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

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53 Citations (Scopus)


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
Issue number4
Publication statusPublished - 9-Apr-2014
Externally publishedYes


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

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