror layers and the detection cell, that is, between the respective mirror layer and the photoactive layer, or between the respective mirror layer and the charge transport layer of the detection cell adjacent to that mirror layer. The optically transparent spacer layer is designed with the optical properties described above and is also electrically insulating. This prevents an electrical signal from the photoactive layer or the corresponding charge transport layer from being read out via the adjacent mirror layer, i.e., from being fed to an evaluation unit.

[0045] According to the invention, the first optoelectronic component of the photodetector according to the second aspect therefore has at least one external contact that adjoins an outer surface of the detection cell, i.e., the photoactive layer or the charge transport layer – if present – ​​which is separated from the adjacent mirror layer by the at least one spacer layer. The external contact consists of an electrically conductive material, as already described with regard to the photodetector according to the first aspect, and is suitable for being electrically connected to an evaluation unit, wherein the evaluation unit is suitable for evaluating the electrical signals generated by the detection cell of the first optoelectronic component.

[0046] Since an electrically conductive contact layer extending over large areas of the cross-sectional area of ​​the first optical cavity is omitted, and the electrical contact is instead located on the outer surface of the detection cell, the optical propagation of the resonance wave within the optical cavity is less disturbed, thus improving the cavity quality of the first optical cavity. Furthermore, the layers arranged in the optical path of the resonance wave can be optimized for their optical properties with respect to their materials. All of this contributes to an improvement in the detection result.

[0047] In a preferred embodiment of the photodetector according to the second aspect, an optically transparent spacer layer, as already described, is arranged between each of the mirror layers and the detection cell, that is, between the respective mirror layer and the photoactive layer or the charge transport layer of the detection cell adjacent to that mirror layer, and the first optoelectronic component has at least two external contacts, with one external contact adjoining the outer surface of the detection cell on a first side and the other adjoining the outer surface of the detection cell on a second side. The first and second sides of the detection cell are oriented opposite each other along the length of the first optical cavity.Thus, each external contact borders either the outer surface of the photoactive layer on a first or second side of the detection cell, or an outer surface of the first charge transport layer or the second charge transport layer, if present.

[0048] A photodetector for the spectrally selective detection of electromagnetic radiation according to a third aspect of the invention comprises a first optoelectronic component for detecting a first wavelength of the electromagnetic radiation and a second optoelectronic component for detecting a second wavelength of the electromagnetic radiation. Here, too, the mere presence or absence of the first or the second wavelength in the electromagnetic radiation incident on the photodetector (qualitative statement) and / or the intensity of the radiation of the first or the second wavelength in the incident electromagnetic radiation (quantitative statement) can be detected.

[0049] The first optoelectronic device has a first optical cavity and at least one detection cell arranged in the first optical cavity. The first optical cavity is formed by two spaced-apart parallel mirror layers, the length of which is such that a corresponding first-order resonance wave is generated in the first optical cavity for the first wavelength. The formula (1) already given above applies.

[0050] Each detection cell arranged in the first optical cavity contains a photoactive layer, as already explained with reference to the photodetector according to the first aspect. The photoactive layer of each detection cell is positioned within the first optical cavity such that exactly one vibration maximum of the i-order resonance wave lies within the photoactive layer. This also corresponds to the first optoelectronic component according to the first aspect. However, unlike the photodetector according to the first aspect, the resonance wave can also be a first-order resonance wave, i.e., i ≥ 1.

[0051] The second optoelectronic device has a second optical cavity and at least one detection cell arranged in the second optical cavity. The second optical cavity is formed by two spaced-apart parallel mirror layers, the length of which is configured such that a corresponding j-order resonance wave is generated in the first optical cavity for the first wavelength. The formula (1) already given above applies, where i is replaced by j.

[0052] Each detection cell arranged in the second optical cavity contains a photoactive layer, as already explained with reference to the first optoelectronic device. The photoactive layer of each detection cell is positioned within the second optical cavity such that exactly one vibration maximum of the j-order resonance wave lies within the photoactive layer. This also corresponds to the structure of the first optoelectronic device. Here, too, the resonance wave can be a first-order or higher-order resonance wave.

[0053] Preferably, at least one detection cell of the first and / or the second optical cavity further comprises a first charge transport layer and a second charge transport layer, as already explained with reference to the photodetector according to the first aspect.

[0054] According to the invention, the length of the second optical cavity differs from the length of the first optical cavity and / or the order of the resonance wave associated with the second wavelength differs from the order of the resonance wave associated with the first wavelength. The resonance waves of both optoelectronic components can also be first-order resonance waves. Furthermore, according to the invention, the first and second optoelectronic components are arranged one above the other such that the lengths of the first and second optical cavities extend along a common line, and the first and second optical cavities are connected to each other by a semi-transparent mirror layer, which is one of the mirror layers of the first optical cavity and the other of the second optical cavity.

[0055] This setup, which resembles a stack of optoelectronic components, allows for two things: firstly, the active area of ​​the photodetector can be reduced; secondly, it enables a photodetector that responds selectively to specific angles of incidence of the incident electromagnetic radiation. Specifically, an optoelectronic component with a long optical cavity detects a defined wavelength in the incident radiation at large angles of incidence, while an optoelectronic component with a shorter optical cavity detects the same defined wavelength in the incident radiation at small angles of incidence, provided both optoelectronic components are of the same order.Naturally, the angle-dependent different response behavior of the two optoelectronic components cannot be achieved solely or exclusively via the length of the optical cavity, but also or additionally via different orders of the optoelectronic components.

