Classifications

• • 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
• • 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
  • H10F77/146—Superlattices; Multiple quantum well 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

Definitions

• the field of the invention is that of electromagnetic wave detectors made of semiconductor material and in particular with a quantum multi-well structure, particularly suitable for the infrared field.
• This type of structure has the advantage of providing very good sensitivities due to the discretization of the energy levels within the conduction bands of the photoconductive materials used.
• the present invention proposes to use lamellar patterns with an architecture of patterns nevertheless making it possible to diffract incident radiation in the different directions of a plane parallel to the plane of the quantum multi-well structure.
• the subject of the present invention is a detector comprising a quantum multi-well structure operating on interband or intersubband transitions by absorption of radiation around a lambda wavelength and comprising means of optical coupling of said radiation, characterized in what:
• the coupling means comprise a set of first diffractive lamellar patterns distributed in at least a first direction and a set of second diffractive lamellar patterns distributed in at least a second direction, said first and second directions being perpendicular to each other and located in a plane. parallel to the plane of the quantum multiwell structure.
• the object of the invention is to strengthen the electromagnetic field in the form of optical modes at the level of the active layer and can therefore be applied to inter-band transitions or to inter-band transitions.
• the detector can comprise first patterns having surfaces of dimensions equivalent to the dimensions of the surfaces of the second lamellar patterns.
• the first lamellar patterns and the second lamellar patterns are distributed so as to form concentric squares or rectangles.
• the first lamellar patterns and the second lamellar patterns are distributed around a center of symmetry with a distribution in four quadrants.
• the first patterns and the second patterns are distributed radially in first and second directions perpendicular to each other.
• the detector according to the invention may comprise a stack of layers produced on the surface of a substrate, said stack comprising the structure with quantum multi-wells and external layers, the lamellar patterns being etched within an external layer.
• the stack of layers is a stack of layers of the GaAs type, doped GaAIAs, the substrate being of the undoped GaAS type.
• the quantum multi-well structure is composed of an alternation of doped GaAs layers and doped GaAIAs layers, the external layers being ohmic contact layers based on GaAs more strongly doped than those constituting of the quantum multiwell structure.
• the detector comprises a substrate transparent to the wavelength of the incident radiation and a reflective layer at said wavelength, said reflective layer being on the surface of the lamellar patterns, so as to operate the detector in reflection.
• the etching depth can be of the order of lambda 4 instead of lambda / 2, according to the network theory known to those skilled in the art and described in particular in "Electromagnetic Theory of Gratings" by R. Petit who shows that the etching depth must be double in the case of a crossed network (2D) compared to a simple lamellar network (1 D). From an industrial point of view, reducing the thickness of the layers to be etched will reduce manufacturing times and costs but will also increase production yields.
• the subject of the invention is also a matrix detector characterized in that it comprises a matrix of unitary detector elements, each unitary detector element comprising a stack of layers, said stack comprising the structure with quantum multi-wells and layers external, the first patterns and the second lamellar patterns being etched within an external layer, said unitary detector elements being produced on the surface of a common substrate.
• Figure 1 illustrates a quantum multiwell structure according to known art.
• FIG. 2 illustrates a quantum multi-well detector having optical coupling means of the matrix diffraction grating type, according to the prior art.
• Figure 3 illustrates a sectional view of a quantum multiwell detector in which the matrix diffraction grating is produced within an encapsulation layer, according to the prior art.
• Figure 4 illustrates an optical coupling structure in which the lamellar patterns are distributed concentrically, used in a first variant of detector according to the invention.
• Figure 5 illustrates a sectional view of the detector illustrated in Figure 4.
• Figure 6 illustrates an optical coupling structure in which the lamellar patterns are distributed in four quadrants, used in a second variant of detector according to the invention.
• Figure 7 illustrates a sectional view of the detector illustrated in Figure ⁇ .
• Figure 8 illustrates an optical coupling structure in which the lamellar patterns are distributed radially
• Figure 9 illustrates an example of a matrix detector according to the invention.
