Characterization of FeS2-pyrite thin films synthesized by sulphuration of amorphous iron oxide films pre-deposited by spray pyrolysis

Abstract

FeS2-thin films with good crystallinity were synthesized by a simple method which consists of sulphuration, under vacuum, of amorphous iron oxide thin films pre-deposited by spray pyrolysis of FeCl 3•6H2O (0.03 M)-based aqueous solution onto glass substrates heated at 350 °C. At optimum sulphuration temperature (450 °C) and duration (6 h), black green layers having granular structure and high absorption coefficient (∼5.104 cm-1) were obtained. The study of the electrical properties of the as-prepared films vs. the temperature variations showed three temperature domain dependence of the conductivity behaviour. The first one corresponds to the high temperature range (330 K-550 K) for which an Arrhenius plot type was obtained. The activation energy value was estimated at about 61.47 meV. The second domain corresponding to the intermediate temperature range (80 K-330 K) showed a variable activation energy between the grain boundaries. The barrier height, qφ̄, was estimated to 27±0.5 meV, and the standard deviation, qσ φ, was evaluated at about 14±0.5 meV. We found that at lower temperatures (20 K-80 K), the conductivity is governed by two conduction types. The density of localised states, was about 2.45×1020 eV-1 cm-3. © 2005 Elsevier Inc. All rights reserved.