Direct observation of metal-insulator transition in single-crystalline Germanium telluride nanowire memory devices prior to amorphization

Pavan Nukala, Rahul Agarwal, Xiaofeng Qian, Moon Hyung Jang, Sajal Dhara, Karthik Kumar, A. T.Charlie Johnson, Ju Li, Ritesh Agarwal

Research output: Contribution to journalArticleAcademicpeer-review

53 Citations (Scopus)

Abstract

Structural defects and their dynamics play an important role in controlling the behavior of phase-change materials (PCM) used in low-power nonvolatile memory devices. However, not much is known about the influence of disorder on the electronic properties of crystalline PCM prior to a structural phase-change. Here, we show that the application of voltage pulses to single-crystalline GeTe nanowire memory devices introduces structural disorder in the form of dislocations and antiphase boundaries (APB). The dynamic evolution and pile-up of APBs increases disorder at a local region of the nanowire, which electronically transforms it from a metal to a dirty metal to an insulator, while still retaining single-crystalline long-range order. We also observe that close to this metal-insulator transition, precise control over the applied voltage is required to create an insulating state; otherwise the system ends up in a more disordered amorphous phase suggesting the role of electronic instabilities during the structural phase-change.

Original languageEnglish
Pages (from-to)2201-2209
Number of pages9
JournalNano Letters
Volume14
Issue number4
DOIs
Publication statusPublished - 9-Apr-2014
Externally publishedYes

Keywords

  • antiphase boundary
  • GeTe
  • in situ microscopy
  • metal-insulator transition
  • phase-change memory
  • weak localization

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