Abstract: A detection base plate and a flat-panel detector. The detection base plate comprises multiple detection pixel units arranged in an array. Each detection pixel unit comprises: a thin-film transistor, a sacrificial layer and a photoelectric conversion part that are disposed on a substrate, wherein the sacrificial layer is located between the thin-film transistor and the photoelectric conversion part; the thin-film transistor comprises an active layer, a first electrode and a second electrode; at least part of an orthographic projection of the active layer on the substrate is located within an orthographic projection of the sacrificial layer on the substrate; and the photoelectric conversion part is electrically connected to the sacrificial layer and the first electrode. In the detection base plate, the sacrificial layers of the detection pixel units are mutually independent.

Abstract: A semiconductor optical amplifier for high-power operation includes a gain medium having a multilayer structure sequentially laid with a P-layer, an active layer, a N-layer from an upper portion to a lower portion in cross-section thereof. The gain medium is extendedly laid with a length L from a front facet to a back facet. The active layer includes multiple well layers formed by undoped semiconductor material and multiple barrier layers formed by n-doped semiconductor materials. Each well layer is sandwiched by a pair of barrier layers. The front facet is characterized by a first reflectance Rf and the back facet is characterized by a second reflectance Rb. The gain medium has a mirror loss ?m about 40-200 cm?1 given by: ?m=(½L)ln{1/(Rf×Rb)}.

Abstract: A semiconductor device includes a substrate, an initial layer, and a superlattice stack. The initial layer is located on the substrate and includes aluminum nitride (AlN). The superlattice stack is located on the initial layer and includes a plurality of first films, a plurality of second films and at least one doped layer, and the first films and the second films are alternately stacked on the initial layer, wherein the at least one doped layer is arranged in one of the first films and the second films, and dopants of the at least one doped layer are selected from a group consisting of carbon, iron, and the combination thereof.

Abstract: The invention relates to a method for fabricating a semiconductor device. The method includes providing a cavity structure comprising a seed area with a seed material. The method further includes growing, within the cavity structure, a quantum dot structure in a first growth direction from a seed surface of the seed material and growing, in the first growth direction, a first embedding layer on a first surface of the quantum dot structure. The method further includes removing the seed material and growing, within the cavity structure, on a second surface of the quantum dot structure, a second embedding layer in a second growth direction. The second surface of the quantum dot structure is different from the first surface of the quantum dot structure and the second growth direction is different from the first growth direction. The invention further relates to devices obtainable by such a method.

Abstract: A light-emitting diode includes an N-type cladding layer, and a superlattice structure, an active layer, a P-type electron-blocking layer, and a P-type cladding layer disposed on the N-type cladding layer in such order. The superlattice structure includes at least one first layered element which has a sub-layer made of a nitride-based semiconductor material including Al, and having an energy band gap greater than that of said electron-blocking layer. The P-type electron-blocking layer is made of a nitride-based semiconductor material including Al, and has an energy band gap greater than that of the P-type cladding layer.

Abstract: A semiconductor device having a large storage capacity per unit area is provided. The semiconductor device includes a stack, and the stack includes a first insulator, a first conductor over the first insulator, and a second insulator over the first conductor. The stack includes a first opening provided in the first insulator, the first conductor, and the second insulator and an oxide on the inner side of the first opening. Furthermore, in the first opening, a third insulator is positioned on the outer side of the oxide, a second conductor is positioned on the inner side of the oxide, and a fourth insulator is positioned between the oxide and the second conductor. The third insulator includes a gate insulating layer positioned at a side surface of the first opening, a tunnel insulating layer positioned on the outer side of the oxide, and a charge accumulation layer positioned between the gate insulating layer and the tunnel insulating layer.

Abstract: An entangled-photon pair emitting device according to an embodiment of the inventive concept includes a piezoelectric structure having a first surface and a second surface, which face each other, wherein the piezoelectric structure includes an opening passing through the piezoelectric structure from the first surface to the second surface, a stress transfer medium that fills the opening, a light source emitting part disposed on the stress transfer medium, an upper electrode disposed on the first surface of the piezoelectric structure, and a lower electrode disposed on the second surface of the piezoelectric structure. Here, the light source emitting part includes a semiconductor thin-film and a quantum dot in the semiconductor thin-film.

