Abstract: CMOS image sensor having high sensitivity and low crosstalk, particularly at far-red to infrared wavelengths, and a method for fabricating a CMOS image sensor. A CMOS image sensor has a substrate, an epitaxial layer above the substrate, and a plurality of pixels extending into the epitaxial layer for receiving light. The image sensor also includes at least one of a horizontal barrier layer between the substrate and the epitaxial layer for preventing carriers generated in the substrate from moving to the epitaxial layer, and a plurality of lateral barrier layers between adjacent ones of the plurality of pixels for preventing lateral diffusion of electrons in the epitaxial layer.

Abstract: Disclosed is a photoelectric surface including: a first group III nitride semiconductor layer that produces photoelectrons according to incidence of ultraviolet rays; and a second group III nitride semiconductor layer provided adjacent to the first group III nitride semiconductor layer and made of a thin-film crystal having c-axis orientation in a thickness direction, the second group III nitride semiconductor layer having an Al composition higher than that of the first group III nitride semiconductor layer.

Abstract: A photodiode for detection of preferably infrared radiation wherein photons are absorbed in one region and detected in another. In one example embodiment, an absorbing P region is abutted with an N region of lower doping such that the depletion region is substantially (preferably completely) confined to the N region. The N region is also chosen with a larger bandgap than the P region, with compositional grading of a region of the N region near the P region. This compositional grading mitigates the barrier between the respective bandgaps. Under reverse bias, the barrier is substantially reduced or disappears, allowing charge carriers to move from the absorbing P region into the N region (and beyond) where they are detected. The N region bandgap is chosen to be large enough that the dark current is limited by thermal generation from the field-free p-type absorbing volume, and also large enough to eliminate tunnel currents in the wide gap region of the diode.

Abstract: A photodiode for detection of preferably very long wavelength infrared radiation wherein low energy photons are absorbed in one region and detected in another. In one example embodiment, an absorbing P region is abutted with an N region of lower doping such that the depletion region is substantially (preferably completely) confined to the N region. The N region is also chosen with a larger bandgap than the P region, with compositional grading of a region of the N region near the P region. This compositional grading mitigates the barrier between the respective bandgaps. Under reverse bias, the barrier is substantially reduced or disappears, allowing charge carriers to move from the absorbing P region into the N region (and beyond) where they are detected. The N region bandgap is chosen to be large enough that the dark current is limited by thermal generation from the field-free p-type absorbing volume, and also large enough to eliminate tunnel currents in the wide bandgap region of the diode.

Abstract: Microelectronic imagers with curved image sensors and methods for manufacturing curved image sensors. In one embodiment, a microelectronic imager device includes an imager die having a substrate, a curved microelectronic image sensor having a face with a convex and/or concave portion at one side of the substrate, and integrated circuitry in the substrate operatively coupled to the image sensor. The imager die can further include external contacts electrically coupled to the integrated circuitry and a cover over the curved image sensor.

Abstract: A method of making a two-dimensional detector array (and of such an array) comprising, for each of a plurality of rows and a plurality of columns of individual detectors, forming an n-doped semiconductor photo absorbing layer, forming a barrier layer comprising one or more of AlSb, AlAsSb, AlGaAsSb, AlPSb, AlGaPSb, and HgZnTe, and forming an n-doped semiconductor contact area.

Abstract: The present invention provides a heterojunction photodiode which includes a pn or Schottky-barrier junction formed in a first material region having a bandgap energy Eg1. When reverse-biased, the junction creates a depletion region which expands towards a second material region having a bandgap energy Eg2 which is less than Eg1. This facilitates signal photocurrent generated in the second region to flow efficiently through the junction in the first region while minimizing the process-related dark currents and associated noise due to near junction defects and imperfect surfaces which typically reduce photodiode device performance. The heterojunction photodiode can be included in an imaging system which includes an array of junctions to form an imager.

Abstract: A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

Abstract: A semiconductor device comprising a vertical stack of layers, comprising: an active layer configured to support a two dimensional carrier gas having an excess of carriers; source and drain contacts provided to said active layer such that a current can flow between said source and drain contacts through said two dimensional carrier gas; a lower conducting region, wherein said lower contact conducting region is a patterned lower conducting region such that said active layer is suspended across gaps in said lower conducting region and said active layer is physically supported by and suspended between parts of said lower conducting region.

