Authors: Floresa, E; Yoda, S; Morales, C; Caballero-Calero, O; Diaz-Chao, P; Martin-Gonzalez, M; Ares, JR; Ferrer, IJ; Sanchez, C

Thin Solid Films. vol: 672. page: 0040-6090.
Date: feb-28. 2019.
Doi: 10.1016/j.tsf.2019.01.020.

Recent published literature dealing with FeS2 pyrite (thin films and single crystals) faces a few and relevant issues: the low photovoltage presented by pyrite (mainly related to the singular nature of its surface), the not yet clearly defined way of making available n and p type reliable samples and the relevance of their stoichiometry. To address the second and third issues, Fe thin films, Ti/Fe and Co/Fe bilayers deposited on sodalime glass and amorphous quartz substrates have been sulfurated at different temperatures (T-s ) (T-s less than or similar to 600 degrees C) during 20 h to obtain pyrite thin films. Seebeck coefficient and Hall Effect measurements have been carried out at room temperature with the sulfurated samples. It has been found that sulfurated Ti/Fe on sodalime glass presents a change of the Seebeck coefficient sign (from negative to positive) due to a strong interaction of the Ti layer with the substrate, which is not present in the Ti/Fe samples deposited on amorphous quartz. As a consequence of the interaction, a new TiO2 layer is formed between the sodalime glass substrate and the pyrite layer. Sulfurated Co/ Fe bilayers on sodalime glass show a coherent behavior according to the obtained results and previously published works. They all appear to be n-type semiconductors when T-s greater than or similar to 175 degrees C. Non-intentionally doped Fe thin films on sodalime glass behave in a non-conclusive fashion from the point of view of their electrical transport characterization. The Seebeck coefficient (S) of the sulfurated films appear to be S > 0 for all values of T-s . However, the value and sign of the Hall constant behave in a non-reproducible way. Results are discussed on the light of present knowledge of synthetic pyrite thin films growth and doping..