Emitter wrap-through structure for rear-side contacting of epitaxial thin-film solar cells

The Epitaxy Wrap-through (EpiWT) cell concept is introduced. It combines the benefits of rear-side contacting with the low-cost potential of epitaxial crystalline silicon thin-film technology. Its advantage over the standard EWT cell upon which it is based is the simplified rear structuring due to the inactive substrate. This paper focuses on the development of the key process: the epitaxial deposition of the base and emitter layers through via holes in the substrate. Samples have been produced and characterised using cross-sections, spreading resistance profiling, conductance-type testing and defect etching. The deposition technique and methods of controlling and optimising the process are discussed.