Impact of Eccentricity on the Performance of Nanotube Phase‐Change Memory Devices

Phase‐change memory (PCM) has emerged as a promising nonvolatile memory candidate due to low power, high speed, and excellent scalability. However, imprecise fabrication processes make these nanoscale devices susceptible to process variation. The process variation can introduce deviations in the structural parameters and even lead to modification in the shape of cylindrical structures. In this aspect, eccentricity is the key parameter that quantifies the irregularity in the cylindrical‐based device structures. Herein, the eccentricity can significantly influence the thermal efficiency and RESET current (I_RESET) of PCM devices. Hence, this study investigates the impact of eccentricity on the performance of low‐power nanotube PCM (NT‐PCM) devices using 3D TCAD simulations. The results reveal that eccentricity alters the NT‐PCM devices transitioning from circular to elliptical cross sections, strongly affecting the Ge₂Sb₂Te₅/heater contact area and heat distribution. Among the three configurations (common eccentric [CE], confocal [CF], and concentric), CE and CF exhibit pronounced sensitivity, i.e., 83% increase in I_RESET for CE and 75% increase in I_RESET for CF configurations when eccentricity is 0.83. The results of this study suggest that eccentricity would play a crucial role in the modeling and simulation of the programming characteristics of cylindrical‐based PCM device architectures.