Sputtered ferroelectric PZT thin films in pyroelectric infrared sensors

Abstract
PZT film of composition Pb(Zr_0.25 Ti_0.75)O₃ deposited on TiO₂/(111)Pt electrode is characterised by a strong (111) orientation. The self polarised films exhibit a pyroelectric coefficient of 2x10^-4 Cm^-2K^-1, a dielectric constant, ε' of 300 and a dielectric loss, tan δ of 0.01. These material properties, including a low tensile stress of the sensor layer stack of +110 MPa, and compatibility with standard Si technology, makes these ferroelectric films suitable for use in pyroelectric sensor arrays. Fabricated single element sensors with radiation sensitive area of 1 mm² exhibited at room temperature a specific detectivity of 3x10⁸ cmHZ^1/2 W^-1. An 11x6 sensor array has been developed for motion detection. The array pixels with a sensitive area of 0.0784 mm² have a NEP of less than 0.7 nW at 1 Hz.