Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-020-03543-z Efect of Cd/S ratio on growth and physical properties of CdS thin flms for photosensor application Ibrahim M. S. Mohammed 1  · Ghamdan M. M. Gubari 1  · Nanasaheb P. Huse 1  · Avinash S. Dive 1,2  · Sung‑Hwan Han 3  · Ramphal Sharma 1,3 Received: 13 February 2020 / Revised: 23 April 2020 / Accepted: 4 May 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract In the present work, we have successfully deposited cadmium sulfde (CdS) thin flms with quantum dot size on a silica glass substrate by using simple and commercial chemical bath deposition (CBD) with varying the concentration of the solution at ~ 50 °C bath temperature, where we found that the deposition parameters such as the precursor ratio of cadmium and thiourea strongly infuence the morphology, physical properties, and photoresponse. There has been a disparity in the proportion of the equivalent elements of the precursors, where the stoichiometric ratio of Cd/S of the precursor was changed, which allows us to understand more about the conditions and infuences on growth. There was a match when comparing standard Joint Committee on Powder Difraction Standards (JCPDS) data with the study of X-ray difraction and confrming the formation of a hexagonal crystal structure for CdS where is observed the size of the crystal varied and it was found that the estimated average of the CdS varied with the varying concentration and resulted in the least crystallite size of ~ 2.9 nm for the ratio of 0.01 M for cadmium and 0.02 M for sulfur. The feld emission scanning electron microscopy (FE-SEM) images show the formation of nanosheets having micrometer-sized petals which got uniformity with varying Cd/S ratio. It can be seen absorption spectra near band edge ~ 400 nm with a slight deviation and presence of an excitonic peak for all samples with an estimated bandgap of CdS Quantum Dot (QD) thin flms found to be varying from ~ 3.124 to ~ 3.11 eV. The photosensitivity was calculated for all CdS QD thin flms and it was found that the photosensitivity increases with an increase in the Cd/S ratio. 1 Introduction In the past few decades, nanostructured materials have got a lot of attention because of their marvellous properties and the possibilities of their applications are expected in several areas, followed by the evolution of quantum dots (QDs) thin flms due to their striking size and their various applica- tions. In inorganic quantum dot technology, many materials have appeared with great new applications, the II–VI group semiconductor nanostructures such as CdS, CdSe, CdTe, ZnS, ZnSe, HgS, etc. have a narrow gap, excellent optical properties, and high photosensitivity. Cadmium sulfide (CdS) is compound belongs to the II–VI semiconductor group and it is one of the investigated smart materials as a result of the expansion of technology applications and the direct bandgap of ~ 2.42 eV hence the photosensitivity in the visible range is very high for CdS thin flms where it has been used more widely in solar cells as window layer [1], light-emitting diodes (LEDs) [2] and photodetectors [3], etc. The CdS thin flms can be prepared by several synthesis methods including thermal evaporation [4, 5], magnetron sputtering [6], spray pyrolysis [7], vacuum deposition [8], successive ionic layer adsorption and reaction [9] and chemi- cal bath deposition (CBD) [10–12]. Besides, the produc- tion of thin flms at somewhat low temperatures is desirable because the substrate consists mostly of organic flms, which can not resist high temperatures if used other methods to pre- pare CdS thin flms such as thermal evaporation [4]. Among all the above-mentioned techniques, the CBD is the most popular and widely used method for its low cost, simplic- ity, ease of handling and large scale production also it is an efective method which can control the thickness, growth * Ramphal Sharma rps.phy@gmail.com 1 Thin Film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Maharashtra, Aurangabad 431004, India 2 Department of Physics, Shri. Dr. R. G. Rathod Arts and Science College, Murtizapur, Akola, India 3 Nano material Lab, Department of chemistry, Hanyang University, Seoul 133-791, South Korea