UV photodetector and sensor device

Abstract

A UV photodetector (10) comprises a photodiode (15) formed in a semiconductor substrate (100) comprising a first main surface (101) being a light incidence surface. The UV photodetector (10) further comprises a converter layer (110) arranged over the first main surface (101), the converter layer (110) being configured to convert a wavelength smaller than 500 nm to a wavelength larger than 500 nm. Additionally, the UV photodetector (10) comprises an optical bandpass filter (115) configured to block electromagnetic radiation having a wavelength larger than 380 nm, the optical bandpass filter (115) being arranged on a side of the converter layer (110) remote from the semiconductor substrate (100).

Description

[0001] UV PHOTODETECTOR AND SENSOR DEVICE

[0002] UV photodetectors generally comprise e . g . a photodiode formed in a silicon substrate . Generally, concepts are being sought , by which the ef ficiency and reliability of UV photodetectors may be improved .

[0003] It is an obj ect of the present invention to provide an improved UV photodetector .

[0004] SUMMARY

[0005] According to embodiments , the above obj ect is achieved by the claimed matter according to the independent claims . Further developments are defined in the dependent claims .

[0006] According to embodiments , a UV photodetector comprises a photodiode formed in a semiconductor substrate comprising a first main surface being a light incidence surface . The UV photodetector further comprises a converter layer arranged over the first main surface , the converter layer being configured to convert a wavelength smaller than 500 nm to a wavelength larger than 500 nm . The UV photodetector additionally comprises an optical bandpass filter configured to block electromagnetic radiation having a wavelength larger than 380 nm, the optical bandpass filter being arranged on a side of the converter layer remote from the semiconductor substrate .

[0007] For example , the converter layer may comprise quantum dots .

[0008] For example , the optical bandpass filter may be operable to reflect electromagnetic radiation of wavelengths larger than 420 nm towards the converter layer . Moreover, the UV photodetector may further comprise a UV transparent filter that is configured to reflect electromagnetic radiation having a wavelength larger than 420 nm towards the converter layer . For example , the UV transparent filter may be arranged between the bandpass filter and the converter layer . The UV transparent filter may be operable as a visible light reflection layer .

[0009] In this way, most of the converted light is reflected back to the sensor area .

[0010] According to embodiments , the UV photodetector may further comprise a UV reflection layer arranged between the semiconductor substrate and the converter layer, the UV reflection layer being configured to reflect electromagnetic radiation having a wavelength less than 500 nm .

[0011] For example , the UV photodetector may further comprise a silicon nitride layer arranged adj acent to the first main surface .

[0012] According to embodiments , the photodiode comprises a well of doped semiconductor material of a f irst conductivity type in a semiconductor substrate portion of a second conductivity type . The UV photodetector further may comprise a portion of semiconductor substrate material of the second conductivity type arranged between the first main surface and the well .

[0013] For example , the well may extend to a depth of more than 1 pm .

[0014] According to embodiments , the UV photodetector may further comprise a layer of UV transparent material on a side of the optical bandpass filter remote from the converter layer . According to embodiments , a UV photodetector comprises a first contact layer, a second metal contact , and a quantum dot layer arranged between the first contact layer and the second metal contact . The quantum dot layer is configured to generate electron hole pairs from incident radiation having a wavelength less than 500 nm .

[0015] According to further embodiments , UV photodetector comprises a first contact layer, a second metal contact , and an organic photodiode arranged between the first contact layer and the second contact layer . The organic photodiode is configured to generate electron hole pairs from incident radiation having a wavelength less than 500 nm .

[0016] For example , the UV photodetector may further comprise a semiconductor substrate . The first contact layer and the second metal contact may be arranged over the semiconductor substrate , the second metal contact being arranged on a side facing the semiconductor substrate .

[0017] According to embodiments , the UV photodetector may further comprise a housing comprising a package carrier and a UV transparent material layer . The first metal layer may be arranged on a side facing the UV transparent material layer .