Abstract: A semiconductor light-receiving device has a substrate including upper, middle and lower regions in its front side. A p-type layer on the lower region has a top surface including a portion on a level with the middle region. An electrode covers at least part of the boundary between the portion of the p-type layer and the middle region. An n-type layer on the p-type layer has a top surface including a portion on a level with the upper region. Another electrode covers at least part of the boundary between the portion of the n-type layer and the upper region.

Abstract: Electromagnetic energy is detected with high efficiency in the spectral range having wavelengths of about 1–2 microns by coupling an absorber layer having high quantum efficiency in the spectral range having wavelengths of about 1–2 microns to an intrinsic semiconducting blocking region of an impurity band semiconducting device included in a solid state photon detector.

Abstract: A light emission device and method for producing the device. The device includes, on a substrate, a stack including an etching stop layer, a first barrier layer, an emitting layer, and a second barrier layer. The stop layer is of the same nature as the emitting layer. One may form a mirror on the stack, eliminate the substrate by etching, and form another mirror on the stop layer to obtain a micro-cavity. The device may be applied in particular to the detection of gas.

Abstract: An interline transfer type image sensing device that can be operated at high speed and with low image smear is described. The device incorporates a refractory metal layer which is used for both a light shield over the vertical charge transfer region and as a wiring layer for low resistance strapping of poly crystalline silicon (polysilicon) gate electrodes for the vertical charge transfer region. Plugs provided by a separate metallization layer connect the refractory light shield to the polysilicon gate electrode. These plugs allow high temperature processing after refractory light shield patterning for improved sensor performance without degradation of the polysilicon gate electrode or the refractory lightshield layer.

Abstract: The invention relates to the design, fabrication, and use of semiconductor devices that employ deep-level transitions (i.e., deep-level-to-conduction-band, deep-level-to-valence-band, or deep-level-to-deep-level) to achieve useful results. A principal aspect of the invention involves devices in which electrical transport occurs through a band of deep-level states and just the conduction band (or through a deep-level band and just the valence band), but where significant current does not flow through all three bands. This means that the deep-state is not acting as a nonradiative trap, but rather as an energy band through which transport takes place. Advantageously, the deep-level energy-band may facilitate a radiative transition, acting as either the upper or lower state of an optical transition.

Abstract: An avalanche photodiode including a multiplication layer is provided. The multiplication layer may include a well region and a barrier region. The well region may include a material having a higher carrier ionization probability than a material used to form the barrier region.

Abstract: A light receiving element, in which nanoparticles obtained by a colloidal synthesis are interconnected so as to serve as a channel for electrons excited by light received by the nanoparticles, thereby improving the performance of the light receiving element and simplifying a process for manufacturing the light receiving element.

Abstract: According to the present invention, there is provided a new GaN-based field effect transistor of a normally-off type, which has an extremely small ON resistance during operation and is capable of a large-current operation.

Abstract: A photosensitive diode has an active region defining a majority carrier of a first conductivity type and a minority carrier of a second conductivity type. At least one extraction region is disposed on a first side of the active region and has a majority carrier of the second conductivity type. Carriers of the second conductivity type are extracted from the active region and into the extraction region under a condition of reverse bias. At least one exclusion region is disposed on a second side of the active region and has a majority carrier of the first conductivity type. The exclusion region prevents entry of its minority carriers, which are of the second conductivity type, into the active region while in a condition of reverse bias. The exclusion region includes a superlattice with a plurality of layers.

Abstract: A highly reflecting back illuminated diode structure allows light that has not been absorbed by a semiconductor absorbing region to be back reflected for at least a second pass into the absorbing region. The diode structure in a preferred embodiment provides a highly reflecting layer of gold to be supported in part by a conducting alloyed electrode ring contact and in part by a passivation layer of SixNy. Conveniently this structure provides a window within the contact which allows light to pass between the absorbing region and the reflecting layer of gold.

Abstract: Ultrafast square-law detectors amplify electric currents and electromagnetic waves with frequencies on the order of 100 GHz or more. The detectors use injection of spin-polarized electrons from a magnetic film or region into another magnetic film or region through a thin semiconductor control region. A signal current flowing through a conductive nanowire induces a magnetic field causing precession of electron spin injected inside the semiconductor layer and thereby changing the conductivity of the detector. With the magnetizations of the magnetic regions being parallel or antiparallel to each other, the resulting spin injection current includes a term proportional to the square of the signal current so that the detector behaves as a square-law detector. Such square-law detectors are magnetic-semiconductor heterostructures and can operate as a frequency doubler for millimeter electromagnetic waves.

