Light-activated resistance switching in SiOx RRAM devices

Abstract

We report a study of light-activated resistance switching in silicon oxide (SiOx) resistive random access memory (RRAM) devices. Our devices had an indium tin oxide/SiOx/p-Si Metal/Oxide/Semiconductor structure, with resistance switching taking place in a 35 nm thick SiOx layer. The optical activity of the devices was investigated by characterising them in a range of voltage and light conditions. Devices respond to illumination at wavelengths in the range of 410–650 nm but are unresponsive at 1152 nm, suggesting that photons are absorbed by the bottom p-type silicon electrode and that generation of free carriers underpins optical activity. Applied light causes charging of devices in the high resistance state (HRS), photocurrent in the low resistance state (LRS), and lowering of the set voltage (required to go from the HRS to LRS) and can be used in conjunction with a voltage bias to trigger switching from the HRS to the LRS. We demonstrate negative correlation between set voltage and applied laser power using a 632.8 nm laser source. We propose that, under illumination, increased electron injection and hence a higher rate of creation of Frenkel pairs in the oxide—precursors for the formation of conductive oxygen vacancy filaments—reduce switching voltages. Our results open up the possibility of light-triggered RRAM devices.

Silicon Oxide (SiOx): A Promising Material for Resistance Switching?

“…Table 1 summarizes the current state‐of‐the‐art switching metrics, including electroforming voltage, operational voltages (both sweeping and pulsing), endurance, retention, and resistance contrast ratio, for various instances of SiO x ReRAM devices. Additional functionalities, such as high‐temperature retention (250 °C or more), multiple stable resistance states, high self‐rectification, in‐built nonlinearity, suitability for flexible and transparent electronics, quantized conductance, neuromorphic functionalities, and optically driven switching, have all been reported. This table highlights the suitability of intrinsic silicon oxide for nonvolatile memories.…”

Percolation Threshold Enables Optical Resistive‐Memory Switching and Light‐Tuneable Synaptic Learning in Segregated Nanocomposites

“…To date, relatively few optical memristors have been reported, with most applying photoconductive effects, inherent to many semiconductors, to induce resistive memory switching . For example, a photocurrent has been used to shift the resistance of the high‐ and low‐resistive switching states as well as the threshold voltage for switching . In these devices the optical and electrical switching have similar origins and result from the charging and discharging of the same long‐lived trapped states, which raise and lower the barrier for charge transport across an interface.…”

Memristors—From In‐Memory Computing, Deep Learning Acceleration, and Spiking Neural Networks to the Future of Neuromorphic and Bio‐Inspired Computing

“…For example, optical control of memristive devices could potentially bring additional benefits in terms of higher bandwidth, lower cross talk, faster operational speeds, and integrate sensing together with memory and processing. [128][129][130][131] Integration of multiple functionalities in a compact nanodevice could lead to even better power efficiency of neuromorphic systems, such as artificial retinas. [132] The progress report presents a broader landscape of ways memristors could be utilized for future computing systems.…”