WO2019213709A1 - Photosensitive device - Google Patents

Photosensitive device Download PDF

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Publication number
WO2019213709A1
WO2019213709A1 PCT/AU2019/050428 AU2019050428W WO2019213709A1 WO 2019213709 A1 WO2019213709 A1 WO 2019213709A1 AU 2019050428 W AU2019050428 W AU 2019050428W WO 2019213709 A1 WO2019213709 A1 WO 2019213709A1
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WO
WIPO (PCT)
Prior art keywords
photodetector
sub
sensor device
electromagnetic sensor
substrate
Prior art date
Application number
PCT/AU2019/050428
Other languages
French (fr)
Inventor
Ann ROBERTS
Timothy Denis JAMES
Evgeniy PANCHENKO
Original Assignee
The University Of Melbourne
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2018901585A external-priority patent/AU2018901585A0/en
Application filed by The University Of Melbourne filed Critical The University Of Melbourne
Publication of WO2019213709A1 publication Critical patent/WO2019213709A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/30—Measuring the intensity of spectral lines directly on the spectrum itself
    • G01J3/36—Investigating two or more bands of a spectrum by separate detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2803—Investigating the spectrum using photoelectric array detector
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/008—Surface plasmon devices
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/201—Filters in the form of arrays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/204—Filters in which spectral selection is performed by means of a conductive grid or array, e.g. frequency selective surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/208—Filters for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/26—Reflecting filters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0005—Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
    • G03F7/0007—Filters, e.g. additive colour filters; Components for display devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0232—Optical elements or arrangements associated with the device
    • H01L31/02327—Optical elements or arrangements associated with the device the optical elements being integrated or being directly associated to the device, e.g. back reflectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H01L31/035209—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures
    • H01L31/035227—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures the quantum structure being quantum wires, or nanorods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2803—Investigating the spectrum using photoelectric array detector
    • G01J2003/2806—Array and filter array
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2823—Imaging spectrometer
    • G01J2003/2826—Multispectral imaging, e.g. filter imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B2207/00—Coding scheme for general features or characteristics of optical elements and systems of subclass G02B, but not including elements and systems which would be classified in G02B6/00 and subgroups
    • G02B2207/101—Nanooptics

Definitions

  • the invention generally relates to photodetector elements and photodetector sub-elements for use in a photodetector element.
  • Photodetector size imposes a fundamental limit on the amount of information that can be recorded by an image sensor.
  • compact, high-resolution sensors are preferred for portable devices such as mobile phones and digital cameras, and as a result, significant effort has been invested in improving the image quality provided by small-area image sensors.
  • Reducing photodetector size faces challenges in implementation and requires improvements in current technology to meet the demand for ultra-compact imaging systems such as cameras.
  • a photodetector sub-element for use in a photodetector element, the photodetector sub-element comprising a substrate, a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element, and a detector element configured to produce an electrical signal in response to electromagnetic radiation transmitted by its corresponding
  • each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its associated detector element.
  • the nanoantennas of the sub-photodetector element are typically arranged in a regular array.
  • Each nanoantenna may include an insulating portion and a conducting layer, wherein the insulating portion is located between the conducting layer of the nanoantenna and the first surface.
  • the insulating portions may have a height of between 80 and 250 nanometres.
  • the spacing between adjacent nanoantennas may be within 100 and 300 nanometres.
  • Each nanoantenna may have a substantially circular cross-section.
  • Each nanoantenna may have a substantially rectangular cross- section.
  • the detector element may be in a solid contact configuration. Alternatively, the detector element may be in an interdigitated contact configuration.
  • the detector element may include an electrode located on the first surface of the substrate. Alternatively, the detector element may include an electrode located on a second surface of the substrate opposite the first surface.
  • the substrate may comprise a semiconductor.
  • a photodetector element comprising at least a first photodetector sub-element according to the previously described aspect and a second photodetector sub-element according to the previously described aspect, wherein the plasmonic filter of the first photodetector sub-element is configured to reflect substantially different wavelengths of radiation when compared to the plasmonic filter of the second photodetector sub- element, and wherein the substrates of the first and second photodetector sub-elements are continuous.
  • an electromagnetic sensor device comprising an arrangement of a plurality of photodetector elements, each photodetector element as according to the preceding aspect.
  • an electromagnetic sensor device comprising a single photodetector element or an arrangement of photodetector elements, each photodetector element associated with a region of a substrate and comprising a plurality of sub-photodetector elements, each sub-photodetector element including a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element and a detector element configured to produce
  • RO/AU an electrical signal in response to electromagnetic radiation transmitted by its corresponding plasmonic filter, wherein each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its associated detector element, and wherein at least two sub-photodetector elements have plasmonic filters configured to reflect different wavelengths of electromagnetic radiation.
  • the photodetector elements are typically arranged in a regular array.
  • the nanoantennas of each sub-photodetector element are typically arranged in a regular array.
  • Each photodetector element may include the same surface structure.
  • Each nanoantenna may include an insulating portion and a conducting layer, wherein the insulating portion is located between the conducting layer of the nanoantenna and the first surface.
  • Each insulating portion may have a height of between 80 and 250 nanometres.
  • Each nanoantenna may have at least a first cross-sectional dimension between 20 and 300 nanometres. The spacing between adjacent nanoantennas may be between 100 and 300 nanometres.
  • Each nanoantenna may have a substantially circular cross-section. Alternatively, each nanoantenna may have a substantially rectangular cross-section.
  • Each detector element may be in a solid contacts configuration. Alternatively, each detector element may be in an interdigitated contacts configuration. Each detector element may include one or more electrodes located on the first surface of the substrate. Alternatively, each detector element may include one or more electrodes located on a second surface of the substrate opposite the first surface.
  • the substrate comprises a semiconductor.
  • each photodetector element includes a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with cyan, a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with magenta, and a sub- photodetector element configured to reflect wavelengths of electromagnetic radiation associated with yellow.
  • each photodetector element includes a sub-photodetector element configured to provide for detection of wavelengths of infrared radiation and/or a sub-photodetector element to provide for detection of wavelengths of ultra-violet radiation.
