Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Effect of annealing process on the properties of undoped and manganese 2+ - doped co-binary copper telluride and tin telluride thin films Meaunfun Kladkaew a , Norasate Samranlertrit b , Veeramol Vailikhit a , Pichanan Teesetsopon c , Auttasit Tubtimtae b, ⁎ a Department of Chemistry, Faculty of Liberal Arts and Science, Kasetsart University Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand b Department of Physics, Faculty of Liberal Arts and Science, Kasetsart University Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand c Department of Physics, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand ARTICLE INFO Keywords: Co-binary thin films Copper telluride Tin telluride Effective annealing process Manganese doping ABSTRACT The binary semiconductor materials Cu 1.81 Te and SnTe materials, without and with manganese (Mn 2+ ) doping, were prepared by dropping a Cu-Sn-Te solution on a commercial glass substrate to fabricate a co-binary thin film. The characteristics, optical, and electrical properties of undoped and Mn 2+ -doped Cu 1.81 Te/SnTe thin films were investigated with variations in the annealing process. The XRD results confirmed the films consisted of the co-binary orthorhombic phase materials Cu 1.81 Te and SnTe, and that for all annealing temperatures from 50 to 400 °C an amorphous structure became prevalent in the Mn 2+ -incorporated co-binary thin films. The optical parameters and electrical performance varied with the annealing temperatures and Mn 2+ doping, showing al- terations in the properties of the co-binary film. These co-binary thin films have feasibility for real applications in surface analysis, electro-optical materials, solar selective surfaces, and photovoltaic thermal devices. 1. Introduction The study of binary chalcogenide compounds and semiconductor structures is of interest for improving their fascinating optical and electronic properties [1]. The development of their properties such as the photoconductivity of conductive and transparent p-type semi- conductor thin films is required for broad spectrum optoelectronic de- vices [2]. In addition, certain transition-metal telluride compounds are very attractive for thermoelectric applications due to high thermo- electric power values, and the ability for doping as n- or p-type mate- rials [3,4]. Copper telluride (Cu 2-x Te) is a I–VI group compound binary p-type semiconductor, with a high thermal conductivity at room temperature (300 K) of 4 W/m K [5]. The highest field effect hole mobility was found to be ∼ 18 cm 2 /V s [6], in which the crystal structure depended upon the phase value (x, where 1 ≤ x ≤ 2) [7,8]. The band gap (E g ) of copper telluride is about 0.9–1.1 eV, which suggests it could be a low-E g back-contact material, and has been proposed to improve the absorp- tion range in the near-infrared (NIR) for optoelectronic devices [9,10]. Cu 2-x Te semiconductor has a high absorption coefficient range of α = 4 × 10 4 –2 × 10 5 cm -1 , as well as a high carrier concentration of 10 19 –10 22 cm -3 [11]. These properties are useful in applications such as electroconductive electrodes, solar cells, photothermal conversion, photodetectors, optical data storage, microwave shielding coatings, and superionic conductivity [12–15]. Furthermore, the Cu–Te system is very complex due to its large deviation of stoichiometry and it has several polymorphs related to the Cu 2-x Te phase [8,16,17]. A rocksalt crystal structure of the binary p-type semiconductor tin telluride (SnTe) is a IV–VI infrared region-tuned band gap material (E g ∼ 0.18–0.8 eV). It has attracted interest with a wide range of applications, for example in photovoltaics [18], thermovoltaic/thermolelectric devices, infrared optical detectors [19], photodetectors [20], and hyperthermal therapy [21]. The synthesis method is one of the important issues in obtaining the optimal properties in a semiconductor thin film. Previously, many single and co-binary semiconductor compounds such as CdTe [22], MnTe [23–25], ZnTe [26], Cu 2-x Te/MnTe [27,28], and CdSe/CdTe [29] have typically been prepared by successive ionic layer absorption and reaction (SILAR) and chemical bath deposition (CBD) methods. These methods are easily performed at room temperature, by mixing the compounds with a solvent of ethanol or methanol and water, to prepare a solution that facilitates the growth of semiconductor nano- particles (NPs) in a mesoporous electrode. Ethanol or methanol pro- mote a high penetration ability of NPs into the film matrices, a high wetting ability, and provide a solution with low surface tension, leading to better coverage of the NPs on the electrode surface [30]. On the other https://doi.org/10.1016/j.ceramint.2018.01.166 Received 19 September 2017; Received in revised form 19 January 2018; Accepted 19 January 2018 ⁎ Corresponding author. E-mail address: faasast@ku.ac.th (A. Tubtimtae). Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2018 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Kladkaew, M., Ceramics International (2018), https://doi.org/10.1016/j.ceramint.2018.01.166