[0056] The semi-transparent mirror layer, which belongs to both optoelectronic components, consists of one or more of the materials already mentioned in connection with the photodetector according to the first aspect, wherein the thickness of the material is adjusted with respect to the reflection of the first or the second wavelength and the transparency of the other wavelength. If the semi-transparent mirror layer serves as an electrical contact for reading out the electrical signals generated in at least one of the two optoelectronic components, then the semi-transparent mirror layer is electrically conductive.

[0057] In embodiments, the number of detection cells arranged in the first optical cavity and / or in the second optical cavity corresponds to the order of the respective resonance wave.

[0058] In one or both optoelectronic components, as described in the first aspect with reference to the first optoelectronic component of the photodetector, an optically transparent and electrically conductive contact layer or a spacer layer can be arranged between one of the mirror layers and a detection cell adjacent to this mirror layer. If one of the optoelectronic components is a component with an order greater than 1, then an optically transparent spacer layer can also be formed between two detection cells arranged one above the other in the optical cavity of this optoelectronic component along the length of this optical cavity, or one or more optically absorbing intermediate layers.

[0059] Furthermore, at least one of the detection cells of the first or second optoelectronic component can have at least one external contact adjacent to an outer surface of the photoactive layer or one of the charge transport layers, made of an electrically conductive material, and suitable for electrically conductive connection to an evaluation unit, wherein the evaluation unit is suitable for evaluating the electrical signals generated by the detection cell. Here, too, the order of the resonance wave in the corresponding optoelectronic component is irrelevant.

[0060] Of course, one or more additional optoelectronic components can also be stacked on top of the first and second optoelectronic components, with a semi-transparent mirror layer being arranged between adjacent optoelectronic components and belonging to both adjacent components.

[0061] The materials of the individual layers of the optoelectronic components of a photodetector according to the second or third aspect of the invention are the same as the materials mentioned in relation to the layers of the optoelectronic component of the photodetector according to the first aspect of the invention.

[0062] The photodetector according to each aspect of the invention can be formed on a substrate and surrounded by an enclosure or encapsulation for protection against environmental influences. However, at least the substrate or enclosure must be transparent to the incident electromagnetic radiation so that it can reach the photodetector.

[0063] In accordance with the invention, the embodiments or individual features for the design of the optoelectronic components and the photodetector can be combined with each other, as long as they do not exclude each other.

[0064] The invention will be illustrated below with reference to exemplary embodiments and figures. The dimensions of the individual elements and their relationships to one another are not to scale, but are shown schematically. Identical reference numerals denote corresponding, similar components.

[0065] The longitudinal section shows, unless otherwise stated: Fig. 1A an illustrative example of the invention, wherein the optoelectronic component is a second-order component and has two detection cells, Fig. 1B an embodiment of the photodetector according to the invention in accordance with the first aspect of the invention, wherein the optoelectronic component is a second-order component and comprises a detection cell, Fig. 1C an illustrative example of the invention, wherein the optoelectronic component is a third-order component and has three detection cells, Fig. 2 an embodiment of the photodetector according to the first aspect of the invention, wherein the optoelectronic component is a second-order component and has an optically absorbing intermediate layer, Fig. 3 an illustrative example of the invention, wherein the optoelectronic component is a second-order component and has spacer layers as well as optically transparent and electrically conductive contact layers, Fig. 4A an illustrative example of the invention, wherein the optoelectronic component is a second-order component and has spacer layers and external electrical contacts, Fig. 4B a top view of a cross-section through the photodetector of the Fig. 4A along line A-A', Fig. 5A an illustrative example of the invention, wherein the photodetector comprises two optoelectronic components arranged side by side, Fig. 5B an embodiment of the photodetector according to the invention in accordance with the first aspect of the invention, wherein the photodetector has two optoelectronic components arranged one above the other, Fig. 6A an illustrative example of the invention, wherein the optoelectronic component is a first-order component and has external electrical contacts and optically transparent spacer layers, Fig. 6B is an illustrative example of the invention, wherein the detection cell comprises charge transport layers, and Fig. 7 an embodiment of the photodetector according to the third aspect of the invention, wherein the photodetector has two first-order optoelectronic components arranged one above the other.

[0066] The Fig. Figures 1A to 5B show different embodiments and illustrative examples of a photodetector according to the first aspect of the invention. A characteristic of all embodiments according to the first aspect of the invention is that at least one optoelectronic component is a second-order or higher-order component.

[0067] Fig. Figure 1A shows one of the photodetectors according to the first aspect of the invention. The photodetector 1 comprises an optoelectronic component 100, which is arranged between a transparent first substrate 201, e.g., made of glass or transparent plastic, and a second substrate 202. The second substrate 202 can also be transparent, but can also be opaque, semi-transparent, or reflective and can, for example, be an encapsulation made of glass, metal, or plastic. The optical properties of the first and second substrates 201, 202 relate to radiation with the first wavelength to be detected in the photodetector 1. Incident radiation 301 falls from a radiation source 300, which, for example, has a broad spectrum of wavelengths from UV light to infrared radiation, i.e., in the range from 100 nm to 50 µm, or even just different wavelengths of a spectral range, e.g.,of the infrared range from 780 nm to 50 µm, or even just a single wavelength in one of these ranges, onto the photodetector 1. The incident radiation 301 can be, for example, radiation that has passed through a medium, e.g., a liquid, or that has been reflected by a medium, e.g., a solid, or radiation directly generated by the radiation source 300. The incident radiation 301 can, as in . Fig. As shown in Figure 1A, the first substrate 201 can enter the optoelectronic device 100, but it can also enter the optoelectronic device 100 through the second substrate 202 if the second substrate 202 is designed accordingly.

