Systems to induce current flow in a circuit formed by intersecting molten metal streams are provided. The systems involve induction type electromagnetic pumps that produce each molten metal stream. In some embodiments, the current induced through the molten metal streams is induction current.

A method of fabricating a four junction solar cell by identifying the composition and band gaps of the upper first, second and third subcells that maximizes the efficiency of the solar cell at a predetermined time after initial deployment by simulation; fabricating one or more four-junction test solar cells in accordance with the identified composition and band gaps of the upper first, second and third subcells; performing one or more optical or electrical tests on the fabricated one or more four-junction test solar cells; based on results of the tests, determining one or more properties of at least one of the upper first, second or third subcells to be modified in subsequent fabrication of four-junction solar cells, including the band gap, doping level and profile, and thickness of each of the subcell layers; and fabricating a further four-junction solar cell in accordance with the modified properties of at least one of the upper first, second or third subcells to optimize the efficiency of the solar cell at the predetermined time.

A method of fabricating a four junction solar cell by identifying the composition and band gaps of the upper first, second and third subcells that maximizes the efficiency of the solar cell at a predetermined time after initial deployment by simulation; fabricating one or more four-junction test solar cells in accordance with the identified composition and band gaps of the upper first, second and third subcells; performing one or more optical or electrical tests on the fabricated one or more four-junction test solar cells; based on results of the tests, determining one or more properties of at least one of the upper first, second or third subcells to be modified in subsequent fabrication of four-junction solar cells, including the band gap, doping level and profile, and thickness of each of the subcell layers; and fabricating a further four-junction solar cell in accordance with the modified properties of at least one of the upper first, second or third subcells to optimize the efficiency of the solar cell at the predetermined time.

A stacked monolithic multi-junction solar cell having at least four subcells, wherein the band gap increases starting from the first subcell in the direction of the fourth subcell, each subcell has an n-doped emitter and a p-doped base, the emitter and the base of the first subcell each have germanium or consist of germanium, all following subcells each have at least one element of main group III and V of the periodic table, a tunnel diode with a p-n junction is placed between each two subcells, all subcells following the first subcell are formed lattice-matched to one another, a semiconductor mirror having a plurality of doped semiconductor layers with alternately different refractive indices is placed between the first and second subcell, and the semiconductor mirror is placed between the first subcell and the first tunnel diode.

A stacked monolithic multi-junction solar cell having at least four subcells, wherein the band gap increases starting from the first subcell in the direction of the fourth subcell, each subcell has an n-doped emitter and a p-doped base, the emitter and the base of the first subcell each have germanium or consist of germanium, all following subcells each have at least one element of main group III and V of the periodic table, a tunnel diode with a p-n junction is placed between each two subcells, all subcells following the first subcell are formed lattice-matched to one another, a semiconductor mirror having a plurality of doped semiconductor layers with alternately different refractive indices is placed between the first and second subcell, and the semiconductor mirror is placed between the first subcell and the first tunnel diode.

A compound solar battery according to the present invention is provided with a laminated film 2 including: a reflection layer 20 formed of an AlGaAs layer; a front surface-side light absorption layer 10 formed between a surface electrode 1 and the reflection layer 20; and a back surface-side light absorption layer 30 formed between the reflection layer 20 and a substrate 3. The reflection layer 20 is formed of a front surface-side reflection layer 20u and a back surface-side reflection layer 20d. A Al content ratio in the front surface-side reflection layer 20u is set to be greater than that in the back surface-side reflection layer 20d. In the back surface-side light absorption layer 30, a first InGaP layer 31, a first GaAs layer 32, a second InGaP layer 33, a second GaAs layer 34, and a third InGaP layer 35 is formed by laminating from the substrate 3 side, and a film thickness of the second GaAs layer 34 is set to be larger than that of the first GaAs layer 32.

A compound solar battery according to the present invention is provided with a laminated film 2 including: a reflection layer 20 formed of an AlGaAs layer; a front surface-side light absorption layer 10 formed between a surface electrode 1 and the reflection layer 20; and a back surface-side light absorption layer 30 formed between the reflection layer 20 and a substrate 3. The reflection layer 20 is formed of a front surface-side reflection layer 20u and a back surface-side reflection layer 20d. A Al content ratio in the front surface-side reflection layer 20u is set to be greater than that in the back surface-side reflection layer 20d. In the back surface-side light absorption layer 30, a first InGaP layer 31, a first GaAs layer 32, a second InGaP layer 33, a second GaAs layer 34, and a third InGaP layer 35 is formed by laminating from the substrate 3 side, and a film thickness of the second GaAs layer 34 is set to be larger than that of the first GaAs layer 32.

A multijunction solar cell including an upper first solar subcell having an emitter and base layers forming a photoelectric junction; a second solar subcell disposed under and adjacent to the upper first solar subcell, and having an emitter and base layers forming a photoelectric junction; and a third solar subcell disposed under and adjacent to the second solar subcell and having an emitter and base layers forming a photoelectric junction; wherein at least one of the base and emitter layers of at least a particular solar subcell from among the upper first solar subcell, the second solar subcell, and the third solar subcell has a graded band gap throughout at least a portion of thickness of its active layer adjacent to the photoelectric junction and being in a range of 20 to 300 MeV greater than a band gap in the active layer in both the emitter layer and the base layer spaced away from the photoelectric junction.

A multijunction solar cell including an upper first solar subcell having an emitter and base layers forming a photoelectric junction; a second solar subcell disposed under and adjacent to the upper first solar subcell, and having an emitter and base layers forming a photoelectric junction; and a third solar subcell disposed under and adjacent to the second solar subcell and having an emitter and base layers forming a photoelectric junction; wherein at least one of the base and emitter layers of at least a particular solar subcell from among the upper first solar subcell, the second solar subcell, and the third solar subcell has a graded band gap throughout at least a portion of thickness of its active layer adjacent to the photoelectric junction and being in a range of 20 to 300 MeV greater than a band gap in the active layer in both the emitter layer and the base layer spaced away from the photoelectric junction.

A method for producing an electronic device having a drive circuit including a solar cell structure, the method including the steps of: having a first wafer having solar cell structures on a starting substrate and a second wafer having drive circuits formed, so that either one of the first wafer or the second wafer has a plurality of independent diode circuits and capacitor-function laminated portions; obtaining a bonded wafer by bonding so that the solar cell structures, the diode circuits, the capacitor-function laminated portions, and the drive circuits are superimposed; wiring; and dicing the bonded wafer; thus creating a method for producing an electronic device including a drive circuit, a solar cell structure, and a capacitor-function portion in one chip and having a suppressed production cost; and such an electronic device.