Effect of substrate modification on properties of thermally evaporated barium disilicide thin-films

Abstract

Orthorhombic BaSi₂ films were grown successfully on flat and modified Ge substrates the by thermal evaporation method at 500 °c with an a-Si supply layer. The obtained results showed that within a short etching time te (less than 15 min), the substrate modification had a negligible impact on improving the crystalline quality and optical properties of the BaSi₂ tilms in comparison with using flat substrate. When to is 15 min, the crystalline quality as well as optical properties were improved significantly. However, the crystalline quality degraded whereas the optical properties was still improved as te > 15 min. Therefore, we chose te of 15 min as the optimized condition for surface modification of Ge substrate. Photo response properties of evaporated BaSi₂ íilms on modified (with fe = 15 min) and flat Ge substrates showed that the film grown on the former has better properties than that on the latter. We also confirmed the bandgap of thermally-evaporated BaSi₂ íilms at 1.29 eV. These results suggest the potential application of the BaSi₂ thin-film evaporated on modified Ge substrate as an absorber for thin-film solar cells.