EFFECT OF THERMAL LOSSES ON THE SPECIFIC DETECTIVITY OF PYROELECTRIC INFRARED DETECTORS

ABSTRACT

From the experimental data of specific detectivity (D*) of an infrared detector of ferroelectric thin film of (Pb,Ca)TiO₃, a pyroelectric detector model has been modified and validated by the development with a Orcad-PSpice tool. In this model the thermal losses through the substrate are included. Comparing the experimental data of D* with the results of the simulation an expression for the thermal losses through the substrate G _cond , is obtained in function of the thickness of the substrate.

On the other hand, a theoretic expression for the specific detectivity, D*, is obtained in analytical form where its dependency on the losses through the substrate is reflected. Substituting the expression obtained for G _cond in the theoretic expression D*, a new figure of merit is obtained which as well as taking into account intrinsic properties of the material, depends on the thickness of the substrate.

With this new figure of merit, the different pyroelectric materials which integrated infrared detectors are made, can be compared.

keywords:

• Pyroelectric infrared detector
• new figure of merit
• thermal conductivity
• integrated detectors