PYROELECTRIC PBTIO3 THIN-FILMS FOR MICROSENSOR APPLICATIONS

Pyroelectric lead titanate (PbTiO3) thin films deposited by sol-gel processing have been characterized for possible use in microsensor applications. Based on a comparison of relevant properties with other IC-compatible pyroelectric materials, PbTiO3 possesses a very high pyroelectric coefficient over a wide operating temperature range. The measured pyroelectric coefficient at 297 K for PbTiO3 films with thicknesses ranging from 0.2 to 0.6 mum is in the range 75 to 96 nC/cm2 K. This paper presents the first use of PbTiO3 as a pyroelectric material integrated into a micromachined membrane structure. This composite structure offers a key advantage of implementing a low thermal mass for high-sensitivity pyroelectric detection. The measured blackbody voltage responsivity for a pyroelectric element with an active area of 4 x 10(-5) cm2 at 297 K and a chopping frequency of 100 Hz is 2.2 x 10(4) V/W. The normalized detectivity D* at 100 Hz is 1.0 x 10(9) cm Hz1/2/W. The response time measured by the pulsed laser-beam method for a device area ranging from 2 x 10(-6) to 7 x 10(-4) cm2 is in the range 2-20 mus.