(Invited) Functional Complex Oxides for Next-Generation Logic, Memory, Sensing, and Beyond

Abstract

Complex-oxide materials possess a range of interesting properties and phenomena that make them candidates for next-generation devices and applications. But before these materials can be integrated into state-of-the-art devices, it is important to understand how to control and engineer their response in a deterministic manner. In this talk, we will discuss some of the state-of-the-art science, engineering, and utilization of complex ferroic materials and their potential for emergent order and phenomena that can enable new device function. We will explore the role of the epitaxial thin-film growth process and the use of epitaxial constraints to engineer a range of systems with special attention to ferroelectric (i.e., materials with robust spontaneous polarization that can be switched with an electric field thereby producing a ferroelectric hysteresis loop), antiferroelectric (i.e., materials which have an antiparallel alignment of polarization (or are non-polar) in the ground state but can be switched to a polar (parallel) order by an external electric field producing a reversible antiferroelectric-to-ferroelectric phase transition and a characteristic double polarization-electric-field hysteresis loop), and relaxor (i.e., chemically complex materials that exhibit a competition between short- and long-range interactions such that it produces a complex, dynamic polarization structure and exotic properties) materials.In recent years, the use of epitaxial constraints has enabled the production of model versions of these complicated materials and the subsequent deterministic study of an array of physical phenomena that are now being widely considered for next-generation applications. Specifically, we will investigate the potential of ferroelectric materials for non-volatile, ultra-low voltage memory and logic applications including their use in ferroelectric-field-effect transistors, the realization of multi-state/neuromorphic function, and more. In turn, we will explore how antiferroelectric and relaxor thin-film materials can open the door to a new generation of thin-film based electromechanical, sensing, high-frequency, and capacitive-energy-storage devices. Along the way we will leverage advanced thin-film growth techniques to control the materials and to solicit new insights about their function, apply state-of-the-art characterization methods, including unique in operando studies under applied stimuli, to understand how materials function, and explore how such materials can be integrated and utilized in realistic device structures. We will try to introduce the listener to these complex materials and their potential for new applications – in effect working to motivate engineers to explore these materials. The discussion will range from the development of fundamental understanding of the physics that lies at the heart of the observed effects, to an illustration of routes to manipulate and control these effects, to the demonstration of rudimentary solid-state devices based on these materials.