An infrared-ray sensing device includes a support and a plurality of photodiodes disposed on the support. Each of the plurality of photodiodes includes a first mesa including a first semiconductor layer of a first conductivity type, a second semiconductor layer of the first conductivity type, a third semiconductor layer of a second conductivity type that is disposed between the first and second semiconductor layers, and a super-lattice region disposed on the support along a reference plane. Each of the third semiconductor layer and the super-lattice region is provided in common for the photodiodes. The first mesas and the second semiconductor layers are aligned along a first axis intersecting the reference plane so that each of the second semiconductor layers is provided in a position corresponding to the position of first mesa. The second semiconductor layer is disposed between the third semiconductor layer and the super-lattice region.

A device for producing electricity. The device includes a substrate having spaced apart first and second surfaces and doped a first dopant type, first semiconductor material layers disposed atop the first substrate surface and doped the first dopant type, and second semiconductor material layers disposed atop the first semiconductor material layers and doped a second dopant type. A first contact is in electrical contact with the second substrate surface or in electrical contact with one of the first semiconductor material layers. A beta particle source emits beta particles that penetrate into the semiconductor material layers; the beta particle source is proximate the uppermost layer of the second plurality of semiconductor material layers. A second contact is in electrical contact with one of the second plurality of semiconductor material layers. In one embodiment, bi-polar contacts (the first and second contacts) are co-located on each major face of the device.

A photodetector comprising a photoabsorber, comprising a doped semiconductor, a contact layer comprising a doped semiconductor and a barrier layer comprising a charge carrier compensated semiconductor, the barrier layer compensated by doping impurities such that it exhibits a valence band energy level substantially equal to the valence band energy level of the photo absorbing layer and a conduction band energy level exhibiting a significant band gap in relation to the conduction band of the photo absorbing layer, the barrier layer disposed between the photoabsorber and contact layers. The relationship between the photo absorbing layer and contact layer valence and conduction band energies and the barrier layer conduction and valance band energies is selected to facilitate minority carrier current flow while inhibiting majority carrier current flow between the contact and photo absorbing layers.

A multijunction solar cell with a graded interlayer disposed between two adjacent solar subcells, the graded interlayer being compositionally graded to lattice match a first solar subcell on one side, and an adjacent second solar subcell on the other side, the graded interlayer being composed of at least four step layers, a particular step layer having a lattice constant in the range of 0.2 to 1.2% greater than the lattice constant of the adjacent layer on which it is grown, and the subsequent steps layers disposed directly on the particular step layer having a lattice constant in the range of 0.1 to 0.6% greater than the particular layer on which it is grown, and wherein the thickness of the particular step layer is at least twice the thickness of each of the other subsequent step layers.

A dual band photodetector includes a first band absorber layer is configured to absorb incident light in a first wavelength spectral band and a second band absorber layer configured to absorb incident light in a second wavelength spectral band. The dual band photodetector further includes an electron-photon blocking (EPB) layer located between the respective layers and includes at least one high band gap layer and at least one intervening layer. The difference in refractive index between the at least one high band gap layer and the at least one intervening layer form a distributed brag reflector (DBR) designed to reflect wavelengths corresponding with radiative recombination photons emitted from at least the first absorber layer to reduce optical crosstalk between the first band absorber layer and the second band absorber layer.

The disclosure provides a solar cell design featuring p-or-n type GaAs with alternating p-n junction regions on the back-surface of the cell, opposite incident solar irradiance. Various layers of p-or-n type GaAs are interfaced together to collect charge carriers, and a thin layer of AlGaAs is applied to the front and back surfaces to prevent recombination of charge carriers. In some embodiments, the layered an doped structure generally provides an AlGaAs window layer of about 20 nm doped to about 4×(10.sup.18) cm.sup.−3, a GaAs absorption layer of about 2000 nm doped to about 4×(10.sup.17) cm.sup.−3, a GaAs emitter layer of about 150 nm and doped to 1×(10.sup.18) cm.sup.−3, an AlGaAs heterojunction layer of about 40 nm doped to about 3×(10.sup.18) cm.sup.−3, and a GaAs emitter-contact layer of about 20 nm doped to about 1×(10.sup.19) cm.sup.−3. Additionally, AlGaAs BSF layer and GaAs BSF-contact layers each have a depth of about 20 nm and are doped to about 4×(10.sup.18) cm.sup.−3 and 1×(10.sup.19) cm.sup.−3 respectively. The emitter layer, heterojunction layer, and emitter-contact layer are doped to a conductivity type opposite the absorption layer.

A method of forming a multijunction solar cell that includes an InGaAs buffer layer and an InGaAlAs grading interlayer disposed below, and adjacent to, the InGaAs buffer layer. The grading interlayer achieves a transition in lattice constant from one solar subcell to another adjacent solar subcell.

Resonant-cavity infrared photodetector (RCID) devices that include a thin absorber layer contained entirely within the resonant cavity. In some embodiments, the absorber region is a single type-II InAs—GaSb interface situated between an n-type region comprising an AlSb/InAs n-type superlattice and a p-type AlSb/GaSb region. In other embodiments, the absorber region comprises one or more quantum wells formed on an upper surface of the n-type region. In other embodiments, the absorber region comprises a “W”-structured quantum well situated between two barrier layers, the “W”-structured quantum well comprising a hole quantum well sandwiched between two electron quantum wells. In other embodiments, an RCID in accordance with the present invention includes a thin absorber region and an nBn or pBp active core within a resonant cavity.

An infrared detector and a method for forming it are provided. The detector includes absorber, barrier, and contact regions. The absorber region includes a first semiconductor material, with a first lattice constant, that produces charge carriers in response to infrared light. The barrier region is disposed on the absorber region and comprises a superlatice that includes (i) first barrier region layers comprising the first semiconductor material, and (ii) second barrier region layers comprising a second semiconductor material, different from, but lattice matched to, the first semiconductor material. The first and second barrier region layers are alternatingly arranged. The contact region is disposed on the barrier region and comprises a superlattice that includes (i) first contact region layers comprising the first semiconductor material, and (ii) second contact region layers comprising the second semiconductor material layer. The first and second contact region layers are alternatingly arranged.

An epitaxially grown III-V layer is separated from the growth substrate. The III-V layer can be an inverted lattice matched (ILM) or inverted metamorphic (IMM) solar cell, or a light emitting diode (LED). A sacrificial epitaxial layer is embedded between the GaAs wafer and the III-V layer. The sacrificial layer is damaged by absorbing IR laser radiation. A laser is chosen with the right wavelength, pulse width and power. The radiation is not absorbed by either the GaAs wafer or the III-V layer. No expensive ion implantation or lateral chemical etching of a sacrificial layer is needed. The III-V layer is detached from the growth wafer by propagating a crack through the damaged layer. The active layer is transferred wafer-scale to inexpensive, flexible, organic substrate. The process allows re-using of the wafer to grow new III-V layers, resulting in savings in raw materials and grinding and etching costs.