Effective Area Formulation for Thermal Detector Characterization

• Published in: Journal of microelectromechanical systems Vol. 23; no. 3; pp. 549 - 554
• Main Authors: Gawarikar, Anand S., Shea, Ryan P., Talghader, Joseph J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorption; Applied sciences; Area measurement; Bolometer; infrared, submillimeter wave, microwave and radiowave receivers and detectors; bolometers; Detectors; Electronics; Equations; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Imaging and optical processing; Infrared detectors; Infrared, submillimeter wave, microwave and radiowave instruments, equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Legged locomotion; Mathematical model; Mechanical instruments, equipment and techniques; Micro- and nanoelectromechanical devices (mems/nems); Micromechanical devices and systems; Optics; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Sensors; Spacecraft; Thermal conductivity; Infrared detectors; bolometers; Under vacuum; Thermal detector; Measurement sensor; Experimental study; Response functions; Imagery; Thermoelectric properties; Thermoelectric effect; Flood; Modelling; Microelectromechanical device
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2013.2291814

We have derived an expression for the effective absorbing area for thermal infrared detectors having non-zero absorption in the support legs, which is different from the geometric areas of the constituent detector elements. This technique is particularly applicable to devices where sensitivity is more important than fill-factor, as opposed to standard imaging arrays. The effective area can simply be substituted in standard equations to obtain a good estimate of the detector performance under uniform flood illumination conditions. The formalism can also be used for estimating the contributions of the individual signal generating elements to the total measured signal. This approximation has been tested for MEMS infrared detectors with thermoelectric readout operating under vacuum. The responsivity of the same device calculated using the effective area approximation and measured using a tightly constrained absorbing area are found to match very closely, within 5% over the most wavelengths and within 15% at the shortest thermal infrared wavelengths.