Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 37: Poster II: Focused electron beam induced processing for the fabrication of nanostructures (focused session, jointly with O); Nanoengineered thin films; Layer properties: electrical, optical, and mechanical properties; Thin film characterization: structure analysis and composition (XRD, TEM, XPS, SIMS, RBS,..); Application of thin films
DS 37.38: Poster
Donnerstag, 29. März 2012, 15:00–17:00, Poster E
The impact of phase segregation on the electrical properties of GeTe1−x SnTex alloys — •Felix Lange, Hanno Volker, Peter Zalden, and Matthias Wuttig — 1. Physikalisches Institut IA, RWTH Aachen University
Phase-change alloys are a unique class of materials that can be reversibly switched between their amorphous and crystalline phase. This transition is accompanied by a significant change in physical properties such as reflectivity and electrical conductivity. Especially the current induced phase transition within nanoseconds [1] makes PCM valuable for non volatile RAM application.
The common PCMs are tellurium based chalcogenides with an average number of three p-electrons per atom in their outer electronic shell. Since the p-band is half-filled it is expected that these alloys develop a band-gap due to Peierls distortions resulting in a thermally activated charge transport. However, experimentally PCM are found to be degenerate semiconductors with carrier concentration in the range of 1020 1/cm3. Edwards et al. [2] recently showed that it is favorable in GeTe to formvacancies on the cation site that shift the Fermi-level well inside the valence band.
This work focuses on the electrical properties of GeTe1−xSnTex alloys. Low temperature electrical conductivity data are interpreted in terms of phase segregation in crystalline GeTe1−xSnTex and amorphous Ge.
[1] G. Bruns et al., Appl. Phys. Lett. 95, 043108 (2009)
[1] Edwards et al., Phys. Rev. B 73, 045210 (2006)