High-Performance Pyroelectric Infrared Detectors

摘要

We report on the fabrication of ultrathin self-supporting LiTaO_3 layers for high-performance pyroelectric single-element detectors. Thereby, only the area of the radiation-sensitive element is reduced to the desired thickness to keep the mechanical stability of the pyroelectric chip. This is done by an ion beam etching process at which a minimum thickness of 600 nm could be achieved. The small element thickness leads to a reduced heat capacity of the radiation-sensitive element resulting in a faster response. Time constants in the range of some milliseconds could be measured. Furthermore, the dielectric properties of the ultrathin lithium tantalate layers have been investigated. Measurements of the detector performance in vacuum revealed a maximum specific detectivity D~* of more than 5-10~9 cm Hz~(1/2) W~(-1).