An uncooled microbolometer infrared detector based on poly-SiGe thermistor

摘要

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), SEM and 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 5 V, the maximum detectivity of 8.3 x 10(8) cm Hz(1/2)/W is achieved at 15 Hz with a thermal response time of 16.6 ms. At a chopper frequency of 30 Hz, the maximum detectivity of 7.48 x 10(8) cm Hz(1/2)/W and approximately 86% of the maximum responsivity are reached at 12.5 V, respectively. (C) 2003 Elsevier B.V. All rights reserved. [References: 15]