Sensor, especially photodiode

Abstract

Sensor, in particular a photodiode, comprising a carrier substrate (1) which carries a semiconductor arrangement arranged between conductive contacts (2, 3), wherein the semiconductor arrangement has at least two layers (4, 5, 6, 7) arranged one above the other, wherein each layer (4, 5, 6, 7) is formed from one to ten monolayers of a semiconducting, photoactive material and, at least in the succession, each of these layers (4, 5, 6, 7) has a different band gap, wherein in the direction of light incidence the band gap of the layers (4, 5, 6, 7) made of semiconducting, photoactive material in the semiconductor arrangement decreases from layer (4, 5, 6, 7) to layer (4, 5, 6, 7).

Description

The invention relates to a sensor, in particular a photodiode, comprising a carrier substrate which carries a semiconductor arrangement arranged between conductive contacts.Sensors and in particular photodiodes of this type are sufficiently known in the prior art and are based on the fact that in a semiconductor arrangement made of a semiconducting material a band gap exists between valence band and conduction band and due to photoactivity of the semiconducting material there is the possibility of absorbing photons and thereby raising electrons from the valence band into the conduction band, so that a charge shift between the conductive contacts and thus in particular a current can be detected as a function of the illumination intensity. In this case, the prior art discloses in particular the publications WO 2013 / 140 181 A1 and WO 2011 / 020 035 A2.Thus, since the absorption wavelength depends on the band gap, a photodiode formed of a particular semiconducting photoactive material is substantially sensitive to photons having an energy greater than the band gap, i.e., greater than the energetic distance between valence band and conduction band.This circumstance furthermore implies that with a photodiode of conventional design it is not possible to distinguish between the wavelength of the detected photons, since all photons are absorbed and thus detected whose energy is greater than the band gap. In order to obtain spectral resolution, i.e. information regarding the wavelength of the detected photons, it is known in the prior art to use photodiodes in which a plurality of semiconductor arrangements made of the same semiconducting material are arranged next to one another in the direction of incidence, wherein, however, an optical filter is arranged in front of each of these semiconductor arrangements with respect to the direction of incidence, said optical filter letting only a specific wavelength or a selected wavelength range pass in the sense of a band pass filter, so that the detected photocurrent is defined by the upstream filter arrangements on which absorbed photon wavelengths are based.It is also problematic that when using one and the same semiconducting material and selecting only via the upstream filters, it is to be taken into account that the absorption behavior, in particular the absorption cross sections for photons of different wavelengths, are not the same for one and the same material.In addition to the aforementioned problems, the known photodiodes also have the disadvantage that they each form rigid arrangements and thus cannot be used in applications in which flexibility is important, because of lack of flexibility. This is a decisive disadvantage in this respect, because in present-day electronic applications the demand for flexible electrical and electronic circuits is increasing more and more.It is therefore an object of the invention to provide a sensor, in particular a photodiode, which, in addition to being able to configure it flexibly, also offers the possibility of absorbing photons in a wavelength-selective manner and thereby generating photocurrents, wherein the spectral sensitivity, i.e. the position of the spectral sensitivity maximum, is preferably displaceable. Preferably, such a sensor is also intended to make it possible to determine the photocurrents as a function of the wavelength.This object is achieved according to the invention as claimed in claim 1.In an embodiment not according to the invention, accordingly, although two layers can certainly have the same band gaps, these then do not follow one another in the layer structure, but rather have at least one layer with a different band gap between them. However, the invention can also provide that there are no two layers with the same band gap in the layer structure of the semiconductor arrangement.In the sense of the invention, a monolayer of the material is understood to mean the physically or chemically thinnest possible layer of the material. In the case of an atomic material, such as graphite, a monolayer accordingly corresponds to an atomic layer of graphite, which is also referred to as graphene.In materials present in molecular form, a monolayer corresponds exactly to a layer of molecules of this material. A monolayer of, for example, molybdenum disulfite, which has three atoms in the molecule, thus has the height of one molecule or of the three atoms in the specific molecular arrangement.Due to the fact that the individual layers arranged one above the other are limited with respect to their layer thickness to a maximum of 10 monolayers, flexibility of the entire semiconductor arrangement already results, so that it can preferably also be provided to arrange such a semiconductor arrangement from the layers arranged one above the other on a correspondingly flexible substrate, i.e. one made of a flexible material. For example, a substrate may