Heterojunction solar cells produced by porous silicon layer transfer technology

In this paper, we present the result of heterojunction solar cells based on porous silicon layer transfer technology. a-Si/c-Si structured solar cells were prepared in which the c-Si was deposited on annealed double-layer porous silicon by low-pressure chemical vapor deposition. The structural properties and the evolvement of the double-layer porous silicon before and after thermal annealing were investigated by scanning electron microscopy. X-ray diffraction, Raman spectroscopy and a microwave photoconductive decay method were used to investigate the properties of the epitaxial silicon thin films deposited at different pressures. And, the influence of the deposition pressure on the properties of the c-silicon thin films was investigated. The spectral responses of the cells were studied by a quantum efficiency test. The results show that the epitaxial silicon thin film deposited at 100 Pa has better carrier lifetime and better spectral response. Furthermore, the Raman peak intensity of the silicon film prepared at 100 Pa is much closer to that of a monocrystalline silicon wafer. A simple solar cell structure without any light-trapping features showed an efficiency of up to 10.1 %.