Thermoelectric photosensor based on ultrathin single-crystalline Si films
Gonçalves Dalkiranis Pereira, Gustavo (Universitat Autònoma de Barcelona. Departament de Física)
Ferrando-Villalba, Pablo (Universitat Autònoma de Barcelona. Departament de Física)
Lopeandía Fernández, Aitor (Universitat Autònoma de Barcelona. Departament de Física)
Abad, Llibertat (Centro Nacional de Microelectrónica)
Rodríguez-Viejo, Javier (Universitat Autònoma de Barcelona. Departament de Física)

Data:	2019
Resum:	Ultrathin Si films have a reduced thermal conductivity in comparison to Si bulk due to phonon scattering at the surfaces. Furthermore, the small thickness guarantees a reduced thermal mass (in the µJ/K range), which opens up the possibility of developing thermal sensors with a high sensitivity. Based on these premises, a thermoelectric (TE) microsensor based on ultrathin suspended Si films was developed and used as a thermal photosensor. The photoresponse of the device was evaluated with an argon laser (λ = 457 nm) with a variable power ranging from 0 to 10 mW in air at atmospheric pressure, with laser diodes at 406 nm, 520 nm and 638 nm wavelengths, and fixed powers in high vacuum conditions. The responsivity per unit area, response time (τ) and detectivity (D*) of the device were determined in air at ambient pressure, being 2. 6 × 10⁷ V/Wm², ~4. 3 ms and 2. 86 × 10 7 c m H z (1 / 2) W - 1, respectively. Temperature differences up to 30 K between the central hot region and the Si frame were achieved during open-circuit voltage measurements, with and without laser diodes. During illumination, the photogeneration of carriers caused a slight reduction of the Seebeck coefficient, which did not significantly change the sensitivity of the device. Moreover, the measurements performed with light beam chopped at different frequencies evidenced the quick response of the device. The temperature gradients applied to the thermoelectric Si legs were corrected using finite element modeling (FEM) due to the non-flat temperature profile generated during the experiments.
Ajuts:	Ministerio de Economía y Competitividad FIS2013-50304-EXP Ministerio de Economía y Competitividad MAT2016-79579-R Ministerio de Economía y Competitividad TEC2015-67462-C2-1-R Ministerio de Economía y Competitividad RyC-2013-12640
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Photosensor ; Thermoelectric effect ; Microsensor
Publicat a:	Sensors (Basel, Switzerland), Vol. 19, Issue 6 (March 2019) , art. 1427, ISSN 1424-8220

DOI: 10.3390/s19061427
PMID: 30909519

8 p, 1.8 MB

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