Optical Properties of Lead-Free NKN Films from Transmission and Spectral Ellipsometry

authors	Schwarz, R; Santos, L; Ayouchi, R; Bhattacharyya, SR; Mardolcar, U; Leal, M; Kholkin, A
nationality	International
journal	FERROELECTRICS
author keywords	Band gap; optical transmission; spectral ellipsometry; NKN; thin film; PLD
keywords	THIN-FILMS; NIOBATE; CERAMICS
abstract	Thin films of lead-free NaxK1-xNbO3 (NKN) were prepared by pulsed laser deposition (PLD) from ceramic targets of stoichiometric NKN or doped with 6% of lithium niobate (LN). At a deposition temperature of 600 degrees C a strong dependence of film morphology on laser fluence is revealed by SEM microscopy. Optical properties like band gap and index of refraction were obtained through transmission measurements and analysis based on the Tauc model. The results were compared to spectral ellipsometry using a fit to the Tauc-Lorentz model, and slightly smaller band gap values were obtained. C-V characteristics of sandwich structures yielded high permittivity of 380 in pure NKN films and tunability at 1kHz of 3.2% at 1.5 MV/m applied electric field.
publisher	TAYLOR & FRANCIS LTD
issn	0015-0193
year published	2013
volume	446
issue	1
beginning page	118
ending page	127
digital object identifier (doi)	10.1080/00150193.2013.821018
web of science category	Materials Science, Multidisciplinary; Physics, Condensed Matter
subject category	Materials Science; Physics
unique article identifier	WOS:000324746300013