[0068] The optoelectronic device 100 comprises a semi-transparent first mirror layer 11, which is adjacent to the first substrate 201, and a second mirror layer 12, which is fully reflective and adjacent to the second substrate 202. Both mirror layers 11 and 12 are made of, for example, silver (Ag), with the first mirror layer 11 having a smaller thickness, e.g., 27 nm, than the second mirror layer 12, which has a thickness of, for example, 100 nm. The first mirror layer 11 and the second mirror layer 12 are arranged parallel to each other at a distance L from each other, thus forming an optical cavity between them. The length of the optical cavity, i.e., the distance L, as well as the thicknesses of the individual layers of the optoelectronic device 100, are each measured perpendicular to the parallel planes of the mirror layers 11 and 12.For specific first wavelengths of the incident radiation 301, standing resonance waves of different orders and corresponding resonance wavelengths are formed in the optical cavity according to the previously mentioned formula (1). An example of a second-order resonance wave 13 is shown in . Fig. Figure 1A shows the wavelength of the first wavelength to be detected in the photodetector 1, which is related to the effective refractive index of the optical cavity and the layers present in the radiation path, e.g., the first substrate 201 and the first mirror layer 11. Two detection cells 21 and 22 are arranged in the optical cavity, i.e., between the mirror layers 11 and 12, for detecting the resonance wave. Each detection cell 21, 22 contains a photoactive layer 210 or 220, respectively, to which a first charge transport layer 211 or 221 is adjacent on one side with respect to the length of the optical cavity, and a second charge transport layer 212 or 222 is adjacent on the other side with respect to the length of the optical cavity. The first charge transport layer 211 or 221 is, for example, a hole-conducting material, while the second charge transport layer 212 or 222 is an electron-conducting material.The photoactive layers 210, 220 consist, for example, of TPDP:C60 and have a thickness of 100 nm. The photoactive layers 210, 220 are each arranged within the optical cavity such that exactly one intensity maximum (also called an antinode) of the resonance wave 13 lies within one of the photoactive layers 210, 220. Since the resonance wave 13 detected by the optoelectronic device 100 is a second-order wave, the optoelectronic device 100 is referred to as a second-order device.

[0069] The first charge transport layer 211 of the first detection cell 21 borders the second mirror layer 12, and the second charge transport layer 222 of the second detection cell 22 borders the first mirror layer 11. Furthermore, the second charge transport layer 212 of the first detection cell 21 and the first charge transport layer 221 of the second detection cell 22 are adjacent to each other. The electrical signals generated in the detection cells 21 and 22 are transmitted through the mirror layers 11 and 12, which are electrically conductive and electrically connected to an evaluation unit. The evaluation unit is capable of generating a qualitative and / or quantitative statement about the radiation of the first wavelength contained in the incident radiation 301 from the electrical signals.

[0070] With regard to the Fig. 1B and Fig. Section 1C will further explain the concept of order in relation to the optoelectronic component. The representation of the substrates and the radiation source is omitted in most of the following figures.

[0071] Fig. Figure 1B shows an optoelectronic component 101 of an embodiment 2 of the photodetector according to the first aspect of the invention. In contrast to the optoelectronic component 100 of the Fig. In 1A, only one detection cell 21 is arranged in the optical cavity of the optoelectronic component 101, which, as with respect to the Fig. 1A is designed as described. Instead of the second detection cell 22 of the optoelectronic component 100 of the Fig. In 1A, an optically absorbing and electrically conductive intermediate layer 30 and an optically transparent spacer layer 40 are arranged between the detection cell 21 and the first mirror layer 11. The photoactive layer 210 of the detection cell 21 is again positioned at exactly one intensity maximum of the resonance wave 13, which is again a second-order resonance wave, while the intermediate layer 30 is positioned at the central node of the resonance wave 13. Since the intermediate layer 30 is optically absorbing, all other resonance waves that would otherwise form in the optical cavity between the mirror layers 11 and 12, and whose nodes do not lie in the intermediate layer 30, are canceled out. In particular, the resonance waves of adjacent orders, i.e., the first-order and third-order resonance waves, are canceled out.

[0072] In the Fig. In the case shown in Figure 1B, the spacer layer 40 is made of a material that is not electrically conductive or only poorly conductive, e.g., Al₂O₃. Therefore, the intermediate layer 30 also serves as a contact layer for transmitting the electrical signals generated in the detection cell 21 to an evaluation unit and is made of an electrically conductive material, e.g., Ag:Ca, with a thickness of, for example, 6 nm. The intermediate layer 30 is electrically connected to the evaluation unit. For this purpose, the intermediate layer 30 is designed so that it extends beyond the lateral edge of the other layers in the optical cavity and can be connected to the evaluation unit via an electrical conductor, e.g., using clamps or other connecting elements, e.g., bond wires. If the material of the spacer layer is electrically conductive, the intermediate layer can also be absorbent and only slightly electrically conductive.Furthermore, the intermediate layer can be omitted entirely if the effect of canceling out other resonance waves is not desired. Similarly, in other embodiments, it is also possible to design the intermediate layer to be non-absorbing but electrically conductive, so that an electrical connection between the detection cell 21 and the evaluation unit is possible via the intermediate layer, but without canceling out resonance waves.

[0073] Although the optoelectronic component 101 only has one detection cell 21, the optoelectronic component 101 is also a second-order component, since it detects and evaluates a second-order resonance wave.

