Electronic device with quantum dot-based pixels

Abstract

Electronic device The present description relates to an electronic device (200) comprising: at least one first pixel (231, 232, 233, 234) having a monojunction; at least one second pixel (235) comprising a heterojunction, based on quantum dots; at least one first filter (122, 124, 126, 128) of a first color, allowing only the wavelengths of said first color and infrared to pass through, arranged vertically above the first pixel (231, 232, 233, 234), and at least partially above the second pixel (235); and an optical element (210) interposed between the first filter and the second pixel; the first filter (122, 124, 126, 128) and the optical element (210) being configured so that the first pixel (231, 232, 233, 234) receives wavelengths of said first color and the second pixel (235) receives only infrared wavelengths. Figure for the abbreviation: Fig. 4

Description

Title of the invention: Electronic device with quantum dot-based pixels. Technical field

[0001] This description relates generally to electronic devices and more specifically to optoelectronic devices comprising photodiodes and associated processes. Previous technique

[0002] A photodiode is a semiconductor component having the ability to capture radiation from the optical domain and transform it into an electrical signal.

[0003] In a common type of photodiode, the space charge region is located in a semiconductor material, usually silicon. However, silicon is poorly reactive to near-infrared (NIR) and short-wave infrared (SWIR) wavelengths. Summary of the invention

[0004] There is a need to provide devices that are sensitive to both wavelengths in the visible range and wavelengths in the infrared range.

[0005] An embodiment overcomes all or part of the disadvantages of known devices.

[0006] One embodiment provides an electronic device comprising: at least one first pixel having a monojunction; at least a second pixel including a heterojunction, based on quantum dots; at least one first filter of a first color, allowing only the wavelengths of said first color and infrared to pass through, arranged directly above the first pixel, and at least partially above the second pixel; and an optical element interposed between the first filter and the second pixel; the first filter and the optical element being configured so that the first pixel receives wavelengths of said first color and the second pixel receives only infrared wavelengths.

[0007] Another embodiment provides a method for manufacturing a device comprising: obtain a first filter of a first color allowing only the wavelengths of said first color and infrared to pass through, and arranged vertically, with at least a first pixel, and at least partially with a second pixel, the first pixel having a monojunction and the second pixel comprising a heterojunction based on quantum dots; insert an optical element between the first filter and the second pixel (235); the first filter and the optical element being configured so that the first pixel receives wavelengths of said first color and the second pixel receives only infrared wavelengths.

[0008] According to one embodiment, the device comprises: at least one third pixel having a monojunction; at least one second filter of a second color, allowing only the wavelengths of said second color and infrared to pass through, arranged vertically, above the third pixel and at least partially above the second pixel (235); the optical element being interposed between the second filter and the second pixel (235); the second filter and the optical element being configured so that the third pixel receives wavelengths of said second color and the second pixel receives only infrared wavelengths.

[0009] According to one embodiment, the heterojunction is sensitive to infrared wavelengths.

[0010] According to one embodiment, the said monojunction(s) are sensitive to wavelengths in the visible range.

[0011] According to one embodiment, the optical element comprises an interference mirror configured to allow infrared wavelengths to pass to the second pixel, and to reflect visible wavelengths.

[0012] According to one embodiment, the optical element includes an optical switching element configured to direct infrared wavelengths towards the second pixel, and visible wavelengths towards a pixel different from the second pixel.

[0013] According to one embodiment, said interference mirror is intercalated between the second pixel and the optical switching element.

[0014] According to one embodiment, the optical switching element comprises a meta surface.

[0015] According to one embodiment, said meta surface comprises metal oxide pillars in a matrix comprising a nitride.

[0016] According to one embodiment, at least two of the pixels are electrically isolated from each other by an insulated conductive wall configured to be connected to a voltage rail receiving a negative voltage.

[0017] According to one embodiment, the second pixel comprises a first doped region of a first type of conductivity, the first region comprising a first layer and a second layer forming said heterojunction, the first layer being in a semiconductor material and the second layer comprising said quantum dots.

