Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
  • H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
  • H10D62/881—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being a two-dimensional material
  • H10D62/882—Graphene
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
  • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
  • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/10—Semiconductor bodies
  • H10F77/14—Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies
  • H10F77/143—Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies comprising quantum structures
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/40—Optical elements or arrangements
  • H10F77/413—Optical elements or arrangements directly associated or integrated with the devices, e.g. back reflectors
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
  • H10K30/60—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation in which radiation controls flow of current through the devices, e.g. photoresistors
  • H10K30/65—Light-sensitive field-effect devices, e.g. phototransistors
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/549—Organic PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to the use of single or multi-layer graphene as the photon detecting layer in a photodetector.
• Photodetectors are used to detect or sense light or other electromagnetic energy.
• Currently available photodetectors are generally used in a variety of practical applications such as wired and wireless communications, sensing, monitoring, scientific instrumentations, national security, and so on.
• Many optical photodetectors use semiconductor materials as the photodetection material system. Semiconductor materials, however, have a band gap, and therefore only photons having energy greater than the band gap can be detected, potentially leaving photons undetected.
• the intrinsic bandwidth of semiconductor based photodetectors is limited by the carrier transit time in the photodetection region. Both of these limitations results in a less than optimal photodetector.
• the present invention provides a photodetecting device in which single or multiple layers of graphene are the photoconducting layer.
• a substrate is provided upon which a gate oxide layer deposited.
• a channel layer of graphene is then deposited on the gate oxide layer and source and drain contact regions are patterned on the graphene layer.
• split gates may be provided on top of the source and drain regions. Also, multiple source and drain regions can be provided.
• multiple photodetection elements can be provided along with conventional signal processing readout circuitry to create a photodetecting array.
• Figure 1 shows a simple FET implementation of a graphene-based photodetector.
• Figure 2 is a graph showing the internal potential generated across the channel of the graphene-based photodetector.
• Figure 3 shows a split-gated FET implementation of a graphene-based photodetector.
• Figure 4 is a graph showing the internal potential generated across the channel of the split- gated graphene-based photodetector.
• Figure 5 shows a split-gated, graphene-based FET implementation of a graphene-based photodetector with integrated waveguide structure.
• Figure 6 shows a graphene-based photodetector with metallic interdigitated fingers for enhancing the effective photo-detection area.
• Figure 7 shows a top view of a graphene-based photodetector array.
• graphene in a photodetector. Because of graphene's unique property of being a zero or very small band gap material, photons at any wavelength (or any energy level) can be absorbed. Hence, graphene can be used as a universal material for a wide range of photonic applications at wavelengths ranging at least from ultraviolet to far- infrared.
• the carrier transport velocity in graphene under high E-f ⁇ eld can approach Fermi velocity 10 6 meter/second, which is 10 to 100 times larger than the carrier transport velocity in conventional semiconductors. This can lead to photodetectors with much higher bandwidth.
• Devices employing the invention can work without direct external biases between the photocurrent generation paths, which naturally leads to zero dark current and may enable many applications in imaging, remote sensing and monitoring where low dark current is essential. Devices employing the invention can also work with direct external biases between the photocurrent generation path, which usually leads to better efficiency but with some dark current.
• a first embodiment of a photodetector made in accordance with this invention has a basic design similar to a conventional field effect transistor (FET) where the photodetection is realized by applying a gate bias to create a graphene p-n junction in order to maximize the detection efficiency.
• Backgate 10 is comprised of silicon back gate (either heavily doped or lightly doped).
• a gate oxide layer 12 is deposited as an insulating layer.
• Gate oxide layer 12 can be SiO 2 or any dielectric material.
• On top of the gate oxide a layer of graphene 14 that may be one or more layers thick is provided.
