Abstract: A photovoltaic device, particularly a solar cell, comprises an interface between a layer of Group III-V material and a layer of Group IV material with a thin silicon diffusion barrier provided at or near the interface. The silicon barrier controls the diffusion of Group V atoms into the Group IV material, which is doped n-type thereby. The n-type doped region can provide the p-n junction of a solar cell in the Group IV material with superior solar cell properties. It can also provide a tunnel diode in contact with a p-type region of the III-V material, which tunnel diode is also useful in solar cells.

Abstract: A photovoltaic device, particularly a solar cell, comprises an interface between a layer of Group III-V material and a layer of Group IV material with a thin silicon diffusion barrier provided at or near the interface. The silicon barrier controls the diffusion of Group V atoms into the Group IV material, which is doped n-type thereby. The n-type doped region can provide the p-n junction of a solar cell in the Group IV material with superior solar cell properties. It can also provide a tunnel diode in contact with a p-type region of the III-V material, which tunnel diode is also useful in solar cells.

Abstract: A photovoltaic device comprises an interface (8) between a layer of Group III-V material (3) and a layer of Group IV material (1) with a thin silicon diffusion barrier (6) provided at or near the interface. The silicon barrier controls the diffusion of Group V atoms into the Group IV material, which is doped n-type thereby. The n-type doped region can provide the p-n junction of a solar cell in the Group IV material with superior solar cell properties. It can also provide a tunnel diode in contact with a p-type region of the III-V material, which tunnel diode is also useful in solar cells. In another aspect, a multijunction photovoltaic device is provided in which there are at least a first light-absorbing layer (111) of SiGe or SiGeSn and a second light-absorbing layer (112) of SiGeSn, both layers being lattice-matched to GaAs.

Abstract: An opto-electronic device, such as a light-emitting diode, comprises a transparent high lateral conductivity current spreading layer 31 overlying a conventional p-n junction active region 10. The current spreading layer 31 comprises a multiple quantum-well heterostructure having a plurality of thin layers 33 of a material having a band-gap narrower than the band-gap of the active region disposed between layers 32 of a material having a band-gap greater than or equal to the band-gap of the active region 10, the wide band-gap layers 32 being more highly doped than said narrow band-gap layers 33. Quantum confinement occurs in the narrow band-gap layers 33, so that it becomes transparent to light emitted from the active region 10. Furthermore, the layers 33 of narrow band-gap material become highly conductive owing to charge carriers which have transferred from the more highly doped wide band-gap material layers 32.