Q-switched Nd: YAG fundamental and second harmonic wavelengths impact on preparing Nb₂O₅ thin films by a PLD technique: a comparative study

We aim to study and investigate the structural, optical, topographical, and morphological properties of Nb₂O₅ thin films deposited under vacuum Q-switched Nd: YAG pulsed laser for the first time to the best of our knowledge. The obtained results of this study can contribute in different fields of applications including the optoelectronic and biomedical fields. The fundamental (1064 nm) and the visible second harmonic (532 nm) wavelengths were utilized for this purpose. The laser energy was fixed at 657 mJ. The number of pulses and the substrate temperatures were 200 laser shots and 450 ºC, respectively. The observed X-ray diffraction patterns were assigned for T-Nb₂O₅ that refers to the orthorhombic and H-Nb₂O₅ which is related to the monoclinic phases supported by Raman spectra analyses. Nb₂O₅ thin film deposited by Nd: YAG fundamental wavelength (1064 nm) showed a thicker film, a higher surface roughness and, on average, a larger particles size It also provided better matching of the lattice d-spacing with the standard d-spacing obtained by JPCDs cards 00-030-0873 and 00-009-0372. The optical properties including the band gap values for both direct and indirect transitions were estimated with the lower gap was reported for the thin film prepared at the fundamental wavelength. The photoluminescence analyses supported that the transitions of both prepared films were indirect. FE-SEM clarified the surface morphology of each prepared film. The EDX analyses provided the elemental compositions and the purity of the Nb₂O₅ prepared films.