[0018] According to embodiments , a sensor device comprises the UV photodetector as described above .

[0019] For example , the sensor device may be selected from an ambient light sensor, a scienti fic tool , or a detector for space observations or agriculture .

[0020] BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this speci fication . The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles . Other embodiments of the invention and many of the intended advantages will be readily appreciated, as they become better understood by reference to the following detailed description . The elements of the drawings are not necessarily to scale relative to each other . Like reference numbers designate corresponding similar parts .

[0021] Fig . 1 shows a schematic cross-sectional view of a UV photodetector according to embodiments .

[0022] Fig . 2 shows an example of absorption / emission characteristics of quantum dots .

[0023] Fig . 3A shows a cross-sectional view of a photodetector according to embodiments .

[0024] Fig . 3B shows a cross-sectional view of a UV photodetector according to further embodiments .

[0025] Fig . 3C shows a cross-sectional view of a UV photodetector according to further embodiments .

[0026] Fig . 4A shows a cross-sectional view of a UV photodetector according to further embodiments .

[0027] Fig . 4B is a cross-sectional view of a UV photodetector according to further embodiments . Fig. 5 is schematic view of a sensor device according to embodiments .

[0028] DETAILED DESCRIPTION

[0029] In the following detailed description reference is made to the accompanying drawings, which form a part hereof and in which are illustrated by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology such as "top", "bottom", "front", "back", "over", "on", "above", "leading", "trailing" etc. is used with reference to the orientation of the Figures being described. Since components of embodiments of the invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope defined by the claims.

[0030] The description of the embodiments is not limiting. In particular, elements of the embodiments described hereinafter may be combined with elements of different embodiments.

[0031] The terms "wafer", "substrate" or "semiconductor substrate" used in the following description may include any semiconductor-based structure that has a semiconductor surface. Wafer and structure are to be understood to include silicon, silicon-on-insulator (SOI) , silicon-on sapphire (SOS) , doped and undoped semiconductors, epitaxial layers of silicon supported by a base semiconductor foundation, and other semiconductor structures. The semiconductor need not be silicon-based. The semiconductor could as well be silicon-germanium, germanium, or gallium arsenide. According to other embodiments, silicon carbide (SiC) , gallium nitride ( GaN) or gallium oxide ( Ga2Os ) may form the semiconductor substrate material .

[0032] The terms " lateral" and "hori zontal" as used in thi s speci fication intends to describe an orientation parallel to a first surface of a substrate or semiconductor body . This can be for instance the surface of a wafer or a die .

[0033] The term "vertical" as used in this speci fication intends to describe an orientation which is arranged perpendicular to the first surface of a substrate or semiconductor body .

[0034] Fig . 1 shows a cross-sectional view of a UV photodetector 10 or a pixel 16 of a UV photodetector . The UV photodetector 10 comprises a photodiode 15 which is formed in a semiconductor substrate 100 . The semiconductor substrate 100 comprises a first main surface 101 which is a light incidence surface . Accordingly, incident electromagnetic radiation 20 enters the substrate 100 from the first main surface 101 . The UV photodetector 10 further comprises a converter layer 110 which is arranged over the first main surface 101 . The converter layer is configured to convert a wavelength smaller than 500 nm to a wavelength larger than 500 nm . The UV photodetector 10 further comprises an optical bandpass filter 115 which is configured to block electromagnetic radiation having a wavelength larger than 380 nm . The optical bandpass filter 115 is arranged on a side of the converter layer 110 remote from the semiconductor substrate 100 .

[0035] For example , the semiconductor substrate 100 may be a silicon substrate . For example , a portion 102 of the substrate may be doped with dopants of the second conductivity type , e . g . p-type . A well portion 105 of the first conductivity type , e . g . n-type , may be arranged in the substrate portion 102 of the second conductivity type . The substrate portion 102 of the second conductivity type is directly adj acent to the well portion 105 of the first conductivity type . As is illustrated in Fig . 1 , the well portion 105 may be directly adj acent to the first main surface 101 of the semiconductor substrate 100 . According to further embodiments , a doped portion of the second conductivity type may be arranged between the well portion 105 and the first main surface 101 , this may be in more detail explained with reference to Fig . 3B . The doped well portion 105 and the substrate portion 102 of the second conductivity type form a photodiode 15 . For example , the well portion 105 of the first conductivity type may extend to a depth of 1 pm or less depth d .