  • a method of producing an electromagnetic sensor device comprising the steps of: forming a surface structure on a semiconductor substrate comprising a plurality of regions, each region associated with a sub-photodetector element of the electromagnetic sensor device, each region having an arrangement of raised portions extending from a first surface of the semiconductor substrate; applying a conducting layer to the plurality of regions thereby forming a plurality of nanoantennas, each nanoantenna corresponding to a raised portion; and applying a conducting layer to the semiconductor substrate thereby forming a detector element associated with each region, the detector element configured to produce an electrical signal in response to incident electromagnetic radiation.
  • the raised portions comprise a glass or Si02.
  • an electromagnetic sensor device having a substrate and a conducting layer on a first surface of the substrate, comprising: an arrangement of photodetector elements, each photodetector element comprising a plurality of sub-photodetector elements and each sub-photodetector element including: a surface structure configured to provide a plasmonic filter configured to reflect predetermined wavelengths of electromagnetic radiation; and a detector element configured to produce an electrical signal in proportion to an intensity of electromagnetic radiation transmitted by its associated plasmonic filter and to transmit said signal to an electrical sensor, wherein the surface structure of each photodetector element is defined by changes in elevation of the first surface of the substrate such that the conducting layer is discontinuous at said changes in elevation, wherein at least one sub- photodetector of each photodetector element has a surface structure different to at least one other-sub photodetector such that each photodetector includes two different plasmonic filters.
  • Figure 1 shows an electromagnetic sensor device 10 according to an embodiment
  • RO/AU Figure 2 shows an example of the surface structure of a sub-photodetector element
  • Figure 3 shows a conducting layer applied to the surface structure of a substrate
  • Figures 4a and 4b show different configurations of nanoantenna shape
  • FIGS 5a and 5b show different photodetector elements and associated configurations of sub- photodetector elements
  • FIG. 6a and 6b show different detector element configurations
  • Figure 7 shows an example manufacturing technique
  • Figure 8 shows measured photoresponse curves
  • Figure 9 shows scanning photocurrent microscopy (SPCM) images of a magenta reflecting sub- photodetector element collected at different wavelengths.
  • Figure 1 shows an electromagnetic sensor device 10 including a substrate 1 1.
  • An arrangement of photodetector elements 12 is formed on a first surface 20a of the substrate 1 1, each photodetector element 12 comprising a surface structure associated with a plurality (in the example, three) of sub- photodetector elements 13.
  • the photodetector elements 12 each have a hexagonal shape and are arranged in a repeating array.
  • the shape of the photodetector elements 12 is not limited by hexagonal arrangement, for example, square photodetector elements 12 may be utilised.
  • the substrate 11 comprises a semiconductor material, for example, n-doped silicon, gallium arsenide, indium phosphide, or germanium.
  • the surface structure of a sub-photodetector element 13 is shown in Figure 2.
  • the surface structure includes raised insulating portions 22 extending tfom the first surface 20a of the substrate 1 1.
  • the insulating portions 22 are typically located above the first surface 20a and are made of glass, S1O2, or other insulating material with glass-like optical properties such as HSQ resist.
  • a conducting layer 21 is applied to the first surface 20a.
  • the conductor layer 21 typically comprises a metallic conductor, for example, aluminium, silver or gold.
  • the material of the conductor layer 21 is selected such as to provide the required plasmonic and electrical properties.
  • the conductor layer 21 is discontinuous due to being applied to both the insulating portions 22 and the first surface 20a of the substrate 11.
  • Each insulating portion 22 combined with the conductor layer 21 defines a nanoantenna 23. Therefore, the arrangement of
  • RO/AU insulating portions 22 coupled with the conducting layer 21 effectively defines an arrangement of nanoantennas 23.
  • the arrangement and structure of the nanoantennas 23 is selected such as to cause reflection, via a plasmonic effect, of particular wavelengths of electromagnetic radiation. Typically, these wavelengths will include portions of the visible and/or near infrared regions of the electromagnetic spectrum.
  • the height of a nanoantenna 23 should be less than the wavelength of the portions of the electromagnetic spectrum over which the sub-photodetector element 13 is intended to operate. In an embodiment, the height of the insulating portions 22 above the first surface 20a is in between 80 and 250 nanometres, depending on the operating wavelength.
  • the entire structure (including and the substrate 11 and the nanoantennas 23) is covered with a glass passivation layer for protection.
  • a glass passivation layer for protection.
  • a 185 nm layer of glass is used.
  • the electrical contact with a conductor layer 21 is implemented via through holes 14.
  • the nanoantennas 23 have a circular shape (when viewed from above).
  • the symmetrical nature of the nanoantennas 23 according to this embodiment results in a non-polarised reflection (and transmission) of the incident electromagnetic radiation.
  • the nanoantennas 23 have a rectangular shape (when viewed from above)— the figure shows curved corners; this is considered rectangular for the disclosure herein.
  • the rectangular shape of the nanoantennas 23 according to this embodiment results in polarised reflection and transmission of the incident electromagnetic radiation.
  • Such rectangular nanoantennas 23 may be referred to as nanorods (due to their rod-like appearance when viewed from above).
  • the spacing between nanoantennas (e.g. the period of the lattice) 23 can be between 100 and 300 nanometres, depending on the desired operating wavelength Other arrangements may be utilised, for example, a rectangular array or an array with at least some variability in the spacing between adjacent nanoantennas 23.
  • the primary determinants of the wavelengths of electromagnetic radiation reflected by the arrangement of nanoantennas 23 due to the plasmonic effect is the size, period, and shape of the nanoantennas 23.
  • size refers to the extent of each nanoantenna 23 over the first surface 20a (i.e. when viewed from above), and may be characterised by one or more dimensions (e.g. a radius for circular nanoantennas 23, a length of a rectangular nanoantenna 23 where a width is fixed, or both length and width of a rectangular nanoantenna 23).
