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- MakaleYalnız künye2026Scopus SJRQ1Influence on the thermoelectric characteristics of the growth parameters of BiSeTe thin films
Yüzüak, G. Durak; Yüzüak, E.
This study systematically investigates the influence of magnetron sputtering parameters on the structural, electronic, and thermoelectric properties of 100 nm thick Bi2SexTe3-x thin films deposited on Si(100). The initial parameters for applied film deposition are used to set the x value. The films are fabricated with sputtering powers ranging from 30 to 100 W and pressures from 3 to 15 mTorr, with films grown under optimal conditions selected for post-deposition annealing at 523 K. A comprehensive characterization suite, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM), is used to establish direct correlations between processing, structure, and performance. XRD analysis reveals that increasing the sputtering pressure from 3 to 15 mTorr was critical for enhancing film crystallinity and promoting a strong (015) preferred orientation, while AFM showed a corresponding increase in average grain size from similar to 46 to similar to 60 nm via heat treatment (HT). EDS shows that films grown at 10 mTorr were almost certainly stoichiometric, but increasing the power to 15 mTorr caused tellurium deficiency. The films exhibited a power factor ranging from 2.5 to 2.8 mW m(- 1) K- 2 at 40 degrees C. HT improved the Seebeck coefficient from -115 mu V K- 1 to -140 mu V K- 1 and decreased the electrical resistivity by over 25 % through defect reduction and enhanced crystalline order. KPFM supported these findings, directly linking the crystallographic texture to the surface electronic structure and enhanced Seebeck effect.
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İncele - MakaleYalnız künye2026Scopus SJRQ1Compositionally segmented thermoelectric BiSbTe thin films on Cr/Si(100)
Yüzüak, G. Durak; Yüzüak, E.
Compositionally segmented thermoelectric (CS-TE) structures improve thermal energy conversion efficiency across large thermal gradients. However, their increased design complexity complicates performance modeling and optimization. In this study, we fabricate CS-TE BiSbTe thin films on Cr-buffered Si(100) substrates. By adopting a multidisciplinary approach, we aim to broaden the technological applicability and strategic relevance of advanced TE systems. We systematically analyze the influence of deposition pressures (5, 7, and 10 mTorr) on TE performance. Variations in working pressure alter the Bi/Sb atomic ratio in the films, while the Te content remains stable. This enables the controlled formation of CS structures. At 323 K, the power factor (PF) of TE thin films reaches 0.7, 2.4, and 7.3 mW/mK2 under 5, 7, and 10 mTorr deposition conditions, respectively. The Cr-buffered layer significantly improves the electrical conductivity of CS-TE BiSbTe films. We further engineer a p-type single-leg device integrating nanostructured Bi0.35Sb1.65Te3, Bi0.37Sb1.63Te3, and Bi0.4Sb1.60Te3 layers. These materials are optimized to achieve peak TE PF values across a wide temperature range (320 to 500 K) while ensuring robust interfacial adhesion. The CS-TE device generates 3 mW/cm2, showing a 15% improvement over single-composition samples at a 100 K temperature difference.
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İncele - MakaleYalnız künye2026Scopus SJRQ1Engineering high-performance BiSeTe ultra-thin film on flexible FEP
Yüzüak, G. Durak; Yüzüak, E.
Flexible thermoelectric (TE) devices hold great promise for powering wearable electronics by harvesting the temperature difference between human skin and the environment. Conventional Bi2Te3, although efficient, suffers from rigidity and limited suitability for flexible applications, while organic alternatives typically lack sufficient TE performance. Here, we demonstrate an n-type BiSeTe thin film deposited on a flexible fluorinated ethylene propylene (FEP) substrate, incorporating a Cr buffer layer, achieving a room-temperature power factor of ∼3.9 μW.cm−1.K−2, which is within the range reported for flexible thin-film TE devices on polymer substrates. The film exhibits excellent mechanical resilience, retaining 90 % of its initial conductivity after 5000 bending cycles, and shows high thermal stability over 50 heating–cooling cycles with deviations below 1.5 %. A four-leg n-type prototype generates 10 mV and 70 nW at ΔT = 40 K, demonstrating its potential for powering low-energy wearable sensors. This work presents a scalable inorganic thin-film TE platform that effectively balances mechanical flexibility, device stability, and practical energy conversion performance for wearable and localized power generation applications.
