Ultrathin Aluminum Oxide Films Induced by Rapid Thermal Annealing for Effective Silicon Surface Passivation

A novel method of preparing ultrathin aluminum oxide films by rapid thermal annealing (RTA) treatment for effective silicon surface passivation is proposed. The high‐temperature RTA processing (750–825 °C) for tens of seconds in an oxygen atmosphere completely converts the thermally evaporated aluminum metal nanofilms (1–5 nm) on crystalline silicon to aluminum oxide (Al 2 O 3 ) films, with a thin SiO x layer formed at the interface between the silicon and the Al 2 O 3 . The generated Al 2 O 3 film can provide superior passivation quality for the silicon surface, even better than that obtained by the thermal atomic layer deposition technique. Moreover, the growth kinetics of the Al 2 O 3 passivating film indicates that it is a diffusion‐controlled activation process, with an energy barrier of 3.3 eV for aluminum ions diffusing across the metal/oxide interface.