ONLINE COVER An artist’s rendering of an optoelectronic memory device based on negative differential resistance (NDR) diodes and a micro-ring resonator. The coming end of Moore-like growth of computational power has increased focus on alternative computing architectures, such as electro-optical computing where light carries information in the circuit rather than electrons. Gherabli et al. demonstrate a fully CMOS-compatible electro-optical memory device, based on a new type of NDR-diode. The new diode is based on a horizontal PN-junction in silicon implemented into a photonic micro-ring resonator to create a bi-stable device with fully optical read-out in the telecom regime.