Abstract: A varactor has a lamellar structure of a plurality of abutting regions of alternate and opposite type conductivity. The structure is produced by thermal gradient zone melting processing.

Abstract: A metal oxide barrier layer is provided at the interface between a refractory oxide-silica investment mold and a contained metal superalloy, allowing directional solidification of the contained superalloy at elevated temperatures without metal-mold reaction.

Abstract: A semiconductor diode comprises a first body of semiconductor material having a selected resistivity and a first type conductivity and a region of second type conductivity and a selected resistivity. The second body consists of recrystallized semiconductor material of a layer thereof having solid solubility of a dopant therein and has the same crystallographic structure as the first body. The second region is formed by a temperature gradient zone melting process embodying the migration of a metal-enriched melt of semiconductor material through the second body of semiconductor material. Preferably, the metal-enriched melt is no greater than approximately 20 microns in thickness. The second body initially has a < 111 > axial crystallographic orientation when it is a wafer. However, the second body initially may be polycrystalline semiconductor material.

Abstract: A solar cell with improved efficiency is provided with a convoluted P-N junction whereby a higher proportion of carriers produced by exposure of the solar cell to a source of radiation will be collected by the P-N junction rather than being lost by recombination. The solar cell has an increased resistance to radiation damage. The solar cell is made from a body of semiconductor material in which two regions of opposite type conductivity are formed. The material of one region is substantially the same as the body and the material of the other region is recrystallized material of the first region having solid solubility of a metal therein to impart a selective type conductivity and resistivity thereto.