Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Author: search.filters.author.Özyüzer, Gülnur AygünSubject: search.filters.subject.Magnetron sputtering

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  • Article
    Citation - WoS: 42
    Citation - Scopus: 46
    Importance of Cds Buffer Layer Thickness on Cu2znsns4-Based Solar Cell Efficiency
    (IOP Publishing Ltd., 2018) Cantaş, Ayten; Türkoğlu, Fulya; Aygün, Gülnur; Akça, Fatime Gülşah; Özdemir, Mehtap; Tarhan, Enver; Özyüzer, Lütfi; Özyüzer, Gülnur Aygün; Özdemir, Mehtap; Özyüzer, Lütfi; Tarhan, Enver; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Cu2ZnSnS4 (CZTS) thin films were grown on Mo-coated soda lime glass (SLG) substrates by the sulfurization of DC magnetron-sputtered Zn, Sn and Cu metallic precursors under a sulfur atmosphere at 550 °C for 45 min. Understanding the composition and structure of the CZTS absorber layer is necessary to obtain efficient solar cells. With this aim, x-ray diffractometry, Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy and x-ray photoelectron spectroscopy were used to investigate the CZTS absorber layers. CZTS absorber films were obtained and found to be Cu-poor and Zn-rich in composition, which are both qualities desired for efficient solar cells. CdS was used as a buffer layer and was grown by the chemical bath deposition technique. The optical properties of CdS films on SLG were searched for using a spectroscopic ellipsometer and the results revealed that the bandgap increases with film thickness increment. CZTS-based solar cells with different CdS buffer layer thicknesses were prepared using a SLG/Mo/CZTS/CdS/ZnO/AZO solar cell configuration. The influence of the CdS buffer layer thickness on the performance of the CZTS solar cells was investigated. Device analysis showed that electrical characteristics of solar cells strongly depend on the buffer layer's thickness. Highly pronounced changes in V OC, fill factor and J SC parameters, which are the main efficiency limiting factors, with changing buffer layer thicknesses were observed. Our experiments confirmed that decreasing the CdS thickness improved the efficiency of CZTS solar cells down to the lowest thickness limit.
  • Article
    Citation - WoS: 10
    Citation - Scopus: 10
    In-Situ Spectroscopic Ellipsometry and Structural Study of Hfo2 Thin Films Deposited by Radio Frequency Magnetron Sputtering
    (American Institute of Physics, 2014) Cantaş, Ayten; Özyüzer, Gülnur Aygün; Aygün, Gülnur; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    We have investigated the reduction of unwanted interfacial SiO2 layer at HfO2/Si interface brought about by the deposition of thin Hf metal buffer layer on Si substrate prior to the deposition of HfO2 thin films for possible direct contact between HfO2 thin film and Si substrate, necessary for the future generation devices based on high-κ HfO2 gate dielectrics. Reactive rf magnetron sputtering system along with the attached in-situ spectroscopic ellipsometry (SE) was used to predeposit Hf metal buffer layer as well as to grow HfO2 thin films and also to undertake the in-situ characterization of the high-κ HfO2 thin films deposited on n-type 〈100〉 crystalline silicon substrate. The formation of the unwanted interfacial SiO2 layer and its reduction due to the predeposited Hf metal buffer layer as well as the depth profiling and also structure of HfO2 thin films were investigated by in-situ SE, Fourier Transform Infrared spectroscopy, and Grazing Incidence X-ray Diffraction. The study demonstrates that the predeposited Hf metal buffer layer has played a crucial role in eliminating the formation of unwanted interfacial layer and that the deposited high-κ HfO2 thin films are crystalline although they were deposited at room temperature.