A High-Performance Ag/TiN/HfOx/HfOy/HfOx/Pt Diffusive Memristor for Calibration-Free True Random Number Generator

True random number generators (TRNGs) that can generate unpredictable data by exploiting physical entropy sources are the main security primitive. Despite impressive demonstrations of TRNGs with various memories by exploiting their spatiotemporal variability, realizing efficient and reliable TRNGs without calibration remains a significant challenge. Diffusive memristors with rich stochastic switching behaviors offer an attractive alternative to designing efficient TRNGs, but they are still plagued by difficulties in improving device performance and inefficient circuit calibration. Here, the authors report a Ag/TiN/HfOx/HfOy/HfOx/Pt diffusive memristor with superior threshold switching characteristics, enabled by the good control of switching dynamics by introducing a TiN barrier and trilayer-hafnia with different ion mobility and migrate barriers. The random integrate-and-fire behaviors of the memristor are exploited as excellent intrinsic entropy sources for random number generation with robustness to device variation and without extra calibration. Experimental measurements validate the highly stochastic, compact, self-clocking TRNG design with a high throughput of approximate to 108 kb s(-1). The generated random bits have successfully passed all 15 National Institute of Standards and Technology randomness test benchmarks. This work demonstrates that high-performance diffusive memristors can play an important role in hardware security electronics deployed in edge computing systems.