be formed from a plastic, preferably from a polyimide, such as is available under the trade name Kapton.With regard to the above-mentioned arrangement of the layers one above the other, it should be noted that such an arrangement of the layers is to be provided in the direction of incidence of light, so that the layers follow one another in a provided direction of incidence of light. The arrangement of the layers one above the other in the direction of light incidence is not necessarily to be understood in such a way that the individual layers mentioned must be arranged in a contacting manner from a maximum of 10 monolayers of a semiconducting and photoactive material, i.e. all or at least a partial number of all layers, although this is possible, but it can likewise be provided to provide at least one layer of other materials in each case between such layers of semiconducting, photoactive materials arranged one above the other, e.g. of insulating and / or of conducting materials, preferably in each case again in a thickness of 1 to 10 monolayers of the selected material. for example, at least one layer of insulating and / or at least one layer of conducting material can be arranged here only between a partial number of all pairs of layers arranged adjacent to one another, or else at least one layer of insulating and / or at least one layer of conducting material can also be arranged between all such pairs, e.g. a dielectric or as a conductor e.g. and preferably graphene in 1 to 10 monolayers.By virtue of the superposition and the fact that each of these layers, at least each of successive semiconducting photoactive layers, has a different band gap, photons of different energy are absorbed in each of these layers. This means that, depending on the layer, the photons penetrating into the semiconductor device are absorbed at different depths of the semiconductor device, wherein the individual layers can be optimized with respect to the absorption wavelength, e.g. by selecting the band gap, for example on the basis of the material and / or the selected number of monolayers within such a layer.It is thus known, for example, that the band gap varies with the number of monolayers in the case of one and the same material, wherein both the energy distance of the band gap can change and the transition type, i.e. whether it is a direct or an indirect band gap between valence band and conduction band.The term band gap chosen here is intended to mean substantially at least the energy distance between valence band and conduction band, regardless of whether it is a direct or indirect transition.According to the invention, transition metal dichalcogenides of empirical formula MX 2 are selected as materials for the layers arranged one above the other from one to ten monolayers in a preferred embodiment, wherein the letter M represents a transition metal, such as Mo, Va, Ti, W, Cr, Nb, Ta, Ni, Zr, and the letter X represents a chalcogenide, such as sulfides (S), selenides (Se) or tellurides (Te). However, the invention is not limited to the selection of these materials in the individual layers arranged one above the other. For example, further materials, such as black phosphorus, can thus be used.In a preferred embodiment of the sensor, it can furthermore be provided that in the light incidence direction, i.e. in an exemplary arrangement from top to bottom, the band gap of a respective layer of semiconducting material in the semiconductor arrangement decreases from layer to layer. This means that the energy distance between valence band and conduction band becomes smaller from layer to layer in the direction of incidence of light and, accordingly, more long-wave photons can penetrate deeper into the semiconductor arrangement in comparison with short-wave photons and are accordingly absorbed in later or deeper layers in the direction of incidence of light.An embodiment can also provide that at least one layer, preferably at least a partial number of all layers and more preferably each layer of a semiconducting photoactive material is formed by exactly only a single monolayer.Regardless of the number of monolayers of each layer, the invention may provide for at least 3 layers of semiconducting photoactive material to be provided.Preferred further embodiments of a sensor can furthermore provide that at least two layers of a semiconducting, photoactive material, in particular all of these layers, have a different band gap profile. In the context of the invention, a band gap profile is understood to mean that the minimum band gap of an individual layer, regardless of whether it is an indirect or direct band transition, differs in height from the band gap of the other layer.Furthermore, as an alternative or in addition to the previous embodiment, it can also be provided that at least two layers of semiconducting, photoactive material have the same band gaps, in particular also the same band gap profile, in particular in that these at least two layers are formed from the same material and the same number of monolayers.In this case, it can preferably be provided that these two layers are used as photoactive layer at different positions in the semiconductor arrangement. This can achieve the effect that photons which, although they would have already had to be absorbed in a light incidence direction in the earlier of the layers, but which did not have occurred because of physical impossible 100% absorption, are then still absorbed in a further layer arranged at another position, so that overall the absorption cross section for photons of this corresponding energy corresponding to the band gap or