Enhanced Contrast of Wavelength-Selective Mid-Infrared Detectors Stable against Incident Angle and Temperature Changes

概要

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A thermal infrared detector with enhanced contrast of its wavelength-selective function has been fabricated. A $2 \times 2$-mm2-size detector with p++-Si--Pt thermopiles on a Si substrate is the base device. A polymer material is deposited on the hot junctions of the thermopiles, working as a wavelength-selective absorber to integrate spectroscopic function into the thermopile detector. The polymer used is polyacrylonitrile (PAN), with a sharp isolated absorption peak at a wavelength of 4455 nm; the detector shows +35% output increase from the baseline at this wavelength. Very little dependence of the center wavelength (CWL) on the incident angle has been confirmed. Temperature dependencies were measured over the range from 20 to 80 °C. The detector shows a smaller CWL shift, which is ${\sim}1/20$ of that of the conventional detector using an optical bandpass filter with a dielectric multilayer on a Si substrate. These features are suitable for miniaturizing the sensor module including the optical setups.
2011-03-25