Finite element analysis of transverse size effect on the pyroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3 -PbTiO3 thin film for infrared array applications

Abstract

Exploring and revealing the influence of the pyroelectric thin film array element size on its structure and pyroelectric performance is crucial for designing integrated pyroelectric infrared detectors. In this work, the transverse size effect on the piezoelectric, dielectric, and especially the pyroelectric properties for a new-generation relaxor ferroelectric material Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIMNT) was studied by a finite element method. The lateral size-dependent piezoelectric and dielectric properties of the PIMNT thin film indicated that with the decrease in the transverse size, the piezoelectric constant d33 and relative dielectric constant ϵr increased substantially. The piezoelectric constant d33 and relative dielectric constant ϵr along ⟨001⟩ and ⟨011⟩ orientation increased faster than those along ⟨111⟩. A critical aspect ratio (in this paper, it was defined as radius/thickness) was found around 1:1 for three directions. We further discovered that the pyroelectric coefficient for PIMNT thin film along the ⟨111⟩ direction (the best crystallographic orientation for pyroelectric performance) decreased from 8.5 × 10−4 to 8.0 × 10−4 C/(m2·K) with the aspect ratio down to 0.01. The variation of the piezoelectric, dielectric, and pyroelectric properties originated from the declamping of the PIMNT thin film from the substrate. This finding gives insight into the transverse size effect on the electrical properties of new-generation relaxor PIMNT thin film and provides a guidance for designing high-performance infrared array detectors.