Infrared absorption in a multilayer bolometric structure with a thin metallic absorber

This paper presents relationships that make it possible to use the matrix method to calculate the reflectance, transmittance, and absorptance in a bolometric structure consisting of an arbitrary number of layers that include a metallic absorber and reflector. Analytic relationships are obtained that can be applied to actual bolometers—for example, fabricated on the basis of amorphous silicon, in which, besides a thin metallic absorber and reflector, there are two insulating layers (a high-resistance heat-sensitive layer and a thermally insulating layer). The relationships make it possible to take into account the imaginary component of the conduction of the metal layers and the gradual falloff of the radiation. This analysis, in particular, showed that taking into account an electron-relaxation time in the absorber equal to or greater than 10−14  s significantly alters not only the parameters of the bolometric structure but also the radiation frequency at which there is virtually complete absorption of the radiation.