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The growth and properties of PbS thin films, chemically deposited on bulk lead titano-zirconate ceramics, are investigated. Scanning electron microscopy photographs reveal that the medium size of crystallites is much larger for PbS films grown on poled ferroelectric substrates than for the films grown onto glass or onto unpoled ferroelectric substrates. In the first case the medium size of crystallites is about 1–1.5 μm while in the second case it is less than 0.3 μm. Spectral distribution of photoconductivity and thermally stimulated currents (TSC) measurements were performed on all samples. Experimental results indicate that the properties of the PbS films can vary, depending on the substrate nature and in the case of poled ferroelectric substrates, on the polarity. The photoconductive signal is usually larger, the dark resistivity is smaller, and the TSC current value is higher for PbS films deposited on the positive face of the ferroelectric substrate than for those deposited on the negative face.

An analytical formula for the optical charging spectroscopy (OCS) discharging current in the case of homogeneous semiconductors is deduced. The computation shows that the OCS current is proportional with the square of the initially trapped carrier concentrations. This result leads to a higher sensitivity in case of the OCS method compared with the thermally stimulated current method. The OCS current formula obtained for one trapping level is generalized in the case of many trapping levels. From the generalized formula it can be seen that the OCS current can change the sign if both electron and hole traps exist in the sample.