Studies on the Characteristics and the Effect of Thickness on the Band Gap Energies of Al_2O_3 Thin Films Prepared by PLD

摘要

Pulsed laser deposition (PLD) method has the advantages of high quality mirror finish, good densification and uniform thickness. In this work, Al_2O_3 thin films with different thicknesses were fabricated via the PLD method. The characteristics of the thin film samples were investigated using Grazing Incidence Diffraction (GID) technique and Field Emission Scanning Electron Microscope (FESEM). For the band gap studies, measurements were done using a UV-Vis NIR spectrophotometer. The deposition was done in the presence of oxygen gas with partial pressure of 2.66 Pa. FESEM images showed high quality, smooth and dense films obtained using the PLD method. The Al_2O_3 thin films have thicknesses of between 71.2 nm to 176 nm. The band gap energies obtained were in the range of 6.29 eV to 6.49 eV. It was observed that the band gap of the thin films increases as the thickness decreases due to the defects in the films.