Growth of Metal Oxide Nanostructures by Thermal Oxidation of Metals Under Influence of External Electric Fields and Electric Current Flow

Abstract

Thermal oxidation of metals in a furnace or a hot plate is a simple and low‐cost method to grow nanowires and other nanostructures of oxides of technological interest. In comparison with evaporation–deposition techniques based on vapor–solid (VS) or vapor–liquid–solid (VLS) mechanisms, thermal oxidation is a more direct and easy technique but does not normally lead to the formation of complex heterostructures or ternary oxides. Application of an external electric field at the sample during thermal oxidation has been used to improve the control of the nanowire dimensions, or final concentration on the starting metal surface. Other approach to grow oxide nanowires during the oxidation process is to heat the sample by Joule effect by the flow of a high‐density electric current in a metal wire. Joule heating has been found to reduce the growth time, typically some hours in thermal oxidation or evaporation–deposition methods, to few seconds or minutes. Herein, the results of representative articles on nanowire growth during thermal oxidation under the presence of an electric field and on the growth during Joule heating are summarized in the frame of mechanisms of stress relaxation‐driven ion diffusion and of thermally assisted electromigration.