Broadband, reconfigurable photonic memristors set the stage for next-generation artificial vision systems.

Artificial vision systems that combine image sensing, memory, and processing in one compact platform are a step closer to real-world application following a major advancement led by researchers at KAUST. The team has developed high-performance, light-controlled memory devices, or photonic memristors, that mark a significant step toward energy-efficient, integrated ‘smart vision’ hardware.

Memristors exhibit a resistance that varies with applied current flow and retain this resistance even when the current is turned off. Their ability to remember resistance based on past current flow enables memory and computation in one component, which is essential for data storage and neuromorphic computing. They display two distinct brain-like resistive switching modes: non-volatile and volatile modes, mimicking long-term and short-term memory, respectively.

Typically, memristors comprise metal-oxide thin films that respond to electrical stimuli but have several manufacturing challenges and performance limitations. Photonic memristors use light, a low-power, non-destructive, and contactless stimulus, to trigger switching, which provides a fast and energy-efficient alternative to conventional devices. The devices that contain atomically-thin two-dimensional materials, such as hexagonal boron nitride (hBN), feature excellent thermal stability, mechanical flexibility, and transparency. However, they are limited to narrow wavelength ranges and work in a single mode.

To harness hBN’s exceptional thermal stability and silicon’s light-absorption capabilities, an international team led by Maolin Chen, Xixiang Zhang, and with co-workers from KAUST have created photonic memristors by combining both materials in a layered arrangement.

The researchers produced uniform nanocrystalline hBN films using a low-temperature process called plasma-enhanced chemical vapor deposition to ensure compatibility with existing silicon-based manufacturing. They incorporated the films into memristor arrays on four-inch wafers, which is consistent with the scalability of the devices to industrial applications.

“Our memristors enable ‘all-in-one’ vision chips: they include image sensing, data storage, and parallel processing,” Chen says. In addition to high memory stability and durability, the devices exhibit a switching ratio exceeding one billion.

Read more at KAUST Discovery.