High-voltage solar cells, combining both vertical p-n junctions in the graded band-gap layer and horizontal p-n junctions in the base layer

Abstract

Two structures of high-voltage solar cells are discussed and analyzed. The first one is a high-voltage solar cell with only vertical p-n junctions. Therefore, the photocurrent value of this structure and-consequently-the efficiency are low because of the small active p-n junction area. In order to improve the main parameters of this structure-particularly the photocurrent and the efficiency-a new structure of high-voltage solar cells, combining both horizontal and vertical p-n junctions is suggested. This structure has been elaborated by combining liquid phase epitaxy with gas-phase zinc diffusion technologies, and was grown on semi-insulating GaAs substrates with /spl rho/=10/sup 12/ /spl Omega//spl middot/cm. This new structure has shown better parameters than the parameters of the high-voltage solar cell with only vertical p-n junctions. It exhibits appreciable values of photocurrent and output voltage. Furthermore, this structure provides both high short wavelength sensitivity, and independent efficiencies of spectral composition of solar radiation. Therefore, it can be successfully utilized in many aspects of modern science and technology, particularly as power supplies in high-located areas, and as photoacceptors for ultraviolet radiation.