Preparations and characterizations of polycrystalline PbSe thin films by a thermal reduction method

Polycrystalline PbSe thin films were deposited on Si substrates by a thermal reduction method with the carbon as the reducing agent. The X-ray diffraction (XRD) spectra show that the deposited thin films predominately crystallize with the rock-salt structures above the evaporation temperature of 600 °C, and the PbSe thin film has the optimal crystal quality at 900 °C. The scanning electron microscopy (SEM) measurements reveal that the PbSe thin film with carbon addition has uniform crystal grain sizes and dense microstructure, while the thin film without carbon consists of loosely distributed and widely size-ranged crystal grains. The optical transmittance spectrum shows that the direct band gap of the PbSe film is about 0.256 eV. By the introduction of element S, PbSe1−xSx (0 ≤ x ≤ 1.0) thin films could be prepared, but excess amount of S additions (>20 at.%) would cause phase segregations between PbSe and PbS phases. The deposition method presented in this paper may be useful for mass-producing polycrystalline lead chalcogenide thin films in the future.