| 摘要 |
PURPOSE:To provide the highly efficient solar battery whose spectral sensitivity for sunlight is expanded, by optimizing the forbidden band width and lattice constant of the semiconductor material of each layer. CONSTITUTION:An N layer 12 and a P layer 13, comprising a mixed crystal Ga1-yInyAs (y=0.15-0.50) are grown on an N type semiconductor substrate 11 of GaAs, InP, InAs, and Ge by a hetero epitaxial method. The lower solar battery 14 is constituted by the P-N junction formed by the layers. A thin P layer 15 and a thin N layer 16, which comprises In1-xAlxAs (x=0.45-0.65) and has a film thickness of 200Angstrom or less and to which high concentration impurities are added, are provided. A tunnel junction 17 comprising said layers 15 and 16 is formed on a P type Ga1-yInyAs layer 13. The upper solar battery 18 and the lower solar battery 14 are connected by said tunnel junction 17. The upper solar battery 18 can be constituted by the solar battery comprising the P-N junction which is obtained by the hetero epitaxial growth of an N layer 19 and a P layer 20 comprising a mixed crystal In1-xAlxAs (x=0.45-0.65). |
