Tikrit Journal of Pure Science Vol. 25 (3) 2020 103 Tikrit Journal of Pure Science ISSN: 1813 – 1662 (Print) --- E-ISSN: 2415 – 1726 (Online) Journal Homepage: http://tjps.tu.edu.iq/index.php/j Effect of Mg Molar Concentration on Structural and Optical Properties of CdO Thin Films Prepared by Chemical Bath Deposition Method Faris Salih Atallah , Hani Hadi Ahmed , Waleed Khalid Jasim Department of Physics , College of Science , Tikrit University , Tikrit , Iraq https://doi.org/10.25130/tjps.v25i3.256 A r t i c l e i n f o. Article history: -Received: 6 / 11 / 2019 -Accepted: 22 / 12 / 2019 -Available online: / / 2020 Keywords: cadmium oxide, Chemical Bath Deposition Method, magnesium ions, Photovoltaic applications. Corresponding Author: Name: Hani Hadi Ahmed E-mail: Hanihd77@gmail.com Tel: ABSTRACT In this study, pure and Mg doped CdO thin films were coated on glass substrate using a chemical bath deposition method. Adding different molar concentrations of magnesium (0, 2, 4, 6) % to the chemical bath solution and their effect on the structural and optical properties were studied. Oxidation of films was conducted at 573 K for 60 minutes in the presence of static air. The thin film properties were diagnosed with X-ray diffraction techniques and UV-VIS-spectrophotometer. The results of X- ray diffraction for the thin films showed that all prepared thin films have a faced-centered cubic crystal structure (FCC) with a preference for growth at level (111), and the synthetic coefficients calculated from the X-ray spectrum are affected with increasing Mg ratios in the chemical bath solution. The results of the optical tests showed that the absorption of the resulting thin films increases with increasing Mg ratios in the chemical bath solution, have a high absorption coefficient in the visible region of the electromagnetic spectrum, and the transmittance decreases with the increase of Mg in the chemical bath solution. The optical energy gap of the prepared thin films changes with increasing Mg doping rates and extends from (2.46) eV to (2.95) eV. The results showed a significant improvement in the structural and optical properties of Mg ion doped CdO films making it suitable for use in many photovoltaic applications such as reagents and solar cells. 1- Introduction Cadmium oxide is a semiconductor material located in the (II-VI) group in the periodic table of elements. It has a cubic crystalline structure and its cell unit is face-centered (FCC). It can be obtained by heating the element cadmium [1] and its color ranges from dark brown to yellowish green [2]. It has low electrical resistivity due to the presence of cadmium atoms in compensatory sites or as a result of the presence of oxygen spaces. It is also used in solar energy systems in order to increase its efficiency because it has a high absorption coefficient [3, 4]. It is regarded as a transparent semiconductor oxide which has special characteristics including high transparency in the visible region and the near and high reflective infrared regions of the electromagnetic spectrum [5]. Its energy gap is relatively big of about (2.7) eV [6] and also has high electrical conductivity when compared with the semiconductor conductivity of the negative type [7]. It is, therefore, used in a wide variety of applications such as projectors and photovoltaic and electro-optical devices [8]. Modern science is based mainly on electronics, which in turn are based on semiconductor materials in the form of thin films, especially in solar cells, computers and integrated circuits [9]. In order to increase the efficiency of solar cells, photovoltaic cells are coated with thin films that have certain properties in order to absorb a certain part of the falling energy and reflect the other part. This property depends on the value of the energy gap being confined. Since the beam from the sun is within the visible part of the electromagnetic spectrum and in order to control the amount of energy absorbed or reflected, the study must choose semiconducting materials for which the energy gap is confined to approximate the energy of photons to the visible part of the spectrum [9].