• the detector according to the invention comprises lamellar patterns in two directions orthogonal to each other and situated in a plane parallel to the plane of the layers making up the structure to quantum multiwells.
• the first total surface corresponding to all of the surfaces of the first lamellar patterns in a first direction is equal to the second total surface corresponding to all of the surfaces of the second lamellar patterns.
• the lamellar patterns are distributed concentrically as illustrated in FIG. 4, the black lines representing the engraved patterns.
• first patterns and second patterns of equal dimensions which form concentric squares. More precisely as shown in FIG. 4, the pattern Mp1 has the same dimensions as the pattern Ms1.
• the detector according to the invention can be conventionally produced on the surface of a substrate made of semiconductor material S.
• An assembly of layers constituting a so-called lower ohmic contact Ci of highly doped semiconductor material is deposited on the surface of the substrate.
• This ohmic contact supports all of the semiconductor layers constituting the MPQ quantum multi-well structure, the latter is in contact with an assembly of layers constituting an ohmic contact called higher Cs, detection being ensured between the two ohmic contacts.
• the lamellar patterns can be etched in the ohmic contact layer as illustrated in FIG. 5 which represents a sectional view along a plane perpendicular to the direction Dy, of the second lamellar patterns Msj.
• the lamellar patterns can be distributed as illustrated in FIG. 6 so as to retain equivalent properties in terms of optical coupling along all of the directions included in a plane parallel to the plane of the quantum multi-well structure and obtaining equivalent diffraction surfaces for the first lamellar patterns and the second lamellar patterns, the first patterns and the second patterns are arranged in four quadrants and around a center of symmetry O.
• the detector according to this second variant can be produced on the surface of a semiconductor substrate, by stacking semiconductor layers to form all of the contact layers and all of the layers constitutive of the quantum multiwell structure.
• the lamellar patterns can be produced within the so-called upper contact layer Cs.
• Figure 7 illustrates a sectional view along a plane perpendicular to the direction Dy.
• the lamellar patterns can be distributed as illustrated in FIG. 8 radially. In this configuration, the first patterns are arranged along first directions Ten, Di + 1 x, and the second patterns are arranged along second directions Diy, Di + 1, directions Ten, Di + 1 x and Diy, Di +1 there being perpendicular to each other.
• optical coupling configurations for an elementary detector which can advantageously be applied within the framework of a matrix detector comprising unitary elements, each of these unitary elements comprising on the surface optical coupling means comprising patterns. diffraction lamellar in the directions Dx and Dy.
• FIG. 9 illustrates an example of a matrix detector according to the invention in which all of the unitary elements are produced on the surface of a common substrate with an ohmic contact layer also common.
• a first ohmic contact layer Ci is also produced on a substrate transparent to the wavelengths to which the detector is sensitive.
• a stack of constituent layers of the quantum multi-well structure is produced on this ohmic contact layer.
• the second ohmic contact layer Cs is deposited.
• the lamellar patterns are etched within the Cs layer.
• Example of embodiment We will describe an example of a detector according to the invention, operating in the infrared range and more particularly adapted to the 8-12 micron ranges:
• the lower ohmic contact layer made of Si doped GaAs is deposited with a doping rate of 5. 10 18 cm ⁇ 3 and a thickness typically of 2 microns.
• the quantum multi-well structure is produced by the stack of 50 wells composed of a layer of GaAs doped with Si with a concentration of charge carriers of 5. 10 18 cm 3 3 of thickness 5 nm, inserted between two barrier layers formed of Ga 0.75 AI 0.25 As of thickness 50 nm.
• the upper contact layer is identical to the lower contact layer and also has a thickness of 2 microns;
• the lamellar patterns are produced within this upper contact layer.
• the etching depths are 0.7 microns and the pitch of the patterns is 2.7 microns (the average structure index being 3.3 microns to 9 microns).
• the filling rate of the surface of the upper contact layer is typically of the order of 50%.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Nanotechnology (AREA)
• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biophysics (AREA)
• Optics & Photonics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Light Receiving Elements (AREA)

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• 2003
  • 2003-05-27 FR FR0306432A patent/FR2855654B1/fr not_active Expired - Fee Related
• 2004
  • 2004-05-26 EP EP04741654A patent/EP1627434A1/de not_active Withdrawn
  • 2004-05-26 US US10/558,187 patent/US7741594B2/en not_active Expired - Fee Related
  • 2004-05-26 WO PCT/EP2004/050932 patent/WO2004107455A1/fr not_active Ceased

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