Abstract: The semiconductor laser device includes: an activation layer having at least one first quantum dot layer and at least one second quantum dot layer having a longer emission wavelength than the first quantum dot layer. The gain spectrum of the active layer has the maximum values at the first wavelength and the second wavelength longer than the first wavelength corresponding to the emission wavelength of the first quantum dot layer and the emission wavelength of the second quantum dot layer, respectively. The maximum value of the gain spectrum at the first wavelength is defined as the first maximum value, and the maximum value of the gain spectrum at the second wavelength is defined as the second maximum value. The first maximum value is larger than the second maximum value.

Abstract: To provide a display device in which parasitic capacitance between wirings can be reduced while preventing increase in wiring resistance. To provide a display device with improved display quality. To provide a display device with low power consumption. A pixel of the liquid crystal display device includes a signal line, a scan line intersecting with the signal line, a first electrode projected from the signal line, a second electrode facing the first electrode, and a pixel electrode connected to the second electrode. Part of the scan line has a loop shape, and part of the first electrode is located in a region overlapped with an opening of the scan line. In other words, part of the first electrode is not overlapped with the scan line.

Abstract: A light emitting device includes a light emitting element adapted to emit blue light, quantum dots that absorb part of the blue light emitted from the light emitting element to emit green light, and at least one of a KSF phosphor adapted to absorb part of the blue light emitted from the light emitting element to emit red light and a MGF phosphor adapted to absorb part of the blue light emitted from the light emitting element to emit red light.

Abstract: Protective coating to prevent sublimation are disclosed. More particularly, the protective coatings comprise one or more alkaline earth halide materials, or mixtures thereof, to prevent sublimation. The alkaline earth halide material of the coating can be judiciously selected to match the coefficient of thermal expansion (CTE) of the material of the external surface of the underlying substrate coated. The protective coatings may be advantageous for protecting external surfaces of thermoelectric materials, parts and devices at high temperature to prevent sublimation and material loss.

Abstract: A quantum dot device is disclosed that includes a quantum well stack, a first and a second plunger gates above the quantum well stack, and a passive barrier element provided in a portion of the quantum well stack between the first and the second plunger gates. The passive barrier element may serve as means for localizing charge in the quantum dot device and may be used to replace charge localization control by means of a barrier gate. In general, a quantum dot device with a plurality of plunger gates provided over a given quantum well stack may include a respective passive barrier element between any, or all, of adjacent plunger gates in the manner as described for the first and second plunger gates.

Abstract: A semiconductor device is provided, which includes a first semiconductor structure, a second semiconductor structure, and an active region. The first semiconductor structure includes a first dopant. The second semiconductor structure is located on the first semiconductor structure and includes a second dopant different from the first dopant. The active region includes a plurality of semiconductor pairs and is located between the first semiconductor structure and the second semiconductor structure. One of the plurality of semiconductor pairs has a barrier layer and a well layer and includes the first dopant. The barrier layer has a first thickness and a first Al content, and the well layer has a second thickness and a second Al content, the second thickness is less than the first thickness, and the second Al content is less than the first Al content.

Abstract: A QLED light-emitting device is provided, including a first electrode layer, an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, a hole injection layer, and a second electrode layer. Wherein, the light-emitting layer includes a plurality of quantum dot layers disposed in a stack, and insulating layers are disposed among the quantum dot layers adjacent to one side of the electron injection layer. Through disposing the insulating layers among the quantum dot layers adjacent to the one side of the electron injection layer, an electron transmission rate is reduced, thereby balancing the electron transmission rate and a hole transmission rate and improving luminous efficiency of QLEDs.

Abstract: A device and method for creating controlled radio frequency (RF) modulated X-ray radiation is described. The device includes an anode housed within a vacuum enclosure which acts to accelerate and convert an electron beam into X-ray radiation. A RF enclosure is housed within the vacuum enclosure and houses a field emission device, such as a carbon nanotube field emission device or similar cold cathode field emission device. The field emission device is biased to emit the electron beam from a field emission cathode via an extraction electrode in the RF enclosure towards the anode. Additionally an RF impedance matching and coupling circuit is connected electrically to the field emission device. The field emission device is thus directly driven with a RF signal to produce an RF modulated electron current to produce an RF modulated X-ray radiation.

Abstract: The present disclosure relates to an integrated package having an active area, an electrical routing circuit, an optical routing circuit, and a vacuum vessel. Methods of making such a package are also described herein.

