Light-controlled nanoscopic writing of electronic memories using the tip-enhanced bulk photovoltaic effect.

The light control of non-volatile nanoscale memories could represent a fundamental step towards novel optoelectronic devices with memory and logic functionalities. However, most of the proposed devices exhibit insufficient control in terms of the reversibility, data retention, photosensitivity, limited-photoactive area, etc. Here, in a proof-of-concept work, we demonstrate the use of tip-enhanced bulk photovoltaic effect (BPV) to realize programmable nanoscopic writing of non-photoactive electronic devices by light control. We show that electronic properties of solid-state memory devices can be reversibly and location precisely manipulated in nanoscale using the bulk photovoltaic effect in combination with the nanoscale contact connection, i.e, atomic force microscopy (AFM) probe technique in this work. More than 105 % reversible switching of tunnelling electroresistance of ferroelectric tunnel junctions is exclusively achieved by light control. Using the same light-controlled AFM probe technique, we also present precise nanoscopic and multiple-state writing of LaAlO3/SrTiO3 two-dimensional electron gas (2DEG) based field-effect transistors. The tip-enhanced BPV effect can offer a novel avenue for reversible and multistate light control of a wide range of electronic memory devices in nanoscale and may lead to more sophisticated functionalities in optoelectronic applications.