The development of diamondlike (i‐carbon) thin films as antireflecting coatings for silicon solar cells

Abstract

There is a need for stable, single layer antireflecting (AR) coatings for low cost terrestrial silicon solar cells. Diamond‐like (i‐carbon) carbon thin films produced by decomposition of hydrocarbon gases have been studied to determine if these films can be developed into AR coatings for silicon. Such coatings would require a refractive index, n (film)?1.9 = √n (silicon).We determined the optical constants n and k over a large range of process parameters and source gas for the diamond‐like carbon films and will report these results. The degree of hydrogen incorporation in these films has also been studied by SIMS analysis. It was found that the lower visible light absorbing films contain more hydrogen. This does not, however, manifest itself in fundamental C–H absorption bands in the infrared. Very efficient single‐layer quarterwave i‐C AR coatings n?1.9 have been produced on single crystal and silicon‐on‐ceramic Si solar cells. An increase in cell efficiency of 40% over uncoated cells has been achieved.