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@INPROCEEDINGS{Hardtdegen:811594,
      author       = {Hardtdegen, Hilde and Riess, Sally and Schuck, Martin and
                      ratajczak, Albert and Keller, Kristof and Jost, Christian
                      and Bornhöfft, Manuel and Du, Hongchu and Schwedt,
                      Alexander and Mayer, Joachim and Roth, Georg and Mussler,
                      Gregor and von der Ahe, Martina and Grützmacher, Detlev and
                      Mikulics, Martin},
      title        = {{MOVPE} and characterization of rhombohedral
                      {G}e1{S}b2{T}e4/{S}i(111)},
      reportid     = {FZJ-2016-04015},
      year         = {2016},
      abstract     = {Chalcogenide alloys in the Ge-Sb-Te system exhibit a large
                      contrast in their optical and electrical properties when
                      their phases switch from the amorphous to the meta-stable
                      cubic crystalline state. Up to now, they have been applied
                      to rewritable optical data storage media[1] such as compact
                      discs (CDs), digital versatile discs (DVD) and blu-ray discs
                      (BRD). Currently, the exploitation of their large change in
                      resistivity upon switching is in the focus of attention for
                      next generation non-volatile memories. However, a high
                      energy imput is required for switching and the resistance
                      especially of the amorphous state drifts with time[2].
                      Therefore, there is a growing interest in memory material
                      systems switching between two distinct crystalline states
                      avoiding the amorphous state and melting and
                      recrystallization processes.The so-called interfacial phase
                      change memory (iPCM) based on GeTe-Sb2Te3 superlattices[3]
                      was reported to be a suitable approach to reduce energy
                      consumption in data storage applications. Here, the
                      resistance change is reported to be evoked by a displacement
                      of Ge atoms at the GeTe-Sb2Te3 interfaces and the structural
                      changes are field induced. Only a fraction of the energy for
                      switching is consumed. The hexagonal superlattices are
                      deposited by sputter deposition or molecular beam epitaxy
                      and are highly textured. In this work, epitaxial Ge-Sb-Te
                      films crystallizing in the thermodynamically stable
                      rhombohedral phase have only lately been accessible.
                      Ge1Sb2Te4 layers were deposited by the industrially relevant
                      method MOVPE on Si (111) substrates[4]. The alloy is
                      expected to have properties similar to those of the
                      superlattices mentioned above. Therefore, the
                      characteristics of this novel material and its potential for
                      non-volatile memory applications is of great interest. In
                      this contribution, we will report shortly on the growth and
                      then mainly center on the structural and electrical
                      characteristics of this new epitaxial material.Growth was
                      carried out in a single wafer horizontal reactor (AIX 200,
                      AIXTRON) on Si (111) substrates using nitrogen as the
                      carrier gas[5]. Further information is given in[4]. The
                      samples were characterized structurally by X-ray
                      diffractometry, aberration corrected high-angle annular
                      dark-field scanning transmission electron microscopy
                      (HAADF-STEM), energy dispersive X-ray (EDX) spectroscopy and
                      electron back scatter diffraction (EBSD). The intrinsic
                      electrical characteristics of the material were
                      characterized by removing Ge1Sb2Te4 platelets from their
                      growth substrate and transferring them to coplanar
                      striplines. It was found, that Ge1Sb2Te4 grows epitaxially
                      and its unit cell consists of 3 seven layered blocks each of
                      which is separated by van der Waals gaps. Alternating anion
                      and cation planes as well as the gaps are found in parallel
                      to the Si (111) substrate surface. Resistive switching
                      measurements were performed without any detectable
                      structural deterioration. Current densities exhibit values
                      from 10-6 down to 10-11A/µm3 at 1V bias switching. Complete
                      structural and electrical characterization will be
                      presented.},
      month         = {Jul},
      date          = {2016-07-10},
      organization  = {18th International Conference on Metal
                       Organic Vapor Phase Epitaxy, San Diego
                       (USA), 10 Jul 2016 - 15 Jul 2016},
      subtyp        = {Other},
      cin          = {PGI-9},
      cid          = {I:(DE-Juel1)PGI-9-20110106},
      pnm          = {523 - Controlling Configuration-Based Phenomena (POF3-523)},
      pid          = {G:(DE-HGF)POF3-523},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/811594},
}