Abstract: A heterojunction bipolar transistor is presented, comprising a substrate having formed thereon a heterojunction bipolar transistor layer structure, and including an emitter layer. The emitter layer includes a strained, n-doped compound of indium arsenic and phosphorus. The transistor further comprises, between the substrate and emitter layer, a subcollector layer, a collector layer, a base layer, and an optional spacer layer. The emitter layer may include a graded portion. A contact layer is formed on the emitter layer to provide contacts for the device.

Abstract: A method for manufacturing an infrared detector forms a p-n junction by forming a low concentration p type HgCdTe layer, forming a diffusion preventing layer for exposing some upper part of the low concentration p type HgCdTe layer, and by forming a low concentration n type HgCdTe layer by diffusing hydrogen ions and atoms to the low concentration p type HgCdTe layer using hydrogen plasma. The hydrogen ions or atoms are diffused on some of the low concentration p type HgCdTe layer to be a predetermined depth using the hydrogen plasma to form the low concentration n type HgCdTe layer in order to prevent an interface of the p-n junction from damaging, and thereby leakage current can be prevented, fabrication cost is not increased and yield is increased due to simple processes.

Abstract: A multi-wavelength semiconductor image sensor comprises a p-type Hg0.7Cd0.3Te photo-absorbing layer formed on a single crystal CdZnTe substrate, a CdTe isolation layer deposited on the photo-absorbing layer, a p-type Hg0.77Cd0.23Te photo-absorbing layer deposited on the CdTe isolation layer, n+ regions which are formed in these photo-absorbing layers and form a pn-junction with each of these photo-absorbing layers, an indium electrode connected to each of these n+ regions and a ground electrode connected to the photo-absorbing layer, the semiconductor isolation layer being electrically isolated from the photo-absorbing layer.

Abstract: In one aspect the invention relates to a high bandwidth shallow mesa semiconductor photodiode responsive to incident electromagnetic radiation. The photodiode includes an absorption narrow bandgap layer, a wide bandgap layer disposed substantially adjacent to the absorption layer, a first doped layer having a first conductivity type disposed substantially adjacent to the wide bandgap layer, and a passivation region disposed substantially adjacent to the wide bandgap layer and the first doped layer.

Abstract: The present invention is a novel field effect transistor having a channel region formed from a narrow bandgap semiconductor film formed on an insulating substrate. A gate dielectric layer is formed on the narrow bandgap semiconductor film. A gate electrode is then formed on the gate dielectric. A pair of source/drain regions formed from a wide bandgap semiconductor film or a metal is formed on opposite sides of the gate electrode and adjacent to the low bandgap semiconductor film.

Abstract: A structure with an optically active layer embedded in a Si wafer, such that the outermost epitaxial layer exposed to the CMOS processing equipment is always Si or another CMOS-compatible material such as SiO2. Since the optoelectronic layer is completely surrounded by Si, the wafer is fully compatible with standard Si CMOS manufacturing. For wavelengths of light longer than the bandgap of Si (1.1 &mgr;m), Si is completely transparent and therefore optical signals can be transmitted between the embedded optoelectronic layer and an external waveguide using either normal incidence (through the Si substrate or top Si cap layer) or in-plane incidence (edge coupling).

Abstract: An integrated circuit is provided that includes a substrate incorporating a semiconductor photodiode device having a p-n junction. The photodiode device includes at least one capacitive trench buried in the substrate and connected in parallel with the junction. In a preferred embodiment, the substrate is formed from silicon, and the capacitive trench includes an internal doped silicon region partially enveloped by an insulating wall that laterally separates the internal region from the substrate. Also provided is a method for fabricating an integrated circuit including a substrate that incorporates a semiconductor photodiode device having a p-n junction.

Abstract: Disclosed is a Group III nitride compound semiconductor light-emitting element formed of Group III nitride compound semiconductor layers, including a multi-layer containing light-emitting layers; a p-type semiconductor layer; and an n-type semiconductor layer, wherein the multi-layer includes a multiple quantum barrier-well layer containing quantum-barrier-formation barrier layers formed from a Group III nitride compound semiconductor and quantum-barrier-formation well layers formed from a Group III nitride compound semiconductor, the barrier layers and the well layers being laminated alternately and cyclically, and a plurality of low-energy-band-gap layers which emit light of different wavelengths; and the multiple quantum barrier-well layer is provided between the low-energy-band-gap layers.

