Activation and Deactivation of Silicon Surface Passivation by Niobium Oxide Films

Abstract

Niobium oxide (Nb2O5) films can provide excellent passivation for crystalline silicon (c‐Si) surface after postdeposition annealing, however, its kinetic behavior and mechanism have not been explored. Herein, it is demonstrated that surface passivation by solution‐processed Nb2O5 films can be activated by low‐temperature annealing (<200 °C) within several minutes, with the activation energy of 0.40 and 0.57 eV for hydrofluoric acid (HF) and RCA pretreated surfaces, respectively. Moreover, passivation is deactivated by higher‐temperature annealing (>350 °C), with the deactivation energy of 0.86 and 1.06 eV for HF and RCA pretreated surfaces, respectively. The results combined with surface‐sensitive X‐Ray photoelectron spectroscopy (XPS) measurements indicate that the passivation kinetics of Nb2O5 on the surface of c‐Si are strongly related to the diffusion of hydrogen into and out of the Nb2O5/c‐Si interface.