Activation and Deactivation of Silicon Surface Passivation by Niobium Oxide Films

Niobium oxide (Nb 2 O 5 ) 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 Nb 2 O 5 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 Nb 2 O 5 on the surface of c-Si are strongly related to the diffusion of hydrogen into and out of the Nb 2 O 5 /c-Si interface.