TaOx based memristors with recessed bottom electrodes and built-in ion concentration gradient as electronic synapses

摘要

Inspired by the computing architecture of human brain, neuromorphic computing promises massively parallel, energy efficient and fault tolerant computation compared with conventional von Neumann approaches. In order to achieve this ambitious goal, one of the crucial tasks is to make devices that can emulate the functions of biological synapses at the physical level. Here we fabricated a novel Pt/TaO/Ta memristor with recessed Ta bottom electrodes, where the TaO film was formed by thermal oxidation of the bottom electrode and thus had a constantly ascending concentration of oxygen vacancies from the Pt/TaO interface to the TaO/Ta interface. Such cell geometry and ion distribution profile gave rise to highly incremental and uniform resistive switching that emulated the potentiation or depression process of synapses. Furthermore, important synaptic learning rules, such as spike timing dependent plasticity, could also be implemented by these devices, making them well suited for electronic synapses in neuromorphic systems.