[0018] According to one embodiment, the second pixel includes a second doped region of a second type of conductivity, the second region being in contact with the second layer.

[0019] According to one embodiment, the first layer is laterally surrounded by said insulated conductive wall, the concentration of dopants in the first layer being greater than that in the second layer.

[0020] According to one embodiment, the first pixel and / or the third pixel comprises a first region with a first layer doped with the first type of conductivity, and a second region doped with the second type of conductivity.

[0021] According to one embodiment, the first layer of the first region of the second pixel includes a notch, the second layer being at least partly formed in said notch.

[0022] One embodiment provides a method of using the device described above, comprising acquiring images in the visible from at least the first pixel and in the infrared from the second pixel. Brief description of the drawings

[0023] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0024] [Fig.1] schematically represents an example of an electronic device;

[0025] Figure 2 schematically represents one embodiment of a device electronics;

[0026] [Fig.3] represents a cross-sectional view along plane AA of an embodiment of the device of [Fig.2];

[0027] [Fig. 4] represents a cross-sectional view along plane AA of another embodiment of the device of [Fig. 2]; and

[0028] [Fig.5] represents a cross-sectional view along plane AA of another embodiment of the device of [Fig.2]. Description of the implementation methods

[0029] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0030] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0031] Unless otherwise specified, when referring to two interconnected elements, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, it means that these two elements can be connected or linked through one or more other elements.

[0032] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0033] Unless otherwise specified, the expressions "approximately", "about", "Sensibly" and "on the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0034] Fig. 1 schematically represents an example of an electronic device 100.

[0035] In the example shown, the device 100 includes, for example, several color filters 122 (G), 124 (B), 126 (R), 128 (G). In one example, each of these filters 122, 124, 126, 128 only allows the visible wavelengths associated with that color to pass through. For example, filter 122 only allows wavelengths of green to pass through, filter 124 only wavelengths of blue, filter 126 only wavelengths of red, and filter 128 only wavelengths of green. In other words, the wavelengths emanating from a filter of a given color are included, for example, more than 50%, preferably more than 80%, and even more preferably more than 90%, in the spectrum associated with that color.In one example, even though filters 122, 124, 126, 128 allow the selection, in the visible range, of the wavelengths associated with their color in the visible range, they allow a majority of the incident infrared radiation to pass through.

[0036] These filters 122, 124, 126, 128 are for example arranged according to a Bayer matrix.

[0037] In one example, the device 100 comprises several, or even dozens, or hundreds, or preferably thousands of sets 120 formed by the four filters.

[0038] In another example, each set 120 includes only one of the filters or only two filters of different colors or even three filters of different colors or not.

[0039] In the text, the color green includes wavelengths between approximately 520 and 565 nm, the color red includes wavelengths between approximately 625 and 740 nm, and the color blue includes wavelengths between approximately 450 and 500 nm. Other filters associated with other visible colors are also possible, such as yellow, orange, cyan, indigo, or violet filters.

[0040] In the text, the infrared domain includes, for example, short-wave infrared (SWIR) wavelengths. In other words, in the text, infrared includes, by Examples include wavelengths greater than or equal to 1 pm, for example 1.1 pm or 1.130 pm. Near-infrared (NIR), with wavelengths ranging from 780 to 1 pm, can also be considered in the following examples, for example by changing the size or nature of quantum dots.

[0041] In the example shown, the device 100 further comprises a matrix 130 of four pixels 131 (L), 132 (B), 133 (R), 134 (L) arranged vertically above the assembly 120. Each of these pixels 131 (L), 132 (B), 133 (R), 134 (L) comprises, for example, a monojunction formed, for example, in a semiconductor substrate 135 such as silicon and is configured to convert the visible wavelengths it receives into electrical charges. The processing of these charges, by a circuit not shown, gives rise to a signal which is then processed to form images, for example.

