Physical and pyroelectric properties of tantalum-oxide-doped lead zirconium titanate [Pb0.9950(Zr0.525Ti0.465Ta0.010)O3] thin films and their application for IR sensors

Thin films of lead zirconium titanate [PbZr0.525Ti0.475O3 (PZT)] and 1% tantalum‐oxide‐doped lead zirconium titanate [Pb0.9950(Zr0.525Ti0.465Ta0.010)O3 (PTZT)] deposited on Pt(200)/SiO2/Si(100) using the dc unbalanced magnetron sputtering (DC‐UBMS) method have been investigated. The films were grown at deposition temperatures in the range of 300 °C to 750 °C for 3 hours, followed by annealing at 700 °C for 1 hour for each deposited film. Observations by X‐ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the physical and pyroelectric properties of the grown films. The films show tetragonal structure with preferred orientation to the (100) and (200) crystal planes. The calculated lattice constants are: a = b = 4.056 Å, c = 4.105 Å for PZT thin film; and a = b = 4.056 Å, c = 4. 068 Å for PTZT thin film. The physical properties extracted from the I–V curves show that the PZT and PTZT films are insulator or dielectric materials. The conductivity (σ) of PZT films is between 2.24 × 10−13 (Ω m)−1 and 5.00 × 10−12 (Ω m)−1, whereas the conductivity (σ) of PTZT films is between 1.02 × 10−9 (Ω m)−1 and 1.90 × 10−8 (Ω m)−1 for films deposited at the temperature ranges mentioned. The voltage responsivity (rv) measured at chopper frequency of 2000 Hz and at wavelength of 947 nm is 62.1–80 μV/W and 61–76.4 μV/W for PZT and PTZT thin films, respectively. Meanwhile, the pyroelectric coefficient (p) is in the range of 9.54 × 10−4 to 12.3 × 10−4 C/m2 K for PZT thin films and 9.35 × 10−4 to 11.7 × 10−4 C/m2 K for PTZT thin films. These results show that PZT and PTZT thin films are suitable for use as a pyroelectric infrared sensor. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)