Abstract

We report on the fabrication and characterization of nanoscale memory elements based on solid electrolytes. When combined with silver, chalcogenide glasses such as Se-rich Ge-Se are good solid electrolytes, exhibiting high Ag ion mobility and availability. By placing an anode that has oxidizable Ag and an inert cathode (e.g., Ni) in contact with a thin layer of such a material, a device is formed that has an intrinsically high resistance, but which can be switched to a low-resistance state at small voltage via reduction of the silver ions. An opposite bias will return the device to a high-resistance state, and this reversible switching effect is the basis of programmable metallization cell technology. In this paper, electron beam lithography was used to make sub-100-nm openings in polymethylmethacrylate layers used as the dielectric between the device electrodes. The solid electrolyte film was formed in these via-holes so that their small diameter defined the active switching area between the electrodes. The Ag-Ge-Se electrolyte was created by the photodiffusion, with or without thermal assistance, of an Ag layer into the Ge-Se base glass. Combined thermal and photodiffusion leads to a nanophase separated material with a dispersed Ag ion-rich material with an average crystallite size of 7.5 nm in a glassy insulating Ge-rich continuous phase. The nanoscale devices write at an applied bias as low as 0.2 V, erase by -0.5 V, and fall from over 107 Ω to a low-resistance state (e.g., 104 Ω for a 10-μA programming current) in less than 100 ns. Cycling appears excellent with projected endurance well beyond 1011 cycles.

Original languageEnglish (US)
Pages (from-to)331-338
Number of pages8
JournalIEEE Transactions on Nanotechnology
Volume4
Issue number3
DOIs
StatePublished - May 1 2005

Keywords

  • Electrical switching
  • Nanoscale devices
  • Nanostructured materials
  • Nonvolatile memory
  • Solid-state electrolytes

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering

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