[0074] In Fig. 1C is an optoelectronic component 102 of an illustrative example of the photodetector according to the first aspect of the invention. Here, a third-order resonance wave 14 is detected, so that the optoelectronic component 102 is a third-order component. The optoelectronic component 102 has three detection cells 21 to 23, each containing a photoactive layer 210, 220, or 230, and two charge transport layers 211 and 212, 221 and 222, or 231 and 232, respectively, and arranged one above the other in the optical cavity. The photoactive layers 210, 220, and 230 are each arranged in the optical cavity such that exactly one oscillation maximum of the resonance wave 14 lies in each of the photoactive layers 210, 220, or 230. Of course, the optoelectronic component 102 could also have only one or two detection cells, while still being a component 3.Order exists as long as the respective photoactive layers of the detection cells are located at exactly the location of a vibration maximum of the resonance wave 14.

[0075] With regard to the Fig. Sections 2 to 4B describe further embodiments and illustrative examples of the optoelectronic component of the photodetector according to the first aspect of the invention, with exemplary second-order components being shown in each case. For example, Fig. 2 an optoelectronic component 103 of an embodiment 4 of the photodetector, wherein the optoelectronic component 103 has two detection cells 21 and 22. An optically absorbing intermediate layer 31, which is not electrically conductive, is arranged between the detection cells 21 and 22. However, the intermediate layer 31 must not impede charge transport if the individual detection cells 21 and 22 are not individually electrically contacted to the outside, as is the case in Fig. Figure 2 illustrates this. In this case, the intermediate layer 31 is conductive for at least one type of charge carrier, i.e., electrons or holes, or for both. This can be achieved by making the intermediate layer 31 very thin. For example, the intermediate layer 31 can consist of a metal layer, e.g., Ag, or a metal alloy layer, e.g., Ag:Ca, with a thickness in the range of 1 nm to 5 nm. The intermediate layer 31 can also consist of a very thin, highly doped organic layer that absorbs in the corresponding wavelength range of the resonance wave, e.g., BFDPB:NDP9 with a thickness of 1 nm. Alternatively, the intermediate layer 31 can also be a structured layer and contain holes that allow charge transport from one adjacent layer to another, while the existing regions of the intermediate layer 31 lead to the cancellation of the resonance waves of adjacent orders.The intermediate layer 31 serves to cancel out resonance waves of adjacent orders (adjacent to the order of the resonance wave 13). To prevent cancellation of the resonance wave 13, the intermediate layer 13 is located within the optical cavity at a point on the central node of the resonance wave 13 and is only thin, e.g., with a thickness in the range of 1 nm to 5 nm. The connection to the evaluation unit is made as in the optoelectronic component 100. Fig. 1A is produced via the electrically conductive mirror layers 11 and 12, but can also be implemented differently in other embodiments.

[0076] For higher-order optoelectronic components designed to detect resonance waves of a higher order than the second order, several optically absorbing intermediate layers are preferably formed. These are arranged such that each node of the resonance wave lies in exactly one optically absorbing intermediate layer.

[0077] Fig. Figure 3 shows an optoelectronic component 104 of an illustrative example of the photodetector, wherein, in addition to the detection cells 21 and 22, spacer layers 40 and electrically conductive, optically transparent contact layers 50 are arranged in the optical cavity of the optoelectronic component 104. The detection cells 21 and 22 are spaced apart from each other and from the adjacent mirror layers 11 and 12, respectively, by the spacer layers 40. Since the spacer layers 40 are not electrically conductive or only poorly conductive in this case, and thus no electrical contact with the detection cells 21 and 22 is possible via the mirror layers 11 and 12, the electrical signals generated by the detection cells 21 and 22 are transmitted to the evaluation unit via the contact layers 50. For this purpose, the contact layers 50 are connected to the first and second charge transport layers 211 and 212 respectively.The contact layers 50 are arranged adjacent to and between the charge transport layers 221 and 222 and the spacer layers 40, and can each be electrically connected to the evaluation unit. The contact layers 50 are planar, meaning they extend over the entire lateral extent of the charge transport layers 211, 212, 221, and 222. Since the contact layers 50 are located in regions of the optical cavity where the intensity of the resonance wave 13 has no node but is non-zero, the contact layers 50 must be made of an optically transparent material to prevent cancellation of the resonance wave 13. The contact layers 50 can be made, for example, of PEDOT:PSS, ITO, ZnO, or other conductive oxides and can each have a thickness of, for example, 10 nm to 40 nm.Here too, the contact layers 50 protrude slightly laterally beyond the other layers in the optical cavity in order to establish an electrical connection to the evaluation unit, as already described with reference to the intermediate layer 30 in . Fig. 1B was explained.

