Thin film growth and characterization of Potassium-Tantalate-Niobate room temperature ferroelectric

Abstract

The primary objective in fabricating ferroelectric thin films is to duplicate the polar properties and characteristics of the corresponding bulk material. Potassium Tantalate-Niobate (KTN), KTa(,-,)Nb,03-, is a continuous solid solution between the perovskite compounds KNbO3 and KTaO3. The Curie temperature of KTN can be varied by a4justing x i.e.., the composition of niobium. In the vicinity of the ferroto-paraelectric phase transition, high dielectric permittivities, large pyroelectric as well as electro-optical and nonlinear optical coefficients can be observed. Bulk KTN single crystals synthesized from high temperature melts have limited device utility due to the occurence of lamellar growth, twins, etc. For these reasons thin films of KTN find enormous applications in spatial light modulators., pyroelectric devices, holographic storage., parametric oscillators and variable delay lines. The research undertaken involved the growth of KTN thin films on lattice matched substrates. The preferential groath directions, optimum growth conditions, ideal charge composition, and ideal regime in phase diagram were established. Liquidphase epitaxy (LPE) was the technique employed for the growth of thin films. The as grown films were optically and electrically characterized.