  • RO/AU required size of the nanoantennas 23 of the sub-photodetector element 13 can be determined via computer simulation and/or through trial. Generally, the nanoantennas 23 of a particular subphotodetector element 13 have the same (or approximately the same) size, period and shape. Furthermore, nanoantennas 23 of like sub-photodetector elements 13 of different photodetector elements 12 have the same (or approximately the same) size, period, and shape.
  • FIG. 5a shows an electron microscope image of a single photodetector element 12 according to an embodiment.
  • the photodetector element 12 comprises three sub-photodetector elements l3a, l3b, l3c, each configured to reflect different wavelengths of electromagnetic radiation. Each sub photodetector element 13 is thereby associated with a colour.
  • the arrangement of nanoantennas 23 of each sub-photodetector element l3a, l3b, l3c is configured to reflect the colour with which it is associated.
  • the size of the nanoantennas 23 of the cyan sub-photodetector element l3a are approximately l70 ⁇ 3 nm
  • the size of the nanoantennas 23 of the magenta sub-photodetector element l3b are approximately 200 ⁇ 3 nm
  • the size of the nanoantennas 23 of the yellow sub-photodetector element l3c are approximately 35 ⁇ 3 nm.
  • the choice of cyan, magenta, and yellow reflecting arrangements of nanoantennas 23 corresponds to transmission wavelengths corresponding to the colours of red, green, and blue (respectively).
  • Figure 8 shows measured photoresponse curves (i.e.
  • FIG. 9 shows scanning photocurrent microscopy (SPCM) images of a magenta reflecting sub-photodetector element 13b collected at different wavelengths (from left to right: 450 nm, 532 nm, 650 nm).
  • Figure 5b shows an electron microscope image of a single photodetector element 12 according to another embodiment.
  • the photodetector element 12 comprises six sub-photodetector elements l3a-l3f, each configured to reflect different wavelengths of electromagnetic radiation.
  • Each sub-photodetector element 13 is associated with a colour in the visible spectrum.
  • Additional channels improve colour representation as well as enable multi- or hyperspectral imaging to obtain spectral information (can be used in spectrometers).
  • each sub-photodetector element 13 of a photodetector element 12 includes a detecting element 30a, 30b, 30c.
  • Each detecting element 30a, 30b, 30c is configured to produce an electrical signal in respect to transmission of electromagnetic radiation by the nanoantennas 23 associated with the same sub-photodetector element 13. In this way, each detecting element 30a, 30b, 30c is configured to respond to different portions of the electromagnetic spectrum.
  • detecting elements 30a, 30b, 30c are defined by the interaction of a first electrode 3 la, 3lb, 3 lc with common electrode 32 (e.g. connected to ground or a biasing potential).
  • the shown arrangement may be referred to as a“solid contact” configuration.
  • “solid contact” means that the electrode surface of a particular detecting element 30a, 30b, 30c covers all, or substantially all, of the underlying substrate 11. This is to be contrasted with the interdigitated configuration described below with reference to Figure 6b, where the first electrode 31 a, 31 b, 3 lc covers a portion of the underlying substrate 11.
  • Each first electrode 3 la, 3 lb, 3 lc comprises the portions of the conductor layer 21 present in the region of the relevant electrodes 3 la, 3 lb, 3 lc which are in turn electrically connected to a corresponding wire 33a, 33b, 33c.
  • Each first electrode 3 l a, 3 lb, 31 c is in a Schottky contact with the underlying substrate 11 and is, thus, electrically coupled to the underlying substrate.
  • the common electrode 32 is not directly in contact with any one of the first electrodes 3 la, 3 lb, 3lc (i.e.
  • first electrodes 3 la, 3 lb, 3 lc and the common electrode 32 are electrically coupled via the semiconductor substrate 1 1 ) and is in the Schottky contact with the underlying substrate 11.
  • the first electrodes 3 la, 3 lb, 3 lc and optionally the common electrode 32 are located on the second surface 20b directly opposite the relevant array of nanoantennas 23.
  • each detecting element 30a, 30b, 30c is defined by the interaction of a first electrode 31 a, 31b, 31 c with a common electrode 32 (e.g. connected to ground or a biasing potential).
  • the shown arrangement may be referred to as an interdigitated contacts configuration.
  • Each first electrode 31 a, 31 b, 3 lc comprises portions of the conductor layer 21 present in the region of the relevant electrode 30a, 30b, 30c and are electrically connected to a corresponding wire 33a, 33b, 33c.
  • Each interdigitated electrode 3 l a, 3 lb, 31 c is in Schottky contact with the underlying substrate 1 1 , and is thus electrically coupled to the underlying substrate.
  • the common electrode 32 e.g. connected to ground or a biasing potential
  • RO/AU electrode 32 is not directly in contact with any one of the first electrodes 31 a, 3 lb, 3lc (i.e. there is no direct electrical connection between the first electrodes 31 a, 31 b, 3 lc and the common electrode 32) and is not in the Schottky contact with the underlying substrate 11.
  • a photocurrent is produced between each first electrode 3 la, 3 lb, 3 lc and the common electrode 32 due to the hot-electron injection or electron-hole pair generation in semiconductor substrate 11 that is modified due to the interaction between the incident electromagnetic field and nanoantenna arrays 23.
  • an electromagnetic sensor device 10 is formed utilising a lithographic technique which includes the formation of the nanoantennas 23 and the detecting elements 30.
  • FIG. 7 shows an example technique which is described below.
  • a sequential ultrasonic cleaning in acetone, IPA and deionised water was performed to remove any contamination that might be present on the wafer. It was then spin- coated with 95 nm thick layer of 6% HSQ and baked for 3 min at 60°C.
  • the raised pillars were exposed using a 100 kV EBPG5000+ electron beam lithography (EBL) system.
  • EBL electron beam lithography
  • the sample was then spin-coated with a 280 nm thick layer of PMMA A4 950k resist and baked at l 80°C for 5 min.
  • the first metallisation layer was exposed using same EBL system.
  • the pattern was then developed in 1 :3 MIBK:1PA solution for 1 minute.