[0078] Another possibility for electrical contact with the evaluation unit is described in relation to an optoelectronic component 105, an illustrative example of the photodetector in the Fig. 4A and Fig. Figure 4B shows the optoelectronic component 105 differing from the optoelectronic component 104. Fig. 3. This is achieved by the fact that there are no planar contact layers, but rather the electrical connection between the charge transport layers 211, 212, 221, and 222 is made via external electrical contacts 60. The external contacts 60 consist of an electrically conductive material, e.g., Ag, and abut at least a portion of the outer surface of the charge transport layers 211, 212, 221, and 222. An outer surface of the charge transport layers 211, 212, 221, and 222 extends along the length of the optical cavity and does not abut any other layer of the optoelectronic device 104, except for the external contacts 60. The external contacts 60 can also overlap a portion of the charge transport layers 211, 212, 221, and 222.The external contacts 60 adjoin a surface of the charge transport layers 211, 212, 221, and 222 that extends parallel to the mirror layers 11, 12, or they can also project into the charge transport layers 211, 212, 221, and 222. However, the external contacts 60 do not extend over the entire lateral extent of the charge transport layers 211, 212, 221, and 222. By extending the external contacts into the optical cavity, the active region of the optoelectronic device, i.e., the region in which standing waves can be generated, is laterally limited, i.e., in a plane perpendicular to the length of the optical cavity. Furthermore, the external contacts can also serve as an optical aperture mask. Thus, the external contacts 60 hardly influence the optical generation or propagation of the resonance wave 13.Preferably, the outer contacts 60 surround the charge transport layers 211, 212, 221 and 222 along the entire circumference of the outer surface in cross-section through the optoelectronic device, as shown in . Fig. 4B is shown. Fig. Figure 4B shows a cross-section through the optoelectronic component 105 of the Fig. 4A along line A-A'. The external electrical contact 60 forms a frame around the first charge transport layer 211. Electrical connecting elements or connecting lines to the evaluation unit can again be attached to the external electrical contacts 60, as already described with reference to Fig. 1B is described.

[0079] Of course, other combinations of the elements in the Fig. The structures and layers of the optoelectronic component described in 1A to 4B are possible, whereby optimization of different layers with regard to their optical and / or electrical properties and optimization of the optoelectronic component with regard to its detection properties and / or its fabrication is possible.

[0080] With regard to the Fig. 5A and Fig. Section 5B describes embodiments and illustrative examples of the photodetector according to the first aspect of the invention, wherein the photodetector comprises two optoelectronic components suitable for detecting different wavelengths in the incident radiation. Naturally, the number of optoelectronic components can be increased as desired, and both embodiments can also be combined.

[0081] The Fig. Figure 5A shows an illustrative example 7 of the photodetector with two optoelectronic devices 106 and 107, arranged laterally adjacent to each other. That is, the optoelectronic devices 106 and 107 are arranged side by side along a direction perpendicular to the lengths of the optical cavities of the two devices 106 and 107. In the illustrated case, the two devices 106 and 107 are arranged side by side on the transparent first substrate 201 and separated from the environment by the second substrate 202 in the form of an encapsulation. The first optoelectronic device 106 has a first mirror layer 11a, a second mirror layer 12a, and two detection cells 21a and 22a, wherein the first optical cavity, which is formed between the mirror layers 11a and 12a, has a length L. aThe second optoelectronic component 107 has a first mirror layer 11b, a second mirror layer 12b and two detection cells 21b and 22b, wherein the second optical cavity, which is formed between the mirror layers 11b and 12b, has a length L b has. L is involved. b < L aIn the illustrated case, both optoelectronic devices 106 and 107 are second-order devices. With identical materials for the individual layers of devices 106 and 107, the first optoelectronic device 106 can detect a first wavelength corresponding to the first resonance wave 13a, and the second optoelectronic device 107 can detect a second wavelength corresponding to the second resonance wave 13b, the first wavelength being greater than the second wavelength. However, in other embodiments, the optoelectronic devices can also differ with respect to the order of the respective resonance wave, given the same optical cavity length, or with respect to the order of the respective resonance wave and the length of the optical cavity.In the illustrated case, the first mirror layers 11a and 11b, as well as the second mirror layers 12a and 12b, serve to read out the electrical signals generated in the optoelectronic components 106 and 107 and are electrically connected to an evaluation unit (not shown) for this purpose. In other embodiments, the electrical signals can also be read out via the [missing information - likely a specific component or element]. Fig. The intermediate or contact layers or external contacts shown in 1B and 3 to 4B are transmitted to the evaluation unit, whereby the detection cells can be electrically isolated from one or both mirror layers of the respective component. In this case, mirror layers of different optoelectronic components that are electrically isolated from an adjacent detection cell can also be formed together and interconnected.

[0082] The Fig. Figure 5B shows an embodiment 8 of the photodetector with two optoelectronic components 108 and 109, which are arranged one above the other. That is, the lengths of the first and second optical cavities of the optoelectronic components 108 and 109 extend along a common line, with the first and second optical cavities being connected by a semi-transparent mirror layer. In other words, the optoelectronic components 108 and 109 are stacked on top of each other, so that the incident radiation reaches one of the two optoelectronic components only after it has passed through the other optoelectronic component. In the illustrated case, the incident radiation 301 enters the optoelectronic component 109 only after passing through the optoelectronic component 108.

[0083] The first optoelectronic device 108 has a semi-transparent mirror layer 11, a semi-transparent mirror layer 11' and two detection cells 21a and 22a, wherein the first optical cavity formed between the mirror layers 11 and 11' has a length L a The second optoelectronic component 109 has the semi-transparent mirror layer 11', a second mirror layer 12 and two detection cells 21b and 22b, wherein the second optical cavity, which is formed between the mirror layers 11' and 12, has a length L b has. In the case shown, L b < L a But also L b > L aThis is possible. Both optoelectronic devices 108 and 109 are second-order devices, whereby, with identical materials for the individual layers of devices 108 and 109, the first optoelectronic device 108 can detect a first wavelength corresponding to the formed first resonance wave 13a, and the second optoelectronic device 109 can detect a second wavelength corresponding to the formed second resonance wave 13b, the first wavelength being greater than the second wavelength. However, in other embodiments, the optoelectronic devices can also differ with respect to the order of the respective resonance wave with the same length of the optical cavity, or with respect to the order of the respective resonance wave and the length of the optical cavity.

