MS2 (M=W, Mo) Photosensitive thin films for solar cells

Photosensitive textured WS2 and MoS2 films can be obtained by the techniques of reactive sputtering and solid state reaction, as long as the substrates used are each coated with a 10-20 nm Ni layer. When MS2 (M = W, Mo) layers are deposited onto these substrates and then annealed for half an hour at 1073k in an argon atmosphere, textured films crystallized in the 2H-MS2 structure are obtained, with their c crystallite axes perpendicular to the plane of the substrate. The films are nearly stoichiometric. The crystallinity enhancement of the films can be attributed to an improvement in the crystallization process related to liquid Ni-S phases present at the grain boundaries during annealing. Residual phases (NixSy; Ni;...) are distributed at the grain boundaries and do not strongly disturb the properties of the WS2 and MoS2 films. The optical absorption spectra are similar to those of single crystals, and the high photosensitivity of the films is attributed to a grain size enhancement by the Ni-S phase.