Abstract: A fast-rate thermoelectric device control system includes a fast-rate thermoelectric device, a sensor, and a controller. The fast-rate thermoelectric device includes a thermoelectric actuator array disposed on a wafer, and the thermoelectric actuator array includes a thin-film thermoelectric (TFTE) actuator that generates a heating and/or a cooling effect in response to an electrical current. The sensor is configured to measure a temperature associated with the heating or cooling effect and output a feedback signal indicative of the measured temperature. The controller is in communication with the fast-rate thermoelectric device and the sensor, and is configured to control the electrical current based on the feedback signal.

Abstract: A micromachining device that utilizes a solid state laser beam scanner to steer and scan laser beams onto a moveable stage. There are no moving parts as in the galvometric scanner devices in current use. The laser beam scanner has two components, a variable frequency signal generator that is electrically connected to at least one substantially transparent and partially conductive substrate plate (hereinafter plate) with a generally planar face thereon that has a series of quantum dots (of an arbitrary size but narrow size distribution) affixed with the plate, where each of the quantum dots possess an inducible dipole moment, and each of the quantum dots are in electrical contact with the plate, where the quantum dots undergo an excitation and successive recombination (or relaxation) by the input of magnetic, optical or electrical signals.

Abstract: A beam scanner for use in conjunction with the operational guidance system of a vehicle. The beam scanner can be used as part of an electromagnetic signal transmit module or an electromagnetic signal receive module in either a transmissive or reflective mode. The beam scanner is a substantially transparent and partially conductive substrate plate having at least one generally planar face thereon with a series of particles affixed with said plate, each of said particles of an arbitrary size, and each of said particles possessing an induced dipole moment, and each of said particles in electrical contact with said partially conductive substrate plate.

Abstract: A structure may include a quantum structure and a barrier layer that may coat the quantum structure. The barrier layer may include aluminum and at least one material that is X1, X2, Si, O, or combinations thereof where X1 and X2 are monovalent positively charged elements and/or divalent positively charged elements. In addition, an agglomerate, a conversion element, and a method of producing a structure are disclosed.

Abstract: The present invention is an electromagnetic signal modulator that is a control unit operationally coupled to a substantially transparent and partially conductive substrate plate assembly having a series of quantum dots that undergo an excitation and successive recombination (or relaxation) of their electrons by the input of magnetic, optical or electrical signals to switch, steer or otherwise modulate an electromagnetic beam incident on the substrate plate assembly. There are four factors that may be used to vary the quantum dot electromagnetic environment, providing operator flexibility as to how the modulation of the incident electromagnetic wave front is accomplished and to what degree.

Abstract: Provided is an optoelectronic device comprising an optoelectronic element and circuitry connected to the optoelectronic element, wherein the optoelectronic element comprises plural quantum dots or plural nanorods, and wherein the circuitry is configured to be capable of switching the optoelectronic element between a configuration in which the circuitry provides an effective forward bias voltage that causes the optoelectronic element to emit light and a configuration in which the circuitry provides an effective reverse bias voltage that causes the optoelectronic element to be capable of generating a photocurrent when light to which the optoelectronic element is sensitive strikes the optoelectronic element.

Abstract: Semiconductor structures and methods for forming those semiconductor structures are disclosed. For example, a semiconductor structure with a p-type superlattice region, an i-type superlattice region, and an n-type superlattice region is disclosed. The semiconductor structure can have a polar crystal structure with a growth axis that is substantially parallel to a spontaneous polarization axis of the polar crystal structure. In some cases, there are no abrupt changes in polarisation at interfaces between each region. At least one of the p-type superlattice region, the i-type superlattice region and the n-type superlattice region can comprise a plurality of unit cells exhibiting a monotonic change in composition from a wider band gap (WBG) material to a narrower band gap (NBG) material or from a NBG material to a WBG material along the growth axis to induce p-type or n-type conductivity.

Abstract: Quantum dot circuit and a method of characterizing such a circuit Voltages that enable control of electron occupation in a series of quantum dots are determined by a method of measuring effects of gate electrode voltages on a quantum dot circuit. The quantum dot circuit comprises a channel (10), first gate electrodes (14a-14e) that extend over locations along the edge of the channel to create potentials barriers defining the potentials well therebetween, as well as second gate electrodes (16a-16d) adjacent to potential wells, for controlling depths of the successive electrical potential wells between the potential barriers. First, channel currents are measured in a pre-scan of bias voltages of the first gates for controlling the potential barriers. The result is used to set their bias levels in, a scan over a two-dimensional range of combinations of bias voltages on the second gates for controlling the depths.