[0084] Thus, with embodiment 8 of the photodetector, it is possible to detect two different wavelengths in the incident radiation 301 in a space-saving manner. One or more further optoelectronic components can also be stacked on top of each other, so that more than two different wavelengths can be detected with a photodetector that only requires the lateral space of one optoelectronic component.

[0085] Furthermore, this embodiment makes it possible to form a photodetector that selectively responds to the angle of incidence α of the incident radiation 301. For example, the optoelectronic component 108 would detect the presence of the first wavelength corresponding to the wavelength of the first resonance wave 13a in the incident radiation 301 at large angles of incidence α, while the optoelectronic component 109 would detect the presence of the first wavelength in the incident radiation 301 at small angles of incidence α by detecting the corresponding second resonance wave 13b. The wavelengths of the first and second resonance waves 13a and 13b correspond to the first wavelength in the incident radiation 301 and the angle of incidence α.

[0086] In the illustrated case, the mirror layers 11, 11' and 12 serve to read out the electrical signals generated in the optoelectronic components 108 and 109 and are therefore electrically connected to an evaluation unit (not shown). In other embodiments, the electrical signals can also be read out via the layers 11, 11' and 12, which are connected to the optoelectronic components 108 and 109. Fig. The intermediate or contact layers or external contacts shown in 1B and 3 to 4B are transmitted to the evaluation unit, whereby the detection cells may be electrically isolated from one or both mirror layers of the respective component.

[0087] Of course, both aspects can also be used in a photodetector with reference to the Fig. 5A and Fig. The embodiments described in section 5B can be configured simultaneously, meaning that different optoelectronic components can be arranged both one above the other and side by side. Furthermore, the optoelectronic components can each be configured according to one of the embodiments described in section 5B. Fig. 1B, and 2 to 4B described embodiments and illustrative examples, i.e. they may have spacer layers, optically absorbing intermediate layers, optically absorbing and electrically conductive intermediate layers, optically transparent and electrically conductive contact layers and / or external electrical contacts, wherein different optoelectronic components may be designed differently.

[0088] Fig. Figure 6A shows an illustrative example 9 of the photodetector according to the invention, as described in the second aspect of the invention. According to the second aspect of the invention, the photodetector can also comprise only a first-order optoelectronic component. This is shown in Fig. 6A the optoelectronic component 110, which has a semi-transparent first mirror layer 11 and a second mirror layer 12, as well as a detection cell 21' in the optical cavity between these mirror layers 11 and 12. The detection cell 21' has a photoactive layer 210, but no charge transport layers. The photoactive layer 210 is arranged in the optical cavity such that a vibration maximum of the resonance wave 15, which is a first-order resonance wave, lies within the photoactive layer 210. The photoactive layer 210 is spaced from the mirror layers 11 and 12, respectively, by spacer layers 40, which are optically transparent and electrically insulating. The photoactive layer 210 is connected to at least two external electrical contacts 60', similar to those already described with reference to the Fig. 4A and Fig. 4B describes external contacts 60 that can be connected to an evaluation unit so that the electrical signals generated in the detection cell 21 can be read out. The external contacts 60' are made of an electrically conductive material, e.g., Ag, and border at least a portion of the outer surface of the photoactive layer 210. An outer surface of the photoactive layer 210 extends along the length of the optical cavity and does not border any other layer of the optoelectronic device 110, except for the external contacts 60'. The external contacts 60' can also overlap a portion of the photoactive layer 210, i.e., border a surface of the photoactive layer 210 that extends parallel to the mirror layers 11, 12, or they can project into the photoactive layer 210.However, the external contacts 60' do not extend over the entire lateral extent of the photoactive layer 210, but at most over a small portion, a maximum of 10% of the total lateral extent. Preferably, the external contacts 60' surround the photoactive layer along the entire circumference of the outer surface in cross-section through the optoelectronic device, similar to the arrangement shown in [reference]. Fig. Figure 4B shows the external contacts 60. In any case, one of the external contacts 60' is arranged on a first side of the photoactive layer 210 and another of the external contacts 60' is arranged on a second side of the photoactive layer 210, the first side and the second side being spaced apart from each other along the length of the optical cavity and facing each other. The first side is closer to the first mirror layer 11, while the second side is closer to the second mirror layer 12. The photoactive layer 210 is at least thick enough that the external contact 60' on the first side of the photoactive layer 210 is electrically separated, i.e., insulated, from the external contact 60' on the second side of the photoactive layer 210. By separating the optical and electrical functions of the individual layers from each other, e.g.,Due to the reflective function of the mirror layers 11, 12 and their external electrical conductivity, all components of the optoelectronic device 110 can be optimized with respect to either their optical or electrical properties. By utilizing the external contacts 60', optical losses within the optical cavity are further reduced, thereby further improving the quality and effectiveness of the photodetector's detection.

[0089] Fig. Figure 6B shows an illustrative example 9' of the photodetector according to the second aspect of the invention. Illustrative example 9' is similar to illustrative example 9. However, the detection cell 21 of the optoelectronic device 110' has, in addition to a photoactive layer 210, a first charge transport layer 211 and a second charge transport layer 212, similar to the detection cells of a photodetector described previously according to the first aspect. The charge transport layers 211 and 212 are spaced from the adjacent mirror layers 11 and 12, respectively, by spacer layers 40, which are optically transparent and electrically insulating. The charge transport layers 211 and 212 are each connected via external electrical contacts 60, as already described with reference to the Fig. 4A and Fig. As explained in 4B, the photoactive layer 210 can be connected to an evaluation unit so that the electrical signals generated in the detection cell 21 can be read out. The photoactive layer 210 in this explanatory example can be thinner than in explanatory example 9. Here, too, all components of the optoelectronic device 110' can be optimized with respect to either their optical or electrical properties. By using the external contacts 60, optical losses within the optical cavity are further reduced, thus further improving the quality and effectiveness of the photodetector's detection.