AtıfScopus2WoS2OpenAlex2İncele - MakaleYalnız künye2025Scopus SJRQ1Evaluation of TiO2/ZnO/SnO2 multilayer thin films on Si(100) as triboelectric friction layer
Yüzüak, G. Durak; Yüzüak, E.
This study presents a novel multilayer-semiconductor triboelectric nanogenerator (MLSC-TENG) that enhances charge transfer and initial charge density to overcome the limitations of conventional TENGs by multilayer thin films composed of TiO2, ZnO, and SnO2. The device operates through contact electrification and electrostatic induction, featuring two distinct electrodes. The active negative layer is deposited on Si substrates with an Ag seed layer using magnetron sputtering, employing a PET/ITO counter-electrode. The system attains a maximum power density of 400 mW/m2 with a 100 MΩ load, a short-circuit current of 20 μA at 10 Hz, and an open-circuit voltage of ±55 V. Additionally, it powers 156 LEDs and exhibits an energy storage capacity of 16.9 μJ at 52 μF, highlighting its applicability for wearable electronics. This scalable and cost-effective approach highlights the significant role of semiconductor (SC) band structures in enhancing TENG performance and presents a viable pathway for sustainable energy harvesting. The demonstrated strategy has the potential to meaningfully influence the application of TENGs in energy harvesting systems, providing a cost-effective solution for powering wearable electronics. The study facilitates progress in sustainable energy solutions for future wearable technologies by tackling critical issues in energy conversion efficiency.
AtıfScopus2WoS3OpenAlex3İncele - MakaleYalnız künye2024Scopus SJRQ2Introducing the chemical potential of Cu–Mn–Al alloys for structural, electrical and thermal properties
Yüzüak, E.; Durak Yüzüak, G.
This study investigates the Martensite transition in Cu–Mn–Al alloys (CMAs) via the use of many methods, including scanning electron microscopy, temperature-dependent X-ray diffraction, resistivity and thermal measurements. The Martensite transition hysteresis and characteristic temperature are primarily determined by the alloy composition, crystal structure and residual stress. Furthermore, these alloys have been reported to have surface and crystallographic characteristics often associated with twinning structures. Resistivity experiments conducted during heating and cooling cycles demonstrate a 2.57-fold increase inside the phase change zone, emphasizing the influence of the transition on electrical conductivity. The Martensite transition temperature may be altered by 110 K by the manipulation of the electron-to-atom ratio (e/a), indicating the high susceptibility of this temperature to changes in chemical composition. Differential scanning calorimetry shows that the transition is accompanied by a maximum entropy shift of 48 J kg−1. K, which offers valuable information on the thermodynamic driving factors involved. This work successfully attains a cooling power of 1350 W, which is equivalent to the cooling power of NiTi wire (1500 W), by using a theoretical manufacturing method and optimizing the CMAs. Overall, this work clarifies the Martensite transition in CMAs, highlighting its impact on their characteristics and indicating their potential for effective thermal energy storage and release applications. It is advisable to further optimize their performance and economic viability by considering the e/a ratio.
AtıfScopus3WoS3OpenAlex4İncele - MakaleYalnız künye2023Scopus SJRQ2Ag seed layer effects on SnO2 thin films for triboelectric devices
Yüzüak, E.; Yüzüak, G. Durak
Materials with triboelectric properties are critical to boosting the efficiency of triboelectric nanogenerators (TENG) by gathering power from waste force and mechanical movement. In this study, we explored tin-oxide (SnO2) thin films with silver (Ag) seed layer properties for friction surfaces at TENGs. Investigation of the triboelectric behavior of semi-conductor/polymer coupling structured TENGs formed by thin films with and without Ag seed layer after heat treatment was explored by X-ray diffraction (XRD), electron microscopy (SEM), atomic force microscopy (AFM), and semi-logarithmic current-voltage measurements. Similar structural characterization studies were carried out in indium tin oxide coated polyethylene terephthalate film (PET/ITO) for the polymer friction layer. Semiconductor/polymer coupling structured TENG efficiency was evaluated in contact-separation mode and the output voltage-current was enhanced to 80 V, 4 μA, and 210 μW of output power calculated by depositing a SnO2 thin film on an Ag seed layer, respectively. Our findings offer a different perspective for synthesizing the semi-conductor/polymer coupling structured TENGs for promising applications in a range of application technologies.
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