Optimizing the Absorption Capability of a microbolometer Pixel's Active Element

A new approach for efficient detection of a wide frequency spectrum of radiation is proposed. A double-layered absorber consisting of a 32 nm thick aluminum (Al) thin film, located on a glass medium (SiO2) of 1 mm thickness, was fabricated and used to design a fine-tuned absorber through a theoretical and finite element modeling process. After optimization processing, the results indicated that the proposed low-cost, double-layered absorber can be tuned based on the metal layer sheet resistance and the thickness of various poly-si media taking advantage of the diversity of the absorption of the metal films in the THz domain (6 to 10 THz). It was found that the composite high TCR absorber could absorb up to 96% (a percentage far exceeding the 50% and previously shown to be the highest achievable when using single thin metal layer) and reflect less than 1% of the incident THz illumination. This approach is making the proposed double-layered absorber a good candidate for a microbolometer pixel's active element.