  • the aluminium layer with a thickness of 40 nm was deposited at 0.7 A/s evaporation rate using IntlVac NanoChrome II electron-beam evaporation system. After evaporation a lift-off step in hot acetone followed by rinsing in IPA was performed.
  • An 185 nm thick passivation layer of Si02 was grown on the sample using Oxford Instruments PLASMALAB 100 PECVD system.
  • the sample was then spin-coated with a 1000 nm thick layer of PMMA A6 950k resist and baked at l00°C for 30 min then at l80°C for 15 min.
  • the pattern defining interlayer vias was exposed using same EBL system.
  • the pattern was then developed in 1 :3 MIBKTPA solution for 1 minute.
  • the developed sample was transferred into an Oxford Instruments PLASMALAB 100 ICP380 reactive ion etching tool.
  • a combination of He and C4F8 gases with flow speeds of 70 and 10 seem respectively was used to etch Si02 layer.
  • the etching was performed at a pressure of 5 mTorr for 70 s.
  • the remaining PMMA was removed using oxygen plasma and hot acetone bath followed by rinsing in IPA.
  • the sample was coated with 600 nm PMMA A4 layer to protect the structures during the next step.
  • a wet dicing saw (Disco DAD321) was used to separate the photodetectors. The dies were glued into a ceramic LCC20 package and bonded using a Kulicke & Soffa 4522D Wedge bonder with aluminium wire.

Abstract

A photodetector sub-element for use in a photodetector element, the photodetector sub-element comprising a substrate, a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element, and a detector element configured to produce an electrical signal in response to electromagnetic radiation transmitted by its corresponding plasmonic filter, wherein each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its associated detector element, and an electromagnetic sensor device comprising said photodetector sub-elements.

Description

PHOTOSENSITIVE DEVICE
Field of the Invention
The invention generally relates to photodetector elements and photodetector sub-elements for use in a photodetector element. Background to the Invention
Photodetector size imposes a fundamental limit on the amount of information that can be recorded by an image sensor. Generally, compact, high-resolution sensors are preferred for portable devices such as mobile phones and digital cameras, and as a result, significant effort has been invested in improving the image quality provided by small-area image sensors. Reducing photodetector size faces challenges in implementation and requires improvements in current technology to meet the demand for ultra-compact imaging systems such as cameras.
An issue with a decrease of the photodetector size is associated with photodetectors utilising colour filters. Usually these filters contain dyes or pigments which absorb certain incident wavelengths while transmitting others. For sufficient absorption, the thickness of a filter must be of the order of several hundreds of nanometres. Thicker filters provide better bandpass characteristics, however, their thicknesses often lead to optical cross-talk between adjacent photodetectors from electromagnetic radiation incident at an angle. The degree of cross-talk is proportional to the thickness of the filter, and can result in blurring of the detected image and a decrease in colour resolution. There is a trade-off, therefore, between the quality of the filter and photodetector cross-talk which applies a lower bound on photodetector dimensions.
Summary of the Invention
According to an aspect of the present invention, there is provided A photodetector sub-element for use in a photodetector element, the photodetector sub-element comprising a substrate, a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element, and a detector element configured to produce an electrical signal in response to electromagnetic radiation transmitted by its corresponding
Substitute Sheet
(Rule 26) RO/AU plasmonic filter, wherein each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its associated detector element.
The nanoantennas of the sub-photodetector element are typically arranged in a regular array. Each nanoantenna may include an insulating portion and a conducting layer, wherein the insulating portion is located between the conducting layer of the nanoantenna and the first surface. The insulating portions may have a height of between 80 and 250 nanometres. The spacing between adjacent nanoantennas may be within 100 and 300 nanometres. Each nanoantenna may have a substantially circular cross-section. Each nanoantenna may have a substantially rectangular cross- section.
The detector element may be in a solid contact configuration. Alternatively, the detector element may be in an interdigitated contact configuration. The detector element may include an electrode located on the first surface of the substrate. Alternatively, the detector element may include an electrode located on a second surface of the substrate opposite the first surface.
The substrate may comprise a semiconductor.
According to another aspect of the present invention, there is provided a photodetector element comprising at least a first photodetector sub-element according to the previously described aspect and a second photodetector sub-element according to the previously described aspect, wherein the plasmonic filter of the first photodetector sub-element is configured to reflect substantially different wavelengths of radiation when compared to the plasmonic filter of the second photodetector sub- element, and wherein the substrates of the first and second photodetector sub-elements are continuous.
According to another aspect of the present invention, there is provided an electromagnetic sensor device comprising an arrangement of a plurality of photodetector elements, each photodetector element as according to the preceding aspect.
According to another aspect of the present invention, there is provided an electromagnetic sensor device comprising a single photodetector element or an arrangement of photodetector elements, each photodetector element associated with a region of a substrate and comprising a plurality of sub-photodetector elements, each sub-photodetector element including a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element and a detector element configured to produce
Substitute Sheet
(Rule 26) RO/AU an electrical signal in response to electromagnetic radiation transmitted by its corresponding plasmonic filter, wherein each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its associated detector element, and wherein at least two sub-photodetector elements have plasmonic filters configured to reflect different wavelengths of electromagnetic radiation.
The photodetector elements are typically arranged in a regular array. The nanoantennas of each sub-photodetector element are typically arranged in a regular array. Each photodetector element may include the same surface structure. Each nanoantenna may include an insulating portion and a conducting layer, wherein the insulating portion is located between the conducting layer of the nanoantenna and the first surface. Each insulating portion may have a height of between 80 and 250 nanometres. Each nanoantenna may have at least a first cross-sectional dimension between 20 and 300 nanometres. The spacing between adjacent nanoantennas may be between 100 and 300 nanometres. Each nanoantenna may have a substantially circular cross-section. Alternatively, each nanoantenna may have a substantially rectangular cross-section.
Each detector element may be in a solid contacts configuration. Alternatively, each detector element may be in an interdigitated contacts configuration. Each detector element may include one or more electrodes located on the first surface of the substrate. Alternatively, each detector element may include one or more electrodes located on a second surface of the substrate opposite the first surface.
