IR bolometers made of polycrystalline silicon germanium下载

This paper reports an uncooled microbolometer infrared detector with polycrystalline silicon–germanium thermistor as the active element. Polycrystalline silicon–germanium (poly-SiGe) films are deposited by ultrahigh vacuum vapor deposition (UHV/CVD) and their structural properties are characterized by Rutherford backscattering spectrometry (RBS),SEMand Raman spectrum. The dependency of the temperature coefficient of resistance on operating temperature and on annealing temperature has been investigated. The complete fabrication of the microbolometer is described. To decrease the thermal conductance of the microbolometer, a poly-SiGe thermistor is formed on a two/four leg suspended microbridge with bulk silicon anisotropic etching and induced couple plasma (ICP) technique. Measurements and calculations show that at a bias voltage of 5V, the maximum detectivity of 8.3 × 108 cm Hz1/2/W is achieved at 15Hz with a thermal response time of 16.6 ms. At a chopper frequency of 30Hz, the maximum detectivity of 7.48 × 108 cm Hz1/2/W and approximately 86% of the maximum responsivity are reached at 12.5V, respectively.