Investigation of the physical properties of Fe/Si for use in a Cu/Fe/Si solar cells contact

Abstract

One of the drawback of the copper metallization, i.e. Cu/Si, for solar cells is the tendency of the metal to diffuse into silicon. This can deteriorate the P/N junction. Thus, a diffusion barrier is necessary. Iron has been found to be a potential candidate to be used as a barrier between Cu and Si. Before the fabrication of the Cu/Fe/Si contact, it is useful to investigate the properties of the Fe/Si first and this is the objective of the present work. We have studied the variation of the electrical properties with the Fe thin film thickness t and the deposition rate. The resistivity ρ values range from 8 to 36 μΩ.cm. Interesting behaviors of the square resistance RL, ρ and the coefficient R are seen as a function of D/t, whereD is the grain size. Also, these nanometric Fe films are characterized by a uniform surface with a relatively low surface roughness, a small strain (less than 1% in magnitude) and a sharp interface with no interdiffusion between Fe and Si; these are also good qualities for Fe to be used as a barrier between Si and Cu.