to the band profile is enlarged.A further embodiment, which can be used alternatively or also in combination with the preceding ones, can provide that at least two layers of semiconducting photoactive material, in particular all of these layers of the semiconductor arrangement, are formed by the same material in each case and the at least two layers have different numbers of monolayers.The different number of monolayers already achieves that the band gaps of the respective layers differ, although this is the same material. A preferred embodiment provides here that in the case of two such adjacent layers, these layers are insulated from one another by a dielectric, in particular a transparent dielectric having a thickness of at least one monolayer. For example, hexagonal boron nitride can be used here as dielectric. Other possible materials are, for example, the following: SiO 2, TiO 2, Si 3 N 4A refinement of the sensor may also provide that at least one of the conductive contacts, in particular at least the first contact in the direction of incidence of light, is formed by at least one monolayer of an at least semiconducting, preferably conducting material. Particularly preferably, the contact can be formed here from at least one monolayer of graphene.This has the particular advantage that graphene acts as a conductive material in a contacting manner and thus offers the possibility of conducting away the electrons and detecting a corresponding photon current, and that graphene furthermore has a particularly high transparency of more than 97% for virtually all wavelengths, which is significantly increased compared to conventional contact materials, such as, for example, so-called TCO materials (transparent conductive oxides). Moreover, graphene also has the advantage of high flexibility in comparison with the other rather rigid or even brittle known contact materials.In order to achieve a correspondingly high flexibility, it can accordingly also be provided to form not only the first contact in the light incidence direction, but also the last contact accordingly by at least one monolayer of such an at least semiconducting, preferably conducting material, such as by at least one monolayer of graphene, for example.A further development can also provide for at least one monolayer of a photoactive or merely absorbing material, such as e.g. again graphene, to be arranged before a last contact in the light incidence direction, in particular which is formed by at least one monolayer of an at least semiconducting, preferably conductive material, preferably by at least one monolayer of graphene, wherein the layer is separated from the contact, i.e. e.g. the at least one monolayer of graphene, by a dielectric layer, for example hexagonal boron nitrite.The invention can also provide that a separating layer is arranged between two layers of semiconducting material, in particular between each pair of two layers. In this way, it can be achieved, in particular if the separating layer is formed from a transparent dielectric or from a semiconductor material with the largest band gap of all layers of the semiconductor arrangement, that the individual layers with in each case only one to 10 monolayer layer thicknesses do not influence one another electronically or only slightly and thus mutually influence one another with regard to the position and size of the band gap.Thus, the particular physical properties of so-called two-dimensional materials can preferably be retained compared to the other properties of so-called bulk materials.In one application, the invention can provide that, via the contacts of the sensor, i.e. the first contact in the direction of incidence and the last contact in the direction of incidence, an influence on the band gaps and thus on the spectral sensitivity of the individual layers and thus overall a spectral sensitivity of the entire sensor arrangement can be changed by applying an electric field between these contacts. The wavelength of maximum spectral sensitivity of such a sensor can thus be shifted with the aid of an applied electrical potential.The invention can furthermore also provide that the contacts of the sensor, in particular both the contact upstream in the light incidence direction and the contact downstream in the light incidence direction, are formed as a doped layer, either as a p-doped or as an n-doped layer. In particular, if both contacts are doped in opposite directions, i.e. one of the contacts is p-doped and the other is n-doped, it is thereby possible to span a static electric field across the layers of the semiconducting materials with one to ten monolayers, as is already known from the principle of so-called PIN photodiodes.An embodiment of the invention can also provide for a respective layer of the semiconducting photoactive material to be surrounded by one to ten monolayers, optionally apart from the uppermost and / or lowermost, by two conductive layers acting as contacts, preferably likewise each made of only one to 10 monolayers of layer thickness, so that as a result virtually each of the semiconducting photoactive layers of the semiconductor arrangement according to the invention forms a dedicated photodiode, wherein the plurality of photodiodes formed in this way is stacked one above the other. Because of the small number of monolayers, each photodiode is transparent and, according to the invention, selective for other wavelengths.Each of these contacting layers can here preferably in turn be formed from at least one monolayer of graphene.The respective arrangement of the semiconducting, photoactive layers according to the