Abstract: The present disclosure relates to a semiconductor image sensor device. In some embodiments, the semiconductor image sensor device includes a semiconductor substrate having a first surface configured to receive incident radiation. A plurality of sensor elements are arranged within the semiconductor substrate. A first charged layer is arranged on an entirety of a second surface of the semiconductor substrate facing an opposite direction as the first surface. The second surface is between the first charged layer and the first surface of the semiconductor substrate.

Abstract: An electro-optic modulator device includes a modulation region, a reflecting region, a conductive line and an anti-reflecting region. The modulation region includes a doped region. The reflecting region is over the modulation region. The conductive line is connected to the doped region. The conductive line extends through the reflecting region. The anti-reflecting region is on an opposite surface of the modulation region from the reflecting region.

Abstract: The invention relates to quantum dot and photodetector technology, and more particularly, to quantum dot infrared photodetectors (QDIPs) and focal plane array. The invention further relates to devices and methods for the enhancement of the photocurrent of quantum dot infrared photodetectors in focal plane arrays.

Abstract: This CIP application builds on Ge quantum dot superlattice (QDSL) based field effect transistors where Ge quantum dot arrays are used as a high carrier mobility channel. The QDSL diodes claims that were withdrawn are included. The diodes are used as light emitting devices and photodetectors. A combination of QDC-FETs, light emitting devise, photodetectors are vertically stacked to form a versatile 3-dimensional integrated circuit. Nonvolatile memories using floating quantum dot gates are included in vertical stacking format. Nonvolatile random access memories are integrated as a stack. Also described is the use of 3-layer stack of QDC-FETs making compact electrical circuits interfacing pixels for an active matrix flat panel displays that results in high resolution. Ge or Si quantum dot transport channel based devices processing spin polarized electrons introduced by magnetic tunnel junctions are described for multi-state coherent logic.

Abstract: Methods of fabrication and monolithic integration of a polycrystalline infrared detector structure deposit Group III-V compound semiconductor materials at a low deposition temperature within a range of about 300° C. to about 400° C. directly on an amorphous template. The methods provide wafer-level fabrication of polycrystalline infrared detectors and monolithic integration with a readout integrated circuit wafer for focal plane arrays.

Abstract: Disclosed is an optoelectronic device including a lanthanum-based active layer and a method for fabricating the same. The optoelectronic device includes an active layer of multiple quantum well (MQW) structure including each well between walls, wherein the wall is a dielectric layer selected from alkali metal halide, alkali earth metal halide, alkali metal chalcogenide and alkali earth metal chalcogenide, and the well is a layer including semiconductor selected from lanthanum-based metal halide, lanthanum-based metal chalcogenide, transition metal (including post transition metal) halide and transition metal chalcogenide. The optoelectronic device including the active layer can be used in applications of LEDs, displays, optical sensors and solar cells. When the active layer is used as a photoconversion layer, displays can be implemented by upconversion or downconversion of short wavelength of UV, blue and IR light source to visible wavelength of red, green and blue.

Abstract: A sensing apparatus for sensing target materials including biological or chemical molecules in a fluid. One such apparatus includes a semiconductor-on-insulator (SOI) structure having an electrically-insulating layer, a fluidic channel supported by the SOI structure and configured and arranged to receive and pass a fluid including the target materials, and a semiconductor device including at least three electrically-contiguous semiconductor regions doped to exhibit a common polarity. The semiconductor regions include a sandwiched region sandwiched between two of the other semiconductor regions, and configured and arranged adjacent to the fluidic channel with a surface directed toward the fluidic channel for coupling to the target materials in the fluidic channel, and further arranged for responding to a bias voltage. The sensing apparatus also includes an amplification circuit in or on the SOI and that is arranged to facilitate sensing of the target material near the fluidic channel.

Abstract: Provided is a photovoltaic device prepared with a semiconductor including a localized level or an intermediate band in a forbidden band and capable of improving the performance than before. The photovoltaic device includes a plurality of first layers made of a first semiconducting material and a plurality of second layers made of a second semiconducting material that is different from the first semiconducting material, wherein the second semiconducting material includes a localized level or intermediate band in a forbidden band, the first layers and the second layers are alternately laminated one by one, at least two of the second layers are each disposed between a pair of the first layers, and a thickness of each of the second layers is thinner than a thickness of four molecular layers of the first semiconducting material.

