Abstract: An optical device formed on an Si substrate comprising: a III-V optical transmitter formed on the Si substrate, a silicon device formed in or on, the Si substrate and an alignment groove formed in the substrate for aligning an optical fiber with said transmitter.

Abstract: A photovoltaic device utilizing compound semiconductor materials that are stable when operated at high temperatures. Hostile environments, and in particular, thermally stressful enviornments such as those generated by use of light concentrating systems, require encapsulation of the device. Sealing of the photo-active junction, the conductive grid, the exposed semiconductor surfaces, and the pads contacting the grid away from the junction area provide such thermal stability. A heterojunction structure can be used along with barrier materials providing a conductive grid in contact with the photo-active surface thereby reducing interdiffusion of that surface with the conductive grid.

Abstract: An improved method of zone-melting and recrystallizing of polysilicon film on an insulator over silicon is described.

Abstract: A method for reducing the defect and dislocation density in III-V material layers deposited on dissimilar substrates is disclosed. The method involves ion implantation of dopant materials to create amorphous regions within the layers followed by an annealing step during which the amorphous regions are recrystallized to form substantially monocrystalline regions. The wafers produced by the process are particularly well suited for optoelectronic devices.

Abstract: An improved method and apparatus for optimizing the electrical properties while crystallizing material is disclosed. In this invention, a material which is to be crystallized is formed on a substrate and subjected to a heat treatment to intentionally induce thermal stress while crystallizing the material. The heat treatment melts the material being crystallized and when the material solidifies, a built-in stress is retained which, in the case of n-doped Si on fused silica results in a tensile stress which produces an electron mobility in the film of 870 cm.sup.2 /volt-sec as compared to similarly fashioned unstressed n-doped Si on SiO.sub.2 coated Si which has an electron mobility of 500 cm.sup.2 /volt-sec.

Abstract: A reactor, suitable for CVD processes, which presents a high aspect ratio to reactant gasses, is described. Substrates are mounted on oppositely disposed susceptors in a vertical chimney-type reactor. Means are provided to rotate the susceptors about an axis perpendicular to gas flow. Side-loading or top-loading mechanisms are provided for loading and unloading the susceptors through a gate valve. A diffuser below the reaction zone adjusts the gas flow into the reaction zone.

Abstract: A method of producing sheets of crystalline material is disclosed, as well as devices employing such sheets. In the method, a growth mask is formed upon a substrate and crystalline material is grown at areas of the substrate exposed through the mask and laterally over the surface of the mask to form a sheet of crystalline material. This sheet is optionally separated so that the substrate can be reused. The method has particular importance in forming sheets of crystalline semiconductor material for use in solid state devices.

Abstract: Transparent heat-mirrors are disclosed which are comprised of composite films. These films include a discrete and continuous layer of metallic silver sandwiched between a transparent, outer, protective, anti-reflection layer and a transparent, phase-matching layer. This combination of layers is chosen to provide high solar transmission with minimum loss of thermal radiation. Transparent heat-mirrors are useful in the collection and trapping of solar energy, and in other applications where it is desired or necessary to have high infrared reflectivity with high solar transmission.

Abstract: A method of producing sheets of crystalline material is disclosed which is employed in the construction of tandem solar cells. In the method, a growth mask is formed upon a substrate and crystalline material is grown at areas of substrate exposed through the mask and laterally over the surface of the mask to form a sheet of crystalline material. This sheet is then separated and used to form a tandem solar cell while the substrate can be reused to form additional sheets.

Abstract: A method of producing sheets of crystalline material is disclosed, as well as devices employing such sheets. In the method, a growth mask is formed upon a substrate and crystalline material is grown at areas of the substrate exposed through the mask and laterally over the surface of the mask to form a sheet of crystalline material. This sheet is separated, and the substrate can optionally be reused. The method has particular importance in forming sheets of crystalline semiconductor material for use in solid state devices.

Abstract: Transparent heat-mirrors are disclosed which are comprised of composite films. These films include a discrete and continuous layer of metallic silver sandwiched between a transparent, outer, protective, anti-reflection layer and a transparent, phase-matching layer. This combination of layers is chosen to provide high solar transmission with minimum loss of thermal radiation. Transparent heat-mirrors are useful in the collection and trapping of solar energy, and in other applications where it is desired or necessary to have high infrared reflectivity with high solar transmission.