invention and the contacting layers surrounding them can in turn be separated from one another by insulating separating layers, such as, for example, hexagonal boron nitrite. Any such layer arrangement, which fundamentally forms an independent photodiode and, on account of the restriction of the respective layer to a maximum of 10 monolayers, is in turn transparent and flexible, thus offers the possibility of realizing a separate electronic tap of the photocurrent generated at each layer height of the sensor formed in this way according to the invention without mutual influence occurring.Preferred embodiments and examples of materials are explained with reference to the following figures and the table:Table 1 first shows a list of a plurality of transition metal dichalcogenides, the respective band gap as a function of the material and also of the monolayer number, the band gap being given as the energy distance between valence and conduction band in electron volts.Furthermore, the table contains information about the type of band transition, i.e. whether it is a direct or indirect band transition.It can be seen that from the totality of these materials, those can be extracted which have different band gaps and which can be arranged one above the other in the height or in the direction of incidence of light of a sensor according to the invention in such a way that their band gap decreases from layer to layer in the direction of incidence of light.As an example, it should be mentioned that in a first layer in the direction of incidence of light, MoS 2 can be arranged in an atomic layer with a band gap of 1.8 eV, in a subsequent layer, for example WSe 2 in a single monolayer with a 1.6 eV band gap, then MoSe 2 in a monolayer of 1.58 eV, then for example CrS 2 in a single monolayer of 0.93 eV and for example as the last monolayer CrSe 2 with a 0.74 eV band gap. The band gaps thus decrease from top to bottom here.The layers can be arranged one above the other in any embodiment, for example, by exfoliation, transfer processes and / or direct deposition on top of one another.In particular, the example of the material MoS 2 also shows that a sensor according to the invention can be formed, for example, only from this one material, wherein in each case a different number of monolayers is provided in the individual layers, in particular an increasing number of monolayers in the direction of incidence of light, so that in a possible example the monolayer number increases by one monolayer from layer to layer. This applies in the same way to other materials. This also achieves the effect that the energy distance between valence band and conduction band decreases from layer to layer.FIG. 1 furthermore shows a schematic configuration according to the invention, in which a sensor has a substrate 1, for example a polyimide, which is lower with respect to the figure and on which a plurality of layers are arranged. In this example, a layer 2 of a monolayer of graphene follows as electrical contact material above the substrate layer, wherein a monolayer of graphene is provided in the same way as the upper light-transmissive contact layer 3, so that these layers make it possible to pick off the photocurrent and also to apply an electrical potential via the further layer system comprising the layers 4, 5, 6 and 7.These layers 4, 5, 6 and 7 form a semiconductor arrangement according to the invention, each of these layers being formed from at least one monolayer and at most 10 monolayers of a semiconducting photoactive material, and each of these layers being selected such that the individual layers have, at least in the succession, different band gaps, i.e. different energy distances between valence band and conduction band. For example, each of the layers 4, 5, 6 and 7 may comprise only a single monolayer of a selected material, such as such a material of Table 1, so that in this case the selected material is also referred to as a so-called 2D material.The invention is not limited to the specific number of the four layers 4, 5, 6, 7 here; two, three or more than four such layers could also be provided.FIG. 2 shows an alternative embodiment which differs from that of FIG. 1 substantially in that above the lower contact layer 2, which is in turn formed here as graphene and in the present case comprises two monolayers of graphene, a further layer 2 aof graphene having a monolayer is provided, wherein the layer 2 ais separated from the layer 2 having the two monolayers of graphene by a separating layer 8, which is formed in the present case by a dielectric. Thus, the layer 2 aof graphene with a monolayer can additionally serve as absorber material.The embodiments illustrated and the above-mentioned description make it clear that, by forming a layer system from semiconducting and photoactive materials with at least one, but at most ten, monolayer, wherein any number between 1 and 10 is likewise possible for each layer, it is possible to create flexible sensors, in particular photodiodes, on the one hand, and also to specifically select the spectral sensitivity of a photodiode created in this way by suitable selection of the respective band gaps of the individual layers, on the other hand. In particular, a potential applied across the layers allows the spectral sensitivity to be shifted on account of the effect of the electric field on the strip thickness. Table 1: Direct and indirect band transitions of selected TMD materials and their layer thickness dependence. Table 1: Direct and indirect band transitions of selected TMD materials and their layer thickness dependence.MoS 2Bulk Material≈1.2 eV

