PbS nanosculptured thin film for phase retarder, anti-reflective, excellent absorber, polarizer and sensor applications

Abstract

Lead-sulphide (PbS) nanosculptured thin film (nSTF) is prepared using a glancing angle deposition (GLAD) technique and the physical vapour deposition (PVD) process. The morphology of the GLAD films clearly shows that an anisotropic structure is obtained and is composed of micro-sheets with sharp top edges (a few tens of nanometres tip width). Due to this anisotropy, optical birefringence is induced in the nSTF as well as linear dichroism. The structural and optical properties of the PbS nSTF have been characterized by scanning electron microscopy, atomic force microscopy, Raman spectroscopy and transmission measurements. The Raman spectra of PbS nSTF exhibit sharp peaks representative of vibrations in nano-crystalline PbS. Due to the absorption of PbS the nSTF is found to act as a linear polarizer with good extinction and contrast in the near infra-red range. Due to its porosity this nSTF also has the ability to sense fluids, which we demonstrate using ethanol–water solution at different concentrations. The combination of these effects in PbS nSTF is believed to constitute a prime candidate for many desirable device applications in different aspects with the low cost of production in large areas.