Some electrical properties of thin PbS films

Abstract

An alloy of PbS has been prepared in an evacuated quartz tube (Pb: S = 50:50). The structure of the ingot examined by X-ray diffraction and found to be polycrystalline of cubic phase structure with dominate orientation at (200) plane. The PbS thin films have been deposited by thermal evaporation technique under pressure 5×10-5 mbar with thickness of about 0.5 µm. These films have been annealed at different temperature (Ta) (373, 423, 473 and 523 K˚ ) under vacuum. The electrical measurements showed that the d.c. conductivity (σd.c.) decreased with increasing Ta, while the activation energy increased with increasing Ta. The Hall effect measurements prove that the films are P-type and the carriers concentration (nH ) decreased with increasing Ta. Hall mobility (µH), drift velocity (υd), carriers life time (τ) and mean free path (ι) have increased with increasing Ta. The thermoelectric power experiment confirmed the Hall Effect measurements. Seebeck coefficient (s), thermal activation energies (Es) and Energy of hopping (∆W) for PbS films have increased with increasing Ta.