FERROELECTRIC PROPERTIES AND PHASE STABILITY IN POTASSIUM NITRATE-POLYMER COMPOSITE FILMS

Abstract

Ferroelectric materials have attracted an immense interest due to their vital role in electronic industry with their wide variety of applications as ferroelectric devices. Many ferroelectric materials, such as, barium titanate (BaTiO3), barium strontium titanate (BST), potassium-di hydrogen phosphate (KDP), potassium nitrate (KNO3), Lithium niobate (LiNb03), lead zirconate titanate (PZT), strontium bismuth tantalate (SBT), strontium barium niobate (SBN) and tri-glycine sulphate (TGS) etc, have been studied in a variety of forms like, single crystal, pellet and thin film for the use of these materials in memory devices operated at low voltage. Usually the ferroelectric materials has very high coercive field (—few kV/cm). Therefore it is necessary to fabricate these materials in thin film form. These ferroelectric materials are usually brittle and show difficulties for fabrication in thin film form. In the recent past, thin films of many ferroelectric materials have been fabricated by various methods viz., sputtering, pulse laser deposition (PLD), pulse laser ablation (PLA), metal organic chemical vapor deposition (MOCVD), chemical solution deposition (CSD), metal organic decomposition (MOD), molecular beam epitaxy (MBE) and sol-gel. Another advantage of obtaining ferroelectrics in thin film form is the possibilities of its integrate to the CMOS. This has been exploited to fabricate dynamic random access memories (DRAMs), nonvolatile random access memories (NV-RAMs) and ferroelectric random access memories (FRAMs). Thin film transistors such as metal ferroelectric semiconductor field effect transistor (MFSFET) has also been fabricated and studied. There are many other applications of thin film ferroelectric materials as voltage tunable dielectric capacitor in resonators and filters. Also recently thin film ferroelectrics arc finding increasing use in micro electronic mechanical systems (MEMS) in producing highly sensitive actuators and sensors with low noise.