Investigations on crystal quality of thin silicon films prepared by zone melting recrystallization on different intermediate layers and cost effective substrates

Crystalline silicon thin-film solar cells are a promising approach to reduce costs and material consumption during solar cell production. The efficiency of so formed solar cells is depending on the crystal size and -quality of the absorbing layers. In this work, zone melting recrystallization (ZMR) is used to create high quality silicon films with grain sizes of several mm in width and up to several cm in length. This method allows live observation of the silicon solidification and optimization of crystal sizes. The crystal orientation obtained, is depending on the used intermediate layer (IL). We investigated the crystal formation on substrates encapsulated with crystalline silicon carbide (SiC) and on substrates encapsulated with SiC and then coated with amorphous SiO2. On both surfaces, crystals of similar sizes up to several mm in width and several cm in length can be grown, but the appearance and grain orientation differs. On SiO2, Si grain surfaces are preferentially <100>-oriented and the grains are subdivided by low angle- or subgrain boundaries; on SiC, Si grain surfaces are nearly <110>-oriented forming large amounts of parallel twin-grain boundaries.