Improved ferroelectric and pyroelectric properties in Mn-doped lead zirconate titanate thin films

We have investigated the effects of Mn doping on the ferroelectric and pyroelectric properties of Pb(Zr0.3Ti0.7)O-3 (PZT) thin films on substrates Pt/Ti/SiO2/Si. The Mn-doped (1 mol %) PZT (PMZT) showed almost no hysteretic fatigue up to 10(10) switching bipolar pulse cycles, coupled with excellent retention properties. We present evidence that while a low permittivity interfacial layer forms between the Pt electrode and PZT films, this does not occur in PMZT. We propose that Mn dopants are able to reduce oxygen vacancy mobility in PZT films and Mn2+ ions consume the oxygen vacancies generated during repeated switching, forming Mn4+ ions. These mechanisms are probably responsible for their low observed fatigue characteristics. Mn doping brings additional benefits to the electrical properties of PZT films. The relevant pyroelectric coefficients (p) of a 700 nm thick film are 3.52x10(-4) C m(-2) K-1 and detectivity figures of merit F-D=3.85x10(-5) Pa-0.5 at 33 Hz for Mn-doped PZT, compared with p=2.11x10(-4) C m(-2) K-1 and F-D=1.07x10(-5) Pa-0.5 for the undoped PZT films. This means that the Mn-doped PZT thin films are excellent candidates as device materials for both memory and pyroelectric applications. (C) 2003 American Institute of Physics.