Optionally, the substrate comprises a semiconductor.
Optionally, each photodetector element includes a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with cyan, a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with magenta, and a sub- photodetector element configured to reflect wavelengths of electromagnetic radiation associated with yellow. Also optionally, each photodetector element includes a sub-photodetector element configured to provide for detection of wavelengths of infrared radiation and/or a sub-photodetector element to provide for detection of wavelengths of ultra-violet radiation.
According to another aspect of the present invention, there is provided a method of producing an electromagnetic sensor device according to any one of the previously discussed aspects, said method utilising one or more lithographic manufacturing steps.
Substitute Sheet
(Rule 26) RO/AU According to yet another aspect of the present invention, there is provided a method of producing an electromagnetic sensor device according to any one of the previously discussed aspects, comprising the steps of: forming a surface structure on a semiconductor substrate comprising a plurality of regions, each region associated with a sub-photodetector element of the electromagnetic sensor device, each region having an arrangement of raised portions extending from a first surface of the semiconductor substrate; applying a conducting layer to the plurality of regions thereby forming a plurality of nanoantennas, each nanoantenna corresponding to a raised portion; and applying a conducting layer to the semiconductor substrate thereby forming a detector element associated with each region, the detector element configured to produce an electrical signal in response to incident electromagnetic radiation. Preferably, the raised portions comprise a glass or Si02.
According to still yet another aspect of the present invention, there is provided an electromagnetic sensor device having a substrate and a conducting layer on a first surface of the substrate, comprising: an arrangement of photodetector elements, each photodetector element comprising a plurality of sub-photodetector elements and each sub-photodetector element including: a surface structure configured to provide a plasmonic filter configured to reflect predetermined wavelengths of electromagnetic radiation; and a detector element configured to produce an electrical signal in proportion to an intensity of electromagnetic radiation transmitted by its associated plasmonic filter and to transmit said signal to an electrical sensor, wherein the surface structure of each photodetector element is defined by changes in elevation of the first surface of the substrate such that the conducting layer is discontinuous at said changes in elevation, wherein at least one sub- photodetector of each photodetector element has a surface structure different to at least one other-sub photodetector such that each photodetector includes two different plasmonic filters.
As used herein, the word“comprise” or variations such as“comprises” or“comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Brief Description of the Drawings
In order that the invention may be more clearly understood, embodiments will now be described, by way of example, with reference to the accompanying drawing, in which:
Figure 1 shows an electromagnetic sensor device 10 according to an embodiment;
Substitute Sheet
(Rule 26) RO/AU Figure 2 shows an example of the surface structure of a sub-photodetector element;
Figure 3 shows a conducting layer applied to the surface structure of a substrate;
Figures 4a and 4b show different configurations of nanoantenna shape;
Figures 5a and 5b show different photodetector elements and associated configurations of sub- photodetector elements;
Figures 6a and 6b show different detector element configurations;
Figure 7 shows an example manufacturing technique;
Figure 8 shows measured photoresponse curves; and
Figure 9 shows scanning photocurrent microscopy (SPCM) images of a magenta reflecting sub- photodetector element collected at different wavelengths.
Description of Embodiments
Figure 1 shows an electromagnetic sensor device 10 including a substrate 1 1. An arrangement of photodetector elements 12 is formed on a first surface 20a of the substrate 1 1, each photodetector element 12 comprising a surface structure associated with a plurality (in the example, three) of sub- photodetector elements 13. In the figure, the photodetector elements 12 each have a hexagonal shape and are arranged in a repeating array. The shape of the photodetector elements 12 is not limited by hexagonal arrangement, for example, square photodetector elements 12 may be utilised. The substrate 11 comprises a semiconductor material, for example, n-doped silicon, gallium arsenide, indium phosphide, or germanium. An example of the surface structure of a sub-photodetector element 13 is shown in Figure 2. The surface structure includes raised insulating portions 22 extending tfom the first surface 20a of the substrate 1 1. The insulating portions 22 are typically located above the first surface 20a and are made of glass, S1O2, or other insulating material with glass-like optical properties such as HSQ resist.
Referring to Figure 3, a conducting layer 21 is applied to the first surface 20a. The conductor layer 21 typically comprises a metallic conductor, for example, aluminium, silver or gold. Typically, the material of the conductor layer 21 is selected such as to provide the required plasmonic and electrical properties. The conductor layer 21 is discontinuous due to being applied to both the insulating portions 22 and the first surface 20a of the substrate 11. Each insulating portion 22 combined with the conductor layer 21 defines a nanoantenna 23. Therefore, the arrangement of
Substitute Sheet
(Rule 26) RO/AU insulating portions 22 coupled with the conducting layer 21 effectively defines an arrangement of nanoantennas 23. The arrangement and structure of the nanoantennas 23 is selected such as to cause reflection, via a plasmonic effect, of particular wavelengths of electromagnetic radiation. Typically, these wavelengths will include portions of the visible and/or near infrared regions of the electromagnetic spectrum. Typically, the height of a nanoantenna 23 should be less than the wavelength of the portions of the electromagnetic spectrum over which the sub-photodetector element 13 is intended to operate. In an embodiment, the height of the insulating portions 22 above the first surface 20a is in between 80 and 250 nanometres, depending on the operating wavelength.
In an embodiment, the entire structure (including and the substrate 11 and the nanoantennas 23) is covered with a glass passivation layer for protection. In an embodiment a 185 nm layer of glass is used. The electrical contact with a conductor layer 21 is implemented via through holes 14.
In an embodiment, as shown in Figure 4a, the nanoantennas 23 have a circular shape (when viewed from above). The symmetrical nature of the nanoantennas 23 according to this embodiment results in a non-polarised reflection (and transmission) of the incident electromagnetic radiation. In an embodiment, as shown in Figure 4b, the nanoantennas 23 have a rectangular shape (when viewed from above)— the figure shows curved corners; this is considered rectangular for the disclosure herein. The rectangular shape of the nanoantennas 23 according to this embodiment results in polarised reflection and transmission of the incident electromagnetic radiation. Such rectangular nanoantennas 23 may be referred to as nanorods (due to their rod-like appearance when viewed from above).
