Ultralow-Leakage-Current and Filament-Conductive Amorphous Germanium Selenide Nanoparticle Ovonic Threshold Switching...

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Advanced memory chips require higher integration density for storage and computing.
• 3D stackable cross-point architectures need selectors with ultralow leakage current (I_off) and low threshold voltage (V_th).
• Conventional ovonic threshold switching (OTS) selectors struggle to optimize both I_off and V_th simultaneously.

Purpose of the Study:

• To overcome limitations of conventional OTS selectors.
• To introduce an innovative material design for improved selector performance.
• To enable superior access performances in memory devices.

Main Methods:

• Fabrication of thermally-robust amorphous Ge₂Se₃ nanoparticle (NP)-assembled nanolayers.
• Characterization of selector performance, including I_off, V_th, and selectivity.
• In situ off-axis electron holography to investigate nanoscale filamentary conduction.

Main Results:

• Selectors achieved an unprecedentedly low I_off of ~pA and high selectivity of ~10⁸.
• Selectors demonstrated a low V_th of ~2.4 V with commendable reliability.
• Evidence of nanoscale filamentary conduction, including subthreshold-conduction and switch-on behaviors, was observed within individual NPs.

Conclusions:

• The novel amorphous Ge₂Se₃ NP-assembled nanolayer design significantly outperforms existing OTS selectors.
• Direct observation of nanoscale filamentary conduction provides new insights into selector physics.
• This work encourages further research into chalcogenide NPs and filamentary conduction for advanced memory applications.