  The current work proposes a novel scheme for developing a light-activated
non-filamentary memristor device by fabricating an Au-nanoparticle embedded
HfO$_2$-bilayer/p-Si MOS structure. Under illumination, the electrons in such
embedded Au-nanoparticles are excited from d-level to quantized s-p level and
are swept out on application of an appropriate gate bias, leaving behind the
holes without recombination. Such photogenerated holes are confined within the
nanoparticles and thus screen the external field to lead to a memristive effect
in the device. The phenomenon is experimentally observed in the fabricated
Pt/HfO$_2$-(layer-II)/Au-NPs/HfO$_2$-(layer-I)/p-Si devices, where such
memristive effect is activated/deactivated by light pulses. The memory window
and high-to-low resistance ratio of the device are obtained to be ~1 V and ~10,
respectively, which suggest the performance of a standard state-of-the-art
memristor. Further, the present device offers a voltage-sweep-endurance up to
at least 150 cycles and the memory retention up to ~10,000 s. Such a device
concept can be extended for a combination of different nanoparticles with
various dimensions and dielectric layers to optimize their memristive effect
for achieving CMOS-compatible memory devices with superior reliability.
