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The effect of annealing temperature on surface roughness and certain optical characteristics of sol-gel spin-coated Nb2O5 thin films

T. ATASER1,* , N. AKIN SONMEZ1,2, T. ASAR1,3, S. OZCELIK1,2,*

Affiliation

  1. Photonics Application and Research Center, Gazi University, 06500 Teknikokullar, Ankara, Turkey
  2. Department of Photonics, Faculty of Applied Sciences, Gazi University, 06500 Teknikokullar, Ankara, Turkey
  3. Department of Physics, Faculty of Science, Gazi University, 06500 Teknikokullar, Ankara, Turkey

Abstract

Nb2O5 thin film was coated onto SLG substrate by sol-gel spin-coated technique and sintered at 120 ˚C, and was named as as-deposited film. Then, pieces of the sample were annealed at different temperatures (200-600 ˚C) to investigate the effect of annealing temperature on surface roughness and certain optical characteristics of the films. The structural and morphological properties of the as-deposited and annealed films were investigated by XRD and AFM measurements and were associated with optical results. The optical properties of the films were further examined by using UV-Vis spectra and calculating optical constants and parameters. The annealing temperature affected on absorption coefficient (α), extinction coefficient (k), refractive index (n) and dielectrics (εr, εi) of the films. It was observed that the surface roughness and particle size of the films as well as the optical constants increased with the annealing temperature. In addition, the optical band gap energy (Eg) of the films red-shifted with increasing annealing temperature, while Urbach energy (EU) and electron-phonon interaction (Ee-p) increased. The most important outcome of this work is that annealing temperature can be used to tune the mentioned optical characteristics of the Nb2O5 films. Furthermore, the results obtained indicated that Eg of the films can be increased up to 4.58 eV by controlling disorders in the band gap region for several optical applications..

Keywords

Nb2O5 thin films, Sol-gel spin-coating, Annealing temperature, Surface roughness, Optical characteristics.

Submitted at: Aug. 23, 2021
Accepted at: April 8, 2022

Citation

T. ATASER, N. AKIN SONMEZ, T. ASAR, S. OZCELIK, The effect of annealing temperature on surface roughness and certain optical characteristics of sol-gel spin-coated Nb2O5 thin films, Journal of Optoelectronics and Advanced Materials Vol. 24, Iss. 3-4, pp. 151-161 (2022)