Effect of operating temperature and film thickness on the pyroelectric response of ferroelectric materials

摘要

The influence of the operating temperature and film thickness on the pyroelectric properties of (001) Ba_(0.6)Sr_(0.4)TiO_(3) (BST 60/40) epitaxial films on (001) LaAlO_(3), MgO, and Si substrates is investigated theoretically via a thermodynamic model. The results are presented using contour maps that can be used to identify "design windows" for film thickness and operating temperature for optimum pyroelectric response. For BST 60/40 on LAO and MgO large pyroelectric coefficients (～0.7 μC cm~(-2) K~(-1)) are observed at near room temperature for moderate film thickness (50-200 nm). The pyroresponse of films on Si is suppressed by two orders of magnitude compared to bulk BST 60/40 due to internal stresses. Significant recovery in the pyroelectric coefficient on Si is expected for lower growth temperatures due to the reduction of thermal stresses.