New pyroelectric phenomena from graded ferroelectric barium strontium titanate thin films

In this study we explored the potential application of graded ferroelectric thin films in uncooled pyroelectric detectors. We built a magnetron sputter system, and developed a method of deposited compositional graded ferroelectric thin films using rf magnetron sputtering, a silicon compatible thin film fabrication process. By obtaining giant effective pyroelectric coefficients from graded ferroelectric BST thin films, we demonstrated their potential in fabricating low cost high sensitive uncooled pyroelectric infrared detectors. Structure and properties of the graded ferroelectric BST thin films were characterized using various techniques, and were correlated with each other. The basic physics of the new pyroelectric effects from the graded thin film devices were investigated, and a phenomenological model was proposed to explain the experimental observations. The model not only successfully explained the experimental results previously observed, but also correctly predicted the results of some newly designed experiments. From our current understanding of the origin and mechanism of the new pyroelectric phenomena discussed in this study, we proposed to further simplify the structure of future pyroelectric infrared detectors by adopting a new operational mode