[0042] In the example shown, each pixel 131, 132, 133, 134 is arranged in line with one of the filters of the set 120. For example, pixel 131 is arranged in line with filter 122, pixel 132 in line with filter 124, pixel 133 in line with filter 126 and pixel 134 in line with filter 128.

[0043] In one example, the device 100 comprises several, or even tens, or hundreds, or preferably thousands of pixel matrices 130 formed by the four pixels 131, 132, 133, 134.

[0044] In another example, each matrix 130 includes only one of the pixels or only two pixels or even three pixels.

[0045] However, using silicon monojunctions for the pixels does not allow for the capture of infrared spectrum information for the same images. Such information can be useful, for example, for determining time of flight or calculating distances.

[0046] It is possible to use pixels employing infrared and visible-sensitive quantum dots to capture both the visible and infrared wavelengths of the same image. However, the efficiency of these devices is limited in the visible range due to the small band gap and high defect density.

[0047] Other solutions, called Above Interconnects (ABIC), are complex to implement with the increasingly high resolutions required and they also suffer from a loss of performance related to dark current and noise.

[0048] To overcome these drawbacks, the described embodiments provide for a device comprising: at least one first pixel having a monojunction; at least a second pixel including a heterojunction, based on quantum dots; at least one first filter of a first color, allowing only the wavelengths of said first color and infrared to pass through, arranged directly above the first pixel, and at least partially above the second pixel; and an optical element interposed between the first filter and the second pixel; the first filter and the optical element being configured so that the first pixel receives wavelengths of said first color and the second pixel receives only infrared wavelengths.

[0049] This solution allows the use of a standard Bayer grid and therefore does not require complex development on image reconstruction.

[0050] Separating visible wavelengths from infrared wavelengths is simpler to implement than separating wavelengths in the visible range from each other.

[0051] This solution also makes it possible to improve the external quantum efficiency (EQE) for each wavelength channel.

[0052] Wavelength rejection is also improved by separating visible and infrared wavelengths.

[0053] The fact that quantum dots are not used in all pixels makes it possible to avoid infrared absorption in pixels with a monojunction, which ultimately improves the rejection between visible and infrared wavelengths in each channel.

[0054] This architecture also makes it possible to limit dark currents because there is no injection of charges by electrodes.

[0055] Noise is also reduced while allowing for simple manufacturing.

[0056] This solution also makes it possible to limit the crosstalk between pixels by means of the physical separation between visible pixels with infrared pixels.

[0057] Figure 2 schematically represents one embodiment of a device electronic 200.

[0058] In the example shown, the device 200 includes an optical assembly similar to the assembly 120.

[0059] In the example shown, the device 200 further includes a matrix 230 of five pixels 231 (G), 232 (B), 233 (R), 234 (G), and 235 (Ir) arranged vertically above the assembly 120. Each of the pixels 231 (G), 232 (B), 233 (R), 234 (G) of the matrix 230 includes, for example, a monojunction formed in a semiconductor substrate 245, such as silicon, and is configured to transform the visible wavelengths it receives into electrical charges.

[0060] Pixel 235, for example, comprises a heterojunction formed from a layer 260, having quantum dots, arranged in contact with a semiconductor structure, for example silicon-based. This semiconductor structure is for example also present in pixels 231, 232, 233, 234 which limits design costs.

[0061] Layer 260 is arranged, for example, only at the level of pixel 235 and does not extend above the visible domain pixels 231, 232, 233 and 234. This improves the optical rejection between pixels 231, 232, 233 and 234 and pixel 235. The localization of layer 260 is achieved, for example, by etching a layer containing the quantum dots or by localized deposition.

[0062] A quantum dot or semiconductor nanoparticle is a nanoscopic material structure that produces electron-hole pairs in the presence of the incidence of photons on the nanoscopic material structure.

