Multilevel Nanophotonic Resistive Switching in Ag-ITO-SiO2 on Silicon With Enhanced Optical Storage Density

Multilevel resistive devices have gained a lot of research attention in the past decade due to their attractive potential applications in high-density non-volatile memory, and unconventional computing. We propose an engineered multilevel nanophotonic resistive switching device with CMOS compatible Ag-ITO-SiO₂ structure on silicon for enhanced storage density and in-memory computing with optical readout functionality. The four-layered structure includes a SiO₂/ITO region strategically positioned between an efficient Ag (top) electrode and an underlying p-Si bottom electrode. The engineered nanophotonic device confined hybrid plasmonic mode, mainly in the SiO₂ region and with an applied voltage conductive filaments form/deform along ITO and SiO₂ layers influencing optical absorption detectable through interaction between the guided hybrid plasmonic mode and conductive filaments. The proposed device achieves stable multiple optical states by controlling compliance current, storing two bits without compromising accuracy to enable parallel computing, and efficient area savings with enhanced storing density for in-memory computing applications on a photonic platform. Additionally, the experimental results demonstrate a significant extinction ratio of 32 dB for the $10\ \mu \text{m} \times 500$ nm device with a low voltage operation. The engineered nanophotonic structure exhibits high retention, high endurance, low operating power, and high speed, making it suitable for various applications, including optical modulation, neuromorphic computation, biochemical sensing, photogating and high-density advanced memory devices.