We describe the optical properties of nonvolatile memory cells based on metal-insulator-semiconductor structures with embedded Pt nanoparticles, fabricated by atomic layer deposition. We show the effect of illumination on the static as well as dynamic properties of two devices, which differ by their respective thicknesses of the tunneling layer. The device with the thicker tunneling layer exhibits a faster response under illumination and significantly better retention properties, while the device with the thinner tunneling layer is faster under dark conditions. © 2002-2012 IEEE.