[0063] A quantum dot comprises a semiconductor core. A quantum dot may also comprise an envelope, preferably made of a semiconductor material, surrounding the core to protect and passivate it. A quantum dot further comprises ligands, aliphatic organic compounds, organometallic or inorganic molecules that extend from the envelope and passivate, protect, and functionalize the semiconductor surface.

[0064] The composition of a quantum dot can be chosen from the following materials. The core is, for example, made of one of the following materials or an alloy of the following materials: CdSe, CdS, CdTe, CdSeS, CdTeSe, AgS, ZnO, ZnS, ZnSe, CuInS, CuInSe, CuInGaS, CuInGaSe, PbS, PbSe, PbSeS, PbTe, InAsSb, InAs, InSb, InGaAs, InP, InGaP, InAlP, InGaAlP, InZnS, InZnSe, InZnSeS, HgTe, HgSe, HgSeTe, Ge, Si. The shell is, for example, made of one of the following materials or an alloy of the following materials: CdSe, CdS, CdTe, CdSeS, CdTeSe, AgS, ZnO, ZnS, ZnSe, CuInS, CuInSe, CuInGaS. CuInGaSe, PbS, PbSe, PbSeS, PbTe, InAsSb, InAs, InSb, InGaAs, InP, InGaP, InAlP, InGaAlP, InZnS, InZnSe, InZnSeS, HgTe, HgSe, HgSeTe, Ge, Si.

[0065] Preferably, all dimensions of the core are less than 20 nm, for example in the range of 2 to 15 nm. In particular, the diameter of each quantum dot is preferably in the range of 2 to 15 nm. By diameter, we mean the diameter of the smallest sphere in which the quantum dot can be inscribed.

[0066] It is possible to choose a size and dimension of quantum dots capable of absorbing, with significant absorption, any wavelength within a wide wavelength range. For example, it is possible to find a size and dimension of quantum dots having an operating wavelength greater than 1 pm, for example between 1 pm and 3 pm, which includes the near-infrared and short-wave infrared. For example, layer 260 includes quantum dots made of InAs, PbS, HgTe, or PbSe, with, for example, a radius less than 10 nm, to obtain an absorption peak linked to quantum confinement in the short infrared, for example 1130 nm or 1360 nm.

[0067] The layer 260 has, for example, a thickness between 100 nm and 500 nm.

[0068] In the example shown, pixel 235 is arranged at the center of matrix 230 of so that it is surrounded by pixels 231, 232, 233, 234. Compared to matrix 130 of [Fig.1], the receiving surface of incident light on each of pixels 231, 232, 233 and 234 is reduced by part of the footprint of the central pixel 235.

[0069] In the example shown, pixel 233 is separated from pixel 232 via pixel 235, and pixel 231 is separated from pixel 234 via pixel 235. This improves crosstalk performance.

[0070] In one example, the surface extent of matrix 230 is similar to that of matrix 130.

[0071] In the example shown, filter 122 is arranged directly above pixel 231 and at least partially above pixel 235; filter 126 is arranged directly above pixel 233 and at least partially above pixel 235; filter 128 is arranged directly above pixel 234 and at least partially above pixel 235; and filter 124 is arranged directly above pixel 232 and at least partially above pixel 235.

[0072] In one example, the device 200 comprises several, or even dozens, or hundreds, or preferably thousands of pixel matrices 230.

[0073] In an example not shown, each matrix 230 comprises only one of the pixels 231, 232, 233 or 234 and pixel 235. In this case, only one of the filters 122, 124, 126, or 128 is present in the associated set 120.

[0074] In an example not shown, each matrix 230 comprises only two of the pixels 231, 232, 233 or 234 and pixel 235. In this case, only two of the filters 122, 124, 126, or 128 are present in the associated set 120.

[0075] In an example not shown, each matrix 230 comprises only three of the pixels 231, 232, 233 or 234 and pixel 235. In this case, only three of the filters 122, 124, 126, or 128 are present in the associated set 120.

