Chalcogenide Letters Vol. 14, No. 10, October 2017, p. 425 - 429 FABRICATION OF ULTRA-THIN CdTe LAYERS BY THE CLOSE-SPACED SUBLIMATION TECHNIQUES FOR CdTe/CdS SOLAR CELLS M. R. KARIM a,* , M. T. RAZA b , Z. A. ALOTHMAN c , H. A. ALTURAIF d , N. AMIN e a Center of Excellence for Research in Engineering Materials (CEREM), Advanced Manufacturing Institute, King Saud University, Riyadh 11421, Saudi Arabia b Department of Industrial Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia c Department of Chemistry, College of Science, King Saud University, Riyadh 11421, Saudi Arabia d Centre for Nanoscale Science & Technology (CNST), Flinders University of South Australia, South Australia 5042, Australia e Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia Close-spaced sublimation (CSS) of ultra-thin (~3–4 μm) CdTe layers for deposition on CdS-coated glass has been performed using a custom-designed CSS system. The deposition characteristics of CdTe have been studied on three types of CdS: firstly, CdS by Sputtering; secondly, CdS by CBD; and thirdly, CdS:O by Sputtering. Surface morphology was then studied using FESEM. XRD was performed to confirm the crystal properties of the film. UV-VIS spectrophotometery was used for determining the optical absorption and transmission characteristics of the film, which was further used to calculate the band gap of the deposited film. (Received October 30, 2016; Accepted October 6, 2017) Keywords: CSS; CdTe; CdS; Solar energy materials; Thin films. 1. Introduction Cadmium Telluride (CdTe) is a group II–IV compound semiconductor, very suitable for the photovoltaic applications due to its near ideal band gap 1.45 eV and its optical absorption coefficient, which is greater than 1×10 5 cm -2 , meaning that 90% of incoming light is likely to be absorbed in the first few microns [1]. The ideal window partner for CdTe deposition is CdS, which acts as an n-type semiconductor in PV devices. CdS has been found to be the most effective hetero-junction partner for CdTe in high-efficiency solar cells because CdTe and CdS are miscible, and a reaction between these two materials during the cell fabrication process leads to the formation of an interfacial layer of CdS 1-x Te x [2]. The thicker CdS layer results in lower cell efficiency, therefore 100-nm thick film of CdS have been found to be optimum for high-efficiency solar cells. It is well known in material science that the quality and characteristics of the growth layer hugely depends on the substrate layer (anchoring film). The influence of the substrate on the growth of CdTe has been analyzed at length in a previous study [3]. In the past, CdTe layers have been deposited by different techniques like sputter deposition [4], electrophoretic deposition [5], chemical bath deposition [6] and high-vacuum evaporation [7]. The close-spaced sublimation technique is reported to be the most effective method for CdTe deposition with CdTe/CdS thin film solar cells because the highest-efficiency lab-scale CdTe solar cells were created with CdTe * Corresponding author: mkarim@ksu.edu.sa