In this paper, we describe the preparation and characterization of nanocrystalline CuS thin films, deposited via an inexpensive and facile chemical bath deposition method at room temperature. X-ray diffraction analysis showed a hexagonal covellite structure. The average diameter of CuS nanocrystals was less than 10 nm, showing quantum size effects. FE-SEM images indicated that the substrate surface was covered by semispherical particles with an average size of about 100 nm. The influence of the deposition time on optical properties of the CuS films was studied. The optical band gap was estimated to be in the range between 2.35 eV and 2.50 eV, exhibiting a considerable blue shift due to quantum size effects. The photoluminescence (PL) spectrum of the CuS films showed two characteristic bands, one narrow and intense band centered at 422 nm and another weak green band at 530 nm.
