Frequency dependence of the dynamic pyroelectric properties of Pb1-xLaxTi1-x/4O3 (PLT) ferroelectric thin films with various La concentrations

Modulation frequency dependences of the pyroelectric properties of PLT (Pb1-xLaxTi1-x/4O3) thin films with La concentrations of 5, 10, and 15 mol% have been investigated by using the dynamic method. The PLT thin film with 10 mol% of La (PLT(10) thin film) shows the best pyroelectric properties among the films. For PLT(10) thin films, the pyroelectric coefficient shows a maximum value of 6.6x10(-9) C/cm(2).K with no frequency dependence. The figures of merit for the voltage. responsivity and specific detectivity are 1.03x10(-11) C.cm/J and 1.46x10(-9) C.cm/J, respectively. The voltage responsivity corresponding to the pyroelectric voltage is almost constant at a low modulation frequency and decreases in proportional to the frequency at a high modulation frequency. The voltage responsivity is 5.15 V/W at 8 Hz. The noise equivalent power (NEP) and the specific detectivity (D*) of the PLT(10) thin film are 9.93 x 10(-8) W/Hz(1/2) and 1.81 x 10(6) cmHz(1/2)/W at a frequency of 100 Hz, respectively. These results indicate that PLT(10) thin films are very suitable for pyroelectric IR sensors.