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


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.



subject category

Materials Science; Physics


Schwarz, R; Santos, L; Ayouchi, R; Bhattacharyya, SR; Mardolcar, U; Leal, M; Kholkin, A

our authors


This work was supported by Fundacao para a Ciencia e a Tecnologia (FCT) through pluriannual funds for ICEMS, through projects PTDC/FIS/108025/2008 and PTDC/CTM-CER/115085/2009. We are grateful to Radeshyam Rai for target preparation. M.L. and S.B. acknowledge research scholarships from FCT. S.B. would like to acknowledge with thanks the support of the staffs and colleagues at S.V. College, W.B., India.

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