Abstract

Ceramic materials contribute important component functions, including resistance, capacitance, magnetic inductance, and environmental sensing to a variety of microelectronics applications. The material choice may be based on dominant magnetic, ferroelectric, piezoelectric, pyroelectric, electrooptic, electrochemical, mechanical, or thermal properties, but the underlying function of primary importance is the electrical conductivity, which determines overall insulation behavior and device utility. Since the components are typically shaped by ceramic processes, understanding of their properties require detailed knowledge of the composition, crystal structure, microstructure, and processing conditions. The role of defects and substitution (stoichiometry) is important also in controlling electrical conduction, especially for materials containing one or more cations of variable valence. Defects likewise play a major role in the performance of ceramic sensor devices, which serve as the detecting or switching element in many circuit operations. The sensing operation is typically based on a sharp change in electrical conduction, which reflects a significant change in the thermal, chemical, mechanical, optical, electrical, or magnetic environment of the device. In this article, the basic definitions of electrical terms relating to conduction, dielectric, magnetic, and sensor properties are presented, but the primary focus is on the influence of the materials characteristics on the electrical properties detailed above, with emphasis on the electrical conductivity mechanisms for the different categories of materials.