Abstract: Devices and methods are disclosed applicable to optical power converters such as solar cells comprising one or more photovoltaic layers for generating an electric potential between a top and bottom surface of the layers. A frontside metal contact is patterned on the top surface using a lithographic process such that open areas between metal features are contiguous. The pattern may include an opening between the contiguous open areas to an edge of the top surface of the layers. A pattern in this form facilitates easy removal of metal in these areas during device fabrication because liftoff of the unused metallization comprises removing metal as a contiguous piece, rather than multiple isolated regions. The opening to the edge further aids processing providing an entry path for solvent to dissolve the lithographic layer underlying the unused metallization.

Abstract: A metamorphic avalanche photodetector includes a substrate, and an active structure supported on the substrate. The active structure has a metamorphic absorption structure that absorbs light and responsively produces primary charge carriers, and an avalanche multiplication structure that receives the primary charge carriers from the metamorphic absorption structure and responsively produces secondary charge carriers. An output electrical contact is in electrical communication with the active structure to collect at least some of the secondary charge carriers. A buffer layer lies between the substrate and the active structure, between the active structure and the output electrical contact, or between the metamorphic absorption structure and the avalanche multiplication structure. A lattice parameter of the buffer layer varies with position through a thickness of the buffer layer.

Abstract: A method of disordering a layer of an optoelectronic device including; growing a plurality of lower layers; introducing an isoelectronic surfactant; growing a layer; allowing the surfactant to desorb; and growing subsequent layers all performed at a low pressure of 25 torr.

Abstract: A method of reducing propagation of threading dislocations into active areas of an optoelectronic device having a III–V material system includes growing a metamorphic buffer region in the presence of an isoelectronic surfactant. A first buffer layer may be lattice matched to an adjacent substrate and a second buffer layer may be lattice matched to device layers disposed upon the second buffer layer. Moreover, multiple metamorphic buffer layers fabricated in this manner may be used in a single given device allowing multiple layers to have their band gaps and lattice constants independently selected from those of the rest of the device.

Abstract: The present invention provides a photovoltaic cell comprising a GaInP subcell comprising a disordered group-III sublattice, a Ga(In)As subcell disposed below the GaInP subcell, and a Ge substrate disposed below the Ga(In)As subcell comprising a surface misoriented from a (100) plane by an angle from about 8 degrees to about 40 degrees toward a nearest (111) plane.

Abstract: A diffused junction semiconductor (12) for detecting light (48) at a predetermined wavelength is provided including a base (30) and an epitaxial structure (32) electrically coupled to the base (30). The epitaxial structure (32) forms a p-n junction (38) in the base (30). The epitaxial structure (32) includes at least one diffusion layer (50) electrically coupled to the base (30). At least one of the diffusion layers (50) contributes impurities in at least a portion of the base (30) to form the p-n junction (38) during growth of the epitaxial structure (32). A method for performing the same is also provided.

Abstract: A method of reducing propagation of threading dislocations into active areas of an optoelectronic device having a III-V material system includes growing a metamorphic buffer region in the presence of an isoelectronic surfactant. A first buffer layer may be lattice matched to an adjacent substrate and a second buffer layer may be lattice matched to device layers disposed upon the second buffer layer. Moreover, multiple metamorphic buffer layers fabricated in this manner may be used in a single given device allowing multiple layers to have their band gaps and lattice constants independently selected from those of the rest of the device.

Abstract: A method of disordering a layer of an optoelectronic device including; growing a plurality of lower layers; introducing an isoelectronic surfactant; growing a layer; allowing the surfactant to desorb; and growing subsequent layers all performed at a low pressure of 25 torr.

Abstract: ABSTRACT A diffused junction semiconductor (12) for detecting light (48) at a predetermined wavelength is provided including a base (30) and an epitaxial structure (32) electrically coupled to the base (30). The epitaxial structure (32) forms a p-n junction (38) in the base (30). The epitaxial structure (32) includes at least one diffusion layer (50) electrically coupled to the base (30). At least one of the diffusion layers (50) contributes impurities in at least a portion of the base (30) to form the p-n junction (38) during growth of the epitaxial structure (32). A method for performing the same is also provided.

Abstract: An improved photovoltaic cell has an active silicon (Si) or silicon-germanium (SiGe) substrate subcell having an active upper side and characterized by a substrate bandgap. One or more upper subcells are disposed adjacent the upper side and current matched with the substrate subcell, with the upper subcell(s) typically having bandgap(s) greater than the substrate bandgap. A transition layer may be placed intermediate the upper side and the upper subcell(s).

Abstract: A multijunction photovoltaic cell comprises a first subcell that initially receives incident light upon the photovoltaic cell, with the first subcell being made of a first material system, having a first thickness, and producing a first photogenerated current output. A second subcell receives the incident light after the first subcell receives the incident light, with the second subcell being disposed immediately adjacent the first subcell. The second subcell is made of the first material system or a similar semiconductor material, has a second thickness that is greater than the first thickness, and produces a second photogenerated current output that is substantially equal in amount to the first photogenerated current output. A tunnel junction is disposed between the first and second subcells. The multijunction cell provides a greater ability to current match to low-current-producing subcells, higher multijunction cell voltage, lower series resistance, and greater radiation resistance.

Abstract: An improved photovoltaic cell, according to one embodiment, includes a base layer; a primary window layer having a first type of doping, with the primary window layer being disposed over the base layer; and a secondary window layer having the first type of doping, with the secondary window layer being disposed over the primary window layer. In another embodiment, the improved photovoltaic cell has a multilayer back-surface field structure; a base layer disposed over the back-surface field structure; and a primary window layer disposed over the base layer. In yet another embodiment, the photovoltaic cell includes a base layer; and a primary window layer disposed over the base layer, with the primary window layer having a thickness of at least about 1000 Angstroms.

Abstract: An improved photovoltaic cell, according to one embodiment, includes a base layer; a primary window layer having a first type of doping, with the primary window layer being disposed over the base layer; and a secondary window layer having the first type of doping, with the secondary window layer being disposed over the primary window layer. In another embodiment, the improved photovoltaic cell has a multilayer back-surface field structure; a base layer disposed over the back-surface field structure; and a primary window layer disposed over the base layer. In yet another embodiment, the photovoltaic cell includes a base layer; and a primary window layer disposed over the base layer, with the primary window layer having a thickness of at least about 1000 Angstroms.

Abstract: A three-dimensional tic-tac-toe game which includes a lattice having cubicles for receiving X or O mating pieces therein. The pieces are held in the cubicles by Velcro patches on the pieces that cooperate with mating patches in the cubicles.

Abstract: A cut-off device for a cigarette or filter rod making machine is designed to work with a knife having an aperture which, when the knife is spent, is detected by a system including a light emitter and a detector, with an electronic timing system sensitive to specific light/dark transitions to enable the presence of an aperture to be detected at various speeds of rotation of the member carrying the knife.