The present invention discloses a photo-detector comprising: an n-type photon absorbing layer of a first energy bandgap; a middle barrier layer, an intermediate layer is a semiconductor structure; and a contact layer of a third energy bandgap, wherein the layer materials are selected such that the first energy bandgap of the photon absorbing layer is narrower than that of said middle barrier layer; wherein the material composition and thickness of said intermediate layer are selected such that the valence band of the intermediate layer lies above the valence band in the barrier layer to create an efficient trapping and transfer of minority carriers from the barrier layer to the contact layer such that a tunnel current through the barrier layer from the contact layer to the photon absorbing layer is less than a dark current in the photo-detector and the dark current from the photon-absorbing layer to said middle barrier layer is essentially diffusion limited and is due to the unimpeded flow of minority carriers, thus reducing generation-recombination (GR) noise of the photo-detector. The principles of the present invention also apply to inverted polarity structures of the form pBp in which all the doping polarities and band alignments described above are reversed.

A semiconductor device is disclosed, which includes: at least one device layer being a crystallized layer for example including: a superlattice layer and/or a layer of group III-V semiconductor materials; and a passivation structure comprising one or more layers wherein at least one layer of the passivation structure is a passivation layer grown in-situ in a crystallized form on top of the device layer, and at least one of the one or more layers of the passivation structure includes material having a high density of surface states which forces surface pinning of an equilibrium Fermi level within a certain band gap of the device layer, away from its conduction and valence bands.

Materials and methods may be provided for short-wave infrared (SWIR) superlattice materials. The superlattice material includes a first sub-layer comprising InAs, and a second sub-layer adjacent to the first sub-layer including AlSb, AlAsSb, or InAlAsSb.

An nitride semiconductor device for the improvement of lower operational voltage or increased emitting output, comprises an active layer comprising quantum well layer or layers and barrier layer or layers between n-type nitride. semiconductor layers and p-type nitride semiconductor layers, wherein said quantum layer in said active layer comprises InxGa1xN (0<x<1) having a peak wavelength of 450 to 540 nm and said active layer comprises laminating layers of 9 to 13, in which at most 3 layers from the side of said n-type nitride semiconductor layers are doped with an n-type impurity selected from the group consisting of Si, Ge and Sn in a range of 510.sup.16 to 210.sup.18/cm.sup.3.

A structure includes a silicon substrate; silicon readout circuitry disposed on a first portion of a top surface of the substrate and a radiation detecting pixel disposed on a second portion of the top surface of the substrate. The pixel has a plurality of radiation detectors connected with the readout circuitry. The plurality of radiation detectors are composed of at least one visible wavelength radiation detector containing germanium and at least one infrared wavelength radiation detector containing a Group III-V semiconductor material. A method includes providing a silicon substrate; forming silicon readout circuitry on a first portion of a top surface of the substrate and forming a radiation detecting pixel, on a second portion of the top surface of the substrate, that has a plurality of radiation detectors formed to contain a visible wavelength detector composed of germanium and an infrared wavelength detector composed of a Group III-V semiconductor material.

A stacked multi-junction solar cell having a first subcell and second subcell, the second subcell having a larger band gap than the first subcell. A third subcell has a larger band gap than the second subcell, and each of the subcells include an emitter and a base. The second subcell has a layer which includes a compound formed at least the elements GaInAsP, and a thickness of the layer is greater than 100 nm, and the layer is formed as part of the emitter and/or as part of the base and/or as part of the space-charge zone situated between the emitter and the base. The third subcell has a layer including a compound formed of at least the elements GaInP, and the thickness of the layer is greater than 100 nm.

A low noise infrared photodetector has an epitaxial heterostructure that includes a photodiode and a transistor. The photodiode includes a high sensitivity narrow bandgap photodetector layer of first conductivity type, and a collection well of second conductivity type in contact with the photodetector layer. The transistor includes the collection well, a transfer well of second conductivity type that is spaced from the collection well and the photodetector layer, and a region of first conductivity type between the collection and transfer wells. The collection well and the transfer well are of different depths, and are formed by a single diffusion.

A semiconductor device and the like having high quantum efficiency or high sensitivity in a near-infrared to infrared region is provided. The semiconductor device includes: a substrate; a multiple quantum well structure disposed on the substrate, and including a plurality of pairs of a layer a and a layer b; and a crystal-adjusting layer disposed between the substrate and the multiple quantum well structure. The crystal-adjusting layer includes a first adjusting layer which is made of the same material as the substrate and is in contact with the substrate, and a second adjusting layer which is made of the same material as the layer a or the layer b of the multiple quantum well structure and is in contact with the multiple quantum well structure.

Photovoltaic devices including direct gap III-V absorber materials and operatively associated back structures enhance efficiency by enabling photon recycling. The back structures of the photovoltaic devices include wide bandgap III-V layers, highly doped (In)GaAs layers, patterned oxide layers and metal reflectors that directly contact the highly doped (In)GaAs layers through vias formed in the back structures. Localized ohmic contacts are formed in the back structures of the devices.

The disclosure describes multi-junction solar cell structures that include two or more graded interlayers.