The preferential growth of pyrite films prepared by thermal sulfuration of Fe2O3 films

Pyrite thin films were prepared by the sol–gel dip coating process and sulfuration treatment. The evolution of crystal orientation for the pyrite films was investigated as a function of sulfuration temperature. And the effect of crystal orientation on the electrical and optical properties was studied. It was found that films show (1 1 1) preferred orientation after sulfurized at low temperature. However, the (2 0 0) and (3 1 1) mixed preferred orientations were observed when pyrite films were sulfurized at higher temperature. Experimental results also indicate that the carrier concentration is high when the films show (1 1 1) preferred orientation. And the optical absorption coefficient is also large when the films grow with (1 1 1) preferred orientation. It is speculated that surface free energy could play a more important role in determination of preferred orientation when films were sulfurized at low temperature. However, the strain energy plays a more important role in determination of preferred orientation when films were sulfurized at higher temperature.