Lateral anodic oxidation of nanoscale aluminum films

Abstract

This communication introduces the electrochemical lateral oxidation of nanoscale aluminum layers into self-powered thin-film structures. A thin aluminum layer (d=20nm) is electrochemically oxidized in one direction in space at remarkable mild conditions (Δφ<1V and aqueous 0.1M NaCl). The time-dependency of this process is controlled by very small electrolyte flows inside the layer structure, the velocities of which are on the order of a few femtoliters to several hundred attoliters per second. The observed optical self-writing effect, which results from a sharp opaque-to-clear transition of the oxidized layer, allows arbitrary optical information to be displayed over time. Because the system works in a self-consuming mode without any external power source, it may provide the basis for a new kind of smart labeling system with time-dependent display functions.