Recent advances in the modelling of the thermal conductance of uncooled microbolometers

Schoeman, Johan P.; Plessis, Monuko du

doi:10.1117/12.2245720

Cited by 1 publication

(1 citation statement)

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“…In most cases, the strut only consists of (i) a low-stress oxide or nitride film acting as the support for the detector structure and (ii) a conductor to electrically contact the thermally sensitive material as shown in Figure . For recently demonstrated microbolometers, the struts commonly have thicknesses on the order of 100s of nm, widths on the order of 1s of μm, and lengths in the 10s of μm, resulting in ∼10 –6 to 10 –8 [W·K –1 ] strut conductances. − Other than improved fabrication techniques and design, there is little that can be done to reduce the thermal conductance of the strut other than reducing the mechanical stress via reduction in the mass of the suspended detector. This reduction, from integrating a nanophotonic absorber for instance, would allow for the struts to be thinner and longer and thus reducing the thermal conductance and improving the specific detectivity.…”

Section: Simple Thermodynamic Model For Thermal Detectorsmentioning

confidence: 99%

Nanophotonic Engineering: A New Paradigm for Spectrally Sensitive Thermal Photodetectors

2020

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Thermal photodetectors rely on thermally sensitive materials to convert the heat generated from incoming light to an electrical signal and are used in, for example, focal plane arrays and for room-temperature, high-photon-flux applications. However, the theory for thermal detectors was initially developed before nanophotonic engineering and, thus, typically assume the integrated absorbers are blackened or have a flat spectral response. Here we discuss recent developments in nanophotonics and metamaterials that have allowed for the creation of spectrally selective absorbers capable of suppressing undesired thermal emission and increasing the potential sensitivity of thermal photodetectors. Furthermore, the subwavelength features of nanophotonic or metamaterial absorbers decrease the amount of material required for absorption, which reduces the detector's thermal capacitance while increasing its response time and sensitivity. The ideal thermal and noise dynamics are derived for both spectrally selective and unselective thermal detectors, revealing exciting opportunities for future thermal photodetectors with increased sensitivities and response times and decreased noise floors.

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