Un-Cooled Microbolometers with Amorphous Germanium-Silicon (a-GexSiy:H) Thermo-Sensing Films

Silicon integrated circuits (IC) in conjunction with the micro-machining technology for thin films, have opened new ways for the development of low cost and reliable night vision systems based on thermal detectors. Among the thermal detectors used as pixels on IR focal plane arrays, the microbolometer appears as one of them. A microbolometer is a device in which the IR transduction is performed through a change in the resistivity of its thermosensing material, due to the heating effect caused by the absorbed radiation. Among the requirements for the materials used as thermo-sensing layer in microbolometers it can be mentioned a high activation energy (Ea), high temperature coefficient of resistance (TCR), low noise, and compatibility with standard CMOS fabrication processes. A variety of materials have been used as thermo-sensing elements in microbolometers, as vanadium oxide (VOx) (B. E. Cole, 1998, 2000), metals (A. Tanaka, 1996), polycrystalline (S. Sedky, 1998) and amorphous semiconductors (A. J. Syllaios, 2000).

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