SURFACE-MICROMACHINED PBTIO3 PYROELECTRIC DETECTORS

Lead titanate (PbTiO3) thin-film pyroelectric infrared detectors have been fabricated on polycrystalline silicon micromechanical membranes. Pyroelectric PbTiO3 thin films of thickness ranging from 0.2 to 0.6-mu-m were prepared by sol-gel spin casting techniques and deposited on 1.0-mu-m-thick polycrystalline silicon membranes suspended 1.0-mu-m above the surface of a silicon wafer. This composite structure offers high sensitivity and low thermal mass. The measured pyroelectric coefficient for 0.36-mu-m-thick PbTiO3 films is 90 nC/cm2 K. The measured blackbody voltage responsivity for a pyroelectric element with an active area of 7 X 10(-4) cm2 at 297 K and a chopping frequency of 50 Hz is 4.2 X 10(4) V/W. The measured normalized detectivity D* at 297 K and 50 Hz is 1.0 X 10(9) cm Hz1/2/W.