Mn and Sb doped-PZT thin films for uncooled infrared detector array

Abstract

Mn and Sb doped-PZT (PMSZT) pyroelectric thin films have been fabricated on Si substrates for uncooled infrared detectors and thermal imaging heads. The electric properties of PMSZT thin films have been investigated. A pyroelectric coefficient p of 45 nC/cm2K, dielectric constant εr of 100, and dielectric loss tanδ of 0.01 at 25°C for the PMSZT thin films have been achieved. The PMSZT detectors exhibited high figures of merit Fv of 1768 cm2/C, and Fd of 0.048 cm3/J½ at 25°C. An IR detector array with the PMSZT thin film deposited on a YBCO microbridge structure for thermal isolation has been fabricated using micromachining techniques. The PMSZT detector with an air gap between the bottom electrode and Si substrates shows a larger voltage response than that of PMSZT detector without an air gap. At a 30 Hz frame frequency, a 3 times larger voltage response of a PMSZT detector with air gap, compared to that without an air gap, has been achieved. The PMSZT detectors with the relatively flat detectivity D*, ranging from 2.5×108 to 6.0×108 cmHz½/W in the 2.5–19.5 μm wavelength band indicate a potential for broad band IR detectors.