Abstract: An improved method and apparatus for crystallizing amorphous or polycrystalline material is disclosed. In this invention, a material which is to be crystallized is formed on a substrate and single crystalline seed material is disposed in contact and/or adjacent to or with at least a portion of the material which is to be crystallized. A layer of material which serves as a "wetting agent" is then formed over the material to be crystallized. The structure thus formed is subjected to a heat treatment which melts the material being crystallized and when the material solidifies its crystalline structure is substantially epitaxial based on the seed material. The "wetting agent" layer serves to prevent deleterious balling up of the material during crystallization.

Abstract: Dislocation densities are reduced in growing semiconductors from the vapor phase by employing a technique of interrupting growth, cooling the layer so far deposited, and then repeating the process until a high quality active top layer is achieved. The method of interrupted growth, coupled with thermal cycling, permits dislocations to be trapped in the initial stages of epitaxial growth.

Abstract: Transparent heat-mirrors are disclosed which are comprised of composite films. These films include a discrete and continuous layer of metallic silver sandwiched between a transparent, outer, protective, anti-reflection layer and a transparent, phase-matching layer. This combination of layers is chosen to provide high solar transmission with minimum loss of thermal radiation. Transparent heat-mirrors are useful in the collection and trapping of solar energy, and in other applications where it is desired or necessary to have high infrared reflectivity with high solar transmission.

Abstract: An improved photovoltaic device in which a charge separation junction is provided over a charge confining heterojunction. The charge separation junction is a junction formed of an n.sup.+ -doped direct bandgap layer on a p-doped direct bandgap active layer. The charge confining heterojunction is formed by the interface of the active layer with a Back Surface Layer (BSL) of higher bandgap material than the active layer to provide a Back Surface Field (BSF). The percentage of Al in the layers may vary from Y=O to x.ltoreq.0.42. The structure applies to both crystalline and amorphous material.

Abstract: Improvements in solar cells based upon low cost semiconductors, such as amorphous silicon, are disclosed. The improved solar cells of this invention have ultrathin active semiconductor layers having a thickness between 0.1 t.sub..alpha. and L.sub.m wherein t.sub..alpha. is the solar spectrum absorption length and L.sub.m is the diffusion length for photogenerated minority charge carriers in the active layer. The back surface reflector has a solar spectrum reflectivity of 70% or greater, so that incident energy not absorbed in a direct pass through the active layer is reflected for another pass. The most preferred embodiment of the cells described herein are shaped to have a light-trapping structure so that light makes mulitple passes through the thin semiconductor layers.

Abstract: A selective-black absorber capable of operation at elevated temperatures and high efficiency as a solar energy absorber is described. A cermet of MgO/Au, MgO/Pt, and Cr.sub.2 O.sub.3 /Cr having high solar energy absorptance and low infrared energy emissivity is coated on a substrate having high infrared reflectivity such as Mo coated on stainless steel; Ni coated on Cu, or steel; aluminum, or steel. Typically an absorption coefficient of about 0.93 with an emissivity of about 0.09 is obtained and operation at a temperature of 300.degree.-400.degree. C. is possible depending on the cermet and substrate materials.

Abstract: Improvements in solar cells based upon low cost semiconductors, such as amorphous silicon, are disclosed. The improved solar cells of this invention have ultrathin active semiconductor layers having a thickness between 0.1 t.sub..alpha. and L.sub.m wherein t.sub..alpha. is the solar spectrum absorption length and L.sub.m is the diffusion length for photogenerated minority charge carriers in the active layer. The back surface reflector has a solar spectrum reflectivity of 70% or greater, so that incident energy not absorbed in a direct pass through the active layer is reflected for another pass. The most preferred embodiment of the cells described herein are shaped to have a light-trapping structure so that light makes multiple passes through the thin semiconductor layers.

Abstract: An improved method and apparatus for crystallizing amorphous or polycrystalline material is disclosed. In this invention, a material which is to be crystallized is formed on a substrate and single crystalline seed material is disposed adjacent and in contact with at least a portion of the material which is to be crystallized. A layer of material which serves as a "wetting agent" is then formed over the material to be crystallized. The structure thus formed is subjected to a heat treatment which melts the material being crystallized and when the material solidifies its crystalline structure is substantially epitaxial based on the seed material. The "wetting agent" layer serves to prevent deleterious balling up of the material during crystallization.

Abstract: A method of compensating grain boundaries or dislocations causing interstices to form particularly in polycrystalline semiconductor materials is disclosed which comprises selectively diffusing opposite impurity-type donor semiconductor material into the interstice to thereby reduce the conductivity of the interstice.