Santa Barbara Research Center

Raytheon Company

Paul R Norton

Michael Moroz

Carol S Talley

Ronald L Williams

William J Hamilton, Jr

William A Radford

Ronald W Berry

Eli E Gordon

Chao Huang

An integrated optical device array structure has a plurality of interconnected solid state microelectronic optical device elements associated together on a substrate structure. The optical device elements may be optical detectors or optical emitters. Each optical device element lies on a nonplanar optical array surface. Each optical device element includes an opto-electronic device that interconverts an optical signal and an opto-electronic device electrical signal, and an electrical interface circuit that is in electrical communication with the opto-electronic device electrical signal. The optical device array structure may be fabricated by preparing a flat array of optical device elements and deforming the flat array into the required shape.

Nonplanar integrated optical device array structure and a method for its fabrication

Absorption coatings utilized in a detector array reduces the optical signature of an infrared detector or detector array by reducing the undesirable reflections from exposed metal surfaces and non-planar surface features within the photodetector array. The application of an absorption coating, consisting of a single layer black coating, a multi-layer dark coating, a moth-eye surface structure, or a combination of these, reduces the undesired reflected radiation for a relevant spectral range. Accordingly, the optical signature of the detector array is reduced and the problems of optical cross-talk and ghost images are eliminated.

Infrared detector with reduced optical signature

Apparatus (102, 202, 302) and method for tunneling rate infrared detection devices formed on a single substrate (100). A counter electrode (104, 207) having a plurality of portions extending from the substrate (100) with the counter electrode (104, 207) suspended above the substrate (100) at a distance from a tunneling electrode (116) so that a tunneling current flows through the counter electrode (104, 207) and tunneling electrode (116) in response to an applied bias voltage. The counter electrode (104, 207) and tunneling electrodes (116) form a circuit that produces an output signal. A force applied to the sensor (102, 202, 302) urges the counter electrode (104, 207, 304) to deflect relative to the tunneling electrode (116) to modulate the output signal. The output signal is a control voltage that is applied between the counter electrode (104, 207, 304) and a control electrode (114) to maintain a constant tunneling current. In the preferred embodiment, two cantilever portions (108, 110) extend from the wafer surface (100). In a further embodiment, three portions (206, 208, 210) extend from the substrate (100). In an alternate embodiment, a counter electrode (304) having a varying width is fabricated.

Method and apparatus for sensing infrared radiation utilizing a

An integrated radiation detector (10) includes a substrate (12) having a first region (14) comprised of Group III-V semiconductor material, such as GaAs, formed over a first surface, and a second region (26) comprised of Group II-VI semiconductor material, for example HgCdTe, formed over a second, opposite surface. The second region has a bandgap selected for absorbing radiation within a first range of wavelengths, such as IR radiation within the range of 12 micrometers to three micrometers. A first detector includes an antenna structure (20) coupled to a Schottky contact (22) for detecting electromagnetic radiation having wavelengths within a second range of wavelengths, such as wavelengths corresponding to frequencies within a range of approximately 30 GHz to approximately 1000 GHz. A second detector includes a photoconductive or photovoltaic infrared detector for collecting charge carriers generated by the absorption of the IR radiation. For a substrate comprised of semi-insulating GaAs, a lattice accommodation region (28) is interposed between the substrate and the second region. An RF potential ground plane is disposed, relative to the Schottky contact, at a distance corresponding to 1/4 of a wavelength. A microlens (42) may be provided in registration with an underlying IR detector for focussing, through the substrate, incident IR radiation.

Integrated IR and mm-wave detector

A back side illuminated focal plane array (10,20) includes a plurality of radiation detectors (12,26) disposed upon a front surface of the array and further includes a plurality of optical flux concentrating structures (16,22) integrally formed upon or within a back, radiation receiving, surface of the array. Each of the flux concentrating structures is in registration with at least one of the radiation detectors for concentrating optical flux thereon. A method of the invention includes the steps of providing a substrate 30 and preparing a surface of the substrate such that the surface has a faster lateral etch rate than a vertical etch rate when exposed to an etchant. The method further includes a step of providing a mask 32 over the surface of the substrate, the mask having a plurality of openings therethrough individual ones of which are located at a position where a lens element is desired. The method further includes the steps of applying an etchant to the surface of the substrate through the openings within the mask, etching the surface of the substrate such that a plurality of depressions 34 are formed within the surface and depositing a layer 36 of material over the surface of the substrate such that the depressions are filled with the material. The method includes an additional step of removing excess material from the surface of the substrate, the material remaining within each of the depressions forming a lens element.

Method and apparatus for concentrating optical flux in a focal plane

Disclosed is a method of fabricating a two-color radiation detector, and two-color photodetectors fabricated by the method. A structure is grown upon a substrate (10) to provide, in sequence, a LPE grown LWIR n-type layer (12), a MWIR p+ type common contact layer (14), and a MWIR n-type layer (16). Following growth of the MWIR n-type layer, a layer of passivation (18) is applied, and the substrate is removed to so as to enable further processing of the structure into an array (1) of two-color photodetectors. The three layer structure is bonded, prior to further processing, to a supporting substrate (22) with an adhesive bond made to the passivation layer. The supporting substrate is comprised of IR transparent material such as Group IIB-VIA semiconductor material, Group IIIA-VA semiconductor material, Group IVA semiconductor material, sapphire, and combinations thereof. The supporting substrate may be subsequently removed after hybridizing a photodetector array (2) with readout electronics to provide a thinned detector array having a reduced cool-down time.