[0036] The photodetector 10 may comprise a plurality of single pixels 16 which are configured in the manner as illustrated in Fig . 1 .

[0037] For example , the photodetector 10 may implement a CMOS sensor . According to further embodiments , the photodetector 10 may also implement a di f ferent type of photodetector, e . g . a CCD sensor .

[0038] As is clearly to be understood, the photodetector 10 may comprise further elements for reading out signals that are generated in response to incident radiation . Since these elements are wel l known, they are omitted here for sake of clarity . For example , further elements may be arranged in the semiconductor substrate 100 . According to further implementations , further components may be arranged in a dielectric layer 108 that is arranged over the first main surface 101 . The dielectric layer 108 may comprise several dielectric layers to insulate components or wirings from each other .

[0039] The converter layer 110 is configured to convert a wavelength smaller than 500 nm to a wavelength larger than 500 nm. As a consequence , due to the conversion of the incident wavelength, an efficiency of the photodetector may be increased. The converter material contains a phosphor.

[0040] Examples of phosphors comprise metal oxides, metal halides, metal sulfides, metal nitrides and others. These compounds may further comprise additives that may result in specific wavelengths being emitted. For example, the additives may comprise rare earth materials. As an example of a yellow phosphor, YAG:Ce3+(cerium-activated yttrium aluminum garnet (Y3AI5O12) ) or (Sr1.7Bao.2Euo.!) SiO4may be employed. Further phosphors may be based on MSiO4:Eu2+, wherein M may be Ca, Sr or Ba. By selecting the cations with an appropriate concentration, a desired conversion wavelength may be selected. Many further examples of suitable phosphors are known.

[0041] According to implementations, the phosphor material, e.g. a phosphor powder may be embedded in a suitable matrix material. For example, the matrix material may comprise a resin or polymer composition such as a silicone or an epoxy resin. For example, a size of the phosphor particles may be in a micron- or nanometer size range.

[0042] According to further implementations, the matrix material may comprise a glass. By way of example, the converter material may be formed by sintering the glass, e.g. SiOo with further additives and phosphor powder to form a phosphor in glass (PiG) .

[0043] According to further implementations, the converter layer 110 may comprise quantum dots. To be more specific, the phosphor material may be in the form of nanoparticles or microcrystals that are implemented as quantum dots.

[0044] Quantum dots ("QDs" also referred to as semiconductor nanocrystals) are small crystals made of II-VI-, III-V-, IV-V- materials, which typically have a diameter of 1 nm to 20 nm, corresponding to the range of the de-Broglie wavelength of the charge carriers. The energy difference of the charge carrier states of a quantum dot is a function of the composition as well as of the physical size of the quantum dots. In other words, with a given material, by varying the size the emission spectrum of the quantum dots may be varied. As a consequence, by using quantum dots, a large range of wavelengths may be generated.

[0045] Usually, the quantum dots may comprise a core material, that is surrounded by a coating material. The band gap of the semiconductor core material may be smaller than the band gap of the semiconductor coating material. For example, the core may be made up of CdSe and the coating may comprise CdS as well as optionally further layers. According to further embodiments, the core may be composed of InP and the coating includes ZnS and, optionally, further layers. According to further embodiments, the coating may include an oxide. Powders made from these quantum dots nanoparticles are commercially available. Basically, quantum dots may comprise one or more of the following materials: CdS, CdSe, CdTe, CdPo, ZnS, ZnSe, ZnTe, ZnPo, HgS, HgSe, HgTe, MgS, MgSe, MgTe, PbSe, PbS, PbTe, GaN, GaP, GaAs, InP, InAs, CuInS2, CdSi-xSe, BaTiO3, PbZrO3, PbZrxTi2-xO3 , BaxSr2-x, SrTiO3, LaMnO3, CaMnO3und Lai-xCaxMnO3.

