Intrinsic Nonlinearity Modulation in Two-Dimensional (Cu,Ag)InP ₂ S ₆ for Selectorless Nonvolatile Memory Array

Selectorless resistive random-access memory is essential for scaling high-density crossbar arrays, yet suppressing sneak path currents (SPCs) without external selector components remains a major challenge. In this work, we investigated a two-dimensional (2D) van der Waals (vdW) mixed cation crystal Cu 0.5 Ag 0.5 InP 2 S 6 (CAIPS) as a switching layer and systematically compared its resistive switching with CuInP 2 S 6 (CIPS) and AgInP 2 S 6 (AIPS). The coexistence of Cu + and Ag + ions produces asymmetric out-of-plane diffusion barriers, as confirmed by first-principles density functional theory (DFT) calculations, leading to self-rectifying transport and the intrinsic suppression of leakage in arrays. CAIPS-based devices exhibit stable bipolar resistive switching, a high intrinsic nonlinearity factor (>10 under a V /3 read scheme), a large memory window (>9× at V read = 0.1 V), and low variability (coefficient of variation down to 5.1%), surpassing the performance of both CuInP 2 S 6 (CIPS) and AgInP 2 S 6 (AIPS). These features, combined with low operational switching voltages, robust endurance, and built-in nonlinearity highlight CAIPS as a promising material for scalable selectorless memory arrays, with direct relevance to energy-efficient neuromorphic and edge-computing architectures.