Thin-Film Silicon Nanosheet-Based Neuromorphic Assemblies

We demonstrate neuromorphic behavior in silicon nanosheet (NS) assemblies. We utilized Cl- and H-passivated Si-NSs that were synthesized through topotactic deintercalation of the Zintl phase of CaSi₂ with concentrated HCl at -35 °C. We utilize a silicon-based platform in which we fabricated Au source-drain (S-D) electrodes on SiO₂/Si wafers by photolithography. We fabricated encapsulated assemblies of Si-NS between gold S-D electrodes at mesoscopic channel lengths (30-80 μm) using solution processing methods. The Si-NS assemblies exhibit novel neuromorphic characteristics in which spiking voltage inputs lead to decaying spiking current outputs, analogous to plasticity known for neuron-synapse systems. Decaying spiking current outputs follow a power-law decay (∼t^-β) with β ∼ 0.7-1.1. DFT and electron-trapping simulations suggest that such neuroplastic characteristics may arise from the charging and release of charge from Si-dangling bonds at the NS surfaces. Higher-frequency measurements also reveal an initial learning phase, where the spiking voltage outputs gradually build up to a maximum value, analogous to the potentiation process in neuron-synapse systems. These observed neuromorphic characteristics indicate that Si-NSs are a promising material for next-generation neuromorphic networks with immense potential for energy-efficient, brain-inspired computing.