Effect of substrate structures on crystal orientation of the FeS_2 thin films

Polycrystalline FeS2 thin films were prepared by annealing the iron films in sulfur atmosphere. The crystal structure was determined and the orientation texture was discussed for the FeS2 films prepared on the substrates with different structures. The results show that the texture distribution of the film can be controlled in a certain extent using the substrre with different crystalline types. The FeS2 films prepared on the substrates Si(lOO), Si(lll) and Al have only on?preferred orientation (200), while those on the microcrystalline TiO2 substrates share two preferred orientations (200) and (220). There is an insignificant effect of amorphous glass substrates on orientation distribution in the film growth. Various substrates induce different interfacial mismatch between the film and substrate, and result in the changes of lattice distortion degree, grain size and texture distribution. The film surface energy and natural orientation of grain growth mainly dominate the resultant distribution of crystal orientation and induce small lattice distortion and fine grains in the film if the substrate is amorphous or has high interfacial mismatch. Besides the film surface energy and natural orientation of grain growth, the interface strain energy participates in the domination to the resultant distribution of crystal orientation and tends to induce strong lattice distortion and coarse grains if the substrate is crystalline and has low interfacial mismatch.