[0076] In the example shown, an optical element 210 (OPT) is interposed between at least one of the filters 122, 124, 126, 128 of the assembly 120 and at least one of the pixels 231, 232, 233, 234, 235 of the matrix 230. In other words, the optical element 210 is arranged above at least one region of one of the filters 122, 124, 126, 128 of the assembly 120, and between a plane in which the filters are formed and a plane of the layer 260, so as to cover at least the pixel 235.

[0077] The filter(s) of assembly 120 and the optical element 210 are configured so that the pixel(s) 231, 232, 233, 234 receive wavelengths of the color of the associated filter but also infrared, and that pixel 235 only receives infrared wavelengths.

[0078] In one example, the optical element 210 includes an interference mirror, or Bragg mirror, configured to allow infrared wavelengths to pass to pixel 235, and to reflect visible wavelengths.

[0079] In one example, the interference mirror consists of a stack of layers of SiON and amorphous silicon a-Si, having for example respective thicknesses of 125 nm and 50 nm.

[0080] The interference mirror, or Bragg mirror, makes it possible to improve the rejection of visible wavelengths which could pollute the signal generated by the pixel dedicated to infrared.

[0081] In another example, the optical element 210 includes an optical switching element configured to direct infrared wavelengths towards pixel 235, and visible wavelengths towards one of pixels 231, 232, 233, 234. In other words, the optical switching element is configured to, for example, deflect visible wavelengths from filters 122, 124, 126 or 128 by a certain angle and deflect infrared wavelengths from filters 122, 124, 126 or 128 by another angle. In this way, infrared wavelengths are directed towards pixel 235, while visible wavelengths are directed towards at least one of pixels 231, 232, 233, 234.

[0082] In one example, the optical switching element 210 comprises a meta-surface. This meta-surface comprises, for example, pillars or reliefs formed in a material with a high optical index (or refractive index), for example above 2, for example in a metal oxide, for example in TiO2. In one example, these pillars are arranged in a matrix with a lower optical index, for example a nitride, for example silicon nitride.

[0083] The arrangement and shape of the pillars or reliefs with a high optical index can be simulated to obtain the different deviations according to the desired wavelengths.

[0084] The implementation of the optical switching element makes it possible to improve the external quantum efficiency of each channel since this compensates for the reduction in the size of pixels 231, 232, 233, 234 for the integration of pixel 235.

[0085] In one example, the optical element 210 comprises an interference mirror, or a Bragg mirror, and the optical switching element where the interference mirror is intercalated between the pixel 235 and the optical switching element.

[0086] In the example shown, a section plane AA crosses vertically through filters 124 and 126, optical element 210, layer 260, and pixels 232, 233 and 235.

[0087] Fig. 3 represents a cross-sectional view along plane AA of an embodiment of device 200 of Fig. 2.

[0088] In the example shown, pixels 232, 235, and 233 are arranged next to each other. Pixel 235 is positioned between pixels 232 and 233, which avoids the phenomenon of crosstalk.

[0089] In this example, pixel 232 is arranged vertically above filter 124, pixel 235 is arranged vertically above part of filter 124 and vertically above part of filter 126, and pixel 233 is arranged vertically above filter 126.

[0090] In the example shown, the optical element 210 is intercalated between the plane formed by the filters 124 and 126 and the plane formed by a face of the pixels 232, 233 and 235 oriented towards the filters.

[0091] In the example shown, the optical element 210 includes the optical switching element 309 and the interference mirror 330. In this example, the optical switching element 309 extends under the filters 124 and 126 so as to be able to deflect the visible wavelengths Xvis1, Xvis2 differently from the infrared wavelengths Xswir. Thus, pixel 232 receives visible wavelengths Xvis1 from the color of filter 124, pixel 233 receives visible wavelengths Xvis2 from the color of filter 126, and pixel 235 receives infrared wavelengths Xswir from optical element 210. The optical switching element 309 comprises pillars 321 with a high refractive index arranged in a matrix 322 with a lower refractive index. It is also possible for the refractive indices of the pillars 321 and their matrix 322 to be reversed.

