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Simulation results of prospective next generation 3D thermopile sensor and array circuitry options

 
: Verheyen, Erik; Erbslöh, Andreas; Viga, Reinhard; Vogt, Holger

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IEEE sensors letters 2 (2018), No.2, Art. 2500604, 4 pp.
ISSN: 2475-1472
English
Journal Article
Fraunhofer IMS ()
Thermopiles; 3D-Integration; thermoelectric; IR detection; tuneable temperature detection

Abstract
This work presents the simulation results and design rules of a new sensor for IR-detection using the thermoelectric effect. Within the Seebeck-effect, thermopiles generate a voltage based on a temperature gradient inside the structure. State of the art thermopiles are manufactured as two-dimensional structures directly on a substrate. Here, a possible method of 3D integration is shown, where the thermoelectric materials are fabricated as thin tubes using an atomic layer deposition (ALD) process. These tubes are connected to an IR-absorber on top, where the IR-radiation causes a temperature gradient relative to the substrate. This has the advantages to achieve a fill factor of nearly 100%. In comparison to microbolometers, the 3D thermopile is a passive structure, which does not need complex readout and supply circuits. Furthermore, the usage of energy harvesting is possible. Additionally, new array circuitry options are discussed to achieve a better signal-to-noise ratio. An electrical series connection of multiple sensors effects a rising specific detectivity and the noise equivalent temperature difference (NETD) decreases analogously. With this technique, groups of pixels of the detector can be merged to one "super-pixel" for detecting even marginal temperature changes of an object.

: http://publica.fraunhofer.de/documents/N-491578.html