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Proceedings Paper

Fabrication and testing of MEMS-based optical filter combined with a HgCdTe detector
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Paper Abstract

The Mid-wave infrared (MWIR) spectrum has applications to many fields, from night vision to chemical and biological sensors. Existing broadband detector technology based on HgCdTe allows for high sensitivity and wide range, but lacks the spectral decomposition necessary for many applications. Combining this detector technology with a tunable optical filter has been sought after, but few commercial realizations have been developed. MEMS-based optical filters have been identified as promising for their small size, light-weight, scalability and robustness of operation. In particular, Fabry-Perot interferometers with dielectric Bragg stacks used as reflective surfaces have been investigated. The integration of a detector and a filter in a device that would be compact, light-weight, inexpensive to produce and scaled for the entire range of applications could provide spectrally resolved detection in the MWIR for multiple instruments. We present a fabrication method for the optical components of such a filter. The emphasis was placed on wafer-scale fabrication with IC-compatible methods. Single, double and triple Bragg stacks composed of germanium and silicon oxide quarter-wavelength layers were designed for MWIR devices centered around 4 microns and have been fabricated on Silicon-On-Insulator (SOI) wafers, with and without anti-reflective half-wavelength silicon nitride layers. Optical testing in the MWIR and comparison of these measurements to theory and simulations are presented. The effect of film stress induced by deposition of these dielectric layers on the mechanical performance of the device is investigated. An optimal SOI substrate for the mechanical performance is determined. The fabrication flow for the optical MEMS component is also determined. Part of this work investigates device geometry and fabrication methods for scalable integration with HgCdTe detector and IC circuitry.

Paper Details

Date Published: 14 February 2011
PDF: 10 pages
Proc. SPIE 7930, MOEMS and Miniaturized Systems X, 79300L (14 February 2011); doi: 10.1117/12.874345
Show Author Affiliations
Dmitry A. Kozak, Univ. of California, Santa Cruz (United States)
EPIR Technologies, Inc. (United States)
Bautista Fernandez, Univ. of California, Santa Cruz (United States)
Michael L. Morley, EPIR Technologies, Inc. (United States)
Silviu Velicu, EPIR Technologies, Inc. (United States)
Joel Kubby, Univ. of California, Santa Cruz (United States)

Published in SPIE Proceedings Vol. 7930:
MOEMS and Miniaturized Systems X
Harald Schenk; Wibool Piyawattanametha, Editor(s)

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