Abstract: A combination of materials is used to form the photodiodes of a vertical color imager cell. The materials used to form the photodiodes have different band gaps that allow the photon absorption rates of the photodiodes to be adjusted. By adjusting the photon absorption rates, the sensitivities of the photodiodes and thereby the characteristics of the imager can be adjusted.

Abstract: A novel photodetector CMOS-compatible photodetector is disclosed in which photo-generation of carriers (electrons) is carried out in the metal of the electrodes, rather than as electron-hole pairs in the semiconductor on which the metal electrodes are deposited. The novel photo detector comprises a silicon or other semiconductor substrate material characterized by an electron energy bandgap, and a pair of metal electrodes disposed upon a surface of the silicon to define therebetween a border area of the surface. One of the two electrodes being exposed to the incident radiation and covering an area of said surface which is larger than the aforesaid border area, the aforesaid metal of the electrodes being characterized by a Fermi level which is within said electron energy bandgap.

Abstract: An edge illuminated epilayer waveguide phototransistor including a subcollector layer formed from an epitaxially grown quaternary semiconductor material, such as heavily doped InGaAsP. A collector region of undoped InGaAs is epitaxially grown on the subcollector layer. A base region of moderately doped InGaAs is epitaxially grown on the collector layer. An emitter region, including a doped InGaAsP layer, a doped InP layer, and a heavily doped InGaAs emitter contact layer, is epitaxially grown on the base layer. The various layers and regions are formed so as to define an edge-illuminated facet for receiving incident light. Also, the base does not have an ohmic contact so that the base thickness can be minimized. Finally, the base doping concentration is minimized so that the gain-bandwidth product can be maximized.

Abstract: A multi-wavelength semiconductor image sensor comprises a p-type Hg0.7Cd0.3Te photo-absorbing layer formed on a single crystal CdZnTe substrate, a CdTe isolation layer deposited on the photo-absorbing layer, a p-type Hg0.7Cd0.23Te photo-absorbing layer deposited on the CdTe isolation layer, n+ regions which are formed in these photo-absorbing layers and form a pn-junction with each of these photo-absorbing layers, an indium electrode connected to each of these n+ regions and a ground electrode connected to the photo-absorbing layer, the semiconductor isolation layer being electrically isolated from the photo-absorbing layer.

Abstract: A photodetector includes a substrate and an optical absorption layer provided on the substrate, wherein the optical absorption layer is formed of a mixed crystal of Si, Ge and C.

Abstract: A heterostructure or multilayer semiconductor structure having lattice matched layers with different bandgaps is grown by MOCVD. More specifically, a wide bandgap material such as AlInSb or GaInSb is grown on a substrate to form a lower-contact layer. An n-type active layer is lattice matched to the lower contact layer. The active layer should be of a narrow bandgap material, such as InAsSb, InTlSb, InBiSb, or InBiAsSb. A p-type upper contact layer is then grown on the active layer and a multi-color infrared photodetector has been fabricated.

Abstract: The photoconductive switch comprises a first confinement layer, a second confinement layer, a photoconductive layer that includes a doped sub-layer and an undoped sub-layer, a first electrode and a second electrode. The first confinement layer is a layer of a first semiconductor material having a first band-gap energy and a first conductivity type. The second confinement layer is a layer of a second semiconductor material having a second band-gap energy. The photoconductive layer is a layer of a third semiconductor material having a third band-gap energy and a second conductivity type, opposite to the first conductivity type. The photoconductive layer is sandwiched between the first confinement layer and the second confinement layer, and the third band-gap energy is less than the first and second band-gap energies. In the photoconductive layer, the doped sub-layer is in contact with the first confinement layer, and the undoped sub-layer is adjacent the second confinement layer.

Abstract: A method of making a diode and the diode wherein there is provided a substrate of p-type group II-VI semiconductor material and an electrically conductive material capable of forming an ohmic contact with the substrate is forced into the lattice of the substrate to create an n-type region in the substrate in contact with the material and forming an electrical contact to the p-type region of said substrate. The substrate is preferably HgCdTe and the electrically conductive material is preferably tungsten or tin coated tungsten or tungsten coated with a mercury amalgam.