[0090] Fig. Figure 7 shows an embodiment 10 of the photodetector according to the third aspect of the invention. According to the third aspect of the invention, the photodetector, similar to the eighth embodiment 8 of the photodetector according to the first aspect of the invention, has two optoelectronic components arranged one above the other, but both optoelectronic components can be first-order components. Accordingly, in the illustrated embodiment, the photodetector 10 has two optoelectronic components 111 and 112 arranged one above the other, such that the lengths of the optical cavities of both components 111 and 112 extend along a common line.The first optoelectronic device 111 comprises a semi-transparent mirror layer 11 and a semi-transparent mirror layer 11', as well as a detection cell 21a arranged between them, wherein the corresponding photoactive layer of the detection cell 21a lies at the oscillation maximum of the resonance wave 15a, which is a first-order resonance wave. The optical cavity of the optoelectronic device 111 has a length L. a , which corresponds to a first wavelength to be detected in the incident radiation. The second optoelectronic device 112 has the semi-transparent mirror layer 11' and a mirror layer 12 as well as a detection cell 21b arranged between them, wherein the corresponding photoactive layer of the detection cell 21b lies at the vibrational maximum of the resonance wave 15b, which is also a first-order resonance wave. The optical cavity of the optoelectronic device 112 has a length L b, which corresponds to a second wavelength to be detected in the incident radiation and, in the example shown, is smaller than the length L a is. In other embodiments, however, L b also larger than L a be.

[0091] As with regard to the Fig. As described in 5B, the dependence of the wavelength of the resonance waves 15a, 15b on the angle of incidence of the incident radiation can also be used for angle-selective detection of certain wavelengths in the incident radiation.

[0092] The two optoelectronic components 111 and 112 share the semi-transparent mirror layer 11'. In the illustrated embodiment, the mirror layers 11, 11', and 12 serve to read out the electrical signals generated in the detection cells 21a and 21b and can be electrically connected to an evaluation unit for this purpose. Of course, in other embodiments, other methods for establishing electrical contact with the charge transport layers of the detection cells can be implemented, e.g., optically transparent and electrically conductive contact layers or external electrical contacts as described above, and / or the detection cells can be spaced apart from adjacent mirror layers by spacer layers. Cited non-patent literature Zynek et al Zynek, J. et al, “Photodiode with resonant cavity based on InGaAs / InP for 1.9 µm band,” Opto-Electron. Rev., 12(1), 149 - 155 (2004) An et al An, K. H. et al, „Organic photodetector with spectral response tunable across the visible spectrum by means of internal optical microcavity“, Organic Electronics 10 (2009) 1152 - 1157 Lao et al Lao, Y.-F. et al, „Design of resonat-cavity-enhanced multiband photodetectors“; Journal of Applied Physics 110, 043112 (2011), https: / / doi.org / 10.1063 / 1.3626812