Abstract: Disclosed herein are multi-layered optically active regions for semiconductor light-emitting devices (LEDs) that incorporate intermediate carrier blocking layers, the intermediate carrier blocking layers having design parameters for compositions and doping levels selected to provide efficient control over the carrier injection distribution across the active regions to achieve desired device injection characteristics. Examples of embodiments discussed herein include, among others: a multiple-quantum-well variable-color LED operating in visible optical range with full coverage of RGB gamut, a multiple-quantum-well variable-color LED operating in visible optical range with an extended color gamut beyond standard RGB gamut, a multiple-quantum-well light-white emitting LED with variable color temperature, and a multiple-quantum-well LED with uniformly populated active layers.

Abstract: A non-planar gate all-around device and method of fabrication thereby are described. In one embodiment, the device includes a substrate having a top surface with a first lattice constant. Embedded epi source and drain regions are formed on the top surface of the substrate. The embedded epi source and drain regions have a second lattice constant that is different from the first lattice constant. A channel nanowire having a third lattice is formed between and are coupled to the embedded epi source and drain regions. In an embodiment, the second lattice constant and the third lattice constant are different from the first lattice constant. A gate dielectric layer is formed on and all-around the channel nanowire. A gate electrode is formed on the gate dielectric layer and surrounding the channel nanowire.

Abstract: An infrared detector includes a quantum dot structure, and an electrode that is coupled to the quantum dot structure, wherein the quantum dot structure is obtained by stacking a plurality of structures each including a quantum dot, a first barrier layer under the quantum dot and a second barrier layer over the quantum dot to cover the quantum dots, and an intermediate layer under the first barrier layer, and wherein the first barrier layer includes a first region and a second region having a lower Al concentration than that of the intermediate layer between the first region and the intermediate layer.

Abstract: An electrical device in which an interface layer is disposed in between and in contact with a conductor and a semiconductor.

Abstract: Methods and systems including a photodetector of a downhole tool for performing downhole operations are provided herein. The photodetector includes a housing configured along a carrier disposed downhole within a borehole and a graphene tunneling photodetector located within the housing configured to perform a downhole operation.

Abstract: The invention relates to quantum dot and photodetector technology, and more particularly, to quantum dot infrared photodetectors (QDIPs) and focal plane array. The invention further relates to devices and methods for the enhancement of the photocurrent of quantum dot infrared photodetectors in focal plane arrays.

Abstract: A quantum dot film and a display device are disclosed herein. The quantum dot film includes a substrate and at least one ultraviolet quantum dot disposed in the substrate and capable of emitting ultraviolet rays having a wavelength in a range of 190 to 280 nm.

Abstract: A semiconductor device including at least one double-barrier resonant tunneling diode (DBRTD) is provided. The at least one DBRTD may include a first doped semiconductor layer, and a first barrier layer on the first doped semiconductor layer and including a superlattice. The DBRTD may further include a first intrinsic semiconductor layer on the first barrier layer, a second barrier layer on the first intrinsic semiconductor layer and also including the superlattice, a second intrinsic semiconductor layer on the second barrier layer, a third barrier layer on the second intrinsic semiconductor layer and also including the superlattice. A third intrinsic semiconductor layer may be on the third barrier layer, a fourth barrier layer may be on the third intrinsic semiconductor layer and also including the superlattice, a second doped semiconductor layer on the fourth barrier layer.

Abstract: A method for making a semiconductor device may include forming at least one a double-barrier resonant tunneling diode (DBRTD) by forming a first doped semiconductor layer, and a forming first barrier layer on the first doped semiconductor layer and including a superlattice. The method may further include forming a first intrinsic semiconductor layer on the first barrier layer, forming a second barrier layer on the first intrinsic semiconductor layer and also comprising the superlattice, forming a second intrinsic semiconductor layer on the second barrier layer, and forming a third barrier layer on the second intrinsic semiconductor layer and also comprising the superlattice. The method may further include forming a third intrinsic semiconductor layer on the third barrier layer, forming a fourth barrier layer on the third intrinsic semiconductor layer, and forming a second doped semiconductor layer on the fourth barrier layer.

Abstract: Apparatuses and systems for a die-integrated aspheric mirror are described herein. One apparatus includes an ion trap die including a number of ion locations and an aspheric mirror integrated with the ion trap die.

