Band alignment between GeTe and SiO2/metals for characterization of junctions in nonvolatile resistance change elements

GeTe materials were characterized using x-ray photoelectron spectroscopy in both the amorphous and crystalline states. Valence and conduction band alignments relative to a SiO2 reference were measured to allow the GeTe band diagram, work function, and electron affinity to be inferred. Hole barrier heights was also studied for several metal/GeTe systems (metal=Al, Ni, W) to extract the charge neutrality level of these interfaces for GeTe in both the crystalline and amorphous states. Near perfect Fermi-level pinning was observed for crystalline GeTe in contact with all of the metals with much less pinning observed for amorphous GeTe. (c) 2011 American Institute of Physics. [doi:10.1063/1.3599057]