In an embodiment, the nanoantennas 23 arranged, within the sub-photodetector element 13, in a regular array (in Figures 3a and 3b, the arrays are hexagonal arrays). The spacing between nanoantennas (e.g. the period of the lattice) 23 can be between 100 and 300 nanometres, depending on the desired operating wavelength Other arrangements may be utilised, for example, a rectangular array or an array with at least some variability in the spacing between adjacent nanoantennas 23.
The primary determinants of the wavelengths of electromagnetic radiation reflected by the arrangement of nanoantennas 23 due to the plasmonic effect is the size, period, and shape of the nanoantennas 23. Flere, size refers to the extent of each nanoantenna 23 over the first surface 20a (i.e. when viewed from above), and may be characterised by one or more dimensions (e.g. a radius for circular nanoantennas 23, a length of a rectangular nanoantenna 23 where a width is fixed, or both length and width of a rectangular nanoantenna 23). For a particular sub-photodetector element 13, the
Substitute Sheet
(Rule 26) RO/AU required size of the nanoantennas 23 of the sub-photodetector element 13 can be determined via computer simulation and/or through trial. Generally, the nanoantennas 23 of a particular subphotodetector element 13 have the same (or approximately the same) size, period and shape. Furthermore, nanoantennas 23 of like sub-photodetector elements 13 of different photodetector elements 12 have the same (or approximately the same) size, period, and shape.
Figure 5a shows an electron microscope image of a single photodetector element 12 according to an embodiment. The photodetector element 12 comprises three sub-photodetector elements l3a, l3b, l3c, each configured to reflect different wavelengths of electromagnetic radiation. Each sub photodetector element 13 is thereby associated with a colour. In an implementation, there is a cyan sub-photodetector element l3a, a magenta sub-photodetector element l3b, and a yellow sub- photodetector element l3c. The arrangement of nanoantennas 23 of each sub-photodetector element l3a, l3b, l3c is configured to reflect the colour with which it is associated. In the implementation shown, the size of the nanoantennas 23 of the cyan sub-photodetector element l3a are approximately l70±3 nm, the size of the nanoantennas 23 of the magenta sub-photodetector element l3b are approximately 200±3 nm, and the size of the nanoantennas 23 of the yellow sub-photodetector element l3c are approximately 35±3 nm. The choice of cyan, magenta, and yellow reflecting arrangements of nanoantennas 23 corresponds to transmission wavelengths corresponding to the colours of red, green, and blue (respectively). Figure 8 shows measured photoresponse curves (i.e. responsivity as a function of incident wavelength) for a cyan reflecting sub-photodetector element l3a, a magenta reflecting sub-photodetector element l3b, and a yellow reflecting sub-photodetector element l3c. Figure 9 shows scanning photocurrent microscopy (SPCM) images of a magenta reflecting sub-photodetector element 13b collected at different wavelengths (from left to right: 450 nm, 532 nm, 650 nm).
Figure 5b shows an electron microscope image of a single photodetector element 12 according to another embodiment. In this case, the photodetector element 12 comprises six sub-photodetector elements l3a-l3f, each configured to reflect different wavelengths of electromagnetic radiation. Each sub-photodetector element 13 is associated with a colour in the visible spectrum. In an implementation, there is a cyan sub-photodetector element 13c, a magenta sub-photodetector element l3e, a yellow sub-photodetector element l3a and intermediate colours such as violet subphotodetector element l3d, an orange sub-photodetector element l3f and a light green sub- photodetector element l3b. Additional channels improve colour representation as well as enable multi- or hyperspectral imaging to obtain spectral information (can be used in spectrometers).
Substitute Sheet
(Rule 26) RO/AU Moreover, if germanium is used as a semiconductor substrate 11 then additional channels l3a-l3f can extend spectral sensitivity into near infrared region.
Referring to Figures 6a and 6b, each sub-photodetector element 13 of a photodetector element 12 includes a detecting element 30a, 30b, 30c. Each detecting element 30a, 30b, 30c is configured to produce an electrical signal in respect to transmission of electromagnetic radiation by the nanoantennas 23 associated with the same sub-photodetector element 13. In this way, each detecting element 30a, 30b, 30c is configured to respond to different portions of the electromagnetic spectrum.
In the embodiment of Figure 6a, detecting elements 30a, 30b, 30c are defined by the interaction of a first electrode 3 la, 3lb, 3 lc with common electrode 32 (e.g. connected to ground or a biasing potential). The shown arrangement may be referred to as a“solid contact” configuration. As used herein,“solid contact” means that the electrode surface of a particular detecting element 30a, 30b, 30c covers all, or substantially all, of the underlying substrate 11. This is to be contrasted with the interdigitated configuration described below with reference to Figure 6b, where the first electrode 31 a, 31 b, 3 lc covers a portion of the underlying substrate 11.
Each first electrode 3 la, 3 lb, 3 lc comprises the portions of the conductor layer 21 present in the region of the relevant electrodes 3 la, 3 lb, 3 lc which are in turn electrically connected to a corresponding wire 33a, 33b, 33c. Each first electrode 3 l a, 3 lb, 31 c is in a Schottky contact with the underlying substrate 11 and is, thus, electrically coupled to the underlying substrate. The common electrode 32 is not directly in contact with any one of the first electrodes 3 la, 3 lb, 3lc (i.e. there is no direct electrical connection between the first electrodes 3 la, 3 lb, 3 lc and the common electrode 32; these are electrically coupled via the semiconductor substrate 1 1 ) and is in the Schottky contact with the underlying substrate 11. In a modification, the first electrodes 3 la, 3 lb, 3 lc and optionally the common electrode 32 are located on the second surface 20b directly opposite the relevant array of nanoantennas 23.
