Estudo das propriedades estruturais, elétricas e ópticas de filmes finos de Niobato de Sódio e Potássio (KNN), fabricados por deposição a laser pulsado (PLD)

Abstract

Environmental problems arising from lead toxicity in materials, such as those in lead zirconate titanate (PZT) have stimulate the search for new lead-free ferroelectrics materials with ferroelectric and piezoelectric characteristics comparable to those of PZT. Potassium sodium niobate (KNN) based materials are possible candidates to replace PZT materials in several applications because their high Curie temperature and high piezoelectric coefficients. Development of microelectronics and optoelectronics requires materials with multifunctional properties and low dimensionality, therefore studies in ferroelectric thin films with applications in ferroelectric memories, ferroelectric transistors, photovoltaic devices, electronic modulators, infrared detectors and varistors are necessary. The main object of this thesis, is the synthesis and characterization of morphological, electrical and optical properties of ferroelectric KNN and samarium doped KNN (KNN:Sm3+) thin films, deposited on three diferents substrates SrTiO3, MgO e Si/SiO2) by pulsed laser deposition method (PLD), in addition, a conductive layer of LaNiO3 was deposited on SrTiO3 substrate before deposition of the ferroelectric films for using as electrode and perform electrical characterizations including current leakage, which limits applications of ferroelectric thin films. Finally, photoluminescence measurements of samarium doped films were performed in order to investigate the interaction of this element with crystal structure of KNN, which provides information about possible multifunctional applications.