Nanophotonic resistive switch based on tapered copper-silicon structure with low power and high extinction ratio

A non-volatile nanophotonic resistive switch in tapered copper-on-silicon structure is proposed with a potential of electrical writing and optical readout. Incorporating tapered hybrid plasmonic structure in the device enables variable areas of the density of conduction filaments in the direction of optical propagation causing enhanced interaction of light with the lossy metal filaments. The tapered Cu-SiO2-Si is shown to have large optical extinction ratio where high mobility of copper ions in thin SiO2 leads to the low power operation. Optical readout of the resistive switching is demonstrated in the 10 nm thin ion conducting layer (SiO2) at a 1550 nm wavelength with well-defined hysteresis curve. Switching between off and on states is attained by voltage induced annihilation/formation of the nanoscale metal filament inside a thin layer of SiO2 sandwiched between copper and silicon. An optical extinction ratio of 18 dB is reported for a 30 μm long device. In addition, the proposed nanophotonic switch exhibits an intrinsic stochastic property of set voltage reduction in each set-reset cycle. High extinction ratio, reduced set voltage, low power consumption, and non-volatility make the device excellent choice for applications in realizing ultra-compact on-chip devices for optical switching, modulation, and neuromorphic computing.