Claims

[1] Photodetector (1-8) for spectrally selective detection of electromagnetic radiation, comprising a first optoelectronic component (100-106, 108) for detecting a first wavelength of the electromagnetic radiation: - a first optical cavity formed by two spaced-apart parallel mirror layers (11, 11a, 11', 12, 12a), wherein the length (L, L a ) the first optical cavity is designed such that for the first wavelength a corresponding resonance wave of order (13, 13a) is formed in the first optical cavity, and - at least one detection cell (21, 21a, 22, 22a, 23) arranged in the first optical cavity, wherein each detection cell (21, 21a, 22, 22a, 23) contains a photoactive layer (210, 220, 230), wherein the photoactive layer (210, 220, 230) is arranged within the first optical cavity such that exactly one vibration maximum of the resonance wave (13, 13a) lies within the photoactive layer (210, 220, 230), wherein the order of the resonance wave (13, 13a) of the first optoelectronic device (100-106, 108) is greater than 1, characterized by, that in the first optical cavity at least one optically absorbing intermediate layer (30, 31) is arranged such that a node of the resonance wave (13) lies in the absorbing intermediate layer (30, 31), wherein the absorbing intermediate layer (30, 31) is suitable to absorb so much energy of a specific electromagnetic wave within the first optical cavity that it is annihilated, wherein the specific electromagnetic wave has a wavelength different from the resonance wavelength associated with the first wavelength. [2] Photodetector (1-8) according to claim 1, characterized by, that at least one detection cell (21, 21a, 22, 22a, 23) arranged in the first optical cavity further comprises a first charge transport layer (211, 221, 231) and a second charge transport layer (212, 222, 232) between which the photoactive layer (210, 220, 230) is arranged, wherein the first charge transport layer (211, 221, 231), the photoactive layer (210, 220, 230) and the second charge transport layer (212, 222, 232) are arranged one above the other along the length of the first optical cavity. [3] Photodetector (1, 3-8) according to claim 1 or 2, characterized by , that the number of detection cells arranged in the first optical cavity (21, 21a, 22, 22a, 23) corresponds to the order of the resonance wave (13, 13a). [4] Photodetector (2) according to any one of the preceding claims, characterized by, that at least one optically absorbing intermediate layer (30) is arranged in the first optical cavity and at least one of the at least one optically absorbing intermediate layer (30) is directly adjacent to one of the at least one detection cell (21), is made of an electrically conductive material and is suitable to be electrically connected to an evaluation unit which is suitable to evaluate the electrical signals generated by the at least one detection cell (21) of the first optoelectronic device (101). [5] Photodetector (1-8) according to claim 1, characterized by, that in the first optical cavity at least one optically transparent contact layer (50) is arranged, which is directly adjacent to one of the at least one detection cell (21, 22), is made of an electrically conductive material and is suitable to be electrically connected to an evaluation unit which is suitable to evaluate the electrical signals generated by the at least one detection cell of the first optoelectronic device (104). [6] Photodetector (6) according to any one of the preceding claims, characterized by, that the first optoelectronic component (105) has at least one external contact (60) adjacent to an external surface of one of the at least one detection cell (21, 22), is made of an electrically conductive material and is suitable for being electrically connected to an evaluation unit suitable for evaluating the electrical signals generated by the at least one detection cell of the first optoelectronic component (105). [7] Photodetector (2, 5, 6) according to any one of the preceding claims, characterized by , that in the first optical cavity at least one optically transparent spacer layer (40) is arranged, which is arranged between one of the mirror layers (11, 11a, 11', 12, 12a) and a detection cell (21, 22) adjacent to this mirror layer (11, 11a, 11', 12, 12a). [8] Photodetector (5, 6) according to any one of the preceding claims, characterized by, that at least two detection cells (21, 22) are arranged in the first optical cavity and an optically transparent spacer layer (40) is arranged between two detection cells (21, 22) arranged one above the other in the first optical cavity along the length of the first optical cavity. [9] Photodetector (7, 8) according to any one of the preceding claims, characterized by , that - the photodetector (7, 8) includes a second optoelectronic component (107, 109) for detecting a second wavelength of the electromagnetic radiation, wherein the second optoelectronic component (107, 109) comprises: • a second optical cavity formed by two spaced-apart parallel mirror layers (11b, 12b, 11', 12), wherein the length of the second optical cavity is designed such that a resonance wave of the jth order (13b) associated with the second wavelength is formed in the second optical cavity, and • at least one detection cell (21b, 22b) arranged in the second optical cavity, wherein each detection cell (21b, 22b) contains a photoactive layer (210, 220), wherein the photoactive layer (210, 220) is arranged within the second optical cavity such that exactly one vibration maximum of the resonance wave (13b) lies within the photoactive layer (210, 220), and - the length (L a ) the first optical cavity of length (L b) the second optical cavity and / or the order of the resonance wave (13b) associated with the second wavelength differs from the order of the resonance wave (13a) associated with the first wavelength. [10] Photodetector (7) according to claim 9, characterized by , that the first and the second optoelectronic device (106, 107) are oriented along a direction perpendicular to the length (L a , L b ) of the first and second optical cavities are arranged side by side. [11] Photodetector (8) according to claim 9, characterized by , that the first and the second optoelectronic components (108, 109) are arranged one above the other, such that the lengths (L a , L b ) of the first optical cavity and the second optical cavity extend along a common line, the first and the second optical cavity being connected to each other by a semi-transparent mirror layer (11'). [12] Photodetector (10) for spectrally selective detection of electromagnetic radiation, comprising: - comprising a first optoelectronic component (111) for detecting a first wavelength of electromagnetic radiation: • a first optical cavity formed by two spaced-apart parallel mirror layers (11, 11') wherein the length (L a ) the first optical cavity is designed such that for the first wavelength a corresponding resonance wave of order (15a) is formed in the first optical cavity, and • at least one detection cell (21a) arranged in the first optical cavity, wherein each detection cell (21a) contains a photoactive layer (210), the photoactive layer (210) being arranged within the first optical cavity such that exactly one vibration maximum of the resonance wave (15a) lies within the photoactive layer (210), and - comprising a second optoelectronic component (112) for detecting a second wavelength of electromagnetic radiation: • a second optical cavity formed by two spaced-apart parallel mirror layers (11', 12), wherein the length (L b ) the second optical cavity is designed such that for the second wavelength a resonance wave of the jth order (15b) is formed in the second optical cavity, and • at least one detection cell (21b) arranged in the second optical cavity, wherein each detection cell (21b) contains a photoactive layer (210), the photoactive layer (210) being arranged within the second optical cavity such that exactly one vibration maximum of the resonance wave (15b) lies within the photoactive layer (210), characterized by , that - the length (L b ) the second optical cavity of length (La ) the first optical cavity and / or the order of the resonance wave (15b) associated with the second wavelength differs from the order of the resonance wave (15a) associated with the first wavelength and - the first and the second optoelectronic components (111, 112) are arranged one above the other, such that the lengths (L a , L b ) of the first and second optical cavities extend along a common line, wherein the first and second optical cavities are connected to each other by a semi-transparent mirror layer (11') which is one of the mirror layers of the first optical cavity and the second optical cavity, respectively. [13] Photodetector (10) according to claim 12, characterized by, that at least one detection cell (21a, 21b) arranged in the first optical cavity or in the second optical cavity further comprises a first charge transport layer (211) and a second charge transport layer (212), between which the photoactive layer (210) is arranged, wherein the first charge transport layer (211), the photoactive layer (210) and the second charge transport layer (212) are arranged one above the other along the length (L a , L b ) are arranged in the first optical cavity or the second optical cavity. [14] Photodetector (10) according to claim 12 or 13, characterized by , that the number of detection cells (21a, 21b) arranged in the first optical cavity and / or in the second optical cavity corresponds to the order of the respective resonance wave (15a, 15b).

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