[46] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly1,29 eV

[37] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly61,37 eV

[47] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly51,4 eV

[47] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly41,45 eV

[47] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly31,35 eV

[35] -1.46 eV

[47] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly21,6 eV

[47] - 1.65 eV

[35] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly11,8 eV

[35] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly1,89 eV

[47] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directlyWS 2Bulk Material1,3 eV

[46] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyMoTe 21,0 eV

[48] - 1.13 eV

[49] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyMoSe 21,1 eV

[50] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly11,55 eV

[51] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly=1.58 eV

[50] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly1,49 eV

[50] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly8=1.41 eV

[51] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly21,38 eV

[51] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyWS 221,95 eV

[52] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyWSe 211,61 eV

[50] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly21,53 eV

[52] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly31,45 eV

[52] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly41,42 eV

[52] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly81,37 eV

[52] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyWTe 210,71 eV

[49] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directlyVSe 21metallic

[53] -CrS 210,93 eV

[53] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly20,68 eV

[53] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyCrSe 210,74 eV

[53] directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly directly20,6 eV

[53] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyBPBulk Material0,3 eV

[33] indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectly indirectlyList of reference numbers:1 . . Substrate 2, 2a Monolayer Graphene 3 Monolayer Graphene 4 1 to 10 monolayers of a semiconducting photoactive material 5 1 to 10 monolayers of a semiconducting photoactive material 6 1 to 10 monolayers of a semiconducting photoactive material 7 1 to 10 monolayers of a semiconducting photoactive material 8 Separating layer, dielectric

Claims

Sensor, in particular photodiode, comprising a carrier substrate (1) which carries a semiconductor arrangement arranged between conductive contacts (2, 3), wherein the semiconductor arrangement has at least two layers (4, 5, 6, 7) arranged one above the other, wherein each layer (4, 5, 6, 7) is formed from one to ten monolayers of a semiconducting photoactive material and each of these layers (4, 5, 6, 7) has a different band gap at least in the succession, wherein the band gap of the layers (4, 5, 6, 7) of semiconducting photoactive material in the semiconductor arrangement decreases from layer (4, 5, 6, 7) to layer (4, 5, 6, 7) in the direction of light incidence.The sensor of claim 1, wherein each layer is formed from one to ten monolayers of transition metal dichalcogenides.Sensor according to one of the preceding claims, characterized in that a. a layer (4, 5, 6, 7) or b. at least a partial number of all layers (4, 5, 6, 7) or c. each layer (4, 5, 6, 7) is formed from a semiconducting, photoactive material by exactly one monolayer.Sensor according to one of the preceding claims, characterized in that a. at least two layers (4, 5, 6, 7) of semiconducting, photoactive material or all layers (4, 5, 6, 7) of semiconducting, photoactive material have a different band gap profile, and / or b. at least two layers (4, 5, 6, 7) of semiconducting, photoactive material have the same band gap profile, in particular these at least two layers (4, 5, 6, 7) are formed from the same material and the same number of monolayers and are used as photoactive layer (4, 5, 6, 7) at different positions in the semiconductor arrangement, and / or c. at least two or all layers (4, 5, 6, 7) of semiconducting, photoactive material of the semiconductor arrangement are formed by in each case the same material and the layers (4, 5, 6, 7) having the same material have different numbers of monolayers, in particular, wherein two adjacent layers (4, 5, 6, 7) of this type are insulated from one another by a dielectric having a thickness of at least one monolayer, in particular by hexagonal boron nitride.Sensor according to one of the preceding claims, characterized in that at least one of the conductive contacts (2, 3) is formed by at least one monolayer of a semiconducting or conducting material, preferably by at least one monolayer of graphene.Sensor according to one of the preceding claims, characterized in that at least one monolayer of a photoactive material is arranged in front of a last contact (2) in the direction of incidence of light, said monolayer being separated from the contact (2) by a dielectric layer (8), preferably being separated from the contact (2) by a dielectric layer of hexagonal boron nitride (h-BN).Sensor according to one of the preceding claims, characterized in that the substrate (1) is formed from a flexible material, in particular is formed from a plastic, preferably is formed from a polyimide.Sensor according to one of the preceding claims, characterized in that a separating layer is arranged between two layers (4, 5, 6, 7) of semiconducting photoactive material, in particular between each pair of two layers (4, 5, 6, 7) of semiconducting photoactive material.Sensor according to Claim 8, characterized in that the separating layer is formed from a transparent dielectric or from a semiconductor material having the largest band gap of all layers of the semiconductor arrangement.Sensor according to one of the preceding claims, characterized in that the contact (3) upstream in the direction of incidence of light and the contact (2) downstream in the direction of incidence of light are formed as doped layers for applying an electric field over the layers (4, 5, 6, 7) of the semiconducting, photoactive materials, in particular wherein both contacts (2, 3) are formed with opposite dopings.

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