Nature of electrical resistivity and structural stability in N-doped GeTe models for reliable phase-change materials

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11 Citations (Scopus)

Abstract

KGaA, Weinheim. We study the effects of nitrogen (N)-doping on the electrical memory reliability of GeSbTe phase-change materials based on GeTe prototype models. We find that the loss of secondary bonding (e.g., resonant interlayer bonding) determines the feasibility of various types of N-doping that can be easily adopted by the GeSbTe system. We give a more generalized explanation beyond compliance with the formation of local Ge3N4 motifs. The nitrogen-induced change in local order produces crystalline GeTe with shallow states near the valence band edge. These states are localized on the nearest-neighbor Ge sites, thus reducing the conductivity in the crystalline phase. This trend carries over to c-GeTe with Ge vacancy. The N-doped amorphous GeTe models exhibit enhanced degrees of band tail overlap, which pins the Fermi energy in the mid-gap and thus gives rise to even higher resistivities in the amorphous phases.
Original languageEnglish
Pages (from-to)431-441
Number of pages11
JournalPhysica Status Solidi (B) Basic Research
Volume252
Issue number2
DOIs
Publication statusPublished - 1 Jan 2015
Externally publishedYes

Keywords

  • Band overlapping
  • Loss of secondary bonding
  • N-doping
  • Phase change memory materials
  • Shallow states

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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