Abstract: A vertical transistor device is characterized by active regions vertically separated by a narrower control region. The control region is defined by conducting layer extensions which extend into a groove within which semiconductor material is regrown during device fabrication. The device is further characterized by regions of isolating material, located horizontally adjacent to the active regions, said isolating material serving to reduce parasitic capacitance and improve thermal distribution within the device, thereby improving frequency and power performance.

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: 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: A negative resist and masking process for microfabrication comprising an evaporated film of aluminum and oxygen which, in the as-deposited state, is highly conductive and has low resistance to etching, but when exposed to active radiation, such as by pulse laser thermal excitation, converts to a low electrical conductivity, high etchant resistive phase.

Abstract: A three-dimensional optical waveguide is disclosed. This waveguide comprises a single crystal semiconductor layer grown upon an insulator which has an index of refraction lower than the semiconductor. The semiconductor layer has a thickness which provides confinement of light propagating in the semiconductor layer in the vertical direction. An effective larger index of refraction over a cross-sectional region of the semiconductor layer provides confinement of light in the lateral direction. This lateral confinement is achieved by side walls in the semiconductor layer which extend toward, but fall short of, the insulator layer.

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 method for fabricating three-dimensional optical waveguides is disclosed. In this method, a single crystal semiconductor layer is grown upon an insulator which has an index of refraction lower than the semiconductor. The semiconductor layer is deposited to a thickness which provides confinement of light propagating in the semiconductor layer in the vertical direction. An effective larger index of refraction over a cross-sectional region of the semiconductor layer is then formed to provide confinement of light in the lateral direction. In the preferred method, the growth of single crystal semiconductor upon the insulator is achieved by a vapor-phase lateral epitaxial overgrowth technique.Devices fabricated according to the method are also disclosed.

Abstract: A layer of material such as the metal base of a transistor is embedded in single crystal. A layer of the material with small, uniformly dimensioned and uniformly spaced openings is formed on a single crystal substrate, and the single crystal is grown from the exposed portions of the substrate over the layer of material. For best results, the layer of material to be embedded is deposited relative to the crystal orientation to provide a much greater rate of crystal growth laterally across the layer than away from the crystal substrate. The method is particularly useful in fabricating a permeable base transistor having slits formed in the metal base layer. An integrated circuit can be fabricated by forming a pattern of conductive material on a single crystal, that pattern having continuous regions which inhibit further crystal growth and narrow regions or regions having openings therein which permit lateral crystal growth across those regions.

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: A method of applying an electrical contact and an anodic reflection coating to an n.sup.+ layer of a direct gap semiconductor device, comprising applying an anodizable metal contact to the n.sup.+ layer and thereafter anodizing the n.sup.+ layer whereby its thickness is reduced and an antireflection layer is formed thereover.

Abstract: Improvements in shallow-homojunction solar cells based upon a plurality of layers of a direct gap semiconductor material such as GaAs, as well as their fabrication, are disclosed. The shallow-homojunction solar cells have a n.sup.+ /p/p.sup.+ structure in which the n.sup.+ top layer is limited to a thickness which permits significant carrier generation to occur in a lower semiconductor layer. An anodic antireflection coating is applied over the n.sup.+ top layer, and a particularly preferred method for applying the antireflection coating is by anodization. These solar cells can be grown on relatively inexpensive substrates, if desired, such as silicon or germanium.

Abstract: A method of passivating imperfections, such as grain boundaries and/or dislocations, in semiconductor materials is disclosed which comprises selectively passing electrical current along the imperfections by employing the semiconductor material as an electrode in an electrolytic cell.