• Graphene layer 14 can be doped or un-doped.
• the graphene layer can be created by a number of processes including mechanical exfoliation, chemical deposition, or growth.
• drain 6 and source 8 contacts are patterned on the graphene/gate oxide layer 12, the graphene then forming a channel between the drain 6 and source 8 contacts.
• the graphene and the source and drain contacts should overlap by at least lOOnm so as to create good metal-graphene junctions.
• Gate bias V G is applied to field-dope the graphene in the middle of channel layer 14. The doping of the graphene close to and underneath the source and drain is dominated by the contacts instead of the back gate. With proper selection of the gate bias V G , good detection efficiency can be obtained because a graphene p-n junction is formed at the source (or drain)-graphene interface.
• Fig. 2 shows the internal potential generated across the width d of the channel layer 14 of Fig. 1.
• the areas of maximum photodetection are in close proximity to the source 8 and drain 6 regions at which a graphene p-n junction is formed and the E- field is maximized in this area, leading to effective separation of photo-generated carriers.
• FIG. 3 another implementation of the photodetector made in accordance with the present invention uses a split gated structure so that a high e-field photodetection region can be created.
• source and drain regions 30 and 32 respectively are deposited on single or few (2 to 5) layers of graphene 38.
• a transparent gate dielectric layer (can be high-K or low-K) 40 is deposited on top of the graphene 38, the source 30, and drain 32 regions. Gates 42 and 44 are then patterned on top of the dielectric layer 40.
• the gate dielectric layer 40 is shown partially cut away for explanatory purposes. This layer may cover the whole of the graphene channel as well as source and drain regions, apart from locations where electrical connections are required.
• a gate bias is applied to gates 42 and 44, respectively, to create a sensitive photo-detection region in channel 38 in which a considerable E-field is produced.
• the magnitude of the gate bias is a function of the thickness of the top gate dielectric 40.
• Fig. 4 graphically illustrates the potential generated by the top gates 42 and 44 between the source 30 and drain 32 regions of the device in Fig. 3.
• Fig.5 shows the split gate photodetection device as seen in Fig. 3, but with the addition of an optical waveguide 50 which underlies the graphene. This device operates the same way as the photodetection device of Fig.
• Waveguide 50 can be fabricated from silicon, silicon nitride, silicon oxy-nitride or any low-loss material, using typical semiconductor processes such as material growth, wafer bonding, wet or dry etches, and so on.
• Fig. 6 shows a modification which may be made to the embodiments previously described. Interdigitated fingers defining multiple source regions (64-67) and drain regions (60-63) are patterned on top of graphene layer 38.
• This implementation provides for a very sensitive photodetector because the effective photo-detection area can be greatly enhanced.
• Different source and drain metals with different work functions can be used in order to produce an internal potential at zero source-drain bias for photo-carrier separation. Applying a source- drain bias can further enhance the photo-detection efficiency. However in this case, a dark current will be introduced into the operation.
• a shadow mask can be used to block the light absorption in
• Photodetector arrays are very useful in applications such as imaging (in very broad wavelength range at least from far infrared to visible) and monitoring.
• the graphene-based photodetector of the present invention can also be fabricated in such an array 70, as shown in Fig. 7, using standard semiconductor processes.
• the addition of conventional signal processing circuitry 72 can provide a readout from all of the photodetecting elements 74 in the detector array, each element 74 of which may comprise a photodetector according to any of the previously described embodiments.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Light Receiving Elements (AREA)
• Photometry And Measurement Of Optical Pulse Characteristics (AREA)
• Thin Film Transistor (AREA)
• Solid State Image Pick-Up Elements (AREA)
• Carbon And Carbon Compounds (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (2)

Family

ID=43604588

Family Applications (1)

Country Status (6)

Cited By (8)

Families Citing this family (119)

Family Cites Families (18)

• 2009
  • 2009-08-24 US US12/546,097 patent/US8053782B2/en active Active
• 2010
  • 2010-08-06 TW TW099126308A patent/TWI496310B/zh active
  • 2010-08-17 JP JP2012526004A patent/JP5937006B2/ja not_active Expired - Fee Related
  • 2010-08-17 CN CN201080035978.1A patent/CN102473844B/zh active Active
  • 2010-08-17 EP EP10744585.0A patent/EP2438635B1/en active Active
  • 2010-08-17 WO PCT/EP2010/061986 patent/WO2011023603A2/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events