The structural and electrical properties of PbS nanoparticles (40–70 nm), produced by a chemical reaction of sodium hydroxide with lead nitrate and electrophoretically deposited onto a conductive substrate, are investigated. The composition and structure of the nanoparticles are identified by X-ray analysis as pure PbS phase with a face-centered cubic lattice. Several minima, related to plasma-resonance absorption at 10–17 μm, are observed in the frustrated total internal reflection (FTIR) spectra. The layer morphology and the nanoparticle shape and sizes are determined by scanning electron and tunneling microscopy. The threedimensional topograms show that the surface fine structure is a set of faceted pyramidal spikes with a size of 5–10 nm and a density of ~400 μm^–2. An analysis of the tunneling current–voltage characteristics of individual nanospikes shows the presence of low-field emission and makes it possible to determine the barrier heights (1.6–1.8 eV), which are explained within the quantum-dot (QD) model.
The transverse and longitudinal photoconductivity, photoluminescence, and cathodoluminescence of sublimated (CdS)_0.9–(PbS)_0.1 films at room temperature and upon cooling are studied. The role of inclusions of the narrow-gap phase in the processes is shown. The films are excited over the entire active surface and pointwise (within one crystallite). The surface recombination rate and the lifetime of majority charge carriers at different generation rates and characters of excitation are estimated. A comparative table of recombination parameters of CdS and CdS–PbS films is presented.
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