Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 58: 2D materials beyond graphene: TMDCs, silicene and relatives II
O 58.1: Talk
Wednesday, March 14, 2018, 10:30–10:45, MA 043
Fabrication of germanane from Ge(111) single-crystal wafers — •Kornelia Huba1, Ulrich Hagemann2, and Hermann Nienhaus1 — 1Faculty of Physics, CENIDE, University of Duisburg-Essen, Duisburg — 2Interdisciplinary Center for Analytics on the Nanoscale (ICAN), CENIDE, Duisburg
Germanane is a layered semiconducting material composed of single two-dimensional Ge sheets with dangling bonds saturated with hydrogen atoms. It is fabricated in a two-step procedure from clean Ge(111) wafers. First, a Zintl phase of CaGe2 is formed under ultrahigh vacuum conditions by evaporating Ca atoms onto Ge at 810∘C. Second, the sample is transferred under atmosphere to the wet-chemical treatment where it is etched in concentrated hydrochloric acid (HCl) at low temperatures for several hours. This leads to deintercalation of Ca and forming layered germanane flakes on top of the Ge(111) substrate. The flakes are exfoliated and transferred to other substrates, e.g., Si wafers for characterisation. The lateral extension of the germanane flakes ranges between 30 and 150 µm. X-ray photoelectron spectroscopy for chemical analysis detects Ge, no Ca and slight oxygen contaminations. From a 20% attenuation of the Si substrate line intensities a germanane layer thickness in the nm range is extracted demonstrating that single layer preparation is feasable. Currently, transmission electron microscope studies and micro-Raman spectroscopy are performed to elucidate morphology and structure of the germanane material.