Intrinsic polarization coupling in 2D α-In2Se3 toward artificial synapse with multimode operations

Emulation of advanced synaptic functions of the human brain with electronic devices contributes an important step toward constructing high-efficiency neuromorphic systems. Ferroelectric materials are promising candidates as synaptic weight elements in neural network hardware due to their controllable polarization states. However, the increased depolarization field at the nanoscale and the complex fabrication process of the traditional ferroelectric materials hamper the development of high-density, low-power, and highly sensitive synaptic devices. Here, we report the implementation of two-dimensional (2D) ferroelectric alpha-In2Se3 as an active channel material to emulate typical synaptic functions. The alpha-In2Se3-based synaptic device features multimode operations, enabled by the coupled ferroelectric polarization under various voltage pulses applied at both drain and gate terminals. Moreover, the energy consumption can be reduced to similar to 1 pJ by using high-kappa dielectric (Al2O3). The successful control of ferroelectric polarizations in alpha-In2Se3 and its application in artificial synapses are expected to inspire the implementation of 2D ferroelectric materials for future neuromorphic systems.