MoS2 textured films grown on glass substrates through sodium sulfide based compounds

In this paper, we show that highly crystallized and (00l)-textured MoS2 thin films can be achieved on glass substrates with NaF additive. The thin films have a direct optical bandgap of 1.77 eV and a p-type electrical conductivity of sigma congruent to 4.5 x 10(-2) S cm(-1) at room temperature, which are near those of the MoS2 single crystals. These properties are required for the application of the MoS2 in thin film solar cells. The influence of the sodium on the crystallization and texturization process has been interpreted as due to the formation of an intermediate sodium thiomolybdate phase. The decomposition of this compound when T > 723 K leads to the achievement of the MoS2 thin films having large crystallites oriented with their c axis perpendicular to the plane of the substrates. This process of texturization has then been generalized to the case of MX2 (M: MO,W; X: S, Se) thin films with Ni and K additives. These results constitute a new step towards the achievement of efficient MoS2 based solar cells.