Abstract: The improved method of the present invention comprises contacting a clean and preferably etched selected crystalline substrate with a controlled thickness of a melt comprising a saturated solution of selected materials capable of forming semi-conductor junctions, preferably heterojunctions, with the substrate. The contacting is carried out while the resulting melt and substrate sandwich is shielded by a protective atmosphere of gas such as hydrogen and while the sandwich is subjected to a progressively lower temperature gradient maintained across the melt-wafer package.The method and apparatus are particularly applicable to the preparation of improved light-emitting diodes by the liquid epitaxial growth technique.

Abstract: In a preferred embodiment, a technique and associated apparatus for producing heteroepitaxial semi-conductor junctions preferably for Group III-V compounds in an improved liquid-solid transport method, placing a prescribed doped "limited-volume" melt directly upon a host substrate and treating these in a very precisely controlled heating-cooling schedule and associated equipment whereby the substrate is melt-back to a prescribed degree, and then very carefully recrystallized in a crystal layer of the desired volume and stoichiometry (determined by the melt-volume).

Abstract: A cold cathode for an image-type tube such as a vidicon. The cathode features a negative electron affinity surface and a field enhanced electron ejection method. The photons generate electron-hole pairs in a compound semi-conductor structure having Group III and Group V compounds to form a heterojunction.

Abstract: A method of producing light emitting diodes of high quantum efficiency in mass production by utilizing an epitaxial deposition from a small size melt such that the substrate itself serves as a saturation source. A silicon doped gallium arsenide wafer is cleaned and etched by normal means and subsequently the wafer is precoated with a properly doped gallium master melt. The coated wafers are inserted into an epitaxial furnace and the gallium master melt effects solution of a portion of the gallium arsenide monocrystal substrate and finally the entire wafer is cooled, maintaining a temperature gradient causing epitaxial growth on the substrate.