Method of fabricating a two-color detector using LPE crystal growth

A radiation detector (1) includes a multi-layered substrate (2,10) having a first major surface, which is a radiation receiving surface, and a second major surface disposed opposite to the first major surface. A first detector is formed adjacent to the first major surface, the first detector being responsive to a wavelength or wavelengths of electromagnetic radiation in the range of approximately 0.3 micrometers (near-UV) to approximately 1.2 micrometers (near-IR). A second detector is formed adjacent to the second major surface of the multi-layered substrate, the second detector being responsive to a wavelength or wavelengths of electromagnetic radiation in the range of approximately one micrometer to approximately twenty micrometers (SWIR to VLWIR). In a presently preferred embodiment the second detector is simultaneously responsive to IR radiation within two distinct spectral bands.

Integrated IR and visible detector

A backside illuminated array (10) of radiation detectors (12) each of which has an output terminal for expressing a center-surround output signal. The array includes a plurality of the radiation detectors (12) disposed substantially adjacent to a first surface of the array, each of the radiation detectors comprising a central radiation detector (20) having a radiation absorbing area that is substantially surrounded by a radiation absorbing area of an associated peripheral radiation detector (22). The array further includes a transmission grating structure (16) disposed over a second surface (14a) of the array opposite the first surface for diffracting incident radiation for uniformly illuminating associated central and peripheral radiation detectors. The array further includes a plurality of flux concentrating structures (18) interposed between the transmission grating structure and the plurality of radiation detectors. Individual ones of the flux concentrating structures are disposed in registration with an individual one of the radiation detectors for concentrating incident optical radiation upon the central radiation detector thereof.

Radiation detector array having center surround pixel output

Photodetectors that produce detectivities close to the theoretical maximum detectivity include an electrically insulating substrate carrying a body of semiconductor material that includes a region of first conductivity type and a region of second conductivity type where the region of first conductivity type overlies and covers the junction with the region of second conductivity type and where the junction between the first and second regions separates minority carriers in the region of second conductivity type from majority carriers in the region of first conductivity type. These photodetectors produce high detectivities where radiation incident on the detectors has wavelengths in the range of about 1 to about 25 microns or more, particularly under low background conditions.

Method of fabricating a trapping-mode

A method for fabricating a plurality of semiconductor photodetectors and an array of same produced by the method. The method includes a first step of selectively removing semiconductor material to form a channel within a semiconductor material for physically isolating a first photodetector from a second photodetector, the semiconductor material having a characteristic energy bandgap. The method includes a second step of selectively increasing the carrier concentration of the semiconductor material within a bottom region of the channel for preventing minority charge carriers from diffusing under the channel from a region associated with the first photodetector to a region associated with the second photodetector. The step of selectively removing is accomplished by the steps of providing a patterned mask upon the semiconductor material and selectively removing the underlying semiconductor material through an opening within the mask. The step of selectively increasing the carrier concentration includes a step of ion implanting the semiconductor material through the opening within the mask.

Implant guarded mesa having improved detector uniformity

Methods of fabricating a two-color infrared detector array, and an array of same fabricated by the methods. There is disclosed (a) selectively forming a plurality of first regions upon or within a surface of a substrate, the first regions being comprised of a first semiconductor material having a first type of electrical conductivity and a significant responsivity to wavelengths within a first spectral band. A second step (b) forms a substantially continuous layer comprised of a second semiconductor material over the surface of the substrate and over the plurality of first regions, the layer being comprised of semiconductor material having a second type of electrical conductivity for forming a plurality of first heterojunctions with the first regions. A third step (c) selectively forms a plurality of second regions upon the layer, individual ones of which are in registration with a corresponding one of the first regions. The second regions are comprised of a semiconductor material having the first type of electrical conductivity for forming a plurality of second heterojunctions with the underlying layer and a significant responsivity to wavelengths within a spectral band that does not significantly overlap the first spectral band.

Two-color radiation detector array and methods of fabricating same

Structure and method of fabricating a trapping-mode

An array [10] of photodetecting active regions [16] includes a layer of photoresponsive material [14] differentiated into a plurality of photodetecting active regions. The layer has a composition which varies across a thickness of the layer from a first surface of the layer to a second surface [14a] of the layer such that a magnitude of an effective energy bandgap of the layer decreases from the first surface to the second surface. A resulting crystal potential field constrains photoexcited minority charge carriers to exist within a region of the layer which is substantially adjacent to the second, narrower energy bandgap surface. The array further includes a plurality of groove structures [18] formed within the second surface of the layer and extending into the layer to a depth less than the thickness of the layer. A groove is interposed between at least two adjacent active regions for substantially preventing minority carriers from laterally diffusing between active regions. The grooves may be combined with ground plane or guard diode structures, each limiting the diffusion of minority charge carriers along a respective axis. The photodetecting active regions may each comprise a reduced area p-n juntion.

Control of optical crosstalk between adjacent photodetecting regions

Photodetectors that produce detectivities close to the theoretical maximum detectivity include an electrically insulating substrate carrying a body of semiconductive material that includes a region of first conductivity type and a region of second conductivity type where the first region overlies and substantially covers the top and sides of the region of second conductivity type and where the junction between the first and second regions creates a depletion layer that separates minority carriers in the region of second conductivity type from majority carriers in the region of first conductivity type. These photodetectors produce high detectivities where radiation incident on the detectors has wavelengths in the range of about 1 to about 25 microns or more, particularly under low background conditions.

Growing community of inventors

Santa Barbara, CA, United States of America

Paul R Norton