Pyroelectric devices based on sputtered PZT thin films

After a short description of thermal conditions in a pyroelectric sensor, substantial requirements to pyroelectric thin film and sensor design are derived from the theoretical basics. A planar multi-target sputtering process is used to deposit PZT thin films for application in pyroelectric IR sensors. The self-polarized PZT are characterized by a pyroelectric coefficient p of 2.10(-4) Cm-2K-1, a dielectric constant epsilon' of 300 and a dielectric loss tan delta of 0.01. These material properties, including a low tensile stress of the sensor layer stack of +110 Mpa, as well as standard microelectronic technologies make the films suitable for the use in pyroelectric sensor arrays. Fabricated single-element sensors have a specific detectivity D-* (500K, 10 Hz) of 3.10(8) cmHz(1/2)W(-1). An 11x6 array sensor has been developed for motion detection. The array pixels with a sensitive area of 0.0784 mm(2) have a noise equivalent power NEP of less than 0.7 nW at 1Hz.