Abstract: A semiconductor photo-detector, which has a high quantum efficiency due to high coupling with an incident beam and operates at higher frequency due to a reduced area of PN junction. In a semiconductor photo-detector of the present invention, reflection layers are deposited on both of the parallel surfaces of a square-shaped wave-guide, while light absorption layers are deposited on at least another pair of parallel surfaces which is one of the parallel pairs of remaining surfaces.

Abstract: The alloy is for making an infrared transducer. It is constituted by (In1−xTlx) (As1−ySby) in which 0≦x<1 and 0<y<1 (where x and y are less than ½). On a GaSb or AlSb substrate, the transducer comprises an active layer of the alloy having a composition such that its lattice is of a size that is equal to that of the substrate material.

Abstract: A semiconductor imaging device includes a semiconductor radiation detector substrate, for example of cadmium zinc telluride, with at least two faces. A first face has at least one charge output contact formed from electrically conductive material or materials and a second face having a contact formed from electrically conductive material or materials. The second face contact is for applying a bias voltage to provide an electric field between the first and second faces. The second face contact, or a third face of the semiconductor imaging device, or an edge between the second and third faces has deposited thereon at least a partial covering of a further material different from the electrically conductive material or materials of the second face contact. The deposited material can be a semiconductor, insulating or passivation material, for example aluminium nitride. Such a radiation detector can provide linear detector behaviour for all possible combinations of exposure and X-ray tube voltage.

Abstract: This is an integral IR detector system with at least two epitaxial HgCdTe sensors on integrated silicon or GaAs circuitry and also a method of fabricating such system. The system can comprise: a) integrated silicon or GaAs circuitry 110; b) an epitaxial lattice-match layer (e.g. ZnSe 114) on a top surface of the circuit; c) an epitaxial insulating layer (e.g. CdTe 102) on the lattice-match layer; and d) at least two epitaxial HgCdTe sensors 101,121 on the insulating layer, with the HgCdTe sensors being electrically connected to the circuitry. Preferably, the circuitry is silicon. Preferably, an IR transparent, spacer layer (e.g. CdTe 120 or CdZnTe) is on the HgCdTe sensors and an HgCdTe filter 122 is on the spacer layer. Preferably, at least one of the HgCdTe sensors and the HgCdTe filter is laterally continuously graded.

Abstract: A method for forming a compound film includes the steps of preparing a source material, depositing the source material on a base and forming a preparatory film from the source material, heating the preparatory film in a suitable atmosphere to form a precursor film, and providing suitable material to said precursor film to form the compound film. The source material includes oxide-containing particles including Group IB and IIIA elements. The precursor film includes non-oxide Group IB and IIIA elements. The compound film includes a Group IB-IIIA-VIA compound. The oxides may constitute greater than about 95 molar percent of the Group IB elements and greater than about 95 molar percent of the Group IIIA elements in the source material. Similarly, non-oxides may constitute greater than about 95 molar percent of the Group IB elements and greater than about 95 molar percent of the Group IIIA elements in the precursor film.

Abstract: A hybrid focal plane array has Hg.sub.1-x Cd.sub.x Te junction photodiodes formed in a substrate of HgCdTe which is capped by a layer of Te-rich CdTe. Type conversion of a low metal vacancy HgCdTe substrate to p-type is performed by annealing the capped substrate at a temperature sufficient to support interdiffusion between the Te-rich CdTe capping layer and the HgCdTe substrate. Use of the CdTe capping layer with a slight excess Te maintains the surface of the HgCdTe substrate in a Te-rich phase condition.

Abstract: This is an integral IR detector system with at least two epitaxial HgCdTe sensors on integrated silicon or GaAs circuitry and also a method of fabricating such system. The system can comprise: a) integrated silicon or GaAs circuitry 110; b) an epitaxial lattice-match layer (e.g. ZnSe 114) on a top surface of the circuit; c) an epitaxial insulating layer (e.g. CdTe 102) on the lattice-match layer; and d) at least two epitaxial HgCdTe sensors 101,121 on the insulating layer, with the HgCdTe sensors being electrically connected to the circuitry. Preferably, the circuitry is silicon. Preferably, an IR transparent, spacer layer (e.g. CdTe 120 or CdZnTe) is on the HgCdTe sensors and an HgCdTe filter 122 is on the spacer layer. Preferably, at least one of the HgCdTe sensors and the HgCdTe filter is laterally continuously graded.

