Silicon DOI 10.1007/s12633-015-9399-z ORIGINAL PAPER Structural and Optical Characterization of Chemically Deposited PbS Thin Films A. N. Fouda 1,2 · M. Marzook 3 · H. M. Abd El-Khalek 1 · S. Ahmed 3 · E. A. Eid 4 · A. B. El Basaty 5 Received: 19 May 2015 / Accepted: 28 December 2015 © Springer Science+Business Media Dordrecht 2016 Abstract PbS thin films were deposited on glass substrates by a chemical bath deposition method. The effect of varying the film thickness on the structural and optical properties has been investigated. XRD analysis reveals the crystallinity of the deposited PbS films with (200) preferred crystal orienta- tion. Increasing the film thickness enhances the crystallinity of the films as well as decreases the strain and dislocation density. The surface morphology features were dramatically changed from small spherical grains to bead-like shape. The absence of impurities in the deposited films was confirmed by energy dispersive x-ray spectrometry (EDX) measure- ments. The optical constants of the deposited films were calculated and a small decrease in the band gap energy was observed with increasing the film thickness. Keywords PbS films · Chemical bath deposition · Surface morphology · XRD  A. N. Fouda alynabieh@yahoo.com 1 Physics Department, Faculty of Science, Suez Canal University, 41522 Ismailia, Egypt 2 Recruitment Department, University of Hail, Hail 2440, KSA Hail Saudi Arabia 3 Basic Science Department, Faculty of Petroleum and Mining Engineering, Suez University, 43721 Suez, Egypt 4 Department of Basic Science, Higher Technological Institute, 10th of Ramadan City, Ramadan Egypt 5 Basic Science Department, Faculty of Industrial Education, Helwan University, 11813 Cairo, Egypt 1 Introduction PbS is one of the most important IV-VI semiconductors with a narrow band gap of 0.41 eV at 300 K [1], and a sufficiently large Bohr radius of 18 nm [2]. This provides strong quan- tum confinement of holes and electrons, regulating the band gap value by controlling the crystallite size according to the effective mass model [3]. PbS thin films have been a sub- ject of extensive research due to their wide applications in gas sensors [4], infrared radiation detectors [5, 6], optoelec- tronics, solar cells, diode laser, etc [7, 8]. PbS thin films is p-type semiconductors [9], and their direct band gap is around 2.2 eV [9]. For these reasons, many research groups have shown a great interest in the study and enhancement of this material by various depositional processes. PbS thin films can be deposited by different chemical and physi- cal methods, such as vacuum evaporation [10], successive ionic layer adsorption and reaction (SILAR) [11], electro- deposition [12], chemical bath deposition (CBD) [13, 14], etc. Among these, CBD is the most simple, with low temperature requirement, low-cost, able to deposit thin films on different types of substrates, and convenient for large area deposition. The CBD method is based on successive absorption and reaction of species on the substrate sur- face from aqueous solution containing Pb 2+ and S 2− . Film growth takes place by a cluster mechanism or ion-by-ion. In this method, we can deposit good adhesive films with different optical and structural properties by optimizing the bath temperature [15], reactant pH [16], reagent con- centration [17], and deposition time [18]. A comparative study has been performed on properties of PbS thin films grown by CBD, TEA was used as the complexing agent in one of the baths, and PbS films were prepared with- out triethanolamine (TEA) [19]. Ubale et al. presented the