Fabrication of high-efficiency n+-p junction InP solar cells by using group VIb element diffusion into p-type InP

The fabrication of n⁺-p homojunction InP solar cells has been studied using thermal diffusion of S, Se, or Te into p-type InP substrates. Sulphur diffusion using an In2S3source was found to be effective in forming a shallow and steep n⁺-p function without surface morphology degradation of substrates. A conversion efficiency (active area) of 18 percent, which is the highest efficiency ever reported for InP homojunction solar cells, was obtained by optimizing fabrication conditions for sulphur-diffused cells. An electron irradiation study on fabricated cells has also been made. The InP solar cell was found to have a higher resistance to radiation degradation than Si and GaAs cells. Through these studies, it has been demonstrated that the InP solar cell has excellent potential for space applications.