Investigation of structural, electrical and thermoelectric properties of bitesb based thin films

Along with technological and digital developments, which have become increasingly important in the modern age, there have been rapid developments in many areas. This development leads to ever greater demand for energy, and human beings damage our planet due to the classical methods they use to meet this demand. Scientists working to prevent this problem and meet the energy demand have used the positive effects of developing technology and researched new energy technologies and energy production systems in this respect. There are many new approaches emerging in accordance with this purpose, and among them, generators and nanogenerators capable of harvesting waste energy are among the most interesting topics. Among these renewable, clean, waste-free energy harvesters that can be produced in a wide variety of forms, thin film thermoelectric nanogenerators, which are a very remarkable method and enable the harvesting of waste heat using the thermoelectric effect, are extremely promising. In this study, BiTeSb semiconductor based thermoelectric thin films capable of generating energy by utilizing waste heat were produced and their properties were investigated. In this study, semiconductor BiTeSb based thermoelectric thin films were deposited on silicon (Si) substrates using the magnetron sputtering method. Structural, electrical and thermoelectric properties of BiTeSb thin films grown at sputtering pressures of 3, 5, 7, 10, 12 and 15 mTorr and sputtering powers of 30, 50, 70 and 100 W were investigated. Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), X-ray diffraction (XRD) and X-ray reflection (XRR) techniques were used to investigate the structural features. Thin films produced at 5, 7 and 10 mTorr sputtering pressures and 50W sputtering power were selected as the optimum production parameters, and their structural and surface morphological properties were determined with these characterization techniques used. For electrical and thermoelectric outputs, the resistivity measurement system and Seebeck measurement system were used. In order to determine the crystal structure of BiTeSb thin films, XRD patterns were taken in the range of 10° < 2θ < 110° and in steps of Δ2θ = 0,02°. (015) and (110) reflection peaks of BiTeSb were clearly observed at all sputtering pressures of the thin films examined by the XRD technique and it was determined that they had a Rhombohedral crystal structure. The thin film produced at 5mTorr sputtering pressure and 50W sputtering power was chosen as the calibration sample, and in the examinations made using the XRR technique, the film thickness was ~20 nm; the surface roughness was measured as 0.7 nm. The thickness of the other films produced was calculated according to this calibration and was found to be ~100 nm. As a result of electrical and thermoelectric measurements of the produced thin films, the highest Seebeck coefficient among the produced films was 236.02 μV⁄K value in the thin film produced at 10 mTorr sputtering pressure; the highest electrical conductivity value was measured at 2,27×10^5 S⁄(m )in the film produced at 5 mTorr pressure. When the thermoelectric output power is analyzed, the highest value of 4.52×10^(-3) W⁄(m.K^2 ) was observed in the thin film produced at a sputtering pressure of 7 mTorr.