Synthesis of thin films of the Olivines Fe2SiS4 and Mn2SiS4 by magnetron sputtering and annealing

Sammanfattning: The photovoltaic industry attracts a lot of interest from researchers worldwide due to active integration of the solar cells. The main idea here is to convert solar energy into electricity. One type of solar cell that shows potential in replacing today’s crystalline silicon cells is the thin film solar cell (TFSC). Yet, the sun absorbing semiconductors used in the commercial TFSCs contain scarce elements such as indium, cadmium and tellurium, which may cause problems if the technique is going to grow to a big scale energy producer. Earth abundant sun absorbing materials are therefore of great interest, and several possible replacements are under investigation.  In this project two olivine structured ternary metal chalcogenides were investigated: manganese silicon sulfide (Mn2SiS4) and iron silicon sulfide (Fe2SiS4). The goal was to deposit thin films by reactive magnetron sputtering from manganese/iron and silicon targets with mixture of Ar and H2S gas. Afterwards the films were crystallized by a sulfurization process at high temperature. The samples were created with a composition gradient and investigated by SEM, EDS and XRD. Results showed that a single phase of Mn2SiS4 was successfully created in thin film form for the first time. Multiple attempts on manufacturing Fe2SiS4 were performed, but didn't show sufficient progress yet. The analysis showed formation of pyrite (FeS2), pyrrhotite (Fe1-xS, x<0.2) and SiS2 phases instead of the targeted material. In both cases it is important to provide additional studies to determine if the selected compounds could be used as an absorber layer in TFSC structures.