Effect of grain boundaries and grains on electrical properties of FeS2 films

摘要

Because of its band gap and excellent optical absorption polycrystalline pyrite is a candidate material for absorber layers of solar cells. Pyrite films with different thicknesses were obtained by sol?gel method and following sulphurisation. The structural characteristics of the films were determined by X-ray diffraction, scanning electron microscopy and atomic force microscopy, while the electrical properties were investigated by Hall instrument and impedance spectroscopy. The grain and grain boundary contributions to the electrical transport mechanism were studied using the brick layer model. The equivalent circuit parameters were calculated by simulating experimental data. According to the results, the pyrite films were observed to crystallise more effectively, and the root mean square roughness tended to increase corresponding with increased film thickness. The grains govern the conductivity mechanism of FeS2 film with a thickness of 109 nm. Both the grains and grain boundaries contribute to the electrical transport, and the grain contribution to the electrical transport mechanism has been further enhanced as the film thickness increases from 230 to 400 nm.