Observation of the Meyer–Neldel rule in nanocrystalline PbSe thin films

In this paper, nanocrystalline lead selenide (nc-PbSe) thin films have been chemically deposited on glass substrates using appropriate chemical reagents in aqueous alkaline media. The structural, morphological, optical and electrical properties of PbSe thin films have been studied. X-ray diffraction (XRD) analysis indicates that these films have a cubic structure with an average grain size of ∼21 nm. The field emission scanning microscope (FE-SEM) micrograph shows that the films have a dense surface with a smooth granular structure and well-defined grain boundaries. The σ(T) measurements were carried out under vacuum over a wide temperature range (77–350 K) for nc-PbSe films with a thickness of 375 ± 10 nm. The temperature dependence of dark dc conductivity σ(T) in PbSe nanocrystalline (nc) thin films is found to obey the Meyer–Neldel rule (MNR). The MNR correlates the spread in the thermal activation energy of conduction (ΔE) with the exponential pre-factor (σ₀) of the Arrhenius conductivity formula. (paper)