Compositional and Optical Gradient in Films of PbZrxTi1-xO3 (PZT) Family

Abstract

Pb(ZrxTi1-x)O3 (PZT) (x = 0-1) films have attracted the attention of researchers for the past 30 years due to their excellent ferroelectric (FE) and electromechanical properties, which have led to the commercialization of thin PZT films for ferroelectric random access memory (FeRAM), forming a market of several millions USD annually. Ferroelectricity of perovskite oxide thin films, especially PZT thin films, can be exploited in semiconductor devices to achieve non-volatile random access memory (NVRAM) with high-speed access and long endurance, which can overcome the barriers, encountered in current semiconductor memory technologies. The ferroelectricity can be also exploited to voltage dependent and thermally sensitive resistors, gas and humidity sensors. Besides, due to large pyroelectric coefficient of PZT, it has drawn interest for use in pyroelectric devices (Izyumskaya et al., 2007; Muralt, 2000; Whatmore et al., 2003). PZT thin films have remarkable advantages over bulk materials: • Can be directly deposited on platinized silicon to allow direct integration with electronics; • Have superior electromechanical properties compared to other ferroelectric ceramics. Thanks to that, PZT films have formed an integral part of the microelectromechanical systems (MEMS) in various applications such as sensors, actuated micromirrors for finetracking high-density optical data storage mechanisms (Yee et al., 2001), and tunable capacitors for high-frequency microwave applications, microelectromechanical systems, infrared detectors, applications in optical devices, for instance, rugate filters (Bovard, 1990), anti-reflection coatings (Oulette et al., 1991), and electro-optic modulators, to name a few. Low density embedded FE memories are being considered for implementation not only in commercial devices, such as smart cards and cellular phones, but also for adaptive FE