In the embodiment of Figure 6b, each detecting element 30a, 30b, 30c is defined by the interaction of a first electrode 31 a, 31b, 31 c with a common electrode 32 (e.g. connected to ground or a biasing potential). The shown arrangement may be referred to as an interdigitated contacts configuration. Each first electrode 31 a, 31 b, 3 lc comprises portions of the conductor layer 21 present in the region of the relevant electrode 30a, 30b, 30c and are electrically connected to a corresponding wire 33a, 33b, 33c. Each interdigitated electrode 3 l a, 3 lb, 31 c is in Schottky contact with the underlying substrate 1 1 , and is thus electrically coupled to the underlying substrate. The common
Substitute Sheet
(Rule 26) RO/AU electrode 32 is not directly in contact with any one of the first electrodes 31 a, 3 lb, 3lc (i.e. there is no direct electrical connection between the first electrodes 31 a, 31 b, 3 lc and the common electrode 32) and is not in the Schottky contact with the underlying substrate 11. A photocurrent is produced between each first electrode 3 la, 3 lb, 3 lc and the common electrode 32 due to the hot-electron injection or electron-hole pair generation in semiconductor substrate 11 that is modified due to the interaction between the incident electromagnetic field and nanoantenna arrays 23.
According to an embodiment, an electromagnetic sensor device 10 is formed utilising a lithographic technique which includes the formation of the nanoantennas 23 and the detecting elements 30.
Figure 7 shows an example technique which is described below.
In the example, photodetectors were fabricated on low doped n-type silicon wafer with bulk resistance of p = 1 -10 Wcih. A sequential ultrasonic cleaning in acetone, IPA and deionised water was performed to remove any contamination that might be present on the wafer. It was then spin- coated with 95 nm thick layer of 6% HSQ and baked for 3 min at 60°C. In the first lithography step the raised pillars were exposed using a 100 kV EBPG5000+ electron beam lithography (EBL) system. The pattern was developed in NaOEkNaCl l%:4% wt. solution for 4 min.
The sample was then spin-coated with a 280 nm thick layer of PMMA A4 950k resist and baked at l 80°C for 5 min. The first metallisation layer was exposed using same EBL system. The pattern was then developed in 1 :3 MIBK:1PA solution for 1 minute. The aluminium layer with a thickness of 40 nm was deposited at 0.7 A/s evaporation rate using IntlVac NanoChrome II electron-beam evaporation system. After evaporation a lift-off step in hot acetone followed by rinsing in IPA was performed. An 185 nm thick passivation layer of Si02 was grown on the sample using Oxford Instruments PLASMALAB 100 PECVD system.
The sample was then spin-coated with a 1000 nm thick layer of PMMA A6 950k resist and baked at l00°C for 30 min then at l80°C for 15 min. The pattern defining interlayer vias was exposed using same EBL system. The pattern was then developed in 1 :3 MIBKTPA solution for 1 minute. The developed sample was transferred into an Oxford Instruments PLASMALAB 100 ICP380 reactive ion etching tool. A combination of He and C4F8 gases with flow speeds of 70 and 10 seem respectively was used to etch Si02 layer. The etching was performed at a pressure of 5 mTorr for 70 s. The remaining PMMA was removed using oxygen plasma and hot acetone bath followed by rinsing in IPA.
Substitute Sheet
(Rule 26) RO/AU The sample was then spin-coated with a 1000 nm thick layer of PMMA A6 950k resist and baked at l00°C for 30 min then at l80°C for 15 min. The pattern defining the interconnects was exposed using same EBL system. The pattern was then developed in a 1:3 MIBK:IPA solution for 1 minute. The developed sample was transferred into an Intlvac Nanochrome AC/DC sputterer and 300 nm of Al was deposited onto the sample. After sputtering, a lift-off step in hot acetone followed by rinsing in IPA was performed.
Finally, the sample was coated with 600 nm PMMA A4 layer to protect the structures during the next step. A wet dicing saw (Disco DAD321) was used to separate the photodetectors. The dies were glued into a ceramic LCC20 package and bonded using a Kulicke & Soffa 4522D Wedge bonder with aluminium wire.
Further modifications can be made without departing from the spirit and scope of the specification.
Substitute Sheet
(Rule 26) RO/AU

Claims

The claims defining the invention are as follows:
1. A photodetector sub-element for use in a photodetector element, the photodetector sub- element comprising a substrate, a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element, and a detector element configured to produce an electrical signal in response to
electromagnetic radiation transmitted by its corresponding plasmonic filter, wherein each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its associated detector element.
2. A photodetector sub-element as claimed in claim 1, wherein the nanoantennas of the sub- photodetector element are arranged in a regular array.
3. A photodetector sub-element as claimed in either one of claims 1 and 2, wherein each nanoantenna includes an insulating portion and a conducting layer, wherein the insulating portion is located between the conducting layer of the nanoantenna and the first surface.
4. A photodetector sub-element as claimed in claim 3, wherein the insulating portion has a height of between 80 and 250 nanometres.
5. A photodetector sub-element as claimed in any one of claims 1 to 4, wherein the spacing between adjacent nanoantennas is within 100 and 300 nanometres.
6. A photodetector sub-element as claimed in any one of claims 1 to 5, wherein each nanoantenna has a substantially circular cross-section.
7. A photodetector sub-element as claimed in any one of claims 1 to 5, wherein each nanoantenna has a substantially rectangular cross-section.
8. A photodetector sub-element as claimed in any one of claims 1 to 6, wherein the detector element is in a solid contact configuration.
Substitute Sheet
(Rule 26) RO/AU
9. A photodetector sub-element as claimed in any one of claims 1 to 6, wherein the detector element is in an interdigitated contact configuration.
10. A photodetector sub-element as claimed in any one of claims 1 to 9, wherein the detector element includes an electrode located on the first surface of the substrate.
11. A photodetector sub-element as claimed in any one of claims 1 to 9, wherein the detector element includes an electrode located on a second surface of the substrate opposite the first surface.
12. A photodetector sub-element as claimed in any one of claims 1 to 11, wherein the substrate comprises a semiconductor.
