Effect of rapid thermal annealing on the optical properties of Nb2O5-Al2O3 nanolaminate films

Nb₂O₅-Al₂O₃ nanolaminate films have been grown by atomic layer deposition using (Nb(OC₂H₅)₅)/H₂O, and Al(CH₃)₃/H₂O precursors, respectively. Effect of rapid thermal annealing (RTA) on the optical properties of the nanolaminate has been studied using Fourier transform infrared spectroscopy (FTIR), and spectroscopic ellipsometry. From the FTIR result, Al₂O₃ suppresses the formation of interfacial layer during RTA. The refractive index of the Nb₂O₅-Al₂O₃ films is found to increase after the RTA at 500°C, while decrease with the RTA temperature above 500°C. Moreover, the optical band gap of Nb₂O₅ film deduced from the extinction coefficient shows a gradual increase with increasing annealing temperature, which is related to a decrease in the film disorder.