Abstract: P-type doping of a molecular beam epitaxy (MBE) grown substrate composed of a Group II-VI combination is accomplished by forming a flux from a Group II-V combination, and applying the flux to the substrate at a pressure less than about 10.sup.-6 atmosphere. The Group II material is selected from Zn, Cd, Hg and Mg, the Group V material from As, Sb and P, and the Group VI material from S, Se and Te. The Group II-V dopant combination is preferably provided as a compound formed predominantly from the Group II material, and having the formulation X.sub.3 Y.sub.2, where X is the Group II material and Y is the Group V material. The doping concentration is controlled by controlling the temperature of the Group II-V combination. Metal vacancies in the lattice structure are tied up by the Group II constituent of the dopant combination, leaving the Group V dopant available to enter the Group VI sublattice and produce a p-type doping.

Abstract: A method is provided for accelerating and improving the recovery of GaAs solar cells from the damage which they experience in space under high energy particle irradiation such as electrons, protons and neutrons. The method comprises combining thermal annealing with injection annealing. Injection annealing is the recovery from radiation damage resulting from minority carrier injection into the damaged semiconductor, nonradiative minority carrier combination of the injected minority carriers, transfer of the recombination energy to the crystal lattice and utilization of this energy to remove the defects caused by the high energy particle irradiation. The combined annealing of this invention is implemented by heating the solar cells to a moderate temperature (on the order of about 200.degree. C. to 300.degree. C.

Abstract: A method is provided for accelerating and improving the recovery of GaAs solar cells from the damage which they experience in space under high energy particle irradiation scuh as electrons, protons and neutrons. The method comprises combining thermal annealing with injection annealing. Injection annealing is the recovery from radiation damage resulting from minority carrier injection into the damaged semiconductor, nonradiative minority carrier combination of the injected minority carriers, transfer of the recombination energy to the crystal lattice and utilization of this energy to remove the defects caused by the high energy particle irradiation. The combined annealing of this invention is implemented by heating the solar cells to a moderate temperature (on the order of about 200.degree. C. to 300.degree. C.

Abstract: The specification discloses a process for growing crystals of a Group III-V material having controlled and high purity. The crystal is grown in the presence of hydrogen containing a predetermined amount of water vapor and the water vapor suppresses the concentration of silicon impurities from the reaction chamber, the associated tubing, and/or the starting materials, which are incorporated in the grown crystal. The crystal growth process may be either an epitaxial process or a bulk process. In one embodiment of the invention, the material grown is indium phosphide. In another embodiment of the invention, the process described above is used to grow a series of epitaxial layers of a Group III-V material with each layer having different predetermined impurity concentrations, to form a Gunn diode device.

Abstract: The specification describes an improved III-V compound solar cell structure and fabrication process therefor wherein a P-type layer of gallium aluminum arsenide is epitaxially grown on an N-type gallium arsenide substrate to form a P-type region and a PN junction in the substrate. Controlled amounts of beryllium are introduced into both the epitaxial layer and the substrate, either during epitaxial growth or by using beryllium ion implantation techniques subsequent to the P-type epitaxial growth step. The homojunction-heterostructure device thus formed exhibits improved power conversion efficiencies in excess of 17%.

Abstract: The specification describes an improved III-V compound solar cell structure and fabrication process therefor wherein a P-type layer of gallium aluminum arsenide is epitaxially grown on an N-type gallium arsenide substrate to form a P-type region and a PN junction in the substrate. Controlled amounts of beryllium are introduced into both the epitaxial layer and the substrate, either during epitaxial growth or by using beryllium ion implantation techniques subsequent to the P-type epitaxial growth step. The homojunction-heterostructure device thus formed exhibits improved power conversion efficiencies in excess of 17%.

Abstract: The specification describes a semiconductor solar cell and fabrication process therefor wherein a thin N-type gallium arsenide layer is deposited on a larger P-type substrate layer which is selected from the group of III-V ternary compounds consisting of aluminum phosphide antimonide, AlPSb, and aluminum indium phosphide, AlInP. P-type impurities are diffused from the substrate layer into a portion of the thin N-type gallium arsenide layer to form P-type region therein which defines a PN junction in the thin gallium arsenide layer. Thus, the quantity of gallium arsenide required to provide this PN photovoltaic junction layer in the cell is minimized, and the P-type substrate serves as a high bandgap window layer for the cell. Such high bandgap of this window material is especially well suited for efficiently transmitting the blue spectrum of sunlight to the PN junction, thus enhancing the power conversion efficiency of the solar cell.

Abstract: The specification describes a semiconductor solar cell and fabrication process therefor wherein a thin N-type gallium arsenide layer is deposited on a larger P-type substrate layer which is selected from the group of III-V ternary compounds consisting of aluminum phosphide antimonide, AlPSb, and aluminum indium phosphide, AlInP. P-type impurities are diffused from the substrate layer into a portion of the thin N-type gallium arsenide layer to form P-type region therein which defines a PN junction in the thin gallium arsenide layer. Thus, the quantity of gallium arsenide required to provide this PN photovoltaic junction layer in the cell is minimized, and the P-type substrate serves as a high bandgap window layer for the cell. Such high bandgap of this window material is especially well suited for efficiently transmitting the blue spectrum of sunlight to the PN junction, thus enhancing the power conversion efficiency of the solar cell.

Abstract: Disclosed is a process for fabricating chromium-doped semi-insulating epitaxial layers of gallium arsenide which includes contacting a gallium arsenide substrate with a chromium-doped saturated solution of gallium arsenide in gallium and maintaining the solution at a relatively low liquid phase epitaxial (LPE) deposition temperature on the order of about 750.degree.-850.degree. C.

Abstract: A process for forming a monolithic gallium arsenide structure having a plurality of electrically insulated gallium arsenide regions.

Abstract: The specification describes a liquid phase epitaxial (LPE) crystal growth process wherein semi-insulating epitaxial layers of gallium arsenide (GaAs) are formed on selected substrates by dipping the substrates into a saturated solution of GaAs in gallium. Prior to exposing the substrates to the above solution, the substrates are shielded by a nonreactive container of a material possessing a high thermal conductivity which, when immersed in the solution, serves to establish a thermal equilibrium between the substrate and the solution. This insures good nucleation in and crystal growth of the high quality semiconductor layers grown, and these layers may be grown to minimum thicknesses on the order of 0.2 micrometers or less with excellent control.

Abstract: Disclosed is a process for fabricating chromium-doped semi-insulating epitaxial layers of gallium arsenide which includes contacting a gallium arsenide substrate with a chromium-doped saturated solution of gallium arsenide in gallium and maintaining the solution at a relatively low liquid phase epitaxial (LPE) deposition temperature on the order of about 750.degree. C-850.degree. C.