铁电薄膜在红外辐射作用下响应的解析解

Analytical Solution for Responses of a Ferroelectric Thin Film under Infrared Radiation

本文研究了红外探测器中红外焦平面列阵的象元———铁电薄膜微桥在红外辐射作用下的输出信号。采用层合板作为力学模型,将铁电薄膜微桥结构简化为一块边长为微米量级、厚度为亚微米量级的夹层板,中间是铁电薄膜,上下表面为金属薄膜,上表面为金黑,下表面为铂(白金),上下表面都是电极。微桥的上表面接收周期为1/30秒的辐射方波脉冲信号。由于微桥十分微小,可以认为红外辐射在板面上均匀分布,又由于板的平面尺寸与厚度之比相当大,因此可以认为热传导只在板厚的方向进行,问题变为一维的。采用适当的力-电-热耦合的控制方程,利用级数解,算出铁电薄膜微桥在红外辐射作用下的力学响应和薄膜内的力、热、电输出信号,并对结果作了分析比较。

The response of a microbolometer pixel structure-the essential component part in an infrared focal planar array of an infrared detector-to an infrared radiation was analyzed, The pixel structure was modeled as a composite laminate thin plate and it was simplified as a sandwich plate whose sides were measured with μm dimension and the thickness of ply was measured with sub-μm dimension, its middle ply is a PZT ferroelectric thin film. Its top surface-the infrared absorber-is covered with gold, while the bottom surface is deposited with reflection metal-platinum. Meanwhile both surfaces are a pair of electrodes, The top surface received infrared radiation pulse whose period was 1/30s, The pulse was supposed square-wave, Because the microbolometer pixel was tiny, the infrared radiation was Considered to be distributed uniformly on the plate. Furthermore. as the ratio of plane dimension to the thickness was dramatically large, we can view the heat to transfer only along the thickness. Therefore, the problem became one-dimensional. The thermal electric mechanical coupling governing equations were solved in a form of Fourier series. Results of the displacement, temperature change and electric output signals of the microbolometer pixel structure under infrared radiation were obtained and analyzed.