Yazar "Seyhan A." seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    A Hydrogenated Amorphous Silicon (a-Si:H) Thin Films for Heterojunction Solar Cells: Structural and Optical Properties
    (Institute of Physics Publishing, 2017) Seyhan A.; Altan T.; Ecer O.C.; Zan R.
    Heterojunction solar cells composed of hydrogenated amorphous silicon (a-Si:H) and c-Si has been widely studied due to its excellent photovoltaic characteristics. In this study, we studied the structural and optical properties of a-Si:H thin films for heterojunction solar cells by using SEM, TEM and ellipsometry. We found that uniform deposition of a-Si:H thin film on substrate is crucial to reach high solar cell efficiencies. © Published under licence by IOP Publishing Ltd.
  • Küçük Resim Yok
    Öğe
    Influence of pre-annealing Cu-Sn on the structural properties of CZTSe thin films grown by a two-stage process
    (Elsevier Ltd, 2018) Olgar M.A.; Başol B.M.; Tomakin M.; Seyhan A.; Bacaksız E.
    In this study CZTSe thin film were synthesized by a two-stage process that included sequential sputter deposition of Cu and Sn layers forming a Cu/Sn structure, pre-annealing the Cu/Sn structure at 200–380 °C for some of the samples, sputtering of additional Zn and Cu over the Cu/Sn structure, evaporation of a Se cap forming a Cu/Sn/Zn/Cu/Se precursor film, and exposing the precursor film to high temperature annealing treatment at 550 °C for 15 min to form the compound. The results of the characterization carried out on the compound layers revealed that the phase content, composition and microstructure of these layers changed noticeably depending on whether or not a pre-annealing step was utilized. Although XRD studies suggested presence of secondary phases, especially in the non-pre-annealed samples, the data was dominated by kesterite CZTSe phase reflections. Raman spectra of the films verified the formation of kesterite CZTSe structure and some other phases, which were determined to be SnSe 2 and possibly ZnSe. SEM micrographs showed denser structure in the pre-annealed samples. © 2018 Elsevier Ltd
  • Küçük Resim Yok
    Öğe
    Low-temperature growth of Ge nanowires by vapor-liquid-solid chemical vapor deposition
    (2012) Simanullang M.; Seyhan A.; Usami K.; Kodera T.; Kawano Y.; Oda S.
    This paper reports the growth of the germanium nanowires (Ge NWs) with a single-step temperature method via vapour-liquid-solid (VLS) mechanism in the low pressure chemical vapour deposition (CVD) reactor at 300, 280 and 260°C. The Ge NWs grown at 300°C tend to have a tapered structure and the sidewalls of the nanowires were observed to be decorated with gold. The tapering was caused by the uncatalysed deposition of Ge via CVD mechanism at the sidewalls of the nanowires and significantly minimised at 260°C which leads to the formation of straight and ultra-thin Ge NWs. The sidewalls of the Ge NWs grown at 260°C were also observed not to be decorated with gold. The Ge NWs grown from 0.1-nm-thick Au at 260°C had diameter as small as ~3 nm which offers an opportunity to fabricate high-performance p-type ballistic Ge NW transistor and to realise nanowire solar cell with higher efficiency. ©The Electrochemical Society.