Graphene-based 3D XNOR-VRRAM with ternary precision for neuromorphic computing

• Published in: NPJ 2D materials and applications Vol. 5; no. 1; pp. 1 - 10
• Main Authors: Alimkhanuly, Batyrbek, Sohn, Joon, Chang, Ik-Joon, Lee, Seunghyun
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.05.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1005/1007; 639/705; 639/925/918/1052; 639/925/927/1007; Arrays; Chemistry and Materials Science; Circuits; Computation; Design optimization; Energy consumption; Graphene; Materials Science; Materials selection; Nanotechnology; Neural networks; Neuromorphic computing; Surfaces and Interfaces; Thin Films; Two dimensional materials
• DOI: 10.1038/s41699-021-00236-x
• ISSN: 2397-7132

Recent studies on neural network quantization have demonstrated a beneficial compromise between accuracy, computation rate, and architecture size. Implementing a 3D Vertical RRAM (VRRAM) array accompanied by device scaling may further improve such networks’ density and energy consumption. Individual device design, optimized interconnects, and careful material selection are key factors determining the overall computation performance. In this work, the impact of replacing conventional devices with microfabricated, graphene-based VRRAM is investigated for circuit and algorithmic levels. By exploiting a sub-nm thin 2D material, the VRRAM array demonstrates an improved read/write margins and read inaccuracy level for the weighted-sum procedure. Moreover, energy consumption is significantly reduced in array programming operations. Finally, an XNOR logic-inspired architecture designed to integrate 1-bit ternary precision synaptic weights into graphene-based VRRAM is introduced. Simulations on VRRAM with metal and graphene word-planes demonstrate 83.5 and 94.1% recognition accuracy, respectively, denoting the importance of material innovation in neuromorphic computing.