Pyroelectric Properties of the B-Polyvilnylidene Fluoride (PVDF) Thin Film Prepared by Vacuum Deposition with Electric Field Application

Abstract

Polyvinylidene fluoride (PVDF) thin film having β phase is prepared by vacuum deposition with electric field application and its pyroelectric properties are studied using a dynamic method to examine the possibility of its application to a pyroelectric IR sensor. The pyroelectric responses of the PVDF thin film are characterized as the frequency dispersion in both low and high modulation frequency regions, and their frequency dependences are observed. In the low frequency region (2–100 Hz), the polarization can easily rotate with the increase of modulation frequency and show the maximum since the reorientation rate of domains is higher than the modulation frequency. On the other hand, in the high frequency region (100–1000 Hz), the pyroelectric response decreases as the frequency increases, because the reorientation rate of domains is suppressed and thus, the change of polarization decreases. Pyroelectric coefficient, figure of merits for noise equivalent power and detectivity of the PVDF thin film are measured as 4.39×10-9 C/cm2·K, 7.72×10-10 C·cm/J, and 2.29×10-9 C·cm/J, respectively. Also, the noise equivalent and the detectivity are 1.66×10-7 W/Hz1/2, and 6.03×105 cm·Hz1/2/W, respectively.