Electrically writable silicon nanophotonic resistive memory with inherent stochasticity

Abstract

An electrically writable resistive memory with optical readout based on silicon nanophotonic structure is proposed. Hybridization of optical and surface plasmonic modes in the device enables nanoscale optical confinement to efficiently detect the resistive memory effect in a 13 nm thick SiO₂ layer sandwiched between p-type silicon and gold. Electrical write and optical readout capabilities of the proposed device are experimentally demonstrated with well-defined optical and electrical hysteresis curves at a wavelength of 1550 nm. The p-type silicon carries multifold benefits-it provides low propagation loss and a defect-free interface resulting from thermally (locally) grown oxide; the combination of p-silicon, SiO₂, and gold results in a self-rectifying operation to enable the realization of a memory stack. An on-off extinction ratio of 10 dB is demonstrated for a 5 mm long device. The proposed device shows an inherent stochastic property where the set (writing) voltage reduces in each set-reset cycle, which can be used for optical readout of synaptic weight for neuromorphic computations.