Unveiling Phosphorus Vacancy-Mediated Resistive Switching in Cu/HfO2/BP/Pt Memristors: Experimental and First-Principles Investigations

Abstract

Memristors integrating 2D materials are promising for neuromorphic computing, yet their microscopic resistive switching mechanisms require further clarification. In this study, a Cu/HfO2/BP/Pt memristor was fabricated to investigate its electrical characteristics and conductive filament (CF) dynamics. The device exhibits compliance-dependent behavior, enabling unipolar volatile switching at 100 μA and bipolar nonvolatile switching at 200 μA. In nonvolatile mode, it demonstrates a concentrated switching voltage distribution (Vset ≈ −1.491 V, Vreset ≈ 1.669 V), stable endurance exceeding 150 cycles, and an ON/OFF ratio of ∼104. The low- and high-resistance states follow ohmic conduction (a hybrid ohmic conduction of electron capture/decapture under negative bias) and Schottky emission, respectively. Furthermore, first-principles CI-NEB calculations indicate that intrinsic phosphorus vacancies (Vp) within the BP layer facilitate directional Cu+ migration (1.54 eV barrier) and spontaneous Pt atom trapping (0.1 eV barrier). This defect-mediated interfacial interaction promotes stable orbital hybridization, anchoring localized CFs. This work provides experimental and theoretical insights for designing oxide/2D material-based neuromorphic hardware.