Analog and Digital Mode α-In2Se3 Memristive Devices for Neuromorphic and Memory Applications

The emergence of 2D ferroelectrics offers a promising path to implement next-generation information technology, including digital memory and analog computing. Here, it is demonstrated that digital or analog memory can be achieved in a single crossbar type two-terminal (Au-Ti) alpha-In2Se3 device depending on the driving voltage. The analog operation is enabled by ferroelectric polarization-modulated Schottky barrier, while resistive filament switching drives the digital operation. By tuning ferroelectric properties, multiple analog conductance states can be obtained for mimicking various synaptic behaviors like excitatory postsynaptic current, inhibitory postsynaptic current, potentiation/depression and spiking-timing-dependent plasticity. A simulated neural network built from these synaptic devices shows good on-line learning accuracy (approximate to 93.2%) for digital recognition of handwriting. Based on filament formation/rupture mechanism, alpha-In2Se3 devices also exhibits excellent digital memory performance with large on/off ratio (>10(3)), high on-current density (10(5) A cm(-2)) and fast switching speed (approximate to 10 ns). The combination of analog and digital memory modes in two-terminal alpha-In2Se3 devices is useful in highly dense and complex electronics.