Abstract: Sn.sub.x Ge.sub.1-x alloys that are substantially free of compositional inhomogeneities and Sn segregation, and have a measurable direct band gap. Methods for making the Sn.sub.x Ge.sub.1-x alloys are also disclosed.

Abstract: A waveguide type semiconductor photodetector comprises a n-InP substrate, and a laminate including a first and second optical confinement layers and an undoped optical absorption layer interposed therebetween. The optical absorption layer has a thickness between 0.2 and 0.5 .mu.m, and a bandgap wavelength smaller than the bandgap wavelength of the first and second optical confinement layers. The photodetector has a large mode field diameter and a small coupling loss between the same and a glass fiber.

Abstract: A detector with quantum structure comprising a small-gap semiconductor material inserted between two large-gap semiconductor materials, the structure comprising a coupling grating between the wave to be detected and the detector zone constituted by the small-gap material. Under these conditions, the detector zone may have a very small thickness (typically of the order of 1,000 .ANG.) and lead to a detectivity, limited by the dark current, that is high.

Abstract: A semiconductor device having: a support substrate having an upper surface; a HgTe layer formed on the support substrate; and a HgCdTe layer directly formed on the HgTe layer. A semiconductor device of another type having: a support substrate having an exposed upper surface tilted from the (100) plane of a single crystal with a diamond structure by a certain angle, along a direction offset by an angle larger than 0.degree. and smaller than 45.degree. from the ?011! direction in the (100) plane; a group III-V compound semiconductor layer formed on the support substrate; and a group II-VI compound semiconductor layer formed on the group III-V compound semiconductor layer.

Abstract: An array 1 of photodiodes 2 is comprised of a Group II-VI material, such as HgCdTe, which may be selectively doped to form a plurality of diode junctions. Array 1 is comprised of a plurality of photodiodes 2 which are disposed in a regular, two dimensional array. Incident IR radiation, which may be long wavelength, medium wavelength or short wavelength (LWIR, MWIR or SWIR) radiation, is incident upon a surface of the array 1. The array 1 comprises a radiation absorbing base layer 3 of Hg.sub.1-x Cd.sub.x Te semiconducting material, the value of x determining the responsivity of the array to either LWIR, MWIR or SWIR. Each of the photodiodes 2 is defined by a mesa structure, or cap layer 3; or the array 1 of photodiodes 2 may be a planar structure. Each of the photodiodes 2 is provided with an area of contact metallization 4 upon a top surface thereof, the metallization serving to electrically couple an underlying photodiode to a readout device.

Abstract: An imaging device (10) has a plurality of unit cells that contribute to forming an image of a scene. The imaging device includes a layer of semiconductor material (16), for example silicon, that has low noise photogate charge-mode readout circuitry (20, 21, 26, 28) (e.g., CCD or CMOS readout circuitry and structures) that is disposed upon a first surface (18) of the layer. A second, opposing surface of the layer is a radiation admitting surface of the layer. The layer has a bandgap selected for absorbing electromagnetic radiation having wavelengths shorter than about one micrometer and for generating charge carriers from the absorbed radiation. The generated charge carriers are collected by the photogate charge-mode readout circuitry. A thermal sensing element (22) is disposed above and is thermally isolated from the first surface of the layer. The thermal sensing element may be, by example, one of a bolometer element, a pyroelectric element, or a thermopile element.

Abstract: An imaging device (10, 10') has a plurality of unit cells (11) that contribute to forming an image of a scene. The imaging device includes a layer of wide bandgap semiconductor (18) material (e.g., silicon) having photogate charge-mode readout circuitry (20, 22, 24), such as CCD or CMOS circuitry, disposed upon a first surface of the layer. In one embodiment a second, opposing surface of the layer is bonded at a heterojunction interface or atomic bonding layer (16) to a surface of a layer of narrower bandgap semiconductor material (e.g., InGaAs or HgCdTe), that is selected for absorbing electromagnetic radiation having wavelengths longer than about one micrometer (i.e., the NIR or longer) and for generating charge carriers. The generated charge carriers are transported across the heterojunction interface for collection by the photogate charge-mode readout circuitry.