Regensburg 2000 – scientific programme

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.23: Poster

Monday, March 27, 2000, 19:00–22:00, Bereich C

Two stoichiometric phases of the Mo:Se system grown on a MoS₂ substrate by van der Waals epitaxy — •Thorsten Böker, Ralf Severin, Torsten Stemmler, Christoph Janowitz, and Recardo Manzke — Institut f. Physik; Humboldt-Universität zu Berlin; Invalidenstraße 110; 10115 Berlin

Van der Waals epitaxy (vdWe) is a powerfull tool to produce high quality thin films of low-dimensional materials. In the present study high-purity Mo and Se was evaporated in a new vdWe system by an electron beam evaporator and a Knudsen type effusion cell, respectively. The deposited film on a MoS₂ substrate was investigated by low energy electron diffraction (LEED), Auger electron spectroscopy (AES), and angular-resolved photoelectron spectroscopy (ARPES). As a result two different stoichiometric phases were identified by AES for different growth parameters. These are MoSe₂ and Mo₆Se₈, respectively. Their crystal structure was checked by LEED and the MoSe₂ film showed a planar hexagonal pattern confirming a layer-by-layer growth mode as typically apparent in vdWe. In contrast the Mo₆Se₈ phase reveals a more wagon-wheel like LEED pattern which is attributed to a facetted surface. ARPES studies on such samples showed a more angle-integrated density of states instead of a dispersive valence-band structure observed for the MoSe₂ phase.