[0046] The quantum dots may be processed e.g. by spin coating. For example, the quantum dots can be cured into silicone or another suitable matrix material and may appear as a yellow powder.

[0047] An optical bandpass filter for selectively transmitting blue light may be arranged on a side of the converter layer remote from the semiconductor substrate. For example, the optical bandpass filter 115 may comprise a dielectric layer stack or a layer sequence of dielectric and metal layers. Accordingly, the optical bandpass filter 115 may be implemented as an interference filter . The optical bandpass filter 115 may block electromagnetic radiation having a wavelength larger than e . g . 380 nm . As a result , only UV light is transmitted to the converter layer 110 . The optical bandpass filter 115 may further be operable to reflect e . g . electromagnetic radiation of wavelengths larger than 500nm, that has been generated within the converter layer 110 . In this way, the detector ef ficiency may be further improved .

[0048] Due to the speci fic configuration illustrated in Fig . 1 , the UV part of incident radiation 20 is transmitted by the optical bandpass filter 115 and converted to wavelengths larger than 500 nm . The converted wavelength is then detected by the photodiode 15 . Due to the presence of the optical bandpass filter, electromagnetic radiation having a wavelength larger than 380 nm is reflected . As a result , incident radiation is selectively transmitted by the bandpass filter 115 . Further, radiation that has been converted by the converter layer 110 is reflected back towards the photodiode 15 . As a consequence , the ef ficiency of the UV photodetector is largely increased . Further, the manufacturing cost for manufacturing the UV photodetector may be reduced .

[0049] Optionally, the UV photodetector 10 may further comprise a UV transparent filter 116 that is configured to reflect electromagnetic radiation having a wavelength larger than 380 nm or 420 nm, e . g . visible light , towards the converter layer 110 . The UV transparent filter 116 may be arranged between the bandpass filter 115 and the converter layer 110 . For example , the UV transparent filter 116 may be implemented as a dielectric layer stack acting as an interference filter . For example, the converter layer 110 may work as a scintillator, where UV light is down-converted to either green light at a wavelength of 500 nm to 570 nm, e.g. approximately 510 nm or red light at a wavelength of 620 to 770 nm, e.g. approximately 630 nm. The down-converted light may be efficiently absorbed by the photodiode 15. For example, the quantum dot material may be Cd-based. The quantum dots may be engineered to have a separation of absorption and emission.

[0050] This is also illustrated in Fig. 2 which shows the absorption of the converter layer 110 which may be implemented as a Cd-based quantum dot layer. The absorption is illustrated by a solid line. Emission at a first wavelength (e.g. green light) is indicated by a broken line. Further, emission at a second wavelength, e.g. red, is indicated by a dotted line. As is illustrated in Fig. 2, the wavelengths of absorption and emission are separated. As a consequence, self-absorption of converted light is reduced. As a result, the efficiency of the UV photodetector may be increased .

[0051] Fig. 3A shows a cross-sectional view of a photodetector 10 or a pixel 16 according to further embodiments. In addition to elements illustrated in Fig. 1, the photodetector further comprises a UV reflection layer 118 which is arranged on a side of the converter layer 110 facing the semiconductor substrate 100. Due to the presence of the UV reflection layer 118, UV radiation that has been transmitted by the converter layer 110 and reflected, is reflected back to the converter layer 110. The UV photodetector 10 or pixel 16 may further comprise a layer of UV transparent material 121 on a side of the optical bandpass filter 115 remote from the converter layer 110. For example, the UV transparent material may comprise a polymer like acrylic or silicone, ceramics or glasses like quartz and fused silica or specialized UV glass compositions. Fig . 3B shows further elements that may be added to the UV photodetector 10 e . g . illustrated in Fig . 1 or 3A. For example , as is shown, the photodetector 10 may further comprise a silicon nitride layer 125 over the semiconductor substrate 100 , e . g . adj acent to the first main surface 101 . The silicon nitride layer 125 may e . g . have a thickness in the order of 50 nm . The si licon nitride layer 125 may be configured to absorb UV radiation . As a result , UV radiation may be prevented from reaching the photodiode 15 . Further, the silicon nitride layer 125 may be operable as an antireflection layer for green or red light . Hence , absorption of green or red light within the photodiode 15 may be improved . The silicon nitride layer 125 may be added without adding the UV reflection layer 118 .

