Tailoring of physical properties of (K,Na)NbO3 thin films using lithium ion implantation

Abstract

The present study demonstrates the tuning of structural, topography, and luminescence properties of 30 keV Li-ion implanted (K,Na)NbO3 thin films synthesized using RF sputtering. The Li-ion implantation of KNN films was carried out at different ion fluences such as 3 × 1014, 1 × 1015, 3 × 1015, and 1 × 1016 ions/cm2. The crystallinity of KNN perovskite structure gets reduced, and (001) plane shifted towards the lower angle due to implantation-induced defects. The uniform and well-shaped morphology feature evolved after ion implantation, and the correlation length gets decreased upon implantation. The improvement in transmittance of KNN films after implantation is minimal, and the optical band gap is increased with fluence. The relative PL intensity of films in the ultraviolet region increases exponentially, and the intensity of implanted sample at 1 × 1016 ions/cm2 is more than doubled that of the pristine sample. An increase in the carrier lifetime is evident after ion implantation, and a maximum of ∼12 ns is achieved for films implanted at 1 × 1015 ions/cm2, and the relative contribution of the slow decay component is increased after implantation. Therefore, the physical properties of KNN thin films can be tuned systematically using Li-ion implantation and the results imply the possible use of KNN for optoelectronic applications.

Keywords

• KNN matrix
• Sputtering
• Ion implantation
• Band gap
• Luminescence