Investigation of annealing effects on structural, morphological, optical, chemical, and luminescent properties of (K,Na)NbO3 thin films

Here, (K,Na)NbO3 (KNN) films were synthesized using RF sputtering under Ar:O-2 (3:1) environment, and eventually annealed by rapid thermal annealing (RTA), and conventional furnace annealing (CFA), at different temperatures. Crystalline films are observed with the evolution of well-shaped regular features of KNN perov-skite after annealing, but the growth scenario is different in RTA and CFA. XPS results reveal the formation of an additional hump of Nb sub-oxides upon annealing via both processes. The transmittance of RTA films is higher than CFA ones where RTA@800 degrees C sample exhibits maximum transmittance with a sharp absorption onset. The band gap is reduced with annealing temperature and it gets decreased to a minimum of 3.19 eV for CFA@800 degrees C films. The samples exhibit an intense PL emission in the ultraviolet region, and the intensity of RTA films is much higher than CFA. A high decay lifetime of RTA films indicates the suppression of non-radiative decay channels.

Automated summary

(K,Na)NbO3 (KNN) films were synthesized using RF sputtering under Ar:O-2 (3:1) environment and annealed by rapid thermal annealing (RTA) and conventional furnace annealing (CFA) at different temperatures. Crystalline films with well-shaped regular features of KNN perov-skite were observed after annealing, but with different growth scenarios in RTA and CFA. XPS results showed the formation of additional Nb sub-oxides upon annealing through both processes. The transmittance of RTA films was higher than CFA films, and the RTA@800 degrees C sample exhibited the highest transmittance with a sharp absorption onset. The band gap decreased with annealing temperature, reaching a minimum of 3.19 eV for CFA@800 degrees C films. The samples exhibited intense PL emission in the ultraviolet region, with RTA films showing much higher intensity compared to CFA films. The high decay lifetime of the RTA films indicated suppression of non-radiative decay channels.