[0052] The UV photodetector 10 may further comprise a portion 123 of the second conductivity type between the well portion 105 of the first conductivity type and the first main surface 101 . The portion 123 of the second conductivity type between the well portion 105 and the first main surface 101 may be generated using ion implantation . For example , the ion-implanted portion 123 may have a thickness of some 10 nm . The ion-implanted portion 123 is electrically connected to the well portion 105 of the photodiode 15 . Due to the presence of the ion-implanted portion 123 , UV radiation may be absorbed at the j unction between the ion- implanted portion 123 and the well portion 105 . This layer may prevent UV radiation from reaching the photodiode 15 arranged in a lower portion of the semiconductor substrate 100 . Photons that are absorbed in this portion do not contribute to a photodiode current . The ion-implanted portion 123 may be present in any of the embodiments described herein without further components explicitly shown in Fig . 3B being present . Fig. 3C shows a cross-sectional view of a photodetector 10 or pixel 16 according to further embodiments. Differing from embodiments described herein above, a depth of the well portion 105 is larger than in other embodiments. For example, the depth d may be larger than 1 pm, e.g. 1 to 4 pm. As a result, electromagnetic radiation having a larger wavelength may be absorbed at a higher ratio. In particular, red wavelengths may be absorbed at higher efficiencies.

[0053] Fig. 4A shows a cross-sectional view of a UV photodetector according to further embodiments. These embodiments are based on the finding that CdSe, PbS, InAs quantum dots are particularly efficient at absorbing UV radiation and converting the absorbed UV radiation into electron-hole pairs. Accordingly, electronhole pairs may be directly generated within the quantum dot layer layer 134 and may be separated upon application of a suitable electrical field.

[0054] Accordingly, the UV photodetector 10 illustrated in Fig. 4A comprises a first contact layer 130, a second metal contact 132 and a quantum dot layer 134 which is arranged between the first contact layer 130 and the second metal contact 132. The quantum dot layer 134 is configured to generate electron-hole pairs from incident radiation 20 having a wavelength less than 500 nm.

[0055] Instead of the quantum dot layer 134, an organic photodiode 136 may be arranged between the first contact layer 130 and the second metal contact 132. For example, the organic photodiode 136 may comprise a fullerene (C60) , optionally with additives. Transport layers for charge carriers may be arranged adjacent to an upper and a lower main surface of the fullerene material. A material of the transport layers may comprise siloxane polymers such as Polydimethylsiloxane (PDMS) . In alternative to siloxane polymers, further polymers such as PEDOT:PSS, PolyTPD, P3HT, PTAA, Spiro-OmeTAD or inorganic compounds like M0O3 and ZnO may be used .

[0056] For example , as is also illustrated in Fig . 4A, the UV photodetector 10 may comprise a plurality of pixels 16 , which may be arranged in a speci fic pattern . For example , the first contact layer 130 may be implemented as a conductive layer which is assigned to a plurality of pixels 16 . Further, each of the second metal contacts 132 may be assigned to corresponding ones of the pixels 16 . For example , a material of the first contact layer 130 may be a transparent conductive material such as a conductive transparent oxide e . g . ITO (" indium tin oxide" ) . A material of the second metal contact 132 may be selected so as to have a large reflectance in a wavelength range of UV radiation, e . g . 200-500 nm . Examples of the material may comprise TiN, TaN, W, aluminum, copper and others . Due to the presence of the second metal contacts 132 having a large reflectance in the wavelength range of UV radiation, UV light which has not been absorbed by the quantum dot layer 134 or the organic photodiode 136 may be reflected back into the quantum dot layer 134 or the organic photodiode 136 . The UV photodetector 10 further comprises a semiconductor substrate 138 . The first contact layer 130 and the second metal contact 132 are arranged over the semiconductor substrate 138 , the second metal contact 132 is arranged on a side facing the semiconductor substrate 138 .

