Pyroelectric, ferroelectric and dielectric properties of Mn and Sb-doped PZT thin films for uncooled IR detectors

Abstract

Mn and Sb-doped Pb(Zr,Ti)O 3 (PMSZT)/YBa 2Cu 3O 7− y (YBCO) heterostructures grown on Si substrates have been investigated for IR detector arrays. The epitaxial PMSZT films deposited on c-oriented YBCO conducting electrodes show “self polarization” behavior and high IR responsivity even without poling. An asymmetric hysteresis loop and C– V curve show that the original polarization state of the capacitors is pointing towards the top electrode in the PMSZT film, and perpendicular to the YBCO thin film. Doping with Mn and Sb has been shown to enhance the pyroelectric and dielectric properties of PZT for enhanced IR sensitivity. The PMSZT IR detectors were examined for their pyroelectric coefficient and their detectivity D*. The PMSZT thin films have relatively high pyroelectric coefficient of 45 nC cm −2 K at 25°C and 148 nC cm −2 K at 90°C. The PMSZT detector shows detectivity D* values from 2.5×10 8 to 6.0×10 8 cmHz 1/2 W −1 in the 2.5–19.5 μm wavelength range.