Thin Film Lithium Tantalate (TFLT) Pyroelectric Detectors

Abstract

Pyroelectric thermal detectors are excellent candidates for detection of broadband radiation. Such detectors utilize permanently poled ferroelectric single crystal lithium tantalate to generate a charge as the crystal heats up by absorbing radiation. The charge, which results in a current output when connected to an external electrical circuit, is directly proportional to the rate of change of temperature of the crystal. The fundamental approach toward enhancing pyroelectric detector response is to form the pyroelectric material into a thin film. An elegant approach for producing bulk quality thin films of pyroelectric materials is by crystal ion slicing. In this paper, we report on the formation of thin film lithium tantalate (TFLT™) pyroelectric detector devices using the ion slicing process. The devices incorporate films less than 9 microns thin and feature apertures as large as 5 mm in diameter. To make functional detectors, ion sliced films were transferred to ceramic carriers in TO-type can test packages. Test results have shown improvement in room temperature detectivity about 20 times higher than the state-of-the-art lithium tantalate pyroelectric detectors.