[0057] Further, conductive elements 135 may implement an electrical connection between the quantum dot layer 134 or the organic photodiode 136 and peripheral circuitry, e . g . CMOS circuitry . The conductive elements 135 may be made of a conducting material like copper, tungsten or aluminum . As is further illustrated in Fig . 4A, the UV photodetector 10 may further comprise an optical bandpass filter 115 which selectively transmits UV radiation towards the quantum dot layer 134 or the organic photodiode 136 . For example , the optical bandpass filter 115 may be operable to reflect electromagnetic radiation of wavelengths larger than 420 nm towards the quantum dot layer 134 or the organic photodiode 136 .

[0058] During operation, a voltage may be applied between the first contact layer 130 and the second metal contact 132 in order to achieve separation of electron-hole pairs as is commonly known .

[0059] Fig . 4B shows a cross-sectional view of a UV photodetector 10 according to further examples . As is shown, elements of the UV photodetector 10 are housed in a housing that may comprise e . g . a package carrier 140 and a UV transparent material 121 , e . g . a UV transparent glass . The UV photodetector 10 further comprises a first contact layer 130 , a second metal contact 132 and a quantum dot layer 134 or an organic photodiode 136 arranged between the first contact and the second metal contact . For example , this arrangement may be placed over a suitable semiconductor substrate 138 , e . g . a silicon substrate . The semiconductor substrate may e . g . be attached to the package carrier 140 via a suitable adhesive 141 . For example , a dielectric layer 108 may be arranged between the quantum dot layer 134 or the organic photodiode 136 and the semiconductor substrate 138 . A first contact element 137 may electrically connect the first contact layer 130 to a suitable terminal . Further, a second contact element 139 may be electrically connected to the second metal contact 132 to suitably connect the second metal 132 contact to a respective terminal . For example , commonly known addressing schemes for activating pixels may be employed . Fig . 5 shows a schematic view of a sensor device 25 . The sensor device 25 comprises the UV photodetector 10 that has been described above . For example , the sensor device 25 may be an ambient light sensor, a scienti fic tool , a detector for space observations or agriculture .

[0060] While embodiments of the invention have been described above , it is obvious that further embodiments may be implemented . For example , further embodiments may comprise any subcombination of features recited in the claims or any subcombination of elements described in the examples given above . Accordingly, this spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein .

[0061] LIST OF REFERENCES

[0062] 10 UV photodetector

[0063] 15 photodiode

[0064] 16 pixel

[0065] 20 incident radiation

[0066] 25 sensor device

[0067] 100 semiconductor substrate

[0068] 101 first main surface

[0069] 102 substrate portion of second conductivity type

[0070] 105 well portion of first conductivity type

[0071] 108 dielectric layer

[0072] 110 converter layer

[0073] 115 optical bandpass filter

[0074] 118 UV reflection layer

[0075] 121 UV transparent layer

[0076] 123 ion-implanted portion

[0077] 125 silicon nitride layer

[0078] 130 first contact layer

[0079] 132 second metal contact

[0080] 134 quantum dot layer

[0081] 135 conductive element

[0082] 136 organic photodiode

[0083] 137 first contact element

[0084] 138 semiconductor substrate

[0085] 139 second contact element

[0086] 140 package carrier

[0087] 141 adhesive

Claims

CLAIMS1. A UV photodetector (10) comprising: a photodiode (15) formed in a semiconductor substrate (100) comprising a first main surface (101) being a light incidence surface; a converter layer (110) arranged over the first main surface (101) , the converter layer (110) being configured to convert a wavelength smaller than 500 nm to a wavelength larger than 500 nm, and an optical bandpass filter (115) configured to block electromagnetic radiation having a wavelength larger than 380 nm, the optical bandpass filter (115) being arranged on a side of the converter layer (110) remote from the semiconductor substrate (100) , wherein the optical bandpass filter (115) is operable to reflect electromagnetic radiation of wavelengths larger than 420 nm towards the converter layer (110) .

