Structural, optical and electrical properties of polycrystalline pyrite (FeS_2) films obtained by thermal sulfuration of iron films

摘要

Iron films deposited by magnetron sputtering were annealed in 80 kPa sulfur vapor at 673 and 773 K for different times. The structural, optical and electrical properties were determined. Pyrite particles formed at 673 K reveal an aggregate morphology evolved from some transitional iron sulfides. With increasing annealing time, the crystallites become distinguishable and the aggregate morphology tends to disappear. The pyrite grains formed at 773 K have more uniform distribution and show more obvious propagation with annealing time than those formed at 673 K. The values of electrical resistivity of the films prepared at both temperatures and optical absorption edge of the film prepared at 673 K significantly increase with annealing time. The films prepared at 673 K generally have higher optical absorption edges, lower electrical resistivity, higher carrier concentration and lower charge mobility than those prepared at 773 K. Film bulk integrity, residual iron amount and grain boundary area could be considered as the factors responsible for the film property changed with annealing temperature and time.