13. A photodetector element comprising at least a first photodetector sub-element as claimed in any one of claims 1 to 12 and a second photodetector sub-element as claimed in any one of claims 1 to 12, wherein the plasmonic filter of the first photodetector sub-element is configured to reflect substantially different wavelengths of radiation when compared to the plasmonic filter of the second photodetector sub-element, and wherein the substrates of the first and second photodetector sub elements are continuous.
14. An electromagnetic sensor device comprising an arrangement of a plurality of photodetector elements, each photodetector element as according to claim 13.
15. An electromagnetic sensor device comprising a single photodetector element or an arrangement of photodetector elements, each photodetector element associated with a region of a substrate and comprising a plurality of sub-photodetector elements, each sub-photodetector element including a plasmonic filter comprising an arrangement of nanoantennas formed on a first surface of the substrate within the region associated with the sub-photodetector element and a detector element configured to produce an electrical signal in response to electromagnetic radiation transmitted by its corresponding plasmonic filter, wherein each plasmonic filter is configured to reflect predetermined wavelengths of electromagnetic radiation such that the reflected radiation is not detected by its
Substitute Sheet
(Rule 26) RO/AU associated detector element, and wherein at least two sub-photodetector elements have plasmonic filters configured to reflect different wavelengths of electromagnetic radiation.
16. An electromagnetic sensor device as claimed in claim 15, wherein the photodetector elements are arranged in a regular array.
17. An electromagnetic sensor device as claimed in either one of claims 15 and 16, wherein the nanoantennas of each sub-photodetector element are arranged in a regular array.
18. An electromagnetic sensor device as claimed in any one of claims 15 to 17, wherein each photodetector element includes the same surface structure.
19. An electromagnetic sensor device as claimed in any one of claims 15 to 18, wherein each nanoantenna includes an insulating portion and a conducting layer, wherein the insulating portion is located between the conducting layer of the nanoantenna and the first surface.
20. An electromagnetic sensor device as claimed in claim 19, wherein each insulating portion has a height of between 80 and 250 nanometres.
21. An electromagnetic sensor device as claimed in any one of claims 15 to 20, wherein each nanoantenna has at least a first cross-sectional dimension between 20 and 300 nanometres.
22. An electromagnetic sensor device as claimed in any one of claims 15 to 21 wherein the spacing between adjacent nanoantennas is between 100 and 300 nanometres.
23. An electromagnetic sensor device as claimed in any one of claims 15 to 22, wherein each nanoantenna has a substantially circular cross-section.
24. An electromagnetic sensor device as claimed in any one of claims 15 to 22, wherein each nanoantenna has a substantially rectangular cross-section.
Substitute Sheet
(Rule 26) RO/AU
25. An electromagnetic sensor device as claimed in any one of claims 15 to 24, wherein each detector element is in a solid contacts configuration.
26. An electromagnetic sensor device as claimed in any one of claims 15 to 24, wherein each detector element is in an interdigitated contacts configuration.
27. An electromagnetic sensor device as claimed in any one of claims 15 to 26, wherein each detector element includes one or more electrodes located on the first surface of the substrate.
28. An electromagnetic sensor device as claimed in any one of claims 15 to 27, wherein each detector element includes one or more electrodes located on a second surface of the substrate opposite the first surface.
29. An electromagnetic sensor device as claimed in any one of claims 15 to 28, wherein the substrate comprises a semiconductor.
30. An electromagnetic sensor device as claimed in any one of claims 15 to 29, wherein each photodetector element includes a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with cyan, a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with magenta, and a sub-photodetector element configured to reflect wavelengths of electromagnetic radiation associated with yellow.
31. An electromagnetic sensor device as claimed in any one of claims 15 to 30, wherein each photodetector element includes a sub-photodetector element configured to provide for detection of wavelengths of infrared radiation and/or a sub-photodetector element to provide for detection of wavelengths of ultra-violet radiation.
32. An electromagnetic sensor device having a substrate and a conducting layer on a first surface of the substrate, comprising:
an arrangement of photodetector elements, each photodetector element comprising a plurality of sub-photodetector elements and each sub-photodetector element including:
Substitute Sheet
(Rule 26) RO/AU a surface structure configured to provide a plasmonic filter configured to reflect predetermined wavelengths of electromagnetic radiation; and
a detector element configured to produce an electrical signal in proportion to an intensity of electromagnetic radiation transmitted by its associated plasmonic filter and to transmit said signal to an electrical sensor,
wherein the surface structure of each photodetector element is defined by changes in elevation of the first surface of the substrate such that the conducting layer is discontinuous at said changes in elevation,
wherein at least one sub-photodetector of each photodetector element has a surface structure different to at least one other-sub photodetector such that each photodetector includes two different plasmonic filters.
33. A method of producing an electromagnetic sensor device according to any one of claims 1 to 32, said method utilising one or more lithographic manufacturing steps.
34. A method of producing an electromagnetic sensor device as claimed in any one of claims 1 to 32, comprising the steps of:
forming a surface structure on a semiconductor substrate comprising a plurality of regions, each region associated with a sub-photodetector element of the electromagnetic sensor device, each region having an arrangement of insulating portions extending from a first surface of the semiconductor substrate;
applying a conducting layer to the plurality of regions thereby forming a plurality of nanoantennas, each nanoantenna corresponding to a insulating portion; and
applying a conducting layer to the semiconductor substrate thereby forming a detector element associated with each region, the detector element configured to produce an electrical signal in response to incident electromagnetic radiation.
35. A method as claimed in claim 34, wherein the raised portions comprise a glass or Si02.
Substitute Sheet
(Rule 26) RO/AU
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7456383B2 (en) * 2003-08-06 2008-11-25 University Of Pittsburgh Surface plasmon-enhanced nano-optic devices and methods of making same
US8750653B1 (en) * 2010-08-30 2014-06-10 Sandia Corporation Infrared nanoantenna apparatus and method for the manufacture thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7456383B2 (en) * 2003-08-06 2008-11-25 University Of Pittsburgh Surface plasmon-enhanced nano-optic devices and methods of making same
US8750653B1 (en) * 2010-08-30 2014-06-10 Sandia Corporation Infrared nanoantenna apparatus and method for the manufacture thereof

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