2. The UV photodetector (10) according to claim 1, wherein the converter layer (110) comprises quantum dots.

3. The UV photodetector (10) according to any of the preceding claims, further comprising a UV transparent filter (116) configured to reflect electromagnetic radiation having a wavelength larger than 420 nm towards the converter layer (110) , the UV transparent filter (116) being arranged between the bandpass filter (115) and the converter layer (110) .

4. The UV photodetector (10) according to any of the preceding claims, further comprising a UV reflection layer (118) arranged between the semiconductor substrate (100) and the converter layer (110) , the UV reflection layer (118) being configured to reflect electromagnetic radiation having a wavelength less than 500 nm.

5. The UV photodetector (10) according to any of the preceding claims, further comprising a silicon nitride layer (125) arranged adjacent to the first main surface (101) .

6. The UV photodetector (10) according to any of the preceding claims, wherein the photodiode (15) comprises a well (105) of doped semiconductor material of a first conductivity type in a semiconductor substrate portion (102) of a second conductivity type, further comprising a portion (123) of semiconductor substrate material of the second conductivity type arranged between the first main surface (101) and the well (105) .

7. The UV photodetector (10) according to any of the preceding claims, wherein the photodiode (15) comprises a well of doped semiconductor material (105) of a first conductivity type in a semiconductor substrate portion (102) of a second conductivity type, wherein the well (105) extends to a depth of more than 1 pm.

8. The UV photodetector (10) according to any of the preceding claims, further comprising a layer (121) of UV transparent material on a side of the optical bandpass filter (115) remote from the converter layer (110) .

9. A UV photodetector (10) , comprising a first contact layer (130) , a second metal contact (132) , a quantum dot layer (134) arranged between the first contact layer (130) and the second metal contact (132) , the quantum dot layer (134) being configured to generate electron hole pairs from incident radiation having a wavelength less than 500 nm,and a semiconductor substrate (138) , the first contact layer (130) and the second metal contact (132) being arranged over the semiconductor substrate (138) , the second metal contact (132) being arranged on a side facing the semiconductor substrate (138) .

10. A UV photodetector (10) , comprising a first contact layer (130) , a second metal contact (132) , an organic photodiode (136) arranged between the first contact layer (130) and the second contact layer (132) , the organic photodiode (136) being configured to generate electron hole pairs from incident radiation having a wavelength less than 500 nm, and a semiconductor substrate (138) , the first contact layer (130) and the second metal contact (132) being arranged over the semiconductor substrate (138) , the second metal contact (132) being arranged on a side facing the semiconductor substrate (138) .

11. The UV photodetector (10) according to claim 9 or 10, further comprising an optical bandpass filter (115) configured to block electromagnetic radiation having a wavelength larger than 380 nm, the optical bandpass filter (115) being arranged on a side of the converter layer (110) remote from the semiconductor substrate (100) .

12. The UV photodetector (10) according to claim 11, wherein the optical bandpass filter (115) is operable to reflect electromagnetic radiation of wavelengths larger than 420 nm.

13. The UV photodetector (10) according to any of claims 9 to 12, further comprising a housing comprising a package carrier (140) and a UV transparent material layer (121) , the firstcontact layer (130) being arranged on a side facing the UV transparent material layer (121) .

14. A sensor device (25) comprising the UV photodetector (10) according to any of the preceding claims.

15. The sensor device (25) according to claim 14, being selected from an ambient light sensor, a scientific tool, a detector for space observations or agriculture.

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