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Proceedings Paper

Encapsulated thermopile detector array for IR microspectrometer
Author(s): Huaiwen Wu; Arvin Emadi; Ger de Graaf; Reinoud F. Wolffenbuttel
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Paper Abstract

The miniaturized IR spectrometer discussed in this paper is comprised of: slit, planar imaging diffraction grating and Thermo-Electric (TE) detector array, which is fabricated using CMOS compatible MEMS technology. The resolving power is maximized by spacing the TE elements at an as narrow as possible pitch, which is limited by processing constraints. The large aspect ratio of the TE elements implies a large cross-sectional area between adjacent elements within the array and results in a relatively large lateral heat exchange between micromachined elements by thermal diffusion. This thermal cross-talk is about 10% in case of a gap spacing of 10 μm between elements. Therefore, the detector array should be packaged (and operated) in vacuum in order to reduce the cross-talk due to the air conduction through the gap. Thin film packaging is a solution to achieve an operating air pressure at1.3 mBar, which reduces the cross-talk to 0.4%. An absorber based on an optical interference filter design is also designed and fabricated as an IC compatible post-process on top the detector array. The combination of the use of CMOS compatible materials and processing with high absorbance in 1.5 - 5 μm wavelength range makes a complete on-chip microspectrometer possible.

Paper Details

Date Published: 27 April 2010
PDF: 9 pages
Proc. SPIE 7680, Next-Generation Spectroscopic Technologies III, 76800Z (27 April 2010); doi: 10.1117/12.849994
Show Author Affiliations
Huaiwen Wu, Delft Univ. of Technology (Netherlands)
Arvin Emadi, Delft Univ. of Technology (Netherlands)
Ger de Graaf, Delft Univ. of Technology (Netherlands)
Reinoud F. Wolffenbuttel, Delft Univ. of Technology (Netherlands)

Published in SPIE Proceedings Vol. 7680:
Next-Generation Spectroscopic Technologies III
Mark A. Druy; Christopher D. Brown; Richard A. Crocombe, Editor(s)

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