Microscopic Origin of Polarity-Dependent V_TH Shift in Amorphous Chalcogenides for 3D Self-Selecting Memory

Area of Science:

• Materials Science
• Solid-State Electronics
• Non-volatile Memory

Background:

• Ovonic threshold switching (OTS) selectors are key to 3D memory technologies due to their self-selecting memory (SSM) behavior.
• Optimization of OTS device composition and operation is hindered by a complex understanding of the memory writing mechanism.

Purpose of the Study:

• To investigate the mechanism behind the polarity-dependent threshold voltage shift (ΔVTH) in OTS selectors.
• To elucidate the role of charged defects and electric fields in the memory writing operation.

Main Methods:

• Theoretical analysis of threshold switching principles.
• Experimental investigation including defect state analysis.
• Examination of the influence of non-uniform electric fields.

Main Results:

• Confirmed that the memory window (ΔVTH) arises from the dynamics of charged defects near electrodes.
• Demonstrated the impact of the non-uniform electric field post-threshold switching on defect distribution.
• Established a link between defect dynamics and polarity-dependent voltage shifts.

Conclusions:

• Provides critical insights into the operational mechanism of OTS-based SSM (selector-only memory).
• Highlights the potential of OTS selectors for high-density, low-cost, and energy-efficient memory solutions.
• Supports advancements in memory technologies for artificial intelligence applications.