SOLAR CELL

PURPOSE:To make use of a light with a long wavelength, which can not be made use of with silicon alone, effectively for power generation by providing a silicon/germanium mixed layer smaller in band gap than silicon at the rear. CONSTITUTION:A crystal layer 13, which is silicon/germanium mixed crystal doped with boron or aluminum in high concentration and in which the composition ratio of germanium is 0.3 or less, is grown on one side of a p-type conductivity of silicon substrate 11 by molecular beam epitaxial growth method. Then, an n-type layer 12 is made by diffusing phosphorus in high concentration and shallow on the opposite side of the wafer. A p-side electrode 14 and a comb- shaped n-side electrode 15 are made, and those are cut in proper sizes to obtain solar cells. Thereby, a light long wavelength can be made use of for power generation, and further, this mixed crystal can have the effect as a rear electric field.