NOVELTY - The semiconductor component has at least one germanium semiconductor layer (14, 15). This is or contains more than 50 At% of germanium. Its front faces the light and on the rear there is at least one silicon carbide layer (16). This is or contains SiC. It (16) is a surface passivation layer for the semiconductor layer. It is also a reflector for radiation with a wavelength exceeding 1600 nm. Its refractive index lies in the range 1.6 to 3.6. Several such layers are included, with differing refractive indices. They function as a Bragg reflector.    USE - A thermophotovoltaic cell. It is used as a multiple solar cell (claimed).    ADVANTAGE - The invention improves over simple germanium-based solar cells. The silicon carbide (or SiC containing-) layer passivates the cell, acts as a diffusion barrier, and reflects photons which have not been converted, back into the semiconductor layer. In this way, cell efficiency is increased. The silicon carbide has high temperature stability. It has outstanding passivation qualities for Ge and Ge-Si. Impurities are prevented from diffusing into adjacent layers. The silicon carbide layer may have atomic, electrical and optical functions. It serves as a source of hydrogen or dopants. By reflecting photons within the band gap energy, their path through the solar cell material is approximately doubled. This is especially valuable with thin solar cells. Long wave IR with lower energy than the band gap, is reflected out. Excessive heating due to absorption in the rear contact is therefore prevented. This is especially significant in space, or for thermophotovoltaics. Bragg reflection is caused by suitable multilayer design.    DETAILED DESCRIPTION - Thickness of the silicon carbide layer is 100-500 nm. It contains amorphous silicon carbide. It is electrically-conductive and is doped with phosphorus, boron and/or nitrogen. The semiconductor component has a reflectivity exceeding 80%, in the waveband 1800-4000 nm. The semiconductor layer (14, 15) has a thickness in the range 100-700 mu m. It includes at least 90 At% germanium. It is SixGe1-x, where x is 0 - 0.5. The silicon carbide layer lies flat on the semiconductor layer. On the side remote from the semiconductor, a dielectric layer is added, at least locally. The dielectric is or includes silica, silicon nitride, magnesium fluoride, tantalum oxide or their mixtures. On the remote surface of the layer, an electrically-conductive layer (18) is added to make contact (19) with the semiconductor layer. The contacting layer (18) is or contains aluminum, gold, silver, palladium, titanium, nickel or their alloys. This layer makes direct local contact (19) with the semiconductor layer. The semiconductor component is a thermophotovoltaic cell. The silicon carbide layer is arranged on the side of the photovoltaic cell facing away from the light. The semiconductor component is a thermophotovoltaic cell converting radiation from a thermal emitter at a temperature of 800-2000 degrees C, into electrical current. The semiconductor cell is a III-V- multiple solar cell. To make the cell, the germanium substrate is coated with the silicon carbide layer by chemical gas phase deposition, thermal chemical vapor deposition or sputtering. Before deposition, the substrate surface is plasma-cleaned. The process gases are methane and silane. The gas percentages determine the stoichiometry of the layers and their functions. An INDEPENDENT CLAIM is included for the method of manufacture.    DESCRIPTION OF DRAWING(S) - The drawing shows an implementation of the semiconductor component.    front contact (11)    anti-reflection layer (12)    front passivation (13)    germanium emitter (14)    germanium base (15)    silicon carbide layer (16)    electrically-conductive layer (18)    rear point contact (19)