PNNL

Abstract

Dielectric thin films have numerous applications in optical, semiconductor, sensor, and display technologies. These materials are the backbone of all dielectric coating technologies. In previous columns I have addressed the measurement of the optical properties of optical and semiconductor materials. But what determines the optical properties of these materials? The answer is basically the same as for electrical properties. Energy band structure, interband transitions, and defect states due to impurities and imperfections all contribute to the optical properties. Optical properties (refractive index and extinction coefficient) can be defined by a complex dielectric constant (refractive index and absorption coefficient), which in turn is related to the physical properties mentioned above. Most dielectric materials have wide wavelength ranges of transparency (low absorption).