Band gap determination using Tauc's plot for LiNbO < inf > 3 < /inf > thin films

Abstract

LiNbO3 thin films were deposited using RF magnetron sputtering technique. Structural studies confirmed the formation of LiNbO3 phase with minor Li deficiency. The RMS roughness and average grain size of the crystallized thin films was found to be in the range of 5.74 -26nm and 26 -152nm respectively. From Tauc's plot, it can be seen that the band gap energy is decreasing with increase in annealing temperature till 700 °C. At 750 °C, band gap is shifted towards blue end. The variation in band gap is primarily due to the Li vacancies and grain size effects which are explained by quantum confinement model.