Resistance Drift in Ge2Sb2Te5 Phase Change Memory Line Cells at Low Temperatures and Its Response to Photoexcitation

TL;DR

This study investigates resistance drift in Ge2Sb2Te5 phase change memory cells at low temperatures, revealing that the drift is mainly electronic and can be modulated by photoexcitation, with implications for memory stability.

Contribution

It provides new insights into the temperature dependence of resistance drift and demonstrates the influence of light on drift behavior in phase change memory materials.

Findings

Resistance drift follows a power-law behavior at low temperatures.

Illumination reduces the drift coefficient significantly.

Photo-excitation causes rapid resistance changes followed by slow charge trap effects.

Abstract

Resistance drift in phase change materials is characterized in amorphous phase change memory line-cells from 300 K to 125 K range and is observed to follow the previously reported power-law behavior with drift coefficients in the 0.07 to 0.11 range in dark. While these drift coefficients measured in dark are similar to commonly observed drift coefficients (~0.1) at and above room temperature, measurements under light show a significantly lower drift coefficient (0.05 under illumination versus 0.09 in dark at 150K). Periodic on/off switching of light shows sudden decrease/increase of resistance, attributed to photo-excited carriers, followed by a very slow response (~30 minutes at 150 K) attributed to contribution of charge traps. Continuation of the resistance drift at low temperatures and the observed photo-response suggest that resistance drift in amorphous phase change materials is predominantly an electronic process.