[0092] In the example shown, the optical element 210 further includes the interference mirror 330. In this example, the interference mirror comprises a double stack of two layers 332 and 333. Layers 332 are, for example, approximately 125 nm thick layers of SiON, and layers 333 are, for example, approximately 50 nm thick layers of amorphous silicon. The purpose of this interference mirror is to allow the passage of infrared wavelengths while rejecting, i.e., for example, by reflecting, visible wavelengths Xvis1 or Xvis2. The number of layers 332 and 333 can be greater than 2, for example, on the order of ten. The interference mirror is, for example, arranged so as to horizontally cover only pixel 235 and not pixels 232 and 233.

[0093] In the example shown, the interference mirror is surrounded laterally, for example, by an insulator 354 which is, for example, different from an insulator 322 surrounding the pillars 321. This insulator is, for example, a silicon oxide.

[0094] In the example of [Fig.3], the layer 260 which includes the quantum dots (QF-N) is located vertically between the interference mirror 330 and a structure 301 of the pixel 235 and horizontally so as to slightly overflow from the structure 301. The layer 260 is surrounded laterally for example by the insulator 354.

[0095] In the example shown, the pixels dedicated to the visible 232 and 233 include a structure 301 similar to that of pixel 235.

[0096] The structure 301 is formed in a semiconductor substrate, for example silicon. The structure 301 comprises a first layer 352 (Si-N) of a first type of conductivity, for example type N. In one example, the thickness of the layer 352 is about 5 to 10 pm.

[0097] In one example, the first layer 352 of pixel 232 receives the visible wavelengths Xvis1 of the color of filter 124, and the first layer 352 of pixel 233 receives the visible wavelengths Xvis2 of the color of filter 126.

[0098] One face of the first region 352 of the structure 301 of pixel 235, oriented towards the optical filters, is in contact with the quantum dot layer 260. This forms the heterojunction of pixel 235. Layer 260 comprises, for example, quantum dots of the same type of conductivity as layer 352, for example, type N. Layer 260 constitutes the photosensitive layer of the photodiode created. In pixel 235, the heterojunction receives infrared wavelengths Xswir from the filters 124, 126 and the optical element 210 and transforms them into electron-hole pairs.

[0099] In one example, the adjacent pixels 232, 233, 235 are electrically isolated from each other by a conductive wall 357 insulated with an electrical insulator 358 and configured to be connected to a voltage rail receiving a negative voltage, for example -IV. This also allows the first layer 352 of the different pixels to be depleted and creates pinch diodes that absorb the photogenerated electrons.

[0100] In the example shown, pixel 235 includes a region 356 (P++ Si) doped with a second type of conductivity, for example P, which is in at least partial contact with the first layer 352. This region 356 is further arranged between the walls 357, 358 and the first layer 352. In one example, the dopant concentration of region 356 is high (P++), for example 118 at.cm3. Region 356, in the case of pixel 235, advantageously allows the band gap difference between layer 260 and the first layer 352 of this pixel to be adjusted in order to allow the removal of photogenerated holes in layer 260. The negatively polarized walls and the region 356 heavily doped with the second type of conductivity create an electric field that enhances the field effect. The arrangement of region 356 also helps to avoid the influence of dark currents. In one example, region 356 is optional or has a lower dopant concentration.

[0101] In the example shown, the pixels dedicated to visible light 232 and 233 also include the region 356 arranged similarly to pixel 235, except that it is not in contact with a quantum dot layer but with the insulator covering the face of the first layer 352 of the respective pixel. For these pixels dedicated to visible light, the region 356 is optional although it is advantageous for amplifying silicon depletion and limiting dark current.

