Influence of the Ge-Chalcogenide Active Layer on Electrical Conduction in Self-Directed Channel Memristors

Area of Science:

• Materials Science
• Solid-State Electronics
• Device Physics

Background:

• Self-directed channel (SDC) memristors utilize multilayer architectures for robust ion conduction, extended cycling life, and thermal stability.
• The electrical performance is primarily governed by the Ge-chalcogenide active layer and the overlying metal-chalcogenide source layer.

Purpose of the Study:

• To investigate the impact of varying chalcogen species (O, S, Se, Te) in the active and source layers on memristor switching characteristics.
• To analyze pre-write regime conduction behavior in pristine and cycled devices at room temperature.

Main Methods:

• Fabrication of memristor devices using Ge-rich chalcogenides and various metal-chalcogenide layers (SnS, SnSe, Ag2Se).
• DC current-voltage (I-V) measurements and analysis using linearization approaches to identify conduction mechanisms (Ohmic, Schottky, Poole-Frenkel, space charge limited).
• Probing the pre-write region of the I-V curve to understand early ionic redistribution and structural changes.

Main Results:

• Chalcogen composition significantly influences threshold voltage, resistance window, and field-enhanced transport onset.
• Conduction behavior transitions between interface injection and bulk-limited regimes based on the material stack and applied bias.
• Evidence of evolving transport dynamics with bias and compliance current, linked to ionic distribution and channel formation.

Conclusions:

• Chalcogen chemistry plays a critical role in governing the switching behavior of SDC memristors.
• Understanding these effects provides essential guidance for selecting materials tailored to specific device applications.
• The study clarifies the interplay between material composition and electrical transport in memristive devices.