Abstract: The various technologies presented herein relate to various hybrid phononic-photonic waveguide structures that can exhibit nonlinear behavior associated with traveling-wave forward stimulated Brillouin scattering (forward-SBS). The various structures can simultaneously guide photons and phonons in a suspended membrane. By utilizing a suspended membrane, a substrate pathway can be eliminated for loss of phonons that suppresses SBS in conventional silicon-on-insulator (SOI) waveguides. Consequently, forward-SBS nonlinear susceptibilities are achievable at about 3000 times greater than achievable with a conventional waveguide system. Owing to the strong phonon-photon coupling achievable with the various embodiments, potential application for the various embodiments presented herein cover a range of radiofrequency (RF) and photonic signal processing applications. Further, the various embodiments presented herein are applicable to applications operating over a wide bandwidth, e.g. 100 MHz to 50 GHz or more.

Abstract: A detector for detecting an agent within an aerosol is provided. The detector may include a liquid feeder configured to generate a droplet comprised of an assay reagent. The detector may further include an aerosol focuser configured to capture and focus the aerosol such that the aerosol is configured to be encapsulated within the droplet in order to cause the assay reagent to react in the droplet. The detector may even further include an interrogator configured to interrogate the droplet in order to detect the agent within the aerosol.

Abstract: A photodetector is disclosed. A first layer of the photodetector has a first semiconductor material having a first band gap energy, a first electric field, and a first doping concentration. A second layer has a second semiconductor material having a second band gap energy higher than the first band gap energy, a non-zero second electric field smaller than the first electric field, and a second doping concentration. The second layer is interfaced with the first layer. A region between the first and second layers has a third doping concentration.

Abstract: Transistors and methods of forming the same include forming a fin having an active layer between two sacrificial layers. A dummy gate is formed over the fin. Spacers are formed around the dummy gate. The dummy gate is etched away to form a gap over the fin. Material from the two sacrificial layers is etched away in the gap. A gate stack is formed around the active layer in the gap. Source and drain regions are formed in contact with the active layer.

Abstract: A quantum semiconductor device is provided. The quantum semiconductor device includes a quantum heterostructure, a dielectric layer, and an electrode. The quantum heterostructure includes a quantum well layer that includes a first 2DEG region, a second 2DEG region, and a third 2DEG region. A first tunnel barrier exists between the first 2DEG region and the second 2DEG region. A second tunnel barrier exists between the second 2DEG region and the third 2DEG region. A third tunnel barrier exists either between the first 2DEG region and the third 2DEG region. The dielectric layer is formed on the quantum heterostructure. The electrode is formed on the dielectric layer directly above the first tunnel barrier.

Abstract: The invention relates to quantum dot and photodetector technology, and more particularly, to quantum dot infrared photodetectors (QDIPs) and focal plane array. The invention further relates to devices and methods for the enhancement of the photocurrent of quantum dot infrared photodetectors in focal plane arrays.

Abstract: A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer, layered upward in this order, each being made of a nitride semiconductor. The active layer includes one or more well layers, and an n-side barrier layer located lower than the one or more well layers. The n-side semiconductor layer includes a composition-graded layer located in contact with the n-side barrier layer. The composition-graded layer has a band-gap energy that decreases toward an upper side of the composition-graded layer, with a band-gap energy of the upper side being smaller than a band-gap energy of the n-side barrier layer. The composition-graded layer has an n-type dopant concentration greater than 5×1017/cm3 and less than or equal to 2×1018/cm3. The n-side barrier layer has an n-type dopant concentration greater than that of the composition-graded layer and a thickness smaller than that of the composition graded layer.

Abstract: A IDCA system with internal nBn photo-detector comprising: a photo-absorbing layer comprising an n-doped semiconductor exhibiting valence band energy level; a barrier layer, a first side of the barrier layer adjacent a first side of the photo-absorbing layer, the barrier layer exhibiting a valence band energy level substantially equal to the valence band energy level of the doped semiconductor of the photo absorbing layer; and a contact area comprising a doped semiconductor, the contact area being adjacent a second side of the barrier layer opposing the first side, the barrier layer exhibiting a thickness and conductance band gap sufficient to prevent tunneling of majority carriers from the photo-absorbing layer to the contact area, blocking the flow of thermalized majority carriers from the photo-absorbing layer to the contact area. Alternatively, a p-doped semiconductor is utilized, equalizing barrier conductance band energy levels and photo-absorbing layers.