Emitter structures in MOCVD InP solar cells

Abstract

InP solar cells have been made by metalorganic chemical vapor deposition (MOCVD) with a graded-junction or front-surface-field structure, in which the doping decreases from 3*10/sup 19/ cm/sup -3/ at the surface to 3*10/sup 18/ cm/sup -3/ at the junction. Improvement was observed in the short-wavelength quantum efficiency and in the overall conversion efficiency relative to standard shallow-homojunction cells, indicating that the graded structure improved collection of carriers generated near the surface. A beginning-of-life conversion efficiency of 19.1% AM0 was measured on a 4-cm/sup 2/ cell. Measurements on similar cells showed an average of 4.7% degradation after irradiation with 10/sup 14/-cm/sup -2/ electrons at 1 MeV.<>