Abstract
PbS thin films with thickness between 100 and 150 nm were grown for the first time by microwave-assisted chemical bath deposition in a commercial automated system with deposition times not exceeding 5 min. X-ray diffraction analysis shows that the thin films have cubic rock salt type structure with good crystallinity. The grain size increased from 18 to 20 nm, as the deposition time increased. Energy dispersive X-ray results confirm that the films are stoichiometric. Optical measurements show that thin films have relatively high absorption coefficients between 104 and 105 cm-1 in the visible range. In addition, the films exhibit a direct gap, within the energy range from 1.0 to 1.35 eV. The electrical properties, such as conductivity, the Seebeck coefficient, carrier concentration, and carrier mobility, are discussed.
Highlights
Lead sulfide (PbS) is an important IV–VI semiconductor material with technological applications including infrared detectors [1] and absorbers in thin film solar cells [2, 3]
Studies of PbS thin films obtained by chemical bath deposition (CBD) showed that this compound has a band gap (Eg) within the range of energies from around 1.39-1.55 to 2.38-2.75 eV, an electrical resistivity of 105Ω cm, and a preference orientation along the (111) or (200) planes with grain sizes about 20 or 34 nm depending on the temperature and/or formulation used [5, 12, 13]
PbS thin films were grown by microwave-assisted chemical bath deposition, following the chemical formulation reported previously [23]
Summary
Lead sulfide (PbS) is an important IV–VI semiconductor material with technological applications including infrared detectors [1] and absorbers in thin film solar cells [2, 3]. Different methods have been used to synthesize PbS; they include chemical bath deposition (CBD) [4, 5], spray pyrolysis [6], pulsed laser deposition [7], vacuum evaporation [8], chemical vapor deposition (CVD) [9], ultrasound [10], and electrodeposition [11]. The authors in [14] prepared PbS films by CBD at room temperature for different deposition times (from 60 to 300 min) using lead acetate as a source of Pb ions, thiourea to produce S ions, and triethanolamine as the complexing agent in water. Nanocrystalline PbS thin films have been reported using a microwaveassisted chemical bath deposition method with deposition times from 30 to 120 min showing a p-type conductivity
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