Ferroelectric materials for thermal ir sensors state-of-the-art and perspectives

The current state of the art with respect to the development of materials for use in pyroelectric infra-red detectors is reviewed and their relevant properties are compared using the appropriate materials figures-of-merit with reference to the physics of their operation. The specific application of these materials to uncooled thermal imaging arrays is discussed and it is shown that the best materials for use in this application are those with high permittivities and high pyroelectric coefficients. The concept of using ferroelectrics in the region of Tc as dielectric bolometers is introduced and it is shown that lead scandium tantalate (PST) is one of the most promising materials for use in this mode. Finally, the technologies for direct deposition of the materials as thin films are introduced and compared and the results of using sol-gel technology for depositing PST thin films are presented.