Synaptic Characteristics of an Ultrathin Hexagonal Boron Nitride (h-BN) Diffusive Memristor

Abstract

A nano-sized two-terminal memristor exhibiting volatile threshold switching (TS) is a promising candidate for the emulation of biological synaptic functions to realize efficient neuromorphic computing systems. The Ca2+ dynamics play a vital role in generating a temporal response for neural functions by changing the synaptic weight of biological synapses. Herein, a thinnest synaptic device is fabricated demonstrating drift dynamics of Ag+ migration through the exfoliated h-BN sheets, which emulates neuromorphic computing operations. The TS characteristics with a large I-ON/OFF up to approximate to 10(5) lead to bio-synaptic applications, including short-term and long-term memory. The experimental realization of the synaptic behavior is demonstrated with paired-pulse facilitation (PPF), spike-rate-dependent plasticity (SRDP), and transition from short-term plasticity (STP) to long-term plasticity (LTP). The transition from STP to LTP in this synaptic device verifies the Atkinson and Shiffrin psychological model of human brain learning experimentally. The input pulses with different spike-times are used to replicate the synaptic functionalities. The two-terminal diffusive memristors constructed with thin sheets of 2D-flexible h-BN resistive materials may lead to flexible neuromorphic devices for biological applications.