[0102] In the example shown, each pixel 232, 233, 235 comprises a detection node 361 connected, preferably linked, to a structure forming a vertical MOS transistor, for example, cylindrical. This transistor is formed by a region 368, of the first type of conductivity, for example, type N, with a high dopant concentration, in contact with the detection node 361, and configured to form a channel. This region 368 is surrounded by a control gate, for example, vertically cylindrical, formed of a conductive core 359, for example, of polysilicon, which is insulated from the region 368 by an insulator 365, for example, silicon oxide. A zone 363, which is part of layer 352, is arranged in contact with zone 368 while being surrounded by insulator 365. A zone 362, doped according to the second type of conductivity, connects for example the region 356 of each pixel to the control grid 359, 365.This area 362 allows for the electrostatic isolation of the pixel's transistors, such as amplifiers and transfer transistors, and controls the potential of layer 356 to discharge the photogenerated electrons. By negatively biasing the control gate, the channel is closed to store the photogenerated electrons, and by positively biasing it, the electrons are discharged to form the signal of the respective pixel. Pixels 232 and 233 thus generate a signal from visible photons linked to the color of their respective filters, and pixel 235 generates a signal from infrared photons passing through filters 124 and 126.

[0103] In the example shown, the color filters 124 and 126 are surmounted by microlenses 302 and 304 respectively. These microlenses make it possible to focus the incident light (represented by an arrow in [Fig.3]) towards the filters and associated pixels.

[0104] Figure [Fig. 4] shows a cross-sectional view of another embodiment of device 200 of Figure [Fig. 2],

[0105] The example in [Fig. 4] is similar to that in [Fig. 3] except that layer 352 of pixel 235 includes a notch 452 in which a portion of layer 260 is arranged. This enhances the field effect. This notch 452 is obtained, for example, by etching layer 352.

[0106] Fig. 5 represents a cross-sectional view along plane AA of another embodiment of the device of Fig. 2.

[0107] The example shown is similar to that of [Fig. 4] except that an optical guiding and reflecting element 530 is optionally arranged between the photodiode structures 301 and a metallic interconnecting layer 520 which is connected, for example, to the individual pixels. The optical guiding and reflecting element 530 is arranged so as to allow the infrared wavelengths to be redirected passing through pixels 232 and 233 to pixel 235 so that they are absorbed by the photosensitive layer 260, thus increasing the quantum efficiency of pixel 235. In the example shown, infrared wavelengths not absorbed by the pixels dedicated to visible light are reflected off the interconnections (illustrated by arrows in the figure) to be redirected to pixel 235, which is dedicated to infrared absorption. In one example, the optical guiding and reflection element 530 includes, for instance, one or more reflective meta-surfaces.

[0108] The device 200 can be used for example in smartphones, in systems using cameras, in sensors sensitive to visible light and for measuring distances, for facial or shape detection, or even in the automotive field.

[0109] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will be apparent to those skilled in the art. In particular, although Figures 3 and 4 show the optical element 210 as comprising both the optical switching element 309 and the interference mirror 330, it is also possible that the optical element 210 comprises only the optical switching element 309 or only the interference mirror 330. In the case where the optical element 210 comprises only the interference mirror 330, the pixels dedicated to visible light may receive infrared wavelengths. However, since these pixels are based on a silicon monojunction, for example, they are practically insensitive to these infrared wavelengths.

[0110] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional specifications given above. In particular, with regard to the examples in Figures 3 and 4, a person skilled in the art can also apply their teachings with 230 pixel matrices composed of only one pixel dedicated to visible wavelengths and one pixel dedicated to infrared. In this case, only one visible color filter can be considered per set 120. A person skilled in the art can also implement 230 pixel matrices composed of only two pixels dedicated to visible wavelengths and one pixel dedicated to infrared. In this case, two different visible color filters can be considered per set 120.The skilled professional will also be able to implement 230 pixel matrices composed solely of three pixels dedicated to visible wavelengths and one pixel dedicated to infrared. In this case, two or three different visible color filters can be used per 120 array.

Claims

Demands

1. Electronic device (200) comprising: at least one first pixel (231, 232, 233, 234) having a monojunction; at least one second pixel (235) comprising a heterojunction, based on quantum dots; at least one first filter (122, 124, 126, 128) of a first color, allowing only the wavelengths of said first color and infrared to pass through, arranged vertically above the first pixel (231, 232, 233, 234), and at least partially above the second pixel (235); and an optical element (210) interposed between the first filter and the second pixel; the first filter (122, 124, 126, 128) and the optical element (210) being configured so that the first pixel (231, 232, 233, 234) receives wavelengths of said first color and that the second pixel (235) receives only infrared wavelengths.

2. Device according to claim 1, wherein the device (200) comprises: at least one third pixel (231, 232, 233, 234) having a single junction; at least one second filter (122, 124, 126, 128) of a second color, allowing only the wavelengths of said second color and infrared to pass through, arranged vertically above the third pixel (231, 232, 233, 234) and at least partially above the second pixel (235); the optical element (210) being interposed between the second filter (122, 124, 126, 128) and the second pixel (235); the second filter (122, 124, 126, 128) and the optical element (210) being configured so that the third pixel receives wavelengths of said second color and that the second pixel (235) receives only infrared wavelengths.

3. Device according to claim 1 or 2, wherein the heterojunction is sensitive to infrared wavelengths.

4. Device according to any one of claims 1 to 3, wherein said monojunction(s) are sensitive to wavelengths in the visible range.

5. Device according to any one of claims 1 to 4, wherein the optical element (210) comprises an interference mirror (330) configured to allow infrared wavelengths to pass to the second pixel (235), and to reflect visible wavelengths.

6. Device according to any one of claims 1 to 5, wherein the optical element (210) comprises an optical switching element (309) configured to direct infrared wavelengths to the second pixel (235), and visible wavelengths to a pixel different from the second pixel.

7. Device according to claim 5 or 6 in its dependence on claim 5, wherein said interference mirror is intercalated between the second pixel and the optical switching element.

8. Device according to claim 6 or 7 in its dependence on claim 6, wherein the optical switching element comprises a meta surface.

9. Device according to claim 8, wherein said meta surface comprises metal oxide pillars in a matrix comprising a nitride.

10. Device or method according to any one of claims 1 to 9, wherein at least two of the pixels (231, 232, 233, 234, 235) are electrically isolated from each other by an insulated conductive wall (357, 358) configured to be connected to a voltage rail receiving a negative voltage.

11. Device according to any one of claims 1 to 10, wherein the second pixel (235) comprises a first doped region of a first type of conductivity, the first region comprising a first layer (352) and a second layer (260) forming said heterojunction, the first layer (352) being in a semiconductor material and the second layer (260) comprising said quantum dots.

12. Device according to claim 11, wherein the second pixel (235) comprises a second region (356) doped with a second type of conductivity, the second region (356) being in contact with the second layer (260).

13. Device according to claim 11 in its dependence on claim 10 or according to claim 12 in its dependence on claims 10 and 11, wherein the first layer (352) is laterally surrounded by said insulated conductive wall (357, 358), the concentration of dopants of the first layer (352) being greater than that of the second layer (260).

14. Device according to any one of claims 4 or 5 to 13 in their dependence on claim 4, wherein the first pixel (231, 232, 233, 234) and / or the third pixel (231, 232, 233, 234) comprises a first region with a first layer (352) doped with the first type of conductivity, and a second region (356) doped with the second type of conductivity.

15. Device according to any one of claims 11 or 12 to 14 in their dependence on claim 11, wherein the first layer (352) of the first region of the second pixel (235) comprises a notch (452), the second layer (260) being at least partly formed in said notch (452).

16. A method of manufacturing the device according to any one of claims 1 to 15 comprising: - obtaining the first filter; and - interposing the optical element (210) between the first filter and the second pixel (235); the first filter (122, 124, 126, 128) and the optical element (210) being configured so that the first pixel (231, 232, 233, 234) receives wavelengths of said first color and the second pixel (235) receives only infrared wavelengths.

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