Suppressing Electrode Diffusion via Interfacial Engineering for High-Temperature Memristors
High-temperature electronics demand non-volatile memories (NVMs) capable of stable operation above 500 °C for applications in space exploration, nuclear energy, and autonomous driving. Conventional silicon-based devices fail above ~250 °C, and silicon carbide (SiC) cannot process data above 300 °C. Memristors offer a promising solution due to their simple structure, low power consumption, and scalability. A recent breakthrough by Yang et al. (Science) demonstrated a graphene (Gra)/HfOx/W memristor achieving data retention at 700 °C, with retention time of 50 h, endurance of 10^9 cycles, ON/OFF ratio exceeding three orders of magnitude, and operation voltage ~1.5 V. The key innovation is replacing the Pt bottom electrode with in-situ grown graphene, which suppresses high-temperature diffusion of the W top electrode through the HfOx layer. In contrast, Pt/HfOx/W devices fail after annealing at 800 °C for 10^4 s due to W migration, forming conductive filaments that lock the device in the ON state. High-resolution TEM and EDS reveal tungsten oxide (WOx) formation at the W/HfOx interface in Pt-based devices, while Gra-based devices show no such degradation. STEM-EELS confirms W migration across the HfOx layer in Pt devices, but graphene acts as a diffusion barrier, preserving stable switching behavior. This interfacial engineering approach provides